7Baggers

White Mountains Insurance Group, Ltd
(NYSE:WTM) 

WTM stock logo

White Mountains Insurance Group, Ltd., through its subsidiaries, provides insurance services in the United States. The company operates through four segments: HG Global/BAM, NSM, Kudu, and Other Operations. The HG Global/BAM segment provides insurance on municipal bonds issued to finance public purp...

Founded: 1980
Full Time Employees: 1,262
Sector: Financial Services
Industry: Insurance-Property & Casualty

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Moat:
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Quarterly
Annual
    Unit: USD2026-03-31 2025-12-31 2025-03-31 2024-12-31 2024-09-30 2024-06-30 2024-03-31 2023-12-31 2023-09-30 2023-06-30 2023-03-31 2022-12-31 2022-09-30 2022-06-30 2022-03-31 2021-12-31 2021-09-30 2021-03-31 2020-12-31 2020-09-30 2020-06-30 2019-12-31 2019-09-30 2019-06-30 2019-03-31 2018-12-31 2018-09-30 2018-06-30 2018-03-31 2017-12-31 2017-09-30 2017-06-30 2017-03-31 2016-12-31 2016-09-30 2016-06-30 2016-03-31 2015-12-31 2015-09-30 2015-06-30 2015-03-31 2014-09-30 2014-06-30 2014-03-31 2013-12-31 2013-09-30 2013-06-30 2013-03-31 2012-12-31 2012-09-30 2012-06-30 2012-03-31 2011-12-31 2011-09-30 2011-06-30 2011-03-31 2010-12-31 2010-09-30 2010-06-30 2010-03-31 2009-12-31 2009-09-30 2009-06-30 2009-03-31 2008-09-30 2006-12-31 2006-09-30 2006-06-30 2006-03-31 2005-12-31 2005-09-30 2005-06-30 2003-12-31 
                                                                             
      expenses:
                                                                             
      p&c insurance and reinsurance
                                                                             
      loss and loss adjustment expenses
    206,700,000  233,500,000 211,800,000 288,300,000 175,700,000 180,000,000 145,700,000 265,800,000 167,500,000 147,800,000 80,200,000 213,700,000 120,500,000 122,000,000 67,000,000 129,200,000 66,000,000               151,700,000 155,900,000 165,000,000 182,000,000 161,100,000 174,800,000 170,000,000 288,300,000 265,400,000 289,100,000 282,700,000 229,300,000 243,300,000 278,300,000 274,600,000 244,300,000 372,200,000 308,100,000 265,000,000 262,700,000 292,900,000 277,100,000 292,400,000 526,500,000 384,100,000 426,100,000 554,600,000 703,200,000 502,900,000 544,100,000 528,900,000 543,200,000 697,600,000 566,800,000 558,100,000 763,800,000 564,000,000 739,100,000 929,600,000 570,200,000  
      acquisition expenses
    98,800,000  83,500,000 76,300,000 96,300,000 68,200,000 66,300,000 2,300,000 2,100,000 1,500,000 2,700,000                                                               
      general and administrative expenses
    47,500,000  35,900,000 54,400,000 68,900,000 42,900,000 42,200,000 19,200,000 17,500,000 14,900,000 17,300,000 19,600,000 15,800,000 17,400,000 16,300,000 14,400,000 12,400,000 16,400,000 15,300,000 13,900,000 12,500,000 11,400,000 12,500,000 12,300,000 14,400,000 11,500,000 11,300,000 13,400,000 11,800,000 -119,300,000 44,100,000 57,500,000 94,200,000 69,500,000 70,200,000 73,100,000 140,500,000 133,400,000 142,600,000 108,100,000 116,400,000 69,300,000 70,300,000 50,300,000 55,800,000 41,500,000 40,200,000 43,800,000 35,900,000 58,700,000 42,100,000 45,500,000 54,900,000 36,200,000 56,200,000 40,500,000 36,600,000 48,100,000 68,500,000 50,500,000 75,200,000 75,100,000 56,800,000 55,900,000 65,300,000 92,800,000 55,800,000 22,200,000 47,500,000 18,100,000 39,500,000 61,500,000  
      change in fair value of contingent consideration
    10,000,000  9,700,000 13,800,000 34,200,000 13,300,000  31,900,000 17,000,000 2,200,000 -2,400,000    100,000 200,000 600,000                                                         
      interest expense
    4,100,000  4,200,000 4,500,000 4,900,000 4,700,000 5,400,000 5,700,000 3,800,000 2,500,000 4,500,000 2,900,000 2,000,000 3,400,000 3,800,000 2,800,000 2,100,000 1,100,000 6,000,000 6,100,000 5,700,000 4,500,000 4,400,000 4,100,000 3,700,000 3,200,000 3,200,000 1,600,000 400,000 -800,000 900,000 500,000 3,700,000 3,100,000 3,800,000 4,100,000 5,900,000 3,375,000 4,900,000 10,900,000 11,100,000 10,300,000 10,000,000 10,100,000                              
      total p&c insurance and reinsurance expenses
    367,100,000  366,800,000 360,800,000 492,600,000 304,800,000 293,900,000 309,700,000 414,000,000 271,200,000 245,400,000 192,900,000 319,100,000 203,600,000 198,800,000 154,500,000 206,800,000 141,600,000                                                        
      asset management
                                                                             
      total asset management expenses
    11,300,000  10,400,000 10,300,000 9,300,000 8,900,000 9,000,000 12,800,000 10,000,000 9,300,000 8,500,000 9,000,000 8,700,000 6,400,000 5,600,000 8,100,000 5,200,000 8,400,000 6,000,000 3,700,000 4,400,000                                                     
      financial guarantee
                                                                             
      total financial guarantee expenses
    6,400,000  7,100,000 6,100,000 8,000,000 23,500,000 23,000,000 27,200,000 23,400,000 18,900,000 24,500,000 24,200,000 19,500,000 25,600,000 19,300,000 16,200,000 15,400,000 18,300,000 17,000,000 15,600,000 14,800,000 13,100,000 14,000,000 13,800,000 15,700,000 13,000,000 12,600,000 14,800,000 13,300,000                                             
      specialty insurance distribution
                                                                             
      broker commission expenses
    17,200,000  15,500,000 13,400,000 15,900,000 12,700,000 9,300,000        20,600,000 15,225,000 20,400,000 18,900,000 14,100,000 17,100,000 21,000,000                                                     
      total specialty insurance distribution expenses
    57,900,000              85,900,000 83,300,000 83,900,000 108,100,000 79,600,000 71,900,000 79,800,000 63,600,000 55,400,000 65,400,000 50,800,000 41,600,000 44,900,000 20,300,000                                              
      p&c insurance distribution
                                                                             
      total p&c insurance distribution expenses
      55,100,000 41,100,000 40,200,000 35,600,000 30,200,000                                                                   
      other operations
                                                                             
      cost of sales
    42,700,000  7,500,000 7,400,000 7,600,000 7,000,000 7,600,000 6,900,000 8,000,000 11,600,000 13,900,000 29,800,000 25,000,000 22,400,000 21,400,000 11,475,000 24,000,000 4,000,000       40,600,000 65,900,000 61,800,000 59,900,000 57,400,000 47,200,000 33,100,000 26,800,000                                          
      total other operations expenses
    100,600,000  66,000,000 60,400,000 49,500,000 57,300,000 58,600,000 59,300,000 51,100,000 61,600,000 54,400,000 82,500,000 66,900,000 73,700,000 51,500,000 51,200,000 40,900,000 40,500,000 60,900,000 47,100,000 27,900,000 38,600,000 30,300,000 31,800,000 30,500,000                                                 
      total expenses
    543,300,000  505,400,000 478,700,000 599,600,000 430,100,000 414,700,000 409,000,000 498,500,000 361,000,000 332,800,000 308,600,000 414,200,000 309,300,000 361,100,000 313,300,000 352,200,000 316,900,000 163,500,000 138,300,000 126,900,000 118,800,000 104,400,000 113,200,000 151,900,000 150,100,000 154,400,000 134,700,000 108,100,000 108,800,000 79,100,000 85,800,000 348,000,000 335,000,000 345,000,000 360,300,000 415,600,000 420,400,000 429,300,000 593,300,000 570,000,000 555,000,000 543,800,000 466,200,000 492,400,000 518,800,000 485,700,000 475,600,000 617,200,000 562,300,000 505,700,000 502,300,000 535,600,000 500,100,000 536,700,000 814,900,000 691,200,000 737,200,000 921,300,000 1,070,900,000 906,500,000 944,400,000 915,100,000 918,100,000 1,098,500,000 1,030,900,000 960,400,000 1,129,200,000 943,900,000 1,050,300,000 1,308,400,000 977,800,000  
      pre-tax income
    -25,500,000  72,400,000 109,350,000 239,500,000 -34,700,000 232,600,000                                                  85,900,000 84,300,000 7,100,000  153,500,000 258,300,000 303,800,000 48,400,000  318,400,000 225,800,000 71,700,000 113,900,000 7,800,000    
      income tax benefit
    -800,000  -9,600,000 -3,700,000 -11,600,000 -6,500,000 -10,800,000 34,900,000 -7,300,000 -200,000 -11,900,000 -67,500,000 7,400,000 16,000,000 3,800,000   9,500,000   -24,100,000 -10,400,000 -8,800,000 100,000  3,600,000 3,600,000 -2,500,000 -700,000 2,500,000 4,000,000 1,000,000 -3,900,000 23,000,000 6,700,000 6,000,000 8,700,000 1,500,000 1,600,000 2,700,000   -23,900,000    600,000  101,000,000 -47,800,000    600,000  9,000,000   800,000 200,000     150,800,000   29,300,000   55,600,000   
      net income
    -26,300,000  62,800,000 -124,400,000 227,900,000 -41,200,000 221,800,000 362,700,000 13,800,000 17,200,000 187,200,000 61,500,000 869,500,000 -210,200,000 -8,400,000 40,000,000 -383,900,000 -110,500,000 473,400,000 222,000,000 107,600,000 45,300,000 43,200,000 15,900,000 272,200,000 -140,500,000 30,600,000 -14,900,000 -66,600,000 12,000,000 551,500,000 3,400,000 33,000,000 -50,600,000 88,600,000 362,500,000 19,300,000 274,000,000 -74,900,000 3,400,000 77,000,000 40,300,000 100,200,000 95,100,000 118,200,000 56,100,000 15,200,000 119,900,000 56,200,000 -11,800,000 38,200,000 110,600,000   32,500,000  89,500,000 75,000,000 13,200,000       299,300,000 162,100,000 115,800,000 96,000,000 33,300,000  146,800,000  
      yoy
    -111.54%  -71.69% -134.30% 1551.45% -339.53% 18.48% 489.76% -98.41% -108.18% -2328.57% 53.75% -326.49% 90.23% -101.77% -81.98% -456.78% -343.93% 995.83% 1296.23% -60.47% -132.24% 41.18% -206.71% -508.71% -1270.83% -94.45% -538.24% -301.82% -123.72% 522.46% -99.06% 70.98% -118.47% -218.29% 10561.76% -74.94% 579.90% -174.75% -96.42% -34.86% -28.16% 559.21% -20.68% 110.32% -575.42% -60.21% 8.41%   17.54%    146.21%           798.80%  -21.12%      
      qoq
      -150.48% -154.59% -653.16% -118.58% -38.85% 2528.26% -19.77% -90.81% 204.39% -92.93% -513.65% 2402.38% -121.00% -110.42% 247.42% -123.34% 113.24% 106.32% 137.53% 4.86% 171.70% -94.16% -293.74% -559.15% -305.37% -77.63% -655.00% -97.82% 16120.59% -89.70% -165.22% -157.11% -75.56% 1778.24% -92.96% -465.82% -2302.94% -95.58% 91.07% -59.78% 5.36% -19.54% 110.70% 269.08% -87.32% 113.35% -576.27% -130.89% -65.46%      19.33% 468.18%        84.64% 39.98% 20.63% 188.29%     
      net income margin %
    -Infinity% NaN% Infinity% -Infinity% Infinity% -Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% -Infinity% -Infinity% Infinity% -Infinity% -Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% 12.33% 62.78% -2341.67% 15.40% -12.18% -158.19% 10.53% 630.29% 3.98% 8.55% -18.87% 24.27% 101.20% 4.52% 40.38% -22.38% 0.58% 11.72% 6.84% 15.35% 16.44% 18.86% 9.77% 3.11% 19.11% 9.92% -1.69% 7.02% 17.54% 0% 0% 5.69% 0% 11.52% 9.13% 1.42% 0% 0% 0% 0% 0% 0% 22.18% 13.67% 9.64% 9.08% 3.15% 0% 12.54%  
      net loss attributable to noncontrolling interests
    -900,000  -28,900,000 -6,000,000 -48,900,000  14,600,000 -76,200,000 9,800,000 2,400,000 -7,700,000                                                               
      net income attributable to white mountains’s common shareholders
    -27,200,000  33,900,000 -130,400,000 179,000,000 -54,600,000 236,400,000 286,500,000 23,600,000 19,600,000 179,500,000 40,400,000 888,200,000 -169,200,000 33,400,000 32,800,000 -371,400,000  489,200,000 232,900,000 115,400,000 60,900,000 48,700,000 20,500,000 284,400,000 -137,500,000 40,800,000 3,500,000 -48,000,000 22,500,000 562,100,000 15,500,000 34,300,000 -33,300,000 91,700,000 341,100,000 13,000,000 267,900,000 -58,900,000 4,300,000 84,300,000 51,500,000 95,600,000 95,600,000                              
      millions, except per share amounts
    2,026                                                                         
      other comprehensive income, net of tax
     -1,100,000.1 1,300,000  -300,000 -899,997.6 -1,700,000 1,400,000 1,200,000 2,999,996.2 -1,400,000 -1,100,000    1,800,000                                                        
      comprehensive income
    -26.2  35.9 -361,899,769.7 180,300,000  236,100,000 -223,599,488.4 21,900,000 21,000,000 180,700,000 -747,099,213.3 890,400,000 -174,300,000                152,025,000 565,100,000 16,300,000  -33,300,000 91,900,000 449,200,000 50,300,000 258,700,000 -73,800,000 -13,300,000 25,600,000 -22,700,000  124,300,000 116,100,000 96,600,000 -74,300,000 108,700,000 70,000,000 91,000,000 24,500,000 116,100,000 663,800,000  28,300,000 33,800,000 30,200,000 220,700,000                
      other comprehensive loss attributable to noncontrolling interests
    -0.4  -0.8 -125,000 -500,000  100,000 99,999.5 700,000 -400,000 -400,000                                                               
      comprehensive income attributable to white mountains’s common shareholders
    -26.6  35.1 -361,399,769.7 179,800,000  236,200,000 -223,499,488.9 22,600,000 20,600,000 180,300,000 -747,499,212.4 890,100,000 -173,800,000                152,000,000 565,100,000 16,200,000 35,200,000 -33,700,000 92,000,000 449,200,000 50,300,000 258,800,000 -73,900,000 -13,300,000 25,600,000 -22,600,000 100,600,000 124,300,000                              
      millions, except for per share amounts
      2,025                                                                       
      millions
       506,000,000 2,024,000,000  2,024,000,000 505,750,000 2,023,000,000 2,023,000,000 2,023,000,000 505,500,000 2,022,000,000 2,022,000,000    2,021,000,000      2,019,000,000                                                  
      earnings per share attributable to white mountains’s common shareholders:
                                                                             
      basic earnings per share
       35.165 69.68                                                    0.393 6.01 0.28 -4.48 10.463 18.02 20.35 3.44 -26.55 8.68 15.05 10.75 8.92     
      diluted earnings per share
       35.165 69.68                                                    0.393 6.01 0.28  10.46 18.02 20.35 3.44  8.653 15.01 10.72 8.89     
      dividends declared and paid per white mountains’s common share
       0.25   0.25   0.25                                                             
      net (income) loss attributable to noncontrolling interests
         -13,400,000                                           500,000 30,900,000                        
      other comprehensive income, net of tax:
                                                                             
      continuing operations
          92.33 21.705 9.19 7.65 69.83 -12.683 -1.66 -58.78    -30.33            1.758 5.36 2.78 7.72 -5.14 6.12 -3.44 2.51 44.2 -12.42 0.76 12.77 7.35 15.1 15.56 19.1 9.2 3.62 19.1 10.45 19.11 3.92 12.59 15.99 1.81 1.51                   
      discontinued operations
               76.243 308.59 1.98    6.03            32.008 125.45 0.61 -0.22 1.11 12.72 70.37 -0.17 1.43 2.41 -0.04 1.32 1.1 0.43 -0.08 -0.04 0.06 0.64 0.07 -0.14 -16.21  0.02                      
      total consolidated operations
          92.33 21.705 9.19 7.65 69.83 63.56 306.93 -56.8    -24.3            33.765 130.81 3.39 7.5 -4.03 18.84 66.93 2.34 45.63 -10.01 0.72 14.09 8.45 15.53 15.48 19.06 9.26 4.26 19.17 10.31 2.9 3.92 12.61                      
      pre-tax income from continuing operations
           327,800,000 21,100,000 17,400,000 199,100,000 129,000,000 -31,000,000 -232,600,000 -12,200,000 36,700,000 -362,300,000  357,300,000 321,200,000 132,700,000 56,500,000 51,100,000 15,800,000 281,700,000 -144,100,000 44,300,000 -12,400,000 -66,000,000 5,200,000 8,400,000 -400,000 37,900,000 -66,800,000 20,000,000 -2,100,000 11,500,000 -25,800,000 -94,600,000 -5,800,000 86,800,000 34,400,000 109,000,000 112,100,000 52,675,000 55,300,000 3,600,000 151,800,000 78,400,000 135,100,000 38,300,000 128,300,000 900,000 1,200,000 34,400,000                   
      net income from continuing operations
           362,700,000 13,800,000 17,200,000 187,200,000 61,500,000 -23,600,000 -216,600,000 -8,400,000 40,000,000 -383,900,000 -129,200,000 474,900,000 222,700,000 108,600,000 46,100,000 42,300,000 15,900,000 271,500,000 -140,500,000 47,900,000 -14,900,000 -66,700,000 7,700,000 12,400,000 600,000 34,000,000 -43,800,000 26,700,000 3,900,000 20,200,000 259,600,000 -93,000,000 -3,100,000 61,800,000 26,600,000 85,100,000 81,800,000 106,800,000 47,100,000 4,200,000 110,200,000 50,200,000 87,300,000 31,700,000 100,300,000 182,600,000 1,800,000 24,900,000                   
      net income from discontinued operations, net of tax - nsm group
                6,300,000                                                             
      net gain from sale of discontinued operations, net of tax - nsm group
                886,800,000                                                             
      other comprehensive income from discontinued operations, net of tax - nsm group
               5,199,994.8 700,000                                                             
      net gain from foreign currency translation from sale of discontinued operations, net of tax - nsm group
               -2,899,997.1 2,900,000                                                             
      insurance acquisition expenses
               1,700,000 1,700,000 4,800,000 3,000,000 1,800,000 3,000,000 1,900,000 1,600,000 1,600,000 2,100,000 1,600,000 1,400,000 1,400,000 1,300,000 1,400,000 1,200,000 1,300,000 1,400,000 900,000 900,000 900,000 46,600,000 52,400,000 56,400,000 50,100,000 52,700,000 41,525,000 55,300,000                                   
      insurance and reinsurance acquisition expenses
               64,500,000 74,800,000 50,200,000 49,900,000 53,600,000 53,700,000 36,700,000                      105,300,000 95,600,000 105,300,000 98,900,000 95,100,000 95,900,000 106,700,000 76,100,000 98,200,000 104,000,000 107,600,000 108,700,000 108,400,000 103,800,000 107,000,000 100,400,000 140,200,000 149,400,000 153,400,000 183,000,000 185,000,000 182,000,000 181,900,000 179,800,000 182,200,000 190,500,000 192,200,000 189,300,000 187,700,000 185,600,000 188,300,000 199,700,000 184,100,000  
      amortization of other intangible assets
               100,000  100,000 9,100,000 10,200,000 8,200,000 8,600,000 10,500,000 5,100,000 6,300,000 5,900,000 4,400,000 4,100,000 5,000,000 3,300,000 5,000,000 2,500,000 2,900,000                                             
      net gain from sale of discontinued operations, net of tax - sirius group
                                                                             
      net loss attributable to non-controlling interests
               -21,100,000 18,700,000 41,000,000    35,200,000                                                        
      other comprehensive loss attributable to non-controlling interests
               100,000 -300,000 500,000                                                            
      net gain from sale of discontinued operations, net of tax - sirius
                                                                             
      net income from nsm group discontinued operations, net of tax
                 6,400,000                                                            
      other comprehensive income from nsm group discontinued operations, net of tax
                 -4,000,000                                                            
      loss on assets held for sale
                     28,700,000                                                        
      net gain from sale of discontinued operations, net of tax
                         400,000 900,000  700,000 -4,300,000 -17,300,000                                               
      net (income) loss attributable to non-controlling interests
                  41,800,000                     -21,400,000 -6,300,000      -4,600,000                               
      income tax expense
                   -10,475,000 -21,600,000  -24,275,000 -98,500,000     -10,200,000                -25,000,000 -7,800,000  -30,300,000 -12,300,000 -8,200,000  -41,600,000   -6,600,000                       
      net income attributable to non-controlling interests
                   -7,200,000 12,500,000  15,800,000 10,900,000 7,800,000 15,600,000 5,500,000 4,600,000 12,200,000 11,800,000 10,200,000 18,400,000 18,600,000         -6,100,000 16,000,000  7,300,000 11,200,000  500,000 3,175,000 1,100,000                            
      other underwriting expenses
                     11,200,000 100,000 100,000 200,000 100,000 100,000 100,000  100,000 100,000 100,000 100,000 100,000 100,000 100,000 51,800,000 53,500,000 49,600,000 51,000,000 55,400,000 53,100,000 56,500,000 80,700,000 81,500,000 81,000,000 81,900,000 81,400,000 87,300,000 80,400,000 84,500,000 79,100,000 93,400,000 76,600,000 79,000,000 74,800,000 67,600,000 67,000,000 74,800,000 94,600,000 108,000,000 96,400,000 100,500,000 115,900,000 138,500,000 122,700,000 128,700,000 115,400,000 120,400,000 143,900,000 122,800,000 122,800,000 115,900,000 72,700,000 105,700,000 128,300,000  
      change in fair value of contingent consideration earnout liabilities
                      -1,700,000 700,000 -1,700,000 -3,500,000 -2,000,000 6,300,000 1,300,000                                                 
      pre-tax loss from continuing operations
                     -138,700,000                                                        
      net income from sale of discontinued operations, net of tax
                     18,700,000 -200,000 -700,000 -1,000,000                                                     
      net loss attributable to white mountains’s common shareholders
                     -75,300,000                                                        
      comprehensive loss
                     -73,500,000                                                        
      other comprehensive income attributable to non-controlling interests
                     -100,000            -25,000  -100,000  25,000 100,000   -25,000 -100,000                                   
      comprehensive loss attributable to white mountains’s common shareholders
                     -73,600,000                                                        
      marketing technology
                                                                             
      total marketing technology expenses
                            54,900,000 79,200,000 69,800,000 67,300,000 71,900,000                                             
      broker commission expense
                         15,900,000 15,300,000 18,200,000 15,700,000 11,400,000 10,900,000 6,600,000                                              
      global asset and wealth management
                                                                             
      total global asset and wealth management expenses
                         1,725,000 4,700,000 2,200,000                                                  
      revenues:
                                                                             
      earned insurance premiums
                           4,300,000 4,200,000 4,200,000 3,300,000 3,400,000 3,000,000 1,800,000 2,400,000 2,200,000 264,800,000 275,900,000 281,300,000 274,700,000 282,100,000 292,200,000 284,900,000                                   
      net investment income
                           5,400,000 5,300,000 4,200,000 4,800,000 4,000,000 3,700,000 -27,400,000 12,200,000 14,700,000 26,100,000 27,200,000 22,500,000 19,200,000 17,900,000 18,200,000 16,800,000 23,800,000 23,300,000 24,700,000 29,100,000 24,300,000 26,400,000 27,300,000 28,700,000 28,500,000 33,800,000 37,600,000 40,400,000 41,800,000 46,400,000 42,800,000 45,800,000 53,500,000 55,700,000 54,700,000 57,500,000 60,600,000 67,900,000 66,200,000 77,200,000 61,100,000 105,700,000 123,900,000 108,700,000 104,400,000 98,500,000 102,200,000 110,800,000 104,600,000  
      net realized and unrealized investment gains
                           11,500,000 11,800,000 6,900,000 -4,100,000 -2,400,000 -7,900,000 -101,900,000 32,500,000 33,700,000 51,300,000 -73,700,000 26,400,000 28,100,000 29,500,000 259,300,000 -43,900,000 -61,100,000 103,400,000 20,800,000 113,900,000 63,800,000 95,600,000 28,200,000 -37,300,000 75,200,000 -5,000,000 72,700,000 -8,100,000 58,600,000 44,500,000 1,700,000 57,300,000 22,700,000 9,600,000  1,800,000 87,000,000 33,500,000 170,700,000 214,900,000           
      other revenues
                           400,000 600,000 400,000 200,000 400,000 200,000                                             
      total financial guarantee revenues
                           21,600,000 21,900,000 15,700,000 4,200,000 5,400,000 -1,000,000                                             
      commission revenues
                           54,900,000 43,300,000 35,500,000 36,600,000 22,600,000                                              
      total specialty insurance distribution revenues
                           66,100,000 49,300,000 38,400,000 39,700,000 23,500,000                                              
      total global asset and wealth management revenues
                           4,400,000                                                  
      advertising and commission revenues
                            48,800,000 79,100,000 74,500,000   25,975,000 38,800,000 33,200,000                                          
      total marketing technology revenues
                            48,800,000 79,100,000 74,500,000 71,800,000 71,700,000                                             
      realized gain and unrealized investment gain from the mediaalpha transaction
                                                                             
      total other operations revenues
                           36,900,000 313,600,000                                                 
      total revenues
                           129,000,000 433,600,000 6,000,000 198,700,000 122,300,000 42,100,000 114,000,000 87,500,000 85,400,000 385,900,000 268,200,000 365,000,000 358,200,000 427,100,000 678,500,000 334,700,000 587,500,000 656,800,000 589,400,000 652,800,000 578,300,000 626,600,000 574,100,000 489,300,000 627,400,000 566,400,000 697,400,000 544,000,000 630,600,000 593,600,000 501,300,000 571,100,000 782,400,000 777,100,000 821,500,000 928,400,000 1,044,100,000 1,060,000,000 1,202,700,000 1,218,900,000 966,500,000 618,000,000 1,349,300,000 1,186,200,000 1,200,900,000 1,057,800,000 1,058,100,000 1,177,600,000 1,170,900,000  
      yoy
                           5.48% 929.93% -94.74% 127.09% 43.21% -89.09% -57.49% -76.03% -76.16% -9.65% -60.47% 9.05% -39.03% -34.97% 15.12% -48.73% 1.59% 4.82% 2.67% 33.42% -7.83% 10.63% -17.68% -10.06% -0.51% -4.58% 39.12% -4.75% -19.40% -23.61% -38.98% -38.49% -25.06% -26.69% -31.70% -23.83% 8.03% 71.52% -10.86% 2.76% -19.52% -41.58% 27.52% 0.73% 2.56%      
      qoq
                           -70.25% 7126.67% -96.98% 62.47% 190.50% -63.07% 30.29% 2.46% -77.87% 43.89% -26.52% 1.90% -16.13% -37.05% 102.72% -43.03% -10.55% 11.44% -9.71% 12.88% -7.71% 9.14% 17.33% -22.01% 10.77% -18.78% 28.20% -13.73% 6.23% 18.41% -12.22% -27.01% 0.68% -5.40% -11.51% -11.08% -1.50% -11.86% -1.33% 26.11% 56.39% -54.20% 13.75% -1.22% 13.53% -0.03% -10.15% 0.57%   
      realized and unrealized gains from the mediaalpha transaction
                            182,200,000                                                 
      other
                                                                             
      total other revenues
                             -127,200,000 80,300,000 21,600,000 -28,600,000                                             
      general and administrative and other incomes
                             15,400,000 26,000,000                                               
      total other incomes
                             16,300,000 27,100,000 32,300,000 22,900,000                                             
      net income from discontinued operations, net of tax
                                  -15,200,000 3,400,000  -7,400,000 14,000,000 -8,000,000 -900,000 7,300,000 3,900,000 -200,000 -100,000 6,700,000 2,600,000 -500,000 -46,900,000 400,000  500,000 -6,125,000 -15,800,000  100,000                      
      advertising & commission revenues
                               71,800,000 70,100,000                                             
      gain from sale of discontinued operations, net of tax
                                100,000       366,600,000  4,550,000 10,300,000 -100,000 8,000,000                                 
      insurance acquisition expense
                                                                             
      other revenue
                                 1,525,000 1,600,000 1,600,000 43,700,000 38,800,000 34,800,000 36,200,000 97,600,000 108,800,000 76,900,000 87,500,000 35,800,000 5,300,000 6,400,000 -3,400,000 10,600,000 18,200,000 400,000 28,300,000 19,300,000 50,300,000 -500,000 31,200,000    10,700,000 5,900,000 36,600,000 10,000,000 31,800,000 69,900,000 63,800,000 28,500,000 17,300,000 6,300,000 44,900,000 90,800,000 36,500,000 29,800,000 44,800,000 65,500,000 59,600,000  
      gain from sale of other discontinued operations, net of tax
                                 138,175,000 554,300,000 -600,000                                          
      net income (income) attributable to non-controlling interests
                                 10,500,000 10,600,000 12,100,000 1,300,000 -6,150,000 3,100,000     900,000       11,100,000 500,000                          
      comprehensive income, net of tax:
                                                                             
      change in foreign currency translation, net of tax
                                 50,000                                            
      comprehensive income from discontinued operations, net of tax
                                 800,000 3,000,000 200,000                                          
      income per share attributable to white mountains’s common shareholders
                                                                             
      basic income per share
                                                                             
      diluted income per share
                                                                             
      dividends declared per white mountains’s common share
                                 0.25   0.25   0.25                                
      change in foreign currency translation
                                   600,000                                       1,600,000   
      income from sale of discontinued operations, net of tax
                                    -1,000,000                -22,750,000 -91,000,000                        
      change in foreign currency translation, pension liability and other, net of tax
                                    900,000  200,000  100,000                                     
      change in foreign currency translation and other from discontinued operations, net of tax
                                       -5,200,000 37,200,000                                     
      gain from sale of tranzact, net of tax
                                      51,900,000                                       
      gain from sale of sirius group, net of tax
                                     600,000 -4,000,000                                       
      income before equity in earnings of unconsolidated affiliates
                                     -50,600,000 88,600,000 362,500,000 19,300,000 266,900,000 -78,800,000 -3,400,000 69,700,000 33,300,000 87,700,000 81,300,000 106,500,000 47,500,000 8,100,000 110,700,000 50,700,000 -19,500,000 31,700,000 100,400,000     12,100,000 67,100,000 7,900,000       86,125,000 156,500,000 101,000,000 87,000,000     
      equity in earnings of unconsolidated affiliates, net of tax
                                         7,100,000 3,900,000 6,800,000 7,300,000 7,000,000 12,500,000 13,800,000 6,225,000 8,600,000 7,100,000 9,200,000 6,100,000 7,700,000 6,500,000                       
      change in equity in net unrealized gains from investments in symetra common shares, net of tax
                                         -5,500,000 3,500,000 -61,800,000 28,900,000 -9,900,000 32,900,000 36,500,000                              
      recognition of foreign currency translation and other from sale of sirius group, net of tax
                                       113,300,000                                      
      change in foreign currency translation, pension liability and other
                                         75,000  44,200,000 -87,600,000 -64,300,000 -27,900,000 -7,800,000                              
      change in foreign currency translation and other from discontinued operations
                                         -15,525,000 -18,400,000                                   
      earned insurance and reinsurance premiums
                                           537,300,000 494,300,000 538,600,000 503,400,000 493,600,000 494,000,000 500,400,000 497,500,000 495,400,000 518,300,000 536,800,000 512,200,000 499,000,000 491,100,000 490,600,000 495,800,000 695,500,000 705,900,000 732,700,000 859,100,000 864,700,000 888,700,000 902,000,000 898,300,000 911,400,000 935,700,000 939,300,000 918,900,000 953,500,000 901,000,000 917,800,000 982,400,000 943,400,000  
      comprehensive income attributable to non-controlling interests
                                                                             
      comprehensive loss (income) attributable to non-controlling interests
                                             100,000                                
      interest expense on debt
                                                10,100,000 11,900,000 10,300,000 10,200,000 11,700,000 11,300,000 10,900,000 10,900,000 16,400,000 12,800,000 12,900,000 13,100,000 13,100,000 13,200,000 14,700,000 16,300,000 16,500,000 17,100,000 18,300,000 18,900,000 20,400,000 13,600,000 12,900,000 11,900,000 11,700,000 9,700,000 11,500,000 11,700,000  
      net income attributable to white mountains’ common shareholders
                                                117,900,000 57,200,000 26,300,000 120,400,000 68,200,000 19,100,000 26,100,000 93,800,000   11,700,000  72,900,000 50,700,000 2,500,000  99,800,000 159,600,000            
      change in equity in net unrealized gains from investments in unconsolidated affiliates
                                                -20,300,000 -7,200,000 -66,000,000  14,825,000 32,300,000 28,200,000  19,300,000 55,100,000 22,100,000  -52,900,000 43,100,000 50,400,000 32,900,000 -14,600,000 127,600,000 97,600,000           
      change in foreign currency translation and other
                                                2,100,000 46,600,000 -34,600,000 -3,700,000 8,325,000 39,600,000 -29,800,000 23,500,000    62,000,000 11,475,000 126,900,000   24,700,000 80,800,000 57,000,000   8,475,000 1,000,000 11,900,000 21,000,000     
      comprehensive (income) loss attributable to non-controlling interests
                                                -5,100,000 -100,000                            
      comprehensive income attributable to white mountains’ common shareholders
                                                111,000,000 96,500,000 -74,300,000 108,700,000 70,400,000 91,400,000 24,500,000 116,100,000 666,600,000 -42,500,000 28,300,000 33,800,000 28,500,000 220,700,000 -16,500,000  75,700,000 368,900,000            
      income per share attributable to white mountains’ common shareholders
                                                                             
      dividends declared per white mountains’ common share
                                                0.25   0.25                        
      net gain income from discontinued operations, net of tax
                                                  3,900,000                           
      change in equity in net unrealized losses from investments in unconsolidated affiliates
                                                   -8,000,000                          
      comprehensive income attributable to noncontrolling interests
                                                    100,000 400,000                        
      net income attributable to noncontrolling interests
                                                      -12,100,000   11,000,000                    
      equity in earnings of unconsolidated affiliates
                                                       10,200,000 4,025,000 1,500,000   8,300,000 7,900,000   6,500,000 8,300,000 8,600,000 900,000 800,000         
      income per share attributable to white mountains’ common shareholders basic income per share
                                                                             
      dividends declared and paid per white mountains’ common share
                                                                           
      income before equity in earnings (losses) of unconsolidated affiliates
                                                          24,600,000                   
      equity in earnings (losses) of unconsolidated affiliates
                                                          7,900,000 6,700,000   5,300,000               
      pre-tax loss
                                                                             
      loss per share attributable to white mountains’ common shareholders
                                                                             
      basic loss per share
                                                           -3.51                  
      diluted loss per share
                                                           -3.51                  
      earnings per share attributable to white mountains’ common shareholders
                                                                             
      equity in (losses) earnings of unconsolidated affiliates
                                                                             
      comprehensive loss attributable to white mountains’ common shareholders
                                                               -18,300,000              
      accretion of fair value adjustment to loss and loss adjustment expense reserves
                                                                2,150,000 3,500,000 2,600,000 2,500,000 4,300,000 6,300,000 6,600,000 6,400,000 5,200,000 8,800,000 9,100,000 9,100,000  
      interest expense - dividends on preferred stock subject to mandatory redemption
                                                                     7,600,000 7,600,000 7,500,000 7,600,000 7,600,000 7,600,000 7,500,000  
      interest expense - accretion on preferred stock subject to mandatory redemption
                                                                     7,700,000 7,300,000 6,900,000 6,400,000 6,000,000 5,700,000 5,400,000  
      income before equity in earnings of unconsolidated affiliates and extraordinary item
                                                                119,500,000 184,400,000 215,200,000           
      excess of fair value of acquired assets over cost
                                                                             
      net income before noncontrolling interests
                                                                113,375,000 192,700,000 223,800,000 37,000,000          
      net income attributable to noncontrolling interest
                                                                             
      comprehensive income before noncontrolling interests
                                                                169,000,000 368,000,000            
      comprehensive net income attributable to noncontrolling interests
                                                                 900,000            
      net income attributable to white mountains common shareholders
                                                                  180,300,000 30,300,000          
      comprehensive net income before noncontrolling interests
                                                                  334,900,000           
      comprehensive net income attributable to white mountains common shareholders
                                                                  333,400,000           
      earnings per share attributable to white mountains common shareholders
                                                                             
      dividends declared and paid per white mountains common share
                                                                            
      net realized and unrealized investment losses
                                                                             
      income before equity in earnings of unconsolidated affiliates, and extraordinary item
                                                                   36,100,000          
      net (income) loss attributable to noncontrolling interest
                                                                             
      comprehensive loss, net of tax:
                                                                             
      comprehensive net income attributable to white mountains shareholders
                                                                   -27,200,000          
      net realized investment gains
                                                                     69,900,000 67,800,000 106,500,000 28,500,000 -6,700,000 18,900,000 63,300,000  
      net unrealized investment losses
                                                                             
      income before equity in earnings of unconsolidated affiliates, extraordinary item, and minority interest
                                                                             
      minority interest
                                                                    52,200,000         
      change in net unrealized gains and losses for investments held
                                                                     69,700,000 151,800,000   75,000  128,600,000  
      recognition of net unrealized losses for investments sold
                                                                             
      comprehensive net income
                                                                    -490,700,000 357,300,000 275,700,000 13,200,000 59,900,000 -26,500,000 -187,100,000 199,300,000  
      dividends declared and paid per common share
                                                                      
      equity in earnings of unconsolidated insurance affiliates
                                                                     7,350,000 5,600,000 14,800,000 9,000,000 5,900,000 8,900,000 9,100,000  
      recognition of net unrealized gains and losses for investments sold
                                                                             
      income tax provision
                                                                             
      net income before equity in earnings of unconsolidated affiliates and extraordinary items
                                                                         57,275,000  137,700,000  
      net income before extraordinary item
                                                                         64,200,000 -6.16 146,800,000  
      excess of fair value of acquired net assets over cost
                                                                             
      basic earnings per share:
                                                                             
      diluted earnings per share:
                                                                             
      pretax income
                                                                           193,100,000  
    Balance Sheets:
    Quarterly
    Annual
      Unit: USD2026-03-31 2025-12-31 2025-03-31 2024-12-31 2024-09-30 2024-06-30 2024-03-31 2023-12-31 2023-09-30 2023-06-30 2023-03-31 2022-12-31 2022-09-30 2022-06-30 2022-03-31 2021-12-31 2021-09-30 2021-03-31 2021-01-01 2020-12-31 2020-09-30 2020-06-30 2019-09-30 2019-06-30 2019-03-31 2018-09-30 2018-06-30 2018-03-31 2017-09-30 2017-06-30 2017-03-31 2016-12-31 2016-09-30 2016-06-30 2016-03-31 2015-12-31 2015-09-30 2015-06-30 2015-03-31 2014-09-30 2014-06-30 2014-03-31 2013-12-31 2013-09-30 2013-06-30 2013-03-31 2012-09-30 2012-06-30 2012-03-31 2011-12-31 2011-09-30 2011-06-30 2011-03-31 2010-12-31 2010-09-30 2010-06-30 2010-03-31 2009-12-31 2009-09-30 2009-06-30 2009-03-31 2008-12-31 2008-09-30 2008-06-30 2008-03-31 2007-09-30 2007-06-30 2007-03-31 2006-12-31 2006-09-30 2006-06-30 2006-03-31 2005-12-31 2005-09-30 2005-06-30 2003-12-31 
                                                                                  
        liabilities
                                                                                  
        p&c insurance and reinsurance
                                                                                  
        loss and loss adjustment expense reserves
      2,585,600,000 2,481,000,000 2,253,900,000 2,127,500,000 2,133,000,000 1,890,100,000 1,744,500,000 1,605,100,000 1,571,800,000 1,421,000,000 1,345,600,000 1,296,500,000 1,329,400,000 1,022,100,000 999,600,000 894,700,000 890,900,000 751,900,000 -696,000,000             1,365,600,000 1,362,000,000 1,376,600,000 1,349,600,000 1,395,800,000 1,433,300,000 3,031,800,000 3,035,000,000 3,022,900,000 3,053,300,000 3,048,400,000 3,079,300,000 3,108,100,000 3,057,900,000 3,100,600,000 3,059,800,000 5,329,800,000 5,510,800,000 5,702,300,000 5,882,000,000 5,642,400,000 6,212,300,000 6,187,200,000 6,415,900,000 6,643,300,000 7,091,000,000 6,802,100,000 6,953,600,000 6,999,800,000 7,260,100,000 7,936,800,000 7,936,800,000 7,946,400,000 8,038,000,000 8,249,300,000 8,364,700,000 8,636,000,000 8,777,200,000 9,114,200,000 9,775,300,000 9,987,000,000 10,231,200,000 10,102,600,000 9,535,800,000 7,728,200,000 
        unearned insurance premiums
      1,613,500,000 1,026,100,000 1,500,600,000 853,300,000 1,149,800,000 1,526,100,000 1,234,700,000 325,800,000 312,300,000 303,700,000 299,800,000 298,300,000 286,700,000 274,000,000 267,300,000 266,300,000 257,000,000 243,700,000 -326,100,000 237,500,000 226,900,000 218,600,000 165,500,000 151,900,000 179,600,000 124,100,000 123,300,000 110,200,000 118,500,000 109,900,000  658,000,000 674,100,000 619,700,000 626,500,000 612,600,000 671,300,000                                        
        debt
      159,300,000 159,700,000 156,100,000 154,500,000 156,800,000 155,000,000 155,400,000 146,900,000 146,800,000 146,700,000 146,600,000 146,500,000 146,400,000 146,300,000 184,800,000 185,900,000 200,700,000 44,100,000 -46,400,000 272,600,000 270,200,000 268,400,000   184,500,000    9,400,000 10,600,000  285,900,000 288,500,000 289,800,000 532,600,000 442,400,000 383,300,000 748,500,000 749,800,000 678,100,000 677,500,000 677,600,000 676,400,000 676,300,000 676,300,000 676,200,000 676,600,000 677,600,000 677,200,000 671,200,000 669,000,000 669,000,000 818,800,000 818,800,000 818,700,000 851,700,000 1,026,100,000 1,050,700,000 1,050,500,000 1,271,400,000 1,349,200,000 1,367,100,000 1,367,100,000 1,520,600,000 1,666,000,000 1,192,800,000 1,183,600,000 1,183,600,000 1,106,700,000 794,200,000 838,200,000 779,100,000 779,100,000 775,200,000 777,600,000 743,000,000 
        reinsurance payable
      610,300,000 286,200,000 385,800,000 149,500,000 230,200,000 367,300,000 262,500,000 81,100,000 146,300,000 247,000,000 193,000,000 251,100,000 312,700,000 418,800,000 348,900,000 424,100,000 481,400,000 487,500,000                                                           
        contingent consideration
      338,300,000 328,300,000 165,000,000 155,300,000 141,500,000 107,300,000 94,000,000 94,000,000 62,100,000 45,100,000 42,900,000 45,300,000 32,900,000 30,200,000 30,100,000 28,000,000 24,000,000                                                            
        other liabilities
      234,400,000 247,200,000 196,700,000 224,700,000 188,900,000 157,200,000 190,100,000 31,800,000 40,000,000 34,600,000 30,100,000 29,000,000 29,500,000 32,700,000 28,300,000 30,900,000 32,500,000 28,600,000 -25,900,000 28,300,000 27,800,000 27,300,000 800,000 800,000 28,100,000 800,000 800,000 300,000 45,400,000 44,900,000 72,100,000 199,900,000 210,900,000 188,500,000 229,800,000 264,700,000 304,900,000 297,300,000 338,500,000 355,400,000 336,800,000 343,300,000 362,900,000 362,700,000 371,500,000 374,400,000 461,800,000 461,900,000 441,400,000 534,100,000 1,310,600,000 1,089,100,000 1,142,800,000 1,245,900,000 1,119,900,000 1,104,800,000 928,100,000 990,000,000 972,100,000 931,700,000 1,031,300,000 904,500,000 904,500,000 820,300,000 864,600,000 901,500,000 775,600,000 825,900,000 913,700,000 1,178,500,000 1,003,200,000 992,900,000 1,165,500,000 1,200,700,000 1,205,500,000 1,333,200,000 
        total p&c insurance and reinsurance liabilities
      5,541,400,000 4,528,500,000 4,658,100,000 3,664,800,000 4,000,200,000 4,203,000,000 3,681,200,000 2,876,100,000 3,081,400,000 3,391,300,000 3,033,300,000 2,520,900,000 2,743,900,000 2,780,300,000 2,554,900,000 2,122,400,000 2,281,000,000 2,006,800,000                                                           
        asset management
                                                                                  
        total asset management liabilities
      456,000,000 446,900,000 330,600,000 316,700,000 294,400,000 271,200,000 265,600,000 275,400,000 257,300,000 254,700,000 246,400,000 273,300,000 313,200,000 298,600,000 260,500,000 261,000,000 235,800,000 111,300,000  96,300,000 81,200,000 77,300,000                                                       
        financial guarantee
                                                                                  
        total financial guarantee liabilities
      499,800,000 499,500,000 463,300,000 464,100,000 453,900,000 532,500,000 519,300,000 531,700,000 519,000,000 499,700,000 488,600,000 501,800,000 484,200,000 469,500,000 306,800,000 321,900,000 310,500,000 283,300,000  291,500,000 280,500,000 263,000,000   219,400,000                                                    
        specialty insurance distribution
                                                                                  
        premiums and commissions payable
      76,300,000 81,300,000 86,200,000 88,100,000 93,700,000 78,800,000 61,700,000                                                                      
        total specialty insurance distribution liabilities
      284,600,000 307,100,000             494,000,000 495,300,000 518,400,000 480,100,000  491,800,000 476,400,000 500,900,000   351,500,000                                                    
        other operations
                                                                                  
        accrued incentive compensation
      50,800,000 102,900,000 28,200,000 79,300,000 64,500,000 17,300,000 11,900,000 27,200,000 19,900,000 14,700,000 12,100,000 28,000,000 21,600,000 16,500,000 11,200,000 24,700,000 21,000,000 11,000,000  25,700,000 19,400,000 14,100,000 600,000 400,000 10,100,000    76,900,000 63,300,000  140,000,000 124,200,000 106,300,000 114,200,000 141,700,000 121,000,000 124,900,000 100,500,000 187,500,000 157,900,000 124,900,000 218,300,000 161,600,000 125,900,000 100,800,000 144,700,000 113,600,000 90,000,000 187,900,000 169,900,000 153,300,000 122,500,000 176,500,000 150,900,000 132,600,000 116,400,000 204,900,000 153,600,000                  
        liabilities held for sale - other
      2,900,000 3,600,000                                                                           
        total other operations liabilities
      211,100,000 269,400,000 130,500,000 181,300,000 157,200,000 140,800,000 115,300,000 141,100,000 120,900,000 104,700,000 98,000,000 158,300,000 137,400,000 620,500,000 71,200,000 95,400,000 113,600,000 83,300,000  133,900,000 236,100,000 95,800,000   80,500,000                                                    
        total liabilities
      6,992,900,000 6,051,400,000 5,865,200,000 4,794,600,000 5,077,700,000 5,294,700,000 4,699,700,000 3,824,300,000 3,978,600,000 4,250,400,000 3,866,300,000 3,454,300,000 3,678,700,000 4,168,900,000 3,687,400,000 3,296,000,000 3,459,300,000 2,964,800,000  1,013,500,000 1,074,200,000 937,000,000 494,400,000 468,500,000 651,400,000 399,500,000 387,900,000 361,200,000 299,900,000 3,022,100,000 2,759,300,000 2,807,500,000 2,881,900,000 2,966,200,000 6,154,500,000 5,916,500,000 6,139,700,000 5,970,800,000 5,968,000,000 7,689,500,000 7,749,300,000 7,888,500,000 7,746,900,000 8,020,300,000 8,093,300,000 8,329,500,000 9,090,400,000 8,946,000,000 9,069,100,000 9,396,100,000 10,562,600,000 9,986,700,000 10,388,300,000 10,273,300,000 10,722,300,000 11,342,300,000 11,567,900,000 11,101,700,000 11,428,100,000 11,699,600,000 12,158,200,000 13,024,000,000 13,024,000,000 13,357,800,000 13,931,100,000 14,097,300,000 13,721,400,000 14,106,500,000 14,385,200,000 14,593,400,000 14,863,700,000 15,209,200,000 15,584,900,000 15,913,000,000 15,092,900,000 11,991,800,000 
        redeemable noncontrolling interests
      131,500,000 131,500,000                                                                           
        equity
                                                                                  
        white mountains’s common shareholders’ equity
                            483,100,000 483,700,000  482,600,000 486,800,000 492,000,000   3,625,100,000                                              
        white mountains’s common shares at 1 par value per share - authorized 50,000,000 shares; issued and outstanding 2,476,670 and 2,479,677 shares
      2,500,000                                                                            
        paid-in surplus
      578,800,000 576,500,000 564,500,000 563,800,000 560,700,000 558,700,000 551,900,000 548,700,000 544,900,000 540,600,000 535,200,000 536,000,000 532,700,000 600,300,000 583,300,000 585,900,000 583,200,000 594,800,000  592,100,000     582,600,000    665,600,000 810,500,000  806,100,000 805,200,000 868,100,000 933,500,000 972,600,000 992,300,000 1,025,200,000 1,032,700,000 1,030,900,000 1,047,700,000 1,046,700,000 1,044,900,000 1,040,400,000 1,036,200,000 1,031,100,000 1,095,600,000 1,102,200,000 1,099,500,000 1,253,700,000 1,262,700,000 1,313,500,000 1,312,600,000 1,350,800,000 1,370,800,000 1,397,600,000 1,423,500,000 1,436,100,000 1,431,600,000 1,427,300,000 1,422,800,000 1,676,700,000 1,676,700,000 1,691,100,000 1,690,600,000 1,723,900,000 1,721,100,000 1,716,600,000 1,716,700,000 1,715,900,000 1,715,600,000 1,715,200,000 1,716,400,000 1,718,500,000 1,719,500,000 1,399,600,000 
        retained earnings
      4,790,800,000 4,845,600,000 3,943,000,000 3,919,000,000 4,048,300,000 3,863,100,000 3,917,700,000 3,690,800,000 3,404,300,000 3,380,700,000 3,367,300,000 3,211,800,000 3,175,900,000 2,725,100,000 2,956,200,000 2,957,500,000 2,935,300,000 3,226,700,000  3,311,200,000 2,822,100,000 2,589,300,000   2,542,300,000    2,800,800,000 2,835,200,000 2,821,700,000 2,797,200,000 2,846,700,000 3,006,600,000 2,959,600,000 3,084,900,000 2,888,300,000 3,069,200,000 3,080,800,000 2,961,500,000 2,965,800,000 2,880,800,000 2,802,300,000 2,684,400,000 2,627,200,000 2,601,400,000 2,577,400,000 2,576,300,000 2,553,700,000 2,789,700,000 2,004,000,000 2,102,000,000 2,094,200,000 2,175,600,000 2,125,900,000 2,108,700,000 2,148,200,000 2,215,900,000 2,116,200,000 1,956,600,000 1,776,300,000 2,495,400,000 2,495,400,000 2,802,200,000 2,837,600,000 2,737,300,000 2,647,500,000 2,566,700,000 2,496,000,000 2,218,200,000 2,077,700,000 1,983,400,000 1,899,800,000 1,888,000,000 1,975,900,000 1,286,400,000 
        accumulated other comprehensive income, after-tax:
                                                                                  
        net unrealized gains from foreign currency translation
      1,400,000 800,000 -500,000 -1,700,000 -1,000,000 -1,800,000 -1,800,000                                                                      
        total white mountains’s common shareholders’ equity
      5,373,500,000 5,425,400,000 4,509,600,000 4,483,700,000 4,610,600,000 4,422,600,000 4,470,400,000 4,240,500,000 3,949,100,000 3,922,200,000 3,902,400,000 3,746,900,000 3,708,000,000 3,323,300,000 3,542,100,000 3,548,100,000 3,521,700,000 3,825,900,000  3,906,000,000 3,407,700,000 3,166,000,000   3,122,000,000    3,468,800,000 3,647,300,000  3,603,300,000 3,652,200,000 3,875,200,000 3,785,900,000 3,913,200,000 3,745,500,000 3,974,600,000 4,011,300,000 4,010,100,000 4,105,500,000 4,014,500,000                                   
        nonredeemable noncontrolling interests
      671,000,000 698,200,000                                                                           
        total equity
      6,044,500,000 6,123,600,000 5,139,700,000 5,131,000,000 5,259,800,000 4,872,200,000 4,890,600,000 4,561,600,000 4,164,200,000 4,125,900,000 4,092,800,000 3,935,000,000 3,866,300,000 3,492,000,000 3,669,300,000 3,704,700,000 3,654,300,000 3,935,900,000  3,817,900,000 3,309,200,000 3,063,300,000 498,000,000 498,600,000 2,978,300,000 497,400,000 502,200,000 507,700,000 3,337,200,000 3,764,100,000 3,757,500,000 3,737,200,000 3,801,400,000 4,099,400,000 4,237,300,000 4,368,000,000 4,206,300,000 4,458,500,000 4,539,800,000 4,498,800,000 4,608,600,000 4,527,900,000 4,397,400,000 4,287,200,000 4,190,400,000 4,282,000,000 4,378,400,000 4,334,500,000 4,309,500,000 4,667,900,000 4,019,100,000 4,215,800,000 4,209,100,000 4,260,800,000 4,271,600,000 4,160,400,000 4,254,900,000 4,341,500,000 4,247,700,000 3,851,400,000 3,482,300,000                
        total liabilities, redeemable noncontrolling interests and equity
      13,168,900,000 12,306,500,000                                                                           
        liabilities held for sale - bamboo group
                                                                                  
        white mountains’s common shares at 1 par value per share—authorized 50,000,000 shares; issued and outstanding 2,479,677 and 2,568,148 shares
       2,500,000                                                                           
        p&c insurance distribution
                                                                                  
        total p&c insurance distribution liabilities
        282,700,000 167,700,000 172,000,000 147,200,000 118,300,000                                                                      
        white mountains’s common shares at 1 par value per share—authorized 50,000,000 shares; issued and outstanding 2,573,726 and 2,568,148 shares
        2,600,000                                                                          
        noncontrolling interests
        630,100,000 647,300,000 649,200,000 449,600,000 420,200,000 321,100,000 215,100,000 203,700,000 190,400,000                                                                  
        total liabilities and equity
        11,004,900,000 9,925,600,000 10,337,500,000 10,166,900,000 9,590,300,000 8,385,900,000 8,142,800,000 8,376,300,000 7,959,100,000 7,389,300,000 7,545,000,000 7,660,900,000 7,356,700,000 7,000,700,000 7,113,600,000 6,900,700,000  4,831,400,000 4,383,400,000 4,000,300,000 992,400,000 967,100,000 3,629,700,000 896,900,000 890,100,000 868,900,000 3,637,100,000 6,786,200,000 6,516,800,000 6,544,700,000 6,683,300,000 7,065,600,000 10,391,800,000 10,284,500,000 10,346,000,000 10,429,300,000 10,507,800,000 12,188,300,000 12,357,900,000 12,416,400,000 12,144,300,000 12,307,500,000 12,283,700,000 12,611,500,000 13,468,800,000 13,280,500,000 13,378,600,000 14,064,000,000 14,581,700,000 14,202,500,000 14,597,400,000 14,534,100,000 14,993,900,000 15,502,700,000 15,822,800,000 15,443,200,000 15,675,800,000 15,551,000,000 15,640,500,000                
        white mountains’s common shares at 1 par value per share—authorized 50,000,000 shares; issued and outstanding 2,568,148 and 2,560,452 shares
         2,600,000 2,600,000                                                                        
        white mountains’s common shares at 1 par value per share—authorized 50,000,000 shares; issued and outstanding 2,568,283 and 2,560,452 shares
           2,600,000                                                                       
        millions
           2,024,000,000      2,022,000,000   2,022,000,000  2,021,000,000   2,020,000,000 2,020,000,000 2,020,000,000                                                       
        revenues:
                                                                                  
        earned insurance premiums
           318,300,000      33,300,000   8,400,000  6,700,000   22,800,000 6,200,000 5,600,000                                                       
        net investment income
           22,300,000      21,500,000   4,600,000  4,400,000   19,500,000 4,700,000 4,900,000                                                       
        net realized and unrealized investment gains
           20,300,000      -105,800,000   -45,100,000  -4,000,000   23,700,000 3,200,000 14,400,000                                                       
        other revenues
           2,400,000      4,600,000   800,000  300,000   2,500,000 400,000 1,200,000                                                       
        total p&c insurance and reinsurance revenues
           363,300,000      1,009,500,000   175,700,000  217,700,000                                                            
        total financial guarantee revenues
           15,700,000      -46,400,000   -31,300,000  7,400,000   68,500,000 14,500,000 26,100,000                                                       
        total asset management revenues
           70,200,000      118,500,000   34,900,000  28,500,000   45,700,000 16,300,000 22,100,000                                                       
        commission and fee revenues
           32,700,000                                                                       
        total p&c insurance distribution revenues
           42,000,000                                                                       
        net realized and unrealized investment gains from investment in mediaalpha
           -139,200,000      -93,000,000   18,800,000  -396,800,000                                                            
        commission and fees revenues
           3,400,000                                                                       
        total other operations revenues
           -95,800,000      76,300,000   81,100,000  -346,000,000   781,400,000 358,000,000 135,300,000                                                       
        total revenues
           395,400,000      1,157,900,000   348,900,000  -10,100,000   1,180,700,000 459,500,000 259,600,000                                                       
        white mountains’s common shares at 1 par value per share—authorized 50,000,000 shares; issued and outstanding 2,565,733 and 2,560,452 shares
            2,600,000                                                                      
        white mountains’s common shares at 1 par value per share—authorized 50,000,000 shares; issued and outstanding 2,560,452 and 2,572,156 shares
             2,600,000 2,600,000 2,600,000                                                                   
        net unrealized gains from foreign currency translation and interest rate swap
             -1,600,000 -2,700,000 -1,700,000 -2,700,000 -3,500,000 -3,200,000 -5,000,000 -400,000                                                              
        millions, except share and per share amounts
                                                                                  
        white mountains’s common shares at 1 par value per share—authorized 50,000,000 shares; issued and outstanding 2,564,484 and 2,572,156 shares
                2,600,000                                                                  
        liabilities held for sale - nsm group
                   504,400,000                                                               
        white mountains’s common shares at 1 par value per share—authorized 50,000,000 shares; issued and outstanding 2,572,156 and 3,017,772 shares
                 2,600,000                                                                 
        accumulated other comprehensive gain, after-tax:
                                                                                  
        non-controlling interests
                 188,100,000 158,300,000 168,700,000 127,200,000 156,600,000 132,600,000 110,000,000  -88,100,000 -98,500,000 -102,700,000 14,900,000 14,900,000 -143,700,000 14,800,000 15,400,000 15,700,000 -131,600,000 116,800,000 132,400,000 133,900,000 149,200,000 224,200,000 451,400,000 454,800,000                                         
        commission revenues
                 11,500,000   70,100,000  67,000,000   232,500,000 58,200,000 63,000,000                                                       
        white mountains’s common shares at 1 par value per share—authorized 50,000,000 shares; issued and outstanding 2,576,232 and 3,017,772 shares
                  2,600,000                                                                
        white mountains’s common shares at 1 par value per share—authorized 50,000,000 shares; issued and outstanding 2,942,877 and 3,017,772 shares
                   2,900,000                                                               
        premiums payable
                    146,000,000 135,900,000 132,500,000 116,000,000  113,400,000 116,900,000 139,700,000   93,400,000                                                    
        white mountains’s common shares at 1 par value per share—authorized 50,000,000 shares; issued and outstanding 2,994,162 and 3,017,772 shares
                    3,000,000                                                              
        total specialty insurance distribution revenues
                    88,500,000  82,300,000   285,100,000 70,700,000 76,100,000                                                       
        white mountains’s common shares at 1 par value per share—authorized 50,000,000 shares; issued and outstanding 3,017,772 and 3,102,011 shares
                     3,000,000                                                             
        net unrealized foreign currency translation and interest rate swap gains
                     1,700,000 200,000 1,300,000                                                           
        white mountains’s common shares at 1 par value per share—authorized 50,000,000 shares; issued and outstanding 3,029,620 and 3,102,011 shares and paid-in surplus
                      3,000,000                                                            
        contingent consideration related to the ark transaction
                       22,500,000                                                           
        accounts payable on unsettled investment purchases
                       61,600,000   6,400,000 3,000,000   1,600,000  2,400,000 2,200,000 49,700,000 114,600,000   30,000,000 69,900,000 6,900,000  46,000,000 57,700,000 92,600,000 76,000,000 28,200,000 80,900,000 20,500,000 28,100,000 55,700,000 25,700,000 47,700,000 44,500,000 103,500,000 34,600,000 57,100,000 44,900,000 99,000,000 22,400,000 110,000,000 51,800,000 37,100,000 9,100,000 60,200,000 64,400,000 23,500,000 17,400,000 17,400,000 72,800,000 106,300,000 85,400,000 32,000,000 19,700,000 66,800,000 303,500,000 63,700,000 165,700,000 43,400,000 162,800,000 95,700,000 371,600,000 
        contingent consideration earnout liabilities
                       7,900,000  14,600,000 11,800,000 11,700,000   27,500,000                                                    
        white mountains’s common shares at 1 par value per share—authorized 50,000,000 shares; issued and outstanding 3,107,267 and 3,102,011 shares and paid-in surplus
                       3,100,000                                                           
        investments
                        594,300,000                                                          
        cash
                        52,000,000    2,100,000 4,300,000 10,400,000 800,000 800,000 1,200,000 48,600,000 53,300,000  149,800,000 244,700,000 135,000,000 178,800,000 179,300,000 200,000,000 354,200,000 335,800,000 543,500,000 331,000,000 338,600,000 382,800,000 411,000,000 348,300,000 411,500,000 549,200,000 811,600,000 605,400,000 705,400,000 557,700,000 483,700,000 452,500,000 434,800,000 401,200,000 348,800,000 345,000,000 366,000,000 258,100,000 405,200,000 448,800,000 220,800,000 220,800,000 198,300,000 229,600,000 185,600,000 172,900,000 186,300,000 159,000,000 210,300,000 191,600,000 183,100,000 187,700,000 205,400,000 204,000,000 89,900,000 
        reinsurance recoverables
                        433,400,000                                                          
        insurance premiums receivable
                        236,700,000    4,300,000 4,100,000 6,500,000 3,800,000 3,700,000 3,100,000 4,500,000 2,800,000  229,900,000 264,600,000 240,400,000 234,300,000 223,300,000 273,300,000                                        
        ceded unearned premiums
                        170,200,000                                       111,100,000 128,600,000 159,200,000 165,700,000 134,300,000 134,300,000 158,800,000 171,900,000 129,200,000 130,900,000 133,600,000 87,900,000 113,700,000 167,100,000 214,200,000 200,700,000 242,200,000 241,900,000 185,300,000 
        value of in-force business acquired
                        71,700,000                                                          
        other assets
                        88,900,000    1,600,000 1,500,000 17,100,000 1,400,000 1,200,000 1,200,000 46,100,000 62,800,000 2,146,300,000 274,600,000 226,300,000 239,400,000 286,900,000 318,700,000 307,700,000 322,700,000 323,600,000 466,700,000 520,100,000 537,700,000 458,100,000 397,300,000 483,300,000 416,500,000 626,500,000 673,000,000 580,900,000 681,900,000 760,200,000 679,300,000 744,400,000 779,400,000 694,900,000 705,000,000 648,500,000 691,500,000 767,500,000 791,400,000 760,100,000 735,300,000 735,300,000 726,600,000 605,000,000 593,100,000 640,800,000 628,800,000 645,100,000 555,500,000 554,400,000 540,100,000 526,500,000 506,600,000 574,800,000 682,200,000 
        ceded reinsurance payable
                        -528,300,000              28,200,000 23,900,000 31,800,000 30,500,000 46,800,000 189,600,000 151,800,000 134,000,000 159,200,000 157,900,000 71,900,000 153,600,000 156,900,000 175,700,000 138,600,000 175,600,000 194,000,000 134,600,000 188,300,000 160,600,000 224,800,000 221,000,000 293,300,000 268,800,000 227,300,000 92,000,000 152,100,000 158,600,000 162,600,000 100,400,000 100,400,000 88,400,000 124,600,000 124,000,000 125,400,000 141,000,000 138,400,000 135,600,000 166,900,000 173,700,000 204,500,000 219,100,000 202,600,000  
        net tangible assets acquired
                        24,500,000                                                          
        goodwill
                        116,800,000            13,400,000                                              
        other intangible assets - syndicate underwriting capacity
                        175,700,000                                                          
        deferred tax liability on other intangible assets
                        -33,400,000                                                          
        net assets acquired
                        283,600,000                                                          
        white mountains’s common shares at 1 par value per share—authorized 50,000,000 shares; issued and outstanding 3,102,011 and 3,185,353 shares
                         3,100,000                                                         
        accumulated other comprehensive loss, after-tax:
                                                                                  
        net unrealized losses from foreign currency translation and interest rate swap
                         -400,000                                                         
        marketing technology
                                                                                  
        advertising and commission revenues
                                                                                  
        total marketing technology revenues
                                                                                  
        net realized and unrealized investment gains from mediaalpha
                         686,000,000                                                         
        realized gain from the 2019 mediaalpha transaction
                                                                                  
        white mountains’s common shares at 1 par value per share—authorized 50,000,000 shares; issued and outstanding 3,102,011 and 3,185,353 shares and paid-in surplus
                          592,100,000                                                        
        net unrealized foreign currency translation and interest rate swap losses
                          -6,500,000 -10,300,000                                                       
        realized gain and unrealized investment gain from the mediaalpha transaction
                                                                                  
        white mountains’s common shares at 1 par value per share—authorized 50,000,000 shares; issued and outstanding 3,101,761 and 3,185,353 shares and paid-in surplus
                           587,000,000                                                       
        assets
                                                                                  
        fixed maturity investments
                            285,200,000 271,600,000  206,600,000 195,300,000 167,500,000                                                 
        short-term investments
                            10,300,000 7,800,000  11,800,000 22,600,000 39,200,000                                                 
        total investments
                            295,500,000 279,400,000 769,400,000 218,400,000 217,900,000 206,700,000 3,280,500,000 2,692,900,000  5,334,800,000 5,213,500,000 5,521,300,000 3,639,700,000 4,280,700,000 3,709,500,000 6,823,400,000 6,906,400,000 6,976,300,000 7,161,800,000 7,213,400,000 7,192,600,000 7,057,500,000 6,945,600,000 6,972,800,000 7,283,600,000 7,224,300,000 7,617,000,000 8,268,000,000 7,199,600,000 7,529,200,000 8,671,200,000 8,732,500,000 8,655,400,000 8,389,300,000 9,128,300,000 9,232,500,000 9,284,600,000 8,921,000,000 8,804,700,000 10,747,000,000 10,747,000,000 11,536,100,000 12,150,200,000 11,910,300,000 11,495,700,000 11,252,100,000 11,332,700,000 9,852,000,000 9,793,700,000 9,829,000,000 9,866,400,000 10,128,700,000 10,091,200,000 8,547,500,000 
        bam surplus notes
                            481,300,000 481,300,000  499,000,000 499,000,000 499,000,000                                                 
        accrued interest receivable on bam surplus notes
                            164,200,000 157,300,000  143,200,000 137,500,000 131,700,000                                                 
        deferred acquisition costs
                            43,400,000 39,100,000 19,600,000 30,300,000 30,000,000 26,000,000 14,100,000 13,000,000  106,900,000 109,600,000 113,900,000 109,800,000 107,600,000 110,800,000 198,100,000 192,000,000 204,400,000 191,200,000 190,000,000 174,700,000 188,200,000 180,600,000 190,400,000 211,300,000 200,000,000 198,800,000 187,000,000 202,900,000 194,100,000 233,500,000 210,800,000 241,700,000 241,900,000 298,300,000 303,800,000 329,200,000 329,400,000 327,700,000 350,400,000 350,400,000 338,400,000 325,900,000 358,600,000 351,600,000 338,600,000 320,300,000 333,500,000 324,900,000 312,200,000 288,400,000 308,300,000 313,000,000 233,600,000 
        accounts receivable on unsettled investment sales
                             100,000 6,100,000    190,100,000 199,500,000  6,200,000 179,000,000 21,500,000 4,500,000 41,900,000 11,500,000 23,300,000 12,000,000 39,000,000 76,600,000 19,900,000 12,100,000 38,200,000 14,000,000 99,000,000 167,200,000 76,200,000 6,500,000 4,700,000 20,300,000 23,400,000 49,900,000 40,000,000 147,400,000 87,100,000 112,300,000 27,600,000 47,000,000 10,300,000 25,600,000 27,000,000 27,000,000 36,500,000 35,300,000 21,700,000 24,300,000 40,200,000 8,500,000 354,100,000 23,600,000 45,700,000 21,700,000 27,000,000 19,500,000 9,100,000 
        total assets
                            992,400,000 967,100,000 3,629,700,000 896,900,000 890,100,000 868,900,000 3,637,100,000 6,786,200,000 6,516,800,000 6,544,700,000 6,683,300,000 7,065,600,000 10,391,800,000 10,284,500,000 10,346,000,000 10,429,300,000 10,507,800,000 12,188,300,000 12,357,900,000 12,416,400,000 12,144,300,000 12,307,500,000 12,283,700,000 12,611,500,000 13,468,800,000 13,280,500,000 13,378,600,000 14,064,000,000 14,581,700,000 14,202,500,000 14,597,400,000 14,534,100,000 14,993,900,000 15,502,700,000 15,822,800,000 15,443,200,000 15,675,800,000 15,551,000,000 15,640,500,000 17,764,400,000 17,764,400,000 18,703,800,000 19,364,800,000 19,718,700,000 19,184,300,000 19,278,200,000 19,443,700,000 18,712,100,000 18,728,000,000 19,081,400,000 19,418,100,000 19,795,800,000 19,184,700,000 14,971,000,000 
        accrued interest payable on bam surplus notes
                                                                                  
        preferred dividends payable to white mountains’s subsidiaries
                            316,600,000 305,000,000  265,500,000 252,800,000 240,300,000                                                 
        preferred dividends payable to non-controlling interests
                            10,900,000 10,400,000  9,100,000 8,600,000 8,200,000                                                 
        fixed maturity investments, at fair value
                              737,600,000    1,490,000,000 1,566,900,000  4,250,200,000 4,131,500,000 4,362,800,000 2,613,200,000 2,639,700,000 2,602,200,000 4,874,500,000 4,771,900,000 4,785,500,000 5,008,000,000 4,988,700,000 5,030,500,000 4,914,000,000 4,931,900,000 4,854,400,000 4,912,400,000 5,248,700,000 5,411,300,000 6,221,900,000 5,287,700,000 5,558,900,000 6,417,000,000 6,379,900,000 6,085,400,000 5,568,600,000 5,828,300,000 6,101,200,000 5,936,200,000 5,929,800,000 5,630,500,000 6,160,100,000 6,160,100,000 6,846,400,000 6,842,600,000 7,436,700,000 7,524,900,000 7,179,900,000 7,911,500,000 7,089,200,000 7,303,600,000 7,265,500,000 7,582,700,000 7,594,200,000 7,760,400,000 6,248,100,000 
        short-term investments, at fair value
                              31,800,000                                                    
        accrued investment income
                              5,400,000    15,400,000 16,000,000  26,100,000 18,900,000 16,000,000 13,400,000 14,000,000 13,700,000 33,700,000 30,400,000 32,700,000 43,600,000 37,000,000 39,300,000 33,700,000 45,900,000 44,700,000 45,500,000 54,100,000 52,000,000 51,400,000 58,300,000 61,900,000 66,300,000 66,900,000 61,600,000 60,600,000 59,400,000 67,400,000 70,500,000 69,900,000 64,500,000 80,000,000 80,000,000 78,000,000 78,600,000 89,100,000 85,800,000 84,700,000 87,400,000        
        total financial guarantee assets
                              834,500,000                                                    
        premium and commission receivable
                              51,900,000                                                    
        goodwill and other intangible assets
                              488,700,000    37,800,000 49,500,000   59,300,000                                            
        total specialty insurance distribution assets
                              661,100,000                                                    
        accounts receivable from publishers and advertisers
                                                                                  
        total marketing technology assets
                                                                                  
        common equity securities, at fair value
                              905,000,000    774,400,000 827,900,000  474,300,000 425,000,000 407,500,000 443,000,000 1,113,900,000 482,100,000 713,800,000 786,900,000 986,100,000 1,206,100,000 1,174,600,000 1,156,800,000 1,110,700,000 1,029,500,000 1,073,200,000 1,004,800,000 919,200,000 868,700,000 755,000,000 669,800,000 703,800,000 756,600,000 710,000,000 636,000,000 556,300,000 577,100,000 458,500,000 307,600,000 262,200,000 318,800,000 1,393,400,000 1,393,400,000 1,620,600,000 1,520,700,000 1,471,300,000 1,402,700,000 1,245,200,000 1,212,600,000 1,042,000,000 1,147,000,000 1,107,000,000 967,800,000 1,000,100,000 1,024,400,000 513,600,000 
        other long-term investments
                              497,600,000    229,600,000 226,500,000  323,300,000 351,400,000 329,200,000 321,800,000 315,800,000 294,600,000 390,100,000 402,600,000 320,900,000 313,000,000 302,300,000 288,900,000 300,000,000 303,300,000 295,200,000 307,100,000 292,500,000 306,700,000 301,300,000 328,800,000 333,300,000 343,400,000 376,100,000 429,700,000 404,000,000 382,600,000 341,300,000 377,500,000 405,400,000 395,100,000                
        assets held for sale
                              3,300,000     3,696,400,000 3,578,900,000 10,100,000 27,000,000 384,600,000 5,215,500,000 4,407,000,000 4,528,100,000  58,000,000 1,699,200,000 1,750,700,000 1,803,100,000 1,880,100,000 1,957,200,000 2,047,000,000 2,155,200,000 2,388,200,000   132,600,000 1,399,500,000 1,213,900,000                         
        total other operations assets
                              2,134,100,000                                                    
        amounts due to publishers and advertisers
                                                                                  
        total marketing technology liabilities
                                                                                  
        white mountains’s common shares at 1 par value per share—authorized 50,000,000 shares; issued and outstanding 3,181,199 and 3,173,115 shares
                              3,200,000                                                    
        net unrealized foreign currency translation losses and interest rate swap
                              -6,100,000                                                    
        short-term investments, at amortized cost
                                  786,500,000 71,600,000  287,000,000 305,600,000 421,800,000 261,700,000 211,300,000 325,000,000 840,500,000 929,200,000 834,900,000 564,000,000 674,000,000 635,900,000 648,000,000 606,800,000 654,400,000 917,300,000 618,400,000 877,500,000 846,000,000 772,800,000 813,500,000 998,200,000 1,106,300,000 1,348,300,000 1,663,700,000 2,102,200,000 2,098,400,000 2,336,600,000 2,023,300,000 2,148,400,000 2,256,600,000 2,256,600,000 1,988,000,000 2,372,200,000 1,614,800,000 1,152,900,000 1,473,600,000 1,344,900,000 1,222,800,000 873,500,000 949,700,000 727,800,000 1,027,300,000 773,100,000 1,546,600,000 
        liabilities held for sale
                                   2,678,800,000 2,535,200,000 5,100,000 7,800,000 150,600,000 3,121,100,000 2,884,000,000 3,032,800,000   1,699,200,000 1,750,700,000 1,803,100,000 1,880,100,000 1,957,200,000 2,047,000,000 2,155,200,000 2,388,200,000   107,600,000 909,400,000 779,900,000                         
        white mountains’s common shares at 1 par value per share - authorized 50,000,000 shares;
                                                                                  
        issued and outstanding 3,749,971 and 4,563,814 shares
                                  3,700,000                                                
        accumulated other comprehensive loss, after tax:
                                                                                  
        net unrealized foreign currency translation losses
                                  -1,300,000   -1,400,000 -600,000 -700,000 -108,300,000 -145,600,000 -142,400,000 -123,700,000 -167,600,000                                9,300,000      
        accumulated other comprehensive income from net change in benefit plan assets and obligations
                                   -3,000,000                                               
        issued and outstanding 4,571,625 and 4,563,814 shares
                                   4,600,000                                               
        financial guarantee assets
                                    699,100,000                                              
        marketing technology assets
                                    53,200,000                                              
        other
                                                                          600,000        
        other intangible assets
                                    4,500,000                                              
        other assets — commissions receivable
                                    21,400,000                                              
        financial guarantee liabilities
                                    126,400,000                                              
        marketing technology liabilities
                                    25,600,000                                              
        white mountains’s common shares
                                    4,600,000                                              
        paid in surplus
                                    802,500,000                                              
        accumulated other comprehensive income, net of tax
                                    -3,700,000                                              
        item 2.
                                                                                  
        reinsurance recoverable on unpaid losses
                                     172,900,000 169,400,000 162,800,000 150,900,000 186,500,000 214,600,000 427,500,000 436,900,000 430,700,000 433,200,000 425,200,000 428,100,000 416,000,000 388,600,000 410,800,000 356,800,000 2,369,400,000 2,465,400,000 2,507,300,000 2,581,200,000 2,193,100,000 2,338,600,000 1,064,900,000 2,621,400,000 2,778,600,000 2,919,600,000 1,217,600,000 1,230,600,000 1,201,100,000 1,329,200,000 1,501,800,000 1,501,800,000 1,622,200,000 1,635,300,000 1,789,300,000 1,864,300,000 2,006,400,000 2,134,500,000 2,348,000,000 2,725,300,000 2,892,000,000 3,003,600,000 2,765,200,000 2,325,700,000 1,213,500,000 
        reinsurance recoverable on paid losses
                                     6,600,000 16,400,000 20,700,000 16,600,000 7,500,000 22,600,000 31,700,000 29,800,000 27,200,000 18,900,000 15,200,000 25,400,000 18,800,000 16,100,000 15,600,000 14,800,000 39,700,000 39,100,000 30,500,000 30,900,000 44,500,000 31,900,000 64,400,000 31,900,000 36,800,000 49,700,000 35,000,000 41,000,000 42,900,000 66,900,000 50,800,000 50,800,000 41,200,000 88,200,000 58,100,000 57,700,000 131,900,000 159,400,000 89,300,000 116,000,000 96,100,000 77,000,000 103,300,000 116,300,000 121,700,000 
        deferred tax asset
                                     126,700,000 119,500,000 122,200,000 133,600,000 112,800,000 133,900,000 440,200,000 417,900,000 439,100,000 462,800,000 484,900,000 512,100,000 555,500,000 540,500,000 539,100,000 555,000,000 504,600,000 524,700,000 536,900,000 431,700,000 407,400,000 480,600,000 499,700,000 483,500,000 567,300,000 551,100,000 564,000,000 512,600,000 567,500,000 658,100,000 484,900,000 484,900,000 324,100,000 253,500,000 238,700,000 222,400,000 242,600,000 276,000,000 288,900,000 324,200,000 317,700,000 341,200,000 338,300,000 310,900,000 260,000,000 
        ceded unearned insurance premiums
                                     44,200,000 35,100,000 34,500,000 36,300,000 29,500,000 41,400,000                                        
        goodwill and intangible assets
                                     55,900,000  53,300,000 371,500,000 375,700,000 381,700,000 355,600,000 362,600,000                                      
        funds held under insurance contracts
                                     153,000,000 156,200,000 140,900,000 134,900,000 137,800,000 100,300,000                                        
        white mountains’s common shares at 1 par value per share—authorized 50,000,000 shares; issued and outstanding 4,563,814 and 5,623,735 shares
                                     4,600,000                                             
        pension liability and other
                                     -3,200,000 -3,700,000 -3,800,000 -4,300,000 -4,300,000 -3,900,000 -4,100,000 -4,400,000 4,500,000 4,300,000 4,200,000 4,100,000 -11,000,000 -11,300,000 -11,500,000 -10,400,000 -9,100,000                             
        issued and outstanding 4,578,698 and 5,623,735 shares
                                      4,600,000                                            
        issued and outstanding 4,963,921 and 5,623,735 shares
                                       5,000,000                                           
        deferred tax liability
                                        7,100,000 7,000,000  264,800,000 254,000,000 303,000,000 336,500,000 353,900,000 356,200,000 329,600,000 317,500,000 337,100,000 399,700,000 368,100,000 384,100,000 365,500,000 360,600,000 374,200,000 369,200,000 373,200,000 368,100,000 320,900,000 339,600,000 355,300,000 343,600,000 309,400,000 289,500,000 369,200,000 369,200,000 453,800,000 390,200,000 327,200,000 312,000,000 311,100,000 311,500,000 241,100,000 241,000,000 277,500,000 274,300,000 281,700,000 281,300,000  
        issued and outstanding 5,415,462 and 5,623,735 shares
                                        5,400,000                                          
        investments in unconsolidated affiliates
                                          392,600,000 397,200,000 450,800,000 413,500,000 419,100,000 373,300,000 321,400,000 331,700,000 331,900,000 383,600,000 376,300,000 337,500,000 294,900,000 275,300,000 458,600,000 422,900,000 394,900,000 389,700,000 440,000,000 410,000,000 365,800,000 344,800,000 356,100,000 209,000,000 99,700,000 195,000,000 195,000,000 289,000,000 362,300,000 404,400,000 381,000,000          
        white mountains’s common shares at 1 par value per share—authorized 50,000,000 shares; issued and outstanding 5,623,735 and 5,986,214 shares
                                         5,600,000                                         
        equity in net unrealized gains from investments in symetra common shares
                                             19,100,000 29,000,000  -40,400,000                                  
        convertible fixed maturity and preferred investments, at fair value
                                          5,600,000 4,500,000 15,800,000                                      
        funds held by ceding entities
                                          4,600,000 137,400,000 99,600,000 123,900,000                                     
        issued and outstanding 5,745,002 and 5,986,214 shares
                                          5,700,000                                        
        accumulated other comprehensive income, after tax:
                                                                                  
        equity in net unrealized gains from investment in symetra common shares
                                          5,500,000 2,000,000 63,800,000                                      
        non-controlling interest - onebeacon ltd.
                                          246,900,000 255,000,000 258,800,000 275,600,000 280,600,000 279,200,000  263,300,000 258,400,000 263,500,000                               
        non-controlling interest - sig preference shares
                                          250,000,000 250,000,000 250,000,000 250,000,000 250,000,000 250,000,000  250,000,000 250,000,000 250,000,000                               
        non-controlling interest - mutuals and reciprocals
                                          -149,400,000 -146,200,000 -140,500,000                                      
        non-controlling interest - other
                                          113,300,000 125,100,000 160,200,000 59,400,000 61,500,000 68,500,000  48,000,000 47,900,000 46,800,000                               
        total non-controlling interests
                                          460,800,000 483,900,000 528,500,000 488,700,000 503,100,000 513,400,000 491,900,000 497,200,000 501,200,000 523,100,000                               
        insurance and reinsurance premiums receivable
                                           711,900,000 706,900,000 677,800,000 717,900,000 734,800,000 518,900,000 684,900,000 706,700,000 717,600,000 678,100,000 747,000,000 737,300,000 489,200,000 644,800,000 672,000,000 838,200,000 635,400,000 842,200,000 861,400,000 1,004,500,000 785,500,000 922,700,000 986,500,000 982,600,000 929,000,000 929,000,000 953,300,000 976,200,000 971,100,000 1,007,300,000 1,007,400,000 913,600,000 1,002,300,000 1,062,400,000 1,099,200,000 1,014,300,000 1,039,700,000 981,900,000 779,000,000 
        ceded unearned insurance and reinsurance premiums
                                           172,400,000 145,100,000 114,300,000 142,000,000 149,500,000 92,400,000 116,400,000 137,000,000 144,100,000 113,600,000 135,200,000 145,500,000 87,300,000 104,400,000 141,300,000 188,800,000 184,700,000 252,300,000 249,300,000 236,400,000                    
        unearned insurance and reinsurance premiums
                                           1,110,800,000 1,102,500,000 1,089,500,000 1,093,400,000 1,116,600,000 901,400,000 1,010,300,000 1,015,000,000 1,064,900,000 1,067,100,000 1,065,400,000 1,074,400,000 846,900,000 976,400,000 1,033,800,000 1,314,400,000 1,140,300,000 1,361,600,000 1,385,700,000 1,698,600,000 1,498,500,000 1,655,400,000 1,704,400,000 1,732,300,000 1,743,600,000 1,743,600,000 1,760,300,000 1,753,800,000 1,743,200,000 1,735,700,000 1,746,600,000 1,584,900,000 1,714,900,000 1,730,700,000 1,742,400,000 1,582,000,000 1,717,900,000 1,759,000,000 1,409,400,000 
        funds held under insurance and reinsurance contracts
                                           145,400,000 143,300,000 132,200,000 124,000,000 127,800,000 127,100,000                                  
        issued and outstanding 5,960,542 and 5,986,214 shares
                                           6,000,000                                       
        issued and outstanding 5,991,584 and 5,986,214 shares
                                            6,000,000                                      
        convertible fixed maturity investments, at fair value
                                             48,900,000 70,700,000 73,800,000 80,500,000 84,800,000 74,100,000 95,600,000 142,000,000 145,500,000 152,800,000 143,800,000 140,500,000 119,700,000 156,000,000 160,200,000 156,000,000 196,700,000 238,100,000 233,100,000 326,700,000 300,300,000 265,000,000 353,000,000 353,000,000 414,600,000 463,000,000 529,500,000 544,700,000 485,800,000         
        variable annuity benefit guarantee
                                             11,700,000 31,800,000 54,100,000 52,800,000 143,700,000 194,100,000 251,600,000 672,400,000 661,800,000 548,500,000 768,500,000                           
        issued and outstanding 6,028,251 and 6,176,739 shares
                                             6,000,000                                     
        net unrealized foreign currency translation gains
                                             -11,900,000 52,500,000 80,500,000 88,400,000 93,500,000 47,200,000 82,000,000 80,800,000 39,500,000 69,400,000 46,100,000 35,700,000 117,600,000 123,200,000 61,400,000 57,400,000   11,500,000 29,700,000   28,700,000 28,700,000 162,300,000 170,000,000 79,100,000 52,800,000 35,900,000 37,200,000 11,500,000       
        non-controlling interest - hg global
                                             18,000,000 18,200,000 18,400,000  16,600,000 16,600,000 16,600,000                               
        non-controlling interest - bam
                                             -114,300,000 -107,200,000 -102,700,000  -80,700,000 -71,700,000 -53,800,000                               
        funds held by ceding companies
                                              89,000,000 93,800,000 106,300,000 101,100,000 98,200,000 110,600,000 102,700,000 107,900,000 111,100,000 106,500,000 131,600,000 135,800,000 106,600,000 118,700,000 120,400,000 111,000,000 103,900,000 123,100,000 123,800,000 141,400,000 145,600,000 203,300,000 203,300,000 221,000,000 231,700,000 352,300,000 366,700,000 438,200,000 452,800,000 467,500,000 554,700,000 566,100,000 620,400,000 707,600,000 735,300,000  
        issued and outstanding 6,150,515 and 6,176,739 shares
                                              6,200,000                                    
        issued and outstanding 6,174,386 and 6,176,739 shares
                                               6,200,000                                   
        equity in net unrealized losses from investments in symetra common shares
                                               -3,900,000                                   
        white mountains’ common shareholders’ equity
                                                                                  
        white mountains’ common shares at 1 par value per share—authorized 50,000,000 shares; issued and outstanding 6,176,739 and 6,290,964 shares
                                                6,200,000                                  
        total white mountains’ common shareholders’ equity
                                                3,905,500,000 3,790,000,000 3,689,200,000 3,758,900,000 3,809,300,000 3,742,500,000 3,718,800,000 4,087,700,000 3,444,700,000 3,620,500,000 3,595,200,000 3,653,000,000 3,667,800,000 3,513,600,000 3,598,300,000 3,657,400,000 3,577,300,000                  
        non-controlling interest — onebeacon ltd.
                                                273,700,000                                  
        non-controlling interest — sig preference shares
                                                250,000,000                                  
        non-controlling interest — hg global
                                                16,600,000                                  
        non-controlling interest — bam
                                                -97,600,000                                  
        non-controlling interest — consolidated limited partnerships and a.w.g. dewar
                                                49,200,000                                  
        funds held under reinsurance treaties
                                                 89,100,000 75,500,000 67,300,000 33,800,000 47,700,000 45,200,000 42,900,000 39,300,000 39,500,000 84,500,000 88,000,000 83,900,000 80,400,000 103,700,000 97,400,000 85,300,000 55,900,000 76,600,000 75,100,000 75,100,000 76,000,000 98,700,000 99,500,000 110,400,000 126,400,000 141,600,000 119,600,000 130,100,000 131,500,000 171,400,000 169,900,000 170,400,000 211,900,000 
        white mountains’ common shares at 1 par value per share - authorized 50,000,000 shares;
                                                                                  
        issued and outstanding 6,176,739 and 6,290,964 shares
                                                 6,200,000                                 
        equity in net unrealized gains from investments in unconsolidated affiliates
                                                 -23,500,000 -16,300,000 49,700,000 59,300,000 27,000,000                             
        issued and outstanding 6,176,489 and 6,290,964 shares
                                                  6,200,000                                
        issued and outstanding 6,176,210 and 6,290,964 shares
                                                   6,200,000                               
        issued and outstanding 6,583,653 and 7,577,855 shares
                                                    6,600,000                              
        noncontrolling interest - onebeacon ltd.
                                                    259,700,000 280,400,000 281,900,000  269,800,000 282,600,000 300,300,000  292,600,000 337,900,000 346,300,000  337,400,000 315,500,000 287,000,000                
        noncontrolling interest - sig preference shares
                                                    250,000,000 250,000,000 250,000,000                            
        noncontrolling interest - hg global
                                                    16,600,000                              
        noncontrolling interest - bam
                                                    -18,000,000                              
        noncontrolling interest - other
                                                    60,800,000 61,600,000 58,800,000                            
        total noncontrolling interests
                                                    569,100,000 592,000,000 590,700,000 580,200,000 574,400,000 595,300,000 613,900,000 607,800,000 603,800,000 646,800,000 656,600,000 684,100,000 670,400,000 647,300,000 616,100,000                
        issued and outstanding 6,630,318 and 7,577,855 shares
                                                     6,600,000                             
        issued and outstanding 6,638,873 and 7,577,855 shares
                                                      6,600,000                            
        equity in net unrealized losses from investments in unconsolidated affiliates
                                                                                  
        white mountains’ common shares at 1 par value per share—authorized 50,000,000 shares; issued and outstanding 7,577,855 and 8,194,925 shares
                                                       7,600,000                           
        equity in unrealized gains from investments in unconsolidated affiliates
                                                        135,700,000 80,600,000 58,500,000 58,500,000 111,400,000 74,300,000 23,800,000  5,600,000                  
        noncontrolling interest—onebeacon, ltd.
                                                       273,100,000    295,000,000    351,000,000                   
        noncontrolling interest—sig preference shares
                                                       250,000,000                           
        noncontrolling interest—consolidated limited partnerships and a.w.g dewar
                                                       57,100,000    62,800,000    83,100,000                   
        shareholders’ equity and noncontrolling interests
                                                                                  
        white mountains’ common shares at 1 par value per share - authorized 50,000,000 shares; issued and outstanding 7,630,717 and 8,194,925 shares
                                                        7,600,000                          
        noncontrolling interest - sirius group preference shares
                                                        250,000,000                          
        noncontrolling interest - consolidated limited partnerships and a.w.g dewar
                                                        54,600,000 62,700,000 63,600,000  61,200,000 58,900,000 60,300,000  83,000,000 81,800,000 79,100,000                
        white mountains’ common shares at 1 par value per share - authorized 50,000,000 shares; issued and outstanding 7,958,589 and 8,194,925 shares
                                                         8,000,000                         
        noncontrolling interest - wmre preference shares
                                                         250,000,000 250,000,000  250,000,000 250,000,000 250,000,000  250,000,000 250,000,000 250,000,000                
        white mountains’ common shares at 1 par value per share - authorized 50,000,000 shares; issued and outstanding 7,975,452 and 8,194,925 shares
                                                          8,000,000                        
        reinsurance recoverable on unpaid losses—berkshire hathaway inc.
                                                           1,312,200,000    1,573,300,000                   
        white mountains’ common shares at 1 par value per share—authorized 50,000,000 shares; issued and outstanding 8,194,925 and 8,860,150 shares
                                                           8,200,000                       
        noncontrolling interest—wmre preference shares
                                                           250,000,000    250,000,000                   
        white mountains’ common shares at 1 par value per share - authorized 50,000,000 shares; issued and outstanding 8,343,050 and 8,860,150 shares
                                                            8,300,000                      
        assets held for sale - onebeacon personal lines transaction
                                                             655,600,000                     
        liabilities held for sale - onebeacon personal lines transaction
                                                             502,300,000                     
        white mountains’ common shares at 1 par value per share - authorized 50,000,000 shares; issued and outstanding 8,532,442 and 8,860,150 shares
                                                             8,500,000                     
        white mountains’ common shares at 1 par value per share - authorized 50,000,000 shares; issued and outstanding 8,775,632 and 8,860,150 shares
                                                              8,800,000                    
        securities lending collateral
                                                                 92,300,000  341,200,000 341,200,000 474,900,000 481,100,000 824,600,000 554,000,000 563,800,000 649,800,000 583,800,000 453,100,000 496,200,000 674,900,000 786,900,000 564,600,000  
        securities lending payable
                                                               1,700,000 1,700,000 96,400,000  349,600,000 349,600,000 476,300,000 481,100,000 824,600,000 554,000,000 563,800,000 649,800,000 583,800,000 453,100,000 496,200,000 674,900,000 786,900,000 564,600,000  
        white mountains’ common shares at 1 par value per share—authorized 50,000,000 shares; issued and outstanding 8,860,150 and 8,808,843 shares
                                                               8,900,000                   
        reinsurance recoverable on unpaid losses - berkshire hathaway inc.
                                                                1,603,500,000 1,623,900,000 1,655,500,000 1,763,600,000 1,763,600,000 1,705,400,000 1,740,000,000 1,792,600,000 1,828,900,000 1,867,300,000 1,881,200,000 1,902,300,000  1,968,000,000 2,022,100,000 2,058,800,000 2,077,800,000 2,260,300,000 
        white mountains’ common shares at 1 par value per share - authorized 50,000,000 shares; issued and outstanding 8,857,586 and 8,808,843 shares
                                                                8,900,000                  
        incentive compensation payable
                                                                 107,600,000 71,700,000 160,300,000 160,300,000 142,900,000 118,900,000            
        white mountains’ shareholders’ equity
                                                                                  
        white mountains common shares at 1 par value per share - authorized 50,000,000 shares; issued and outstanding 8,857,586 and 8,808,843 shares
                                                                 8,900,000                 
        equity in unrealized losses from investments in unconsolidated affiliates
                                                                                  
        total white mountains shareholders’ equity
                                                                 3,204,100,000 2,866,200,000                
        securities lending investment assets - onebeacon
                                                                  46,900,000                
        securities lending collateral - onebeacon
                                                                                  
        securities lending collateral - wmre america
                                                                  105,800,000                
        securities lending payable - onebeacon
                                                                  48,600,000                
        securities lending payable - wmre america
                                                                  112,800,000                
        white mountains common shares at 1 par value per share - authorized 50,000,000 shares; issued and outstanding 8,854,086 and 8,808,843 shares
                                                                  8,900,000                
        other investments
                                                                   583,900,000 583,900,000 666,500,000 642,500,000 549,300,000 558,500,000 532,200,000 524,800,000 498,000,000 469,600,000 506,800,000 588,100,000 507,100,000 533,300,000 239,200,000 
        trust account investments, at amortized cost
                                                                      309,200,000 308,700,000 312,000,000 335,400,000 338,900,000        
        preferred stock subject to mandatory redemption:
                                                                                  
        held by berkshire hathaway inc.
                                                                      288,900,000 268,500,000 259,200,000 250,500,000 242,300,000 234,500,000 227,300,000 220,400,000 214,000,000 207,900,000 202,200,000 174,500,000 
        minority interest - onebeacon ltd.
                                                                   337,100,000 337,100,000              
        minority interest - wmre group preference shares
                                                                   250,000,000 250,000,000 250,000,000 250,000,000 250,000,000           
        minority interest - consolidated limited partnerships
                                                                   91,400,000 91,400,000 98,700,000 97,100,000 102,500,000 111,600,000 113,000,000         
        total minority interest
                                                                   678,500,000 678,500,000 748,700,000 754,500,000 888,800,000 887,600,000 628,800,000 603,200,000        
        common shareholders’ equity
                                                                                  
        common shares at 1 par value per share - authorized 50,000,000 shares; issued and outstanding 10,441,964 and 10,553,572 shares
                                                                   10,400,000 10,400,000              
        net unrealized gains on investments
                                                                       184,300,000 144,000,000 214,700,000 194,000,000 165,700,000 53,100,000 167,600,000 233,900,000 288,800,000 411,200,000  
        total common shareholders’ equity
                                                                   4,061,900,000 4,061,900,000 4,597,300,000 4,679,200,000 4,732,600,000 4,575,300,000 4,542,900,000 4,455,300,000 4,118,700,000 3,864,300,000 3,872,200,000 3,833,200,000 3,882,800,000 4,091,800,000 2,979,200,000 
        total liabilities, minority interest and common shareholders’ equity
                                                                   17,764,400,000 17,764,400,000 18,703,800,000 19,364,800,000 19,718,700,000 19,184,300,000 19,278,200,000 19,443,700,000        
        minority interest - onebeacon, ltd.
                                                                     400,000,000 407,400,000 536,300,000           
        common shares at 1 par value per share - authorized 50,000,000 shares; issued and outstanding 10,552,376 and 10,553,572 shares
                                                                     10,600,000             
        common shares at 1 par value per share - authorized 50,000,000 shares; issued and outstanding 10,570,234 and 10,553,572 shares
                                                                      10,600,000            
        long-term incentive compensation payable
                                                                       202,500,000 181,500,000 139,300,000 285,200,000        
        reserves for structured contracts
                                                                       78,800,000 87,300,000 142,600,000 147,100,000 153,500,000 214,200,000 222,800,000 224,600,000 268,300,000 278,200,000  
        held by others
                                                                         20,000,000 20,000,000 20,000,000 20,000,000 20,000,000 20,000,000 20,000,000 20,000,000 20,000,000 
        common shares at 1 par value per share - authorized 50,000,000 shares; issued and outstanding 10,842,613 and 10,782,753 shares
                                                                       10,800,000           
        minority interest - onebeacon insurance group, ltd.
                                                                        526,000,000 515,800,000         
        minority interest - white mountains re group, ltd. preference shares
                                                                        250,000,000          
        common shares at 1 par value per share - authorized 50,000,000 shares; issued and outstanding 10,842,538 and 10,782,753 shares
                                                                        10,800,000          
        investments in unconsolidated insurance affiliates
                                                                         356,300,000 335,500,000 529,100,000 412,000,000 437,500,000 479,700,000 486,800,000 531,200,000 515,900,000 
        common shares at 1 par value per share - authorized 50,000,000 shares; issued and outstanding 10,833,788 and 10,782,753 shares
                                                                         10,800,000         
        minority interest- onebeacon insurance group, ltd.
                                                                          490,700,000        
        minority interest- consolidated limited partnerships
                                                                          112,500,000        
        common shares at 1 par value per share — authorized 50,000,000 shares; issued and outstanding 10,782,753 and 10,779,223 shares
                                                                          10,800,000        
        unearned compensation - restricted common share awards
                                                                                  
        investment income accrued
                                                                           81,800,000 89,400,000 84,300,000 93,500,000 91,000,000 96,600,000 73,000,000 
        common shares at 1 par value per share—authorized 50,000,000 shares;issued and outstanding 10,780,053 and 10,779,223 shares
                                                                           10,800,000       
        minimum pension liability and other
                                                                                  
        total liabilities and common shareholders’ equity
                                                                           18,712,100,000 18,728,000,000 19,081,400,000 19,418,100,000 19,795,800,000 19,184,700,000  
        reinsurance recoverable on unpaid losses — berkshire hathaway inc.
                                                                            1,935,600,000      
        common shares at 1 par value per share — authorized 50,000,000 share issued and outstanding 10,780,053 and 10,779,223 shares
                                                                            10,800,000      
        accumulated other comprehensive income, after-tax
                                                                                  
        common shares at 1 par value per share - authorized 50,000,000 shares; issued and outstanding 10,780,053 and 10,779,223 shares
                                                                             10,800,000     
        common shares at 1 par value per share ­ authorized 50,000,000 shares; issued and outstanding 10,779,223 and 10,772,789 shares
                                                                              10,800,000    
        common shares at 1 par value per share - authorized 50,000,000 shares; issued and outstanding 10,773,723 and 10,772,789 shares
                                                                               10,800,000   
        minimum pension liability
                                                                                  
        common shares at 1 par value per share - authorized 50,000,000 shares; issued and outstanding 10,774,273 and 10,772,789 shares
                                                                                10,800,000  
        convertible preference shares
                                                                                  
        minority interest - mandatorily redeemable preferred stock of subsidiaries
                                                                                  
        common shares at 1 par per share– authorized 50,000,000 shares; issued and outstanding 9,007,195 and 8,351,387 shares
                                                                                 9,000,000 
        unrealized gains on investments
                                                                                 286,000,000 
        unrealized foreign currency translation losses
                                                                                  
        total liabilities, convertible preference shares, minority interest and common shareholders’ equity
                                                                                 14,971,000,000 
      Cashflow Statements:
      Quarterly
      Annual
        Unit: USD2026-03-31 2025-03-31 2024-12-31 2024-09-30 2024-06-30 2024-03-31 2023-12-31 2023-09-30 2023-06-30 2023-03-31 2022-12-31 2022-09-30 2022-06-30 2022-03-31 2021-12-31 2021-03-31 2020-12-31 2020-09-30 2019-12-31 2019-09-30 2019-06-30 2019-03-31 2018-12-31 2018-09-30 2018-06-30 2018-03-31 2017-12-31 2017-09-30 2017-06-30 2017-03-31 2016-12-31 2016-09-30 2016-06-30 2016-03-31 2015-12-31 2015-09-30 2015-06-30 2015-03-31 2014-09-30 2014-06-30 2014-03-31 2013-12-31 2013-09-30 2013-06-30 2013-03-31 2012-09-30 2012-06-30 2012-03-31 2011-12-31 2011-09-30 2011-06-30 2011-03-31 2010-12-31 2010-09-30 2010-06-30 2010-03-31 2009-12-31 2009-09-30 2009-06-30 2009-03-31 2008-12-31 2008-09-30 2008-06-30 2008-03-31 2007-06-30 2007-03-31 2006-12-31 2006-09-30 2006-06-30 2006-03-31 2005-12-31 2005-09-30 
                                                                                
          cash flows from operations:
                                                                                
          net income
        -26,300,000 62,800,000 -124,400,000 227,900,000 -41,200,000 221,800,000 362,700,000 13,800,000 17,200,000 187,200,000 61,500,000 869,500,000 -210,200,000 -8,400,000 40,000,000  473,400,000 222,000,000 45,300,000 43,200,000 15,900,000 272,200,000 -140,500,000 30,600,000 -14,900,000 -66,600,000 12,000,000 544,700,000 3,400,000 33,000,000 -50,600,000 88,600,000 362,500,000 19,300,000 274,000,000 -74,900,000 3,400,000 77,000,000 40,300,000 100,200,000 95,100,000 118,200,000 56,100,000 15,200,000 119,900,000 -11,600,000 38,200,000 110,600,000 820,500,000 -26,800,000 32,500,000 -16,800,000 89,500,000 75,000,000 13,200,000 -38,200,000    30,300,000 -212,600,000 -276,700,000 -9,200,000 -56,800,000 102,600,000 92,200,000 299,300,000 162,100,000 115,800,000 96,000,000 33,300,000 -66,300,000 
          adjustments to reconcile net income to net cash from operations:
                                                                                
          net realized and unrealized investment losses
        -10,800,000 -86,600,000 83,800,000   -16,200,000 -217,000,000 11,500,000 -88,700,000 -112,900,000  29,400,000    -1,100,000         -10,500,000 53,700,000                                  23,300,000             
          net realized and unrealized investment losses from investment in mediaalpha
        65,200,000 36,600,000 121,700,000   -210,700,000 -66,000,000 46,800,000 77,300,000 -85,200,000  18,600,000    41,700,000                                                         
          net gain on sale of the bamboo group
        -2,400,000                                                                        
          change in fair value of ark’s contingent consideration
        10,000,000                                                                        
          interest income from bam surplus notes
        -6,900,000                                                                        
          deferred income tax expense
        4,200,000 1,700,000 7,400,000 4,100,000 9,400,000 -9,800,000 -48,800,000 6,400,000 -900,000 -3,600,000 -9,200,000 18,100,000 -600,000 4,600,000 -200,000 -1,400,000               -9,600,000 -300,000 7,500,000 5,300,000   -10,400,000 12,200,000 -2,900,000 900,000 21,700,000 34,300,000 -2,800,000 -17,600,000 25,800,000 18,500,000 5,600,000 26,300,000                         
          amortization of restricted share awards
        4,100,000 3,800,000 4,500,000 4,300,000 4,300,000 3,200,000 4,100,000 4,000,000 4,100,000 3,100,000 3,700,000 3,800,000 3,600,000 2,900,000                                                           
          amortization and depreciation
        4,800,000 1,100,000 1,100,000   -2,100,000 -7,500,000 -5,300,000 -2,600,000 -2,400,000 -2,700,000 -1,400,000 -7,600,000 16,000,000 20,700,000 12,800,000 16,200,000 9,800,000 10,000,000 7,800,000 3,700,000 8,300,000 7,300,000 9,600,000 4,000,000 4,800,000 -3,500,000 6,700,000 4,600,000 14,600,000 29,800,000 12,200,000 5,100,000 17,400,000 20,700,000 1,800,000 22,800,000 22,200,000                                   
          other operating items:
                                                                                
          net change in reinsurance recoverables
        -343,200,000 -331,400,000 159,000,000 115,800,000 -168,800,000 -253,000,000 96,400,000 131,300,000 -99,100,000 24,700,000 14,800,000 -152,200,000 14,000,000 35,700,000 17,200,000 -15,700,000                                                         
          net change in insurance premiums, commissions and fees receivable
        -455,600,000 -504,200,000 249,600,000 151,500,000 -210,900,000 -394,900,000                                                                   
          net change in deferred acquisition costs
        -89,500,000 -114,500,000 31,100,000 43,400,000 -32,800,000 -68,800,000  52,300,000 -24,100,000 -82,200,000  40,000,000 -13,400,000 -71,600,000 18,200,000 -51,300,000 -1,800,000 -1,100,000 -700,000 -900,000 -900,000 -600,000 -1,400,000 -400,000 -1,300,000 -1,100,000 -700,000 -1,100,000 1,100,000 -3,500,000 2,700,000 4,300,000 -4,100,000 -2,200,000 3,200,000 20,000,000 -3,400,000 -20,200,000 -19,800,000 -1,200,000 -15,300,000 9,500,000 -4,900,000 8,000,000 4,500,000 -8,000,000       30,900,000 8,900,000 10,900,000 4,800,000        7,700,000         
          net change in loss and loss adjustment expense reserves
        103,200,000 133,100,000 -1,400,000 248,200,000 153,800,000 142,400,000 33,300,000 150,800,000 75,400,000 49,100,000 -32,900,000 307,300,000 22,500,000 104,900,000 3,800,000 56,000,000              2,900,000 2,600,000 -14,300,000 32,700,000 -46,200,000 -37,500,000 163,000,000 -40,400,000 -39,300,000 42,000,000 4,900,000 -44,600,000 -69,500,000 4,300,000 -13,200,000 -86,200,000 123,900,000   -209,300,000      -113,700,000 279,200,000                815,300,000 
          net change in unearned insurance premiums
        589,200,000 650,300,000 -284,100,000 -357,500,000 316,600,000 499,400,000 -227,500,000 -383,300,000 256,900,000 501,800,000 -146,500,000 -226,600,000 144,200,000 388,200,000 -91,400,000 245,500,000 10,500,000 8,400,000 8,300,000 15,700,000 8,200,000 3,600,000 19,800,000 700,000 15,300,000 3,400,000 18,300,000 8,600,000 6,900,000 20,700,000 -16,500,000 54,100,000 -5,000,000 13,900,000 -58,700,000                                      
          net change in reinsurance payable
        324,100,000 236,300,000 -80,700,000 -137,100,000 104,800,000 181,400,000 -65,200,000 -100,700,000 54,000,000 -58,100,000 -61,600,000 -106,100,000 69,900,000 -75,200,000 -57,400,000 -40,700,000                                                         
          net change in premiums and commissions payable
        -5,000,000 -1,900,000 -5,600,000 14,900,000 17,100,000 12,500,000                                                                   
          net change in accrued incentive compensation from other operations
        -52,100,000 -51,100,000                                                                       
          contributions to kudu’s participation contracts
        -25,400,000 -68,000,000 -103,300,000   -55,500,000 -26,700,000 -50,700,000 -30,900,000                                                               
          net other operating activities
        -57,100,000 -10,400,000 -21,600,000 55,300,000 -15,500,000 -68,700,000 -47,200,000 38,900,000                                                                 
          net cash from operations
        30,500,000 -40,200,000 64,100,000   36,500,000 24,500,000 222,900,000 71,100,000 85,600,000  117,000,000    -92,800,000              -56,100,000   -94,800,000 -92,400,000   22,000,000 -57,700,000  4,800,000 -47,200,000 -30,200,000 193,600,000 -39,500,000 -224,900,000                            
          capital expenditures
                                                           
          free cash flows
        30,500,000 -40,200,000 64,100,000   36,500,000 24,500,000 222,900,000 71,100,000 85,600,000  117,000,000    -92,800,000              -56,100,000   -94,800,000 -92,400,000   22,000,000 -57,700,000  4,800,000 -47,200,000 -30,200,000 193,600,000 -39,500,000 -224,900,000                            
          cash flows from investing activities:
                                                                                
          net change in short-term investments
        384,100,000 -52,200,000 -62,400,000 293,500,000 -124,000,000 441,300,000 -300,900,000 -152,300,000 -90,200,000 47,600,000 280,300,000 -948,000,000 68,100,000 144,500,000 141,600,000 -103,100,000 429,000,000 -454,300,000 76,400,000 -85,400,000 86,200,000 -55,300,000 99,500,000 8,100,000 440,900,000 -587,500,000 610,500,000 -715,000,000 47,200,000 55,600,000 18,600,000 119,000,000 -157,300,000 -50,400,000 113,400,000 43,700,000 69,000,000 -86,100,000 -291,100,000 111,800,000 -61,500,000 44,700,000 -34,100,000 -2,100,000 26,300,000 -299,000,000   61,900,000 -50,100,000 33,200,000 129,500,000 233,800,000   12,100,000   142,500,000 89,800,000             
          sales of fixed maturity investments
        145,100,000 96,700,000 108,600,000 58,700,000 76,400,000 185,800,000 87,200,000 17,400,000 35,900,000 54,600,000 -23,700,000 59,000,000 66,900,000 86,500,000                                                   1,715,400,000 1,331,700,000 1,177,800,000 1,053,700,000 1,266,800,000 1,077,900,000 1,439,700,000 1,931,500,000 
          maturities, calls and paydowns of fixed maturity investments
        143,800,000 109,700,000 93,200,000 95,000,000 146,500,000 81,800,000 53,900,000 66,300,000 79,500,000 66,800,000 91,200,000 31,700,000 36,600,000 39,000,000                                                   213,300,000 333,200,000 220,500,000 168,100,000 222,100,000 223,200,000   
          sales of common equity securities and investment in mediaalpha
        35,600,000 120,700,000                                                                     
          distributions and redemptions of other long-term investments
        6,300,000 21,900,000 25,800,000 53,800,000 24,600,000 91,500,000 90,100,000 8,100,000 16,700,000 2,000,000 60,400,000 8,500,000                  16,500,000 9,100,000 9,700,000 7,100,000 3,000,000 28,100,000 500,000 49,700,000 6,400,000 18,200,000 3,000,000 23,900,000 21,500,000 13,300,000 2,400,000 20,900,000 900,000 8,900,000 11,100,000 60,700,000 12,100,000 23,900,000 54,000,000 106,700,000 18,900,000 -400,000 8,000,000 52,400,000                
          release of cash (pre-funding) of investment purchases
        30,000,000                                                                        
          proceeds from the sale of bamboo group
        6,000,000                                                                        
          purchases of fixed maturity investments
        -425,400,000 -222,500,000 -335,500,000 -609,400,000 -315,300,000 -417,300,000 -199,800,000 -152,400,000 -112,900,000 -127,600,000 -111,400,000 -143,300,000 -215,800,000 -115,000,000                                                           
          purchases of common equity securities and investment in mediaalpha
        -123,900,000     -10,000,000                                                                 
          purchases of other long-term investments
        -217,700,000 -39,700,000 -32,000,000 -48,300,000 -30,000,000 -79,900,000 -27,500,000 -21,800,000 -69,800,000 -146,100,000 -41,900,000 -86,500,000 -29,000,000 -21,400,000 -11,500,000 -101,000,000 -15,800,000 -18,700,000 -4,700,000 -3,900,000 -108,500,000 -60,600,000 -30,000,000 -18,800,000 -1,100,000 -46,000,000 -16,400,000 -12,600,000 -32,700,000 -22,400,000 -2,200,000 -24,000,000 -2,400,000 -10,900,000  2,800,000 -23,800,000 -9,500,000 -13,900,000 -4,700,000 -13,000,000  -9,800,000 -4,500,000 -17,400,000 -14,900,000                           
          net other investing activities
        -13,700,000 -27,300,000 22,900,000 -28,700,000 -14,300,000 29,200,000 6,400,000 1,800,000 -400,000 -11,200,000                                                               
          net cash from investing activities
        -29,800,000 7,300,000 -163,200,000   100,600,000 -88,900,000 -232,200,000 -126,200,000 -96,600,000  234,300,000                                                        -128,500,000 -11,800,000 168,300,000   
          cash flows from financing activities:
                                                                                
          draw down of debt and revolving lines of credit
        6,400,000 116,300,000 21,100,000    200,000                                                                  
          repayment of debt and revolving lines of credit
        -8,700,000 -1,000,000 -1,400,000 -2,600,000 -1,500,000 -32,600,000 -1,400,000                                                                  
          cash dividends paid to common shareholders
        -2,400,000 -2,600,000 -2,500,000 -2,600,000                                                               
          repurchases and retirements of common shares
        -25,900,000 -9,900,000 200,000 -8,100,000                                                                  
          contributions from other noncontrolling interests
        700,000 600,000                                                                       
          distributions to other noncontrolling interests
        -19,400,000 -41,100,000                                                                       
          net other financing activities
         16,200,000 8,200,000 -7,400,000   -200,000 -100,000                                                                 
          net cash from financing activities
        -49,300,000 78,500,000 19,500,000   -34,200,000  17,600,000 6,900,000 -41,300,000  -487,600,000    6,500,000      105,500,000 47,900,000 4,900,000 -457,500,000 -9,600,000 25,700,000 -713,500,000 -2,300,000 -8,900,000 -19,500,000 -323,900,000 -500,200,000 -98,800,000 -51,600,000 -118,900,000 -31,800,000 -12,300,000 -80,000,000 -32,100,000 -21,100,000 -9,400,000 -2,100,000 -8,000,000 -167,000,000 -31,500,000                           
          net change in cash during the period
        -48,600,000 45,600,000  90,800,000 29,900,000 102,900,000                               26,500,000 -42,700,000 216,500,000 -13,200,000 -10,300,000 -9,900,000 49,500,000 64,100,000 10,400,000 -246,100,000                           
          cash balance at beginning of period
        185,600,000 266,400,000                                                                       
          cash balance at end of period
        137,000,000 312,000,000                                                                       
          supplemental cash flows information:
                                                                                
          interest paid
        -18,100,000 -15,900,000  -15,000,000 -14,700,000 -16,700,000  -6,400,000 -5,800,000 -5,800,000  -4,600,000 2,100,000 -8,400,000  -7,500,000  -4,700,000  -4,400,000 -3,600,000 -3,700,000  -4,600,000 -400,000 -300,000  -100,000 -200,000 -200,000  -6,500,000 1,100,000 -1,600,000  12,900,000 -9,000,000 -12,800,000 -22,200,000 -6,300,000 -12,800,000  -12,700,000 -6,400,000 -12,900,000 -500,000 -8,100,000 -12,800,000  -14,800,000 -10,900,000 -12,800,000  -18,700,000 -17,700,000 -13,200,000  -14,900,000 -28,500,000 -14,800,000  -15,400,000 -24,600,000 -14,000,000 -21,800,000 -7,200,000  46,400,000 -21,600,000 -900,000  43,200,000 
          net income tax payments
        -3,700,000 -3,500,000  -4,800,000 -9,100,000 -5,300,000  -2,100,000 -10,000,000 -17,800,000  600,000 -3,500,000 -300,000  -1,400,000                                                         
          interest income from bam surplus notes subsequent to deconsolidation, net of interest payments received of 10.8 and 5.8
                                                                                
          change in fair value of bam surplus notes
          15,300,000                                                                      
          unrealized loss on deconsolidation of bam
                                                                               
          proceeds from kudu’s participation contracts sold
            600,000 11,700,000 62,900,000                                                               
          proceeds from the sale of bamboo group, nsm group and other operating businesses, net of cash sold of 135.0, 0.0 and 0.8
                                                                                
          purchases of consolidated subsidiaries, net of cash acquired of 1.9, 44.9 and 0.0
                                                                                
          payments of principal received on the bam surplus notes subsequent to deconsolidation
                                                                                
          impact to cash from deconsolidation of bam
                                                                               
          bam member surplus contributions prior to deconsolidation
                                                                                
          cash balance at beginning of year
                                                                                
          cash balance at end of year
                                                                                
          change in fair value of contingent consideration - ark
         9,700,000 13,800,000 34,200,000                                                                     
          interest income from bam surplus notes subsequent to deconsolidation
         -7,500,000                                                                       
          purchases of consolidated subsidiaries, net of cash acquired of 0.0 and 44.9
                                                                                
          interest income from bam surplus notes subsequent to deconsolidation, net of interest payments received of 5.8
                                                                                
          net loss from discontinued operation, net of tax - nsm group
                                                                                
          net loss from sale of discontinued operations, net of tax - nsm group
                                                                                
          net cash from operations - continuing operations
              24,500,000 222,900,000 71,100,000 85,600,000  115,000,000          -41,100,000  -5,000,000 19,300,000 -44,800,000  1,800,000 -10,100,000 -56,100,000   -102,400,000 -41,700,000   22,600,000 -65,600,000  20,900,000 -32,600,000   -7,400,000 -184,200,000                            
          net cash from operations - nsm group discontinued operations
                   2,000,000                                                             
          proceeds from the sale of nsm group and other operating businesses, net of cash sold of 0.0, 0.8 and 144.4
                                                                                
          purchases of consolidated subsidiaries, net of cash acquired of 44.9, 0.0, and 0.3
                                                                                
          release of cash (pre-funding) for ils funds managed by elementum
                                                                                
          net cash from investing activities - continuing operations
              -88,900,000 -232,200,000 -126,200,000 -96,600,000  234,300,000                                                             
          net cash from investing activities - nsm group discontinued operations
                                                                               
          net (contributions to) distributions from discontinued operations
                                                                                
          net cash from financing activities - continuing operations
              24,000,000 17,600,000 6,900,000 -41,300,000  -487,000,000          105,500,000  4,900,000 -457,500,000 -9,600,000    -8,900,000  -314,700,000 -506,800,000 -101,200,000  -116,500,000 -31,800,000 -12,300,000 -80,000,000 -32,100,000 -21,100,000  -2,100,000 -8,000,000 -167,000,000 -31,500,000                           
          net cash from financing activities - nsm group discontinued operations
                   -600,000                                                             
          net change in cash during the period - continuing operations
              -40,400,000 8,300,000 -48,200,000 -52,300,000 9,300,000 -137,700,000           -2,500,000 -18,300,000 10,900,000 23,100,000 48,500,000 -4,700,000 -2,100,000 -25,700,000 -97,800,000 112,900,000 -29,700,000 -3,100,000 -9,700,000                                      
          cash balance at end of year (includes restricted cash balances of 73.6, 0.7 and 18.3 and excludes discontinued operations cash balances of 0.0, 0.0 and 0.0
                                                                                
          proceeds from the sale of other operating businesses, net of cash sold of 0.0 and 0.8
                                                                                
          purchases of consolidated subsidiaries, net of cash acquired of 44.9 and 0.0
           -231,800,000                                                                   
          bam member surplus contributions prior to the deconsolidation of bam
                                                                                
          net contributions from (distributions to) other noncontrolling interests
           -1,400,000 -11,200,000 1,100,000 2,300,000 2,200,000 -5,800,000 -1,700,000                                                               
          cash balances at beginning of period
           122,400,000  255,000,000  -111,600,000 259,300,000  211,200,000   110,300,000  97,100,000  -69,600,000 149,800,000  -6,300,000 173,500,000  -111,500,000 349,500,000 326,700,000  212,600,000 251,900,000  -4,600,000 -39,800,000 148,100,000  148,900,000  183,900,000  -8,500,000 171,300,000 159,000,000  187,700,000  
          cash balances at end of period
           90,800,000 29,900,000 225,300,000  8,300,000 -48,200,000 202,700,000  -137,700,000 56,300,000 327,100,000  488,500,000  3,500,000  -1,100,000 18,100,000 132,200,000  -18,900,000 10,900,000 120,200,000  -4,700,000 -71,700,000 125,000,000  109,700,000 -35,400,000 170,400,000  -150,100,000 26,500,000 306,800,000 216,500,000 -13,200,000 316,400,000  49,500,000 64,100,000 223,000,000 -244,100,000 206,300,000 245,300,000  26,600,000 -17,100,000 154,900,000  -25,300,000 16,200,000 137,200,000  -79,200,000 -83,500,000 318,100,000  -9,500,000 -50,100,000 229,600,000 -13,400,000 186,300,000  18,700,000 8,500,000 183,100,000  1,400,000 
          adjustments to reconcile net income to net cash provided from (used for) operations:
                                                                                
          net realized and unrealized investment (gains) losses
                     8,400,000       -35,200,000 -245,600,000        -51,300,000                                           
          net realized and unrealized investment (gains) losses from investment in mediaalpha
                     -18,800,000                                                           
          amortization (accretion) and depreciation
                                                                                
          net cash provided from (used for) operations
                     -41,500,000             2,000,000 71,500,000                                             
          net cash provided from (used for) investing activities
                     139,800,000   36,600,000 -61,000,000                                          145,600,000             
          bam member surplus contributions
            14,600,000 11,400,000 26,400,000 19,900,000 14,700,000 11,800,000                                                               
          fidus re premium payments
            -3,400,000 -3,500,000 -3,300,000 -3,400,000 -3,400,000 -3,500,000                                                               
          net cash provided from (used for) financing activities
                     -31,100,000     57,800,000 21,700,000                                             191,100,000 32,500,000       
          net loss from sale of discontinued operations, net of tax - sirius group
                                                                                
          net change in insurance premiums receivable
              169,400,000 296,500,000 -167,600,000 -365,300,000 154,500,000 196,500,000 -135,200,000 -343,600,000 66,400,000 -199,700,000              2,700,000 35,200,000 -23,800,000 -8,500,000 -11,000,000 49,800,000                                      
          net change in deferred acquisition costs and value of in-force business acquired
                                                                                
          proceeds from the sale of nsm group and other operating businesses, net of cash sold of 0.8, 144.4 and 0.0
                                                                                
          release of cash pre-funded/placed in escrow for ark transaction
                      646,300,000                                                         
          purchases of common equity securities
                  -336,500,000 -49,900,000 -100,000 -38,000,000 -83,700,000 -68,800,000 -100,000 -25,000,000 -100,000 -100,000 -4,600,000 -75,300,000 -89,800,000 -53,800,000 -109,400,000 -62,600,000 -136,700,000 -568,500,000 -113,400,000 -288,600,000 -108,300,000 -55,300,000 -86,100,000 -80,500,000 211,800,000 -491,700,000 -49,500,000 -39,400,000 -59,000,000 -65,000,000 -74,600,000 -105,700,000 -108,600,000 -143,300,000 -58,700,000                           
          purchases of consolidated subsidiaries, net of cash acquired of 0.0, 0.3, and 52.2
                                                                                
          issuances of shares to noncontrolling interests
                                                                                
          net cash from financing activities – continuing operations
                                                                                
          cash balance at end of year (includes restricted cash balances of 0.7, 18.3 and 4.5 and excludes discontinued operations cash balances of 0.0, 0.0 and 111.6
                                                                                
          net change in restricted cash
               -13,400,000 400,000 800,000 3,300,000 1,600,000 1,800,000 1,000,000 -3,000,000 4,800,000 -4,500,000 -13,400,000 -10,700,000 -21,800,000 28,000,000 10,800,000 8,700,000        8,400,000 -2,600,000 11,000,000 4,100,000 8,100,000 -5,300,000 4,000,000 -5,600,000 33,900,000 18,300,000                               
          sales of common equity securities
               10,700,000       160,300,000 205,000,000 474,900,000 25,100,000 82,000,000 223,600,000 136,500,000 40,100,000 10,800,000 104,600,000 14,400,000 16,300,000 223,900,000 166,200,000 17,700,000 239,700,000 109,800,000 83,800,000 767,500,000 90,800,000 -206,000,000 496,600,000 80,000,000 217,100,000 64,200,000 63,400,000 108,600,000 64,300,000 166,300,000 181,900,000 40,900,000 36,600,000 22,200,000 112,400,000 40,500,000 24,200,000 60,700,000 60,200,000 15,700,000 80,000,000 15,900,000 7,700,000 4,900,000 104,500,000 192,600,000  118,200,000 110,900,000 138,400,000 131,900,000 136,100,000  305,400,000 189,500,000 62,800,000   
          proceeds from the sale of nsm group and other operating businesses, net of cash sold of 0.8 and 144.4
                                                                                
          purchases of consolidated subsidiaries, net of cash acquired of 0.0 and 0.3
                                                                                
          proceeds from the sale of other businesses, net of cash sold of 0.8 and 0.0
                17,300,000                                                               
          draw down of debt and revolving line of credit
                   8,800,000 188,000,000 15,000,000  105,300,000  57,000,000 42,900,000 106,500,000 33,200,000   15,000,000 350,000,000   250,000,000 -4,500,000 107,000,000 61,500,000 114,500,000 15,000,000 4,500,000                                   
          repayment of debt and revolving line of credit
                -3,100,000 -20,000,000  -8,100,000 12,400,000 -14,800,000  -93,700,000  -1,600,000 -700,000 -500,000 -6,900,000 -14,800,000 -4,200,000 -5,100,000 -3,800,000 -2,300,000 -400,000 -351,300,000 -12,100,000 -1,200,000 -2,800,000 -251,300,000 -135,400,000 -15,100,000 -2,700,000 -75,300,000 -16,300,000 -1,300,000                                   
          common shares repurchased
                -7,400,000 -25,300,000  -508,900,000 -66,800,000 -34,800,000 -13,000,000      -7,200,000      -20,300,000 -319,500,000 -374,600,000 -166,900,000 -100,000,000 -151,500,000 -12,800,000 -4,300,000 -74,900,000 -14,800,000 -10,900,000 -800,000 -79,000,000 -26,500,000                           
          acquisition of subsidiary shares from non-controlling interest shareholders
                                                                               
          net change in other assets and liabilities
                 -3,400,000 127,700,000 9,000,000 17,100,000 -63,400,000 -21,900,000 -34,700,000 39,000,000 51,100,000 12,800,000 13,700,000 25,400,000 -33,200,000 -25,300,000 15,300,000 24,200,000 -41,300,000 700,000 16,600,000 25,900,000 -64,000,000 -75,800,000 -30,200,000 -88,900,000 -31,800,000 4,500,000 81,500,000 9,400,000 -55,300,000 163,500,000 66,600,000 -77,000,000 -25,400,000 -1,300,000 114,600,000 -24,700,000 14,400,000 18,200,000 35,800,000  109,400,000       -145,600,000   24,200,000       36,800,000      
          net (income) income from discontinued operation, net of tax - nsm group
                                                                                
          net (gain) income from sale of discontinued operations, net of tax - nsm group
                                                                                
          net (gain) income from sale of discontinued operations, net of tax - sirius group
                                                                                
          net change in ceded unearned premiums
                  500,000 45,700,000 -18,600,000 -19,700,000 25,000,000 24,800,000              -8,200,000  -600,000 1,800,000 -6,800,000  59,200,000 -21,100,000 -61,500,000 14,300,000 11,000,000 -60,600,000  23,900,000 -2,100,000 -52,400,000 27,800,000    28,500,000 46,200,000 1,800,000                     
          proceeds from kudu participation contracts sold
                                                                                
          contributions to kudu participation contracts
                                                                                
          net cash provided from (used for) operations - continuing operations
                                                                                
          net cash provided from
                                                                                
          proceeds from the sale of nsm group, net of cash sold of 143.9, 0.0 and 0.0
                                                                                
          proceeds from the sale of other operating businesses, net of cash sold of 0.5 0.0 and 0.0
                                                                                
          cash pre-funded for ils funds managed by elementum
                                                                                
          purchases of consolidated subsidiaries, net of cash acquired of 0.3, 52.2, and 1.5
                                                                                
          net cash provided from (used for) investing activities - continuing operations
                                         139,800,000                                       
          issuances of shares to non-controlling interests
                                                                                
          bam member surplus contribution
                                                                                
          net contributions from (distributions to) other non-controlling interests
                                                                                
          other financing activities
                  500,000 -300,000 2,400,000 -4,200,000 -4,600,000 300,000         -100,000 -1,600,000 -7,600,000                                           
          net cash provided from (used for) financing activities - continuing operations
                                                                                
          net cash provided from (used for) financing activities – continuing operations
                                                                                
          cash balance at end of year (includes restricted cash balances of 12.2, 4.5 and 0.0 and excludes discontinued operations cash balances of 0.0, 111.6 and 126.6
                                                                                
          millions
                        2,019,000,000  2,018,000,000           2,015,000,000 2,014,000,000  2,013,000,000 2,012,000,000  2,011,000,000    2,010,000,000  2,009,000,000   2,008,000,000 2,007,000,000       
          investments
                     594,300,000                                                           
          cash
                     52,000,000                                                           
          reinsurance recoverables
                     433,400,000                                                           
          insurance premiums receivable
                     236,700,000                                                           
          ceded unearned premiums
                     170,200,000                                                           
          value of in-force business acquired
                     71,700,000                                                           
          other assets
                     88,900,000                                                           
          loss and loss adjustment expense reserves
                     -696,000,000                                                           
          unearned insurance premiums
                     -326,100,000                                                           
          debt
                     -46,400,000                                                           
          ceded reinsurance payable
                     -528,300,000                                                           
          other liabilities
                     -25,900,000                                                           
          net tangible assets acquired
                     24,500,000                                                           
          goodwill
                     116,800,000                                                           
          other intangible assets - syndicate underwriting capacity
                     175,700,000                                                           
          deferred tax liability on other intangible assets
                     -33,400,000                                                           
          net assets acquired
                     283,600,000                                                           
          net loss from sale of discontinued operations, net of tax - nsm group and sirius group
                                                                                
          investments in kudu participation contracts
                   -45,100,000    -11,000,000  -100,000                                                       
          proceeds from the sale of nsm group, net of cash sold of 143.9 and 0.0
                                                                                
          proceeds from the sale of other operations, net of cash sold of 0.5 and 0.0
                                                                                
          purchases of consolidated subsidiaries, net of cash acquired of 0.3 and 52.2
                                                                               
          other investing activities
                   -2,000,000 1,300,000 4,400,000 5,200,000 60,900,000 41,600,000 -26,700,000 -14,400,000 82,900,000 -78,400,000 -17,400,000 -38,000,000                                                  
          cash dividends paid to the company’s common shareholders
                   -3,000,000 100,000 -3,100,000 -3,200,000 -3,800,000 -4,600,000 -5,400,000 -6,000,000 -6,200,000 -6,200,000                           
          net distributions from non-controlling interest shareholders
                   -2,700,000                                                             
          contributions from discontinued operations
                                  15,100,000                                             
          capital contributions from bam members
                   26,000,000 24,000,000 12,300,000 17,400,000 13,800,000 22,000,000 15,400,000 11,700,000 23,000,000 12,000,000 7,900,000 26,900,000 12,100,000 9,900,000 4,900,000 11,700,000 8,400,000 7,700,000 9,600,000 9,800,000 11,500,000 10,000,000 6,700,000 8,900,000 8,800,000 6,900,000 4,600,000 3,900,000 2,900,000 4,800,000 5,600,000 3,500,000                              
          acquisition of subsidiary shares by non-controlling interest shareholders
                     400,000                                                          
          fidus re premium payment
                   -1,800,000 -1,900,000 -1,900,000  -3,200,000  -700,000 -800,000 -700,000 -800,000 -700,000 -700,000 -600,000                                                 
          net loss from nsm group discontinued operation, net of tax
                                                                                
          net loss from sale of sirius group, net of tax
                                                                                
          proceeds from the sale of consolidated subsidiaries, net of cash sold of 0.0 and 0.0
                                                                                
          net (gain) income from sale of discontinued operations, net of tax
                          800,000      -100,000                                               
          net change in premiums and commissions receivable
                     -12,600,000   -9,100,000 9,000,000                                                       
          net change in premiums payable
                     10,100,000 3,300,000 2,600,000 -3,500,000 -22,800,000                                                       
          distributions and redemptions of other long-term investments and settlements of forward contracts
                     39,800,000 8,200,000 40,100,000 5,400,000 400,000  24,900,000 1,900,000 1,900,000  1,200,000 200,000 -6,900,000                                               
          purchases of consolidated subsidiaries, net of cash acquired of — and 52.0
                                                                                
          net contributions from non-controlling interest shareholders
                     300,000 -500,000                                                          
          contingent consideration payments related to acquisitions of subsidiaries
                       -6,700,000                                                         
          effect of exchange rate changes on cash
                     600,000 -400,000 -300,000 -2,600,000 900,000 1,400,000 -600,000 -500,000 300,000              6,400,000 -8,500,000 -13,800,000 3,400,000 -200,000 -1,200,000 3,700,000 -2,100,000 -600,000 3,800,000 -2,500,000 1,700,000   100,000 2,300,000 2,100,000    3,300,000     700,000 3,100,000   2,600,000 600,000 3,400,000 1,800,000   
          net change in cash during the period - continuing operations, including the effect of exchange rate changes
                     67,800,000 -51,400,000 277,300,000 -3,600,000 3,500,000  -1,100,000 18,100,000 21,900,000                                                   
          net realized and unrealized investment losses from mediaalpha
                                                                                
          realized loss from the 2019 mediaalpha transaction
                                                                                
          net loss from sale of discontinued operations, net of tax
                                                                                
          net change in commissions receivable
                      -6,200,000 -200,000                                                         
          net change in investments in kudu participation contracts
                                                                                
          purchases of fixed maturity and convertible investments
                      -220,700,000 -411,100,000 -126,400,000 -117,900,000 -111,200,000 -130,600,000 -145,100,000 -152,300,000 -137,100,000 -141,500,000 -154,500,000 -537,100,000 -1,175,400,000 -412,500,000 180,300,000 -957,600,000 -1,367,900,000 -968,000,000 -3,151,800,000 -315,200,000                                       
          purchases of consolidated subsidiaries, net of cash acquired of 52.2, 13.4, and 12.8 and including restricted cash of 0.0, 8.4, 0.0
                                                                                
          proceeds from issuance of shares to non-controlling interest shareholders
                          62,700,000                                                   
          contingent considerations related to acquisition of subsidiaries
                                                                                
          net realized and unrealized investment gains
                                   -32,500,000     -28,100,000 -29,500,000   61,100,000 -103,400,000 -20,800,000 -113,900,000 -63,800,000 -95,600,000 -28,200,000 37,300,000 -75,200,000 -72,700,000                           
          net realized and unrealized investment loss (gains) from investment in mediaalpha
                                                                                
          amortization of restricted share and option awards
                       4,000,000  3,500,000 2,200,000 2,900,000 2,600,000 2,800,000 3,300,000 3,200,000 3,300,000 3,200,000                                               
          net cash provided from operations
                                                                                
          sales of fixed maturity and convertible investments
                       97,800,000  49,000,000 41,700,000 51,100,000 148,500,000 93,000,000 80,000,000 186,900,000 315,100,000 1,266,500,000 493,200,000 431,500,000 331,200,000 868,500,000 995,300,000 979,900,000 1,251,200,000 202,300,000                                       
          maturities, calls and paydowns of fixed maturity and convertible investments
                       31,400,000  41,500,000 26,600,000 31,200,000 35,900,000 25,600,000 16,600,000 27,400,000 56,400,000 40,600,000 34,800,000 64,800,000 -62,000,000 175,800,000 196,600,000 213,800,000 160,600,000 155,900,000                                       
          purchases of consolidated subsidiaries, net of cash acquired of 52.2 and 13.4
                                                                                
          net cash (used to) provided from investing activities
                                                                                
          net cash provided from financing activities
                         12,500,000                                          23,000,000    341,100,000         
          net loss
                       -110,500,000                                                         
          net gain from sale of discontinued operations, net of tax
                       -18,700,000 1,500,000 700,000   -700,000      -554,300,000                                             
          purchases of consolidated subsidiaries, net of cash acquired of 52.0 and 0.0
                       11,100,000                                                         
          net cash (used for) provided from investing activities
                       363,900,000   600,000 52,100,000                                                     
          distribution to non-controlling interest shareholders
                       -900,000   -100,000 -27,600,000  -1,500,000    -400,000 4,600,000 -5,100,000  -300,000    -8,100,000 -300,000 -700,000                                   
          capital contributions to non-controlling interest shareholders
                       -400,000   900,000 700,000                                                   
          net realized and unrealized investment gains from mediaalpha
                                                                                
          realized gain from the 2019 mediaalpha transaction
                                                                                
          deferred income tax (benefit) expense
                                     -1,100,000                                           
          investments in asset management firms - kudu
                          -44,000,000                                                      
          purchases of consolidated subsidiaries, net of cash acquired of 13.4, 12.8, and 90.9 and including restricted cash of 8.4, 0.0, 53.4
                                                                                
          cash pre-funded/placed in escrow for ark transaction
                                                                                
          acquisitions of additional shares from non-controlling interest
                                                                                
          repurchase of shares from non-controlling interest shareholders
                          -21,100,000                                                   
          capital contributions from non-controlling interest shareholders
                                                                                
          distributions to non-controlling interest shareholders
                                                                                
          payments to contingent considerations related to purchases of consolidated subsidiaries
                                                                                
          fixed maturity investments
                        22,000,000 -300,000 24,400,000 -300,000 200,000 8,100,000  -1,400,000 -2,000,000 10,900,000                                               
          short-term investments
                        1,000,000 3,700,000 1,300,000  -300,000 -500,000 2,600,000                                               
          investment in mediaalpha
                                                                                
          common equity securities
                        6,100,000 -1,700,000 11,000,000 -400,000 -2,500,000 5,400,000  600,000 -2,200,000 5,000,000                                               
          other long-term investments
                        -28,300,000 53,600,000 23,100,000 -1,800,000 7,200,000 1,600,000  2,600,000 -3,300,000 1,900,000                                               
          total investment income
                        60,700,000 51,600,000 62,200,000 -2,500,000 4,900,000 16,400,000  1,500,000 -8,000,000 20,400,000                                               
          third-party investment expenses
                        -900,000 -900,000 -100,000 100,000 -400,000  100,000 100,000 -700,000                                               
          net investment income
                                                                                
          realized gain from the mediaalpha transaction
                          -1,300,000 -66,200,000                                                   
          purchases of consolidated subsidiaries, net of cash acquired of 13.4 and 12.8
                                                                                
          payments on contingent consideration earnout liabilities
                         -600,000                                                       
          net investment income, pre-tax
                         51,600,000 61,300,000 -2,600,000 5,000,000 16,000,000  1,600,000 -7,900,000 19,700,000                                               
          net cash (used for) provided from operations
                             -41,100,000 -600,000 -5,100,000       -13,000,000                                          
          purchases of consolidated subsidiaries, net of cash acquired of 11.9 and 12.8
                                                                                
          net income tax refunds
                           -100,000      200,000                                               
          charges (credits) to reconcile net income to net cash provided from (used for) operations:
                                                                                
          net income from discontinued operations
                                  15,200,000       -7,300,000 -65,700,000 -15,500,000 7,900,000 -6,700,000       24,600,000                           
          net cash from continuing operations
                                                                                
          net cash provided from discontinued operations
                                                                                
          sales of unconsolidated affiliates and consolidated subsidiaries, net of cash sold
                                     -11,000,000                                          
          net settlement of investment cash flows and contributions with discontinued operations
                                100,000    -5,400,000                                          
          purchases of consolidated subsidiaries, net of cash acquired of 12.8, 90.9, and 0.0 and including restricted cash of 0.0, 53.4, 0.0
                                                                                
          net cash (used for) provided from investing activities — continuing operations
                                                                                
          net cash provided from investing activities — discontinued operations
                                                                                
          distributions from discontinued operations
                                                                                
          net cash provided from (used for) financing activities — continuing operations
                                                                                
          net cash from financing activities — discontinued operations
                                                                                
          add: cash held for sale at the beginning of period
                                     900,000                                          
          deferred income expense
                           7,400,000 -3,500,000 7,500,000                                                   
          purchases of consolidated subsidiaries, net of cash acquired of 12.8 and 71.6
                                                                               
          payments on contingent consideration earnout liability
                                                                               
          acquisition of additional subsidiary shares from non-controlling interest
                                                                               
          restricted share statutory withholding tax payments
                           -4,900,000  -8,400,000                                               
          net cash provided from operations - discontinued operations
                                                         8,000,000                       
          net cash (used for) provided from investing activities - continuing operations
                                                                                
          net cash from investing activities - discontinued operations
                                                                                
          net cash from financing activities - discontinued operations
                                   -19,900,000                                             
          purchases of consolidated subsidiaries, net of cash acquired of 0.4
                             -9,600,000                                                   
          net cash provided from investing activities - continuing operations
                             -42,800,000  -18,200,000 449,100,000 77,500,000  687,100,000 -31,700,000 39,300,000  409,600,000    -47,800,000 29,300,000 43,700,000 147,700,000 -5,400,000 43,600,000  -166,400,000 81,600,000 362,200,000 -521,200,000 178,300,000 814,900,000  8,900,000                       
          net cash provided from investing activities
                             -42,800,000 -49,200,000   77,400,000 20,800,000   39,300,000 -65,400,000 393,300,000 774,100,000 174,800,000 -49,600,000 -4,800,000 29,900,000 35,800,000 144,600,000 10,700,000 58,200,000 30,900,000 -145,700,000 113,700,000 402,900,000 -365,600,000 178,300,000 814,900,000 140,500,000 174,700,000 251,300,000 233,100,000 2,400,000 159,000,000 186,800,000 137,100,000 10,800,000 -27,900,000        137,000,000     246,600,000  
          deferred income tax benefit
                                                                                
          net gain on sale of discontinued operations
                                       -47,900,000                                         
          proceeds paid to non-controlling common shareholders from the sale of consolidated subsidiaries
                                                                               
          purchases of consolidated subsidiaries, net of cash acquired of 90.9, including 53.4 of restricted cash
                                                                                
          net change in unsettled investment purchases and sales
                                -4,300,000 42,900,000  -55,500,000 -79,100,000 -1,000,000 142,800,000 -197,400,000 46,000,000 44,300,000 -76,400,000 -16,600,000 -46,800,000 135,200,000 86,700,000 -110,400,000 52,600,000 25,300,000 -52,100,000 115,100,000 -80,800,000 -87,900,000 -128,700,000 67,100,000 -7,000,000 15,500,000 -28,200,000 66,700,000     -31,700,000 -40,900,000 56,200,000 68,600,000 -61,100,000 -45,900,000 -34,800,000 225,800,000     -80,000,000 98,400,000 -114,200,000 59,700,000 
          net cash provided from investing activities — continuing operations
                                                                                
          proceeds from issuances of common shares
                                                      -100,000   -100,000   700,000       1,600,000 200,000 500,000 100,000 800,000 
          net cash from financing activities — continuing operations
                                                                                
          less: cash held for sale at the end of period
                                      -2,900,000                                          
          gain from sale of tranzact reported in discontinued operations
                                  51,900,000                                           
          add back reclassification from continuing operations for the release of a tax valuation allowance
                                  30,200,000                                           
          increase to white mountains’s book value from sale of tranzact
                                                                              
          charges (credits) to reconcile net income to net cash from operations:
                                                                                
          deferred income benefit
                               -3,100,000 -800,000 -800,000  -2,100,000                                             
          net cash (used for) provided from operations - discontinued operations
                                                                                
          purchases of consolidated subsidiaries, net of cash acquired of 71.9
                                                                                
          net cash provided from investing activities - discontinued operations
                                       -16,300,000       -3,100,000 16,100,000 14,600,000  20,700,000 32,100,000 40,700,000                            
          add: cash held for sale, excluding discontinued operations, at the beginning of period
                                                                               
          less: cash held for sale, excluding discontinued operations, at the end of period
                                                                                
          investment income:
                                                                                
          purchases of consolidated subsidiaries, net of cash acquired
                                                                                
          net acquisitions of property and equipment
                                -2,300,000 -100,000  1,100,000 300,000 -400,000  500,000 -1,000,000 -2,700,000    -5,000,000 -4,600,000 -3,400,000 -500,000 -2,700,000 -4,200,000 -2,700,000 -3,500,000 -700,000                           
          payments of contingent consideration
                                                                                
          net cash provided from (used for) operations - discontinued operations
                                 100,000           -600,000 7,900,000                                   
          net cash provided from used for operations
                                 -44,700,000                                               
          net cash (used for) provided from investing activities - discontinued operations
                                 -100,000        35,000,000   600,000 -7,900,000                                   
          net gain on sale of unconsolidated affiliates
                                                                                
          undistributed equity in earnings from unconsolidated affiliates, after-tax
                                                                                
          purchases of consolidated affiliates and other assets
                                                                                
          distributions, settlements and redemptions of other long-term investments
                                   -600,000                                             
          purchases of unconsolidated affiliates and consolidated subsidiaries, net of cash acquired
                                                                                
          payments of contingent consideration related to purchases of consolidated subsidiaries
                                       -7,800,000                                       
          net income tax refund from national governments
                                                                               
          net income on sale of discontinued operations
                                     1,000,000                                           
          net change in reinsurance recoverable on paid and unpaid losses
                                     1,400,000 6,600,000 -2,400,000 -16,500,000 26,500,000 43,200,000 -99,300,000 16,000,000 20,000,000 -30,500,000 -11,700,000 13,900,000 9,500,000 -20,500,000 15,900,000 20,100,000 -28,800,000 86,700,000 40,200,000   97,800,000 84,400,000 104,100,000    45,900,000 8,300,000 193,300,000 39,700,000 40,100,000 32,100,000 93,600,000 76,700,000 257,600,000 167,000,000 218,700,000 178,800,000 192,900,000 147,800,000   
          net change in funds held under insurance treaties
                                     -4,300,000  15,200,000 6,000,000 -2,800,000                                       
          net cash from operations - discontinued operations
                                        7,600,000 -50,700,000     3,100,000 -16,100,000 -14,600,000  -20,700,000 -32,100,000 -40,700,000                            
          onebeacon ltd. common shares repurchased and retired
                                      -11,500,000 -1,900,000 -200,000 100,000 -1,700,000                                   
          contributions to discontinued operations
                                       -3,000,000                                       
          increase to white mountains book value from sale of tranzact
                                     82,100,000                                           
          charges (credits) to reconcile net income to net cash (used for) provided from operations:
                                                                                
          net gain on sale of consolidated and unconsolidated affiliates
                                                                                
          net income (income) from discontinued operations
                                        6,000,000 900,000       500,000                                
          net (gain) loss on sale of discontinued operations
                                                                                
          net change in ceded unearned insurance premiums
                                                                                
          net change in funds held under insurance contracts
                                                                                
          net cash (used for) provided from continuing operations
                                                                                
          net cash (used for) provided from discontinued operations
                                                                                
          purchases of consolidated and unconsolidated affiliates
                                                                                
          net (acquisitions) dispositions of property and equipment
                                                                                
          net cash provided from (used for) investing activities — continuing operations
                                                                                
          change in capital lease obligation
                                                                                
          (contributions to) distributions from discontinued operations
                                                                                
          capital contributions from non-controlling interest of consolidated lps
                                                                              
          redemptions paid to non-controlling interest of consolidated lps
                                                                              
          f-4
                                                                                
          net gain on sale of unconsolidated affiliates and consolidated subsidiaries
                                                                                
          undistributed equity in earnings from unconsolidated affiliates, net of tax
                                           -3,900,000 -6,800,000 -7,300,000 -7,000,000 -12,500,000 -13,800,000  -8,600,000 -7,100,000 -9,200,000 -7,700,000                           
          net change in funds held by ceding entities
                                           45,600,000 -34,500,000 21,400,000                                   
          net change in ceded reinsurance payable
                                       4,000,000 -8,100,000 1,300,000  -79,300,000 35,500,000 56,400,000 -16,100,000 1,400,000 78,600,000  -17,600,000 -4,900,000 75,700,000 -11,700,000 -11,300,000 54,500,000      6,000,000 55,900,000 137,000,000                 
          net cash (used for) provided from operations - continuing operations
                                                                                
          payments on capital lease obligation
                                       -400,000 -500,000 -500,000  -700,000 -1,500,000 -1,300,000 -1,400,000 -1,300,000 -1,300,000  -1,300,000 -900,000 -1,800,000                            
          cash dividends paid to onebeacon ltd.’s non-controlling common shareholders
                                       -4,700,000 -4,800,000 -4,700,000 -4,900,000 -4,900,000 -5,000,000 -4,900,000 -4,900,000 -5,000,000 -4,900,000 -5,000,000 -5,000,000 -4,900,000 -5,000,000                            
          acquisition of additional shares from non-controlling interest
                                                                               
          net cash (used for) provided from financing activities - discontinued operations
                                                                                
          net gain on sale of unconsolidated subsidiaries
                                                                                
          sales of consolidated and unconsolidated subsidiaries, net of cash sold
                                                                                
          net settlement of investment cash flows with discontinued operations
                                                                                
          purchases of consolidated and unconsolidated subsidiaries, net of cash acquired
                                        -8,100,000                                       
          net cash provided from (used for) financing activities - discontinued operations
                                                                                
          cash held for sale at the beginning of period
                                                                                
          cash held for sale at the end of period
                                                                                
          scope
                                                                                
          united states first event
                                        75,000,000                                       
          united states second event
                                        45,000,000                                       
          japan first event
                                        25,000,000                                       
          net change in variable annuity benefit guarantee liabilities
                                         -400,000 1,300,000 -2,800,000 1,500,000 -400,000 -20,100,000 -22,300,000 1,300,000 -90,900,000 -50,400,000 -57,500,000 -189,900,000 10,600,000                           
          net change in variable annuity benefit guarantee derivative instruments
                                         7,000,000  -1,200,000 11,200,000 9,400,000 9,500,000 14,800,000 -20,400,000  49,800,000                              
          funding from operational cash flows for discontinued operations
                                                                                
          transfer of proceeds from symetra sale to sirius group
                                         -559,800,000                                       
          net cash provided from financing activities - discontinued operations
                                         2,400,000                                       
          net income tax refund from (payment to) national governments
                                         13,500,000                                       
          net (gain) loss on sale of other discontinued operations
                                                                                
          net change in ceded reinsurance premiums payable
                                                                                
          net change in variable annuity benefit derivative instruments
                                                    22,500,000 88,400,000                           
          net cash provided from (used for) continuing operations
                                                                                
          net cash provided from (used for) discontinued operations
                                                                                
          sales of unconsolidated affiliates, net of cash sold and held in escrow
                                                                                
          contributions to other long-term investments
                                                                                
          funding of operational cash flows for discontinued operations
                                              3,100,000 -16,100,000 -14,600,000 21,200,000 -20,700,000 -32,100,000 -40,700,000                            
          net dispositions (acquisitions) of property and equipment
                                          -4,500,000 -15,000,000                                     
          distributions from (contributions to) discontinued operations
                                          -3,000,000                                      
          distribution to non-controlling interest shareholders of tranzact and mediaalpha
                                                                                
          net cash (used for) provided from financing activities — discontinued operations
                                                                                
          gain on sale of subsidiaries - hamer and essentia
                                                                                
          net cash provided from operations - continuing operations
                                                                                
          sales of fixed maturity and convertible fixed maturity investments
                                           -1,211,200,000 965,400,000 1,110,800,000 1,313,500,000 1,314,600,000 1,026,300,000 528,900,000 711,500,000 676,500,000 1,962,900,000 1,679,200,000 789,400,000 2,450,200,000 576,200,000 794,800,000 982,600,000 1,128,300,000 1,045,800,000 671,700,000 718,100,000 442,400,000 481,000,000 666,500,000 409,100,000 834,000,000 333,000,000 1,065,200,000 741,000,000 1,527,200,000         
          maturities, calls and paydowns of fixed maturity and convertible fixed maturity investments
                                           -6,600,000 117,900,000 138,200,000 90,700,000 87,900,000 189,700,000 85,800,000 69,700,000 134,000,000 176,300,000 112,100,000 101,700,000 194,900,000 148,300,000 189,600,000 343,100,000 482,600,000 346,500,000 314,800,000 326,200,000 846,600,000 350,300,000 312,500,000 336,800,000 249,500,000 213,300,000 219,600,000 626,500,000 359,400,000         
          sales of consolidated and unconsolidated affiliates, net of cash sold
                                             12,800,000  31,300,000                7,400,000 4,200,000         
          funding from (of) operational cash flows for discontinued operations
                                           10,200,000 -600,000 7,900,000                                   
          purchases of fixed maturity and convertible fixed maturity investments
                                           1,169,500,000 -1,187,400,000 -1,282,300,000 -1,232,600,000 -1,393,300,000 -1,138,300,000 -728,200,000 -798,600,000 -862,700,000 -1,742,500,000 -1,747,300,000                           
          purchases of consolidated and unconsolidated affiliates, net of cash acquired
                                           -30,900,000 -2,400,000 -32,200,000  -9,200,000                            
          gain on sale of subsidiary - hamer and citation
                                                                                
          net change in unearned insurance and reinsurance premiums
                                            -10,900,000 181,300,000 41,800,000 -26,700,000 217,700,000 -103,700,000 -21,100,000 -33,800,000 146,100,000 -18,300,000 10,000,000 214,900,000  11,900,000 -77,600,000 152,100,000  -87,600,000 -48,700,000 204,100,000  -90,900,000 -58,200,000 149,800,000 -103,100,000 43,900,000 9,900,000 109,200,000 -17,600,000 167,300,000  37,800,000 -25,800,000 156,200,000   
          net change in funds held under reinsurance treaties
                                            9,800,000 15,000,000 -3,900,000 700,000 54,000,000 11,700,000 9,400,000 23,700,000 -3,100,000 3,700,000 1,300,000        6,400,000                 
          net change in insurance and reinsurance premiums receivable
                                            12,700,000 -190,500,000 -1,900,000 16,800,000 -212,400,000 156,500,000 47,900,000 -12,000,000 -179,700,000 56,300,000                     95,100,000      
          cash dividends paid on sig preference shares
                                                -9,400,000                             
          collateral provided by interest rate cap counterparties
                                            600,000 -1,200,000 -900,000 -1,900,000 -2,600,000 1,100,000                               
          net income tax (payment to) refund from national governments
                                                                                
          gross beginning balance
                                            -124,800,000 3,159,800,000 4,900,000 -30,900,000 3,079,300,000  -42,700,000 -68,300,000 3,168,900,000 -181,000,000 -191,500,000 5,702,300,000  -117,400,000 -427,400,000 6,187,200,000    6,802,100,000  -260,300,000 -140,000,000 7,400,100,000   -24,100,000 8,062,100,000 -141,200,000 8,777,200,000       
          less beginning reinsurance recoverable on unpaid losses
                                            47,000,000 -483,900,000 -8,000,000 2,900,000 -428,100,000  22,200,000 18,300,000 -429,100,000 96,000,000                           
          net income and lae reserves
                                            -77,800,000 2,675,900,000 -3,100,000 -28,000,000 2,651,200,000  -20,500,000 -50,000,000 2,739,800,000 -85,000,000 -149,600,000 3,195,000,000  -6,200,000 -354,500,000 3,810,100,000    4,011,200,000  -100,600,000 -74,300,000 4,349,700,000   68,500,000 4,594,200,000 800,000 4,761,500,000       
          loss and lae reserves consolidated — ssie
                                                13,600,000                                
          loss and lae incurred relating to:
                                                                                
          current year losses
                                            33,200,000 266,800,000 22,800,000 37,900,000 240,500,000  -100,000 47,100,000 242,900,000 49,800,000 10,500,000 257,900,000  5,100,000 -247,500,000 550,200,000    719,500,000  40,900,000 -17,300,000 563,900,000   -34,900,000 618,300,000 -2,300,000 630,100,000       
          prior year losses
                                            -10,300,000 -1,400,000 -16,400,000 15,500,000 -11,200,000  3,800,000 -16,800,000 1,400,000 -6,700,000 -8,200,000 4,800,000               28,900,000 20,400,000         
          total incurred losses and lae
                                            22,900,000 265,400,000 6,400,000 53,400,000 229,300,000  3,700,000 30,300,000 244,300,000 43,100,000 2,300,000 262,700,000  -15,300,000 -234,100,000 526,500,000    703,200,000  15,200,000 -14,300,000 543,200,000   -6,000,000 638,700,000         
          foreign currency translation adjustment to loss and lae reserves
                                            29,900,000 -22,400,000 -23,000,000 -2,300,000 1,800,000  16,900,000 5,000,000 -9,600,000 24,100,000 -23,900,000 11,800,000   -11,000,000 21,100,000      -3,900,000      25,900,000 -200,000 3,700,000       
          loss and lae paid relating to:
                                                                                
          total loss and lae payments
                                            31,200,000 -320,800,000 -8,100,000 -12,600,000 -272,900,000  22,600,000 16,600,000 -307,200,000 56,500,000                           
          net ending balance
                                            6,200,000 2,598,100,000 -27,900,000 -3,100,000 2,623,200,000  22,800,000 -20,500,000 2,689,800,000 -257,400,000 -85,000,000 3,045,400,000  -148,500,000 -424,400,000 3,873,700,000    4,171,400,000  -55,300,000 -100,600,000 4,275,400,000   -43,900,000 4,662,700,000 -90,800,000 4,762,300,000       
          plus ending reinsurance recoverable on unpaid losses
                                            -9,400,000 436,900,000 -2,500,000 8,000,000 425,200,000  27,400,000 -22,200,000 410,800,000 -2,012,600,000 -96,000,000 2,465,400,000  388,100,000 -145,500,000 2,338,600,000    2,919,600,000  9,100,000 -159,700,000 2,984,700,000   -47,700,000 3,375,300,000 -180,500,000 3,873,700,000       
          gross ending balance
                                            -3,200,000 3,035,000,000 -30,400,000 4,900,000 3,048,400,000  50,200,000 -42,700,000 3,100,600,000 -2,270,000,000 -181,000,000 5,510,800,000  239,600,000 -569,900,000 6,212,300,000    7,091,000,000  -46,200,000 -260,300,000 7,260,100,000   -91,600,000 8,038,000,000 -271,300,000 8,636,000,000       
          gain on sale of subsidiary - citation
                                                                                
          net income tax (payment) refund to national governments
                                             -15,000,000                                   
          gain on sale of subsidiary - citation and essentia
                                              -700,000                                
          excess of fair value of acquired net assets over cost - ashmere
                                                                                
          draw down of revolving line of credit
                                                 50,000,000 20,000,000 50,000,000 80,000,000                            
          repayment of revolving line of credit
                                              -40,000,000   -50,000,000 -20,000,000 -50,000,000 -155,000,000                            
          purchase of interest rate cap
                                                                               
          net income tax refund (payment) to national governments
                                              6,200,000 -2,200,000 3,800,000                                
          loss and lae reserves acquired
                                                                                
          accretion of fair value adjustment to loss and lae reserves
                                              -100,000 200,000  100,000 -1,100,000 1,200,000 -100,000 -5,900,000 7,100,000  2,100,000    2,100,000  900,000 100,000 2,500,000   -100,000 4,200,000 300,000 5,100,000       
          net change in funds held by ceding companies
                                               4,700,000 12,600,000 -21,600,000 1,000,000 9,800,000 25,200,000 7,200,000      22,000,000 1,900,000   16,900,000 -3,500,000 38,900,000 19,000,000 6,000,000  -15,100,000 9,400,000 16,100,000 73,700,000 11,900,000  94,700,000 7,800,000 55,000,000   
          excess of fair value of acquired net assets over cost - american fuji
                                                  -6,900,000                            
          net (gain) loss on sale of consolidated and unconsolidated affiliates
                                                                                
          excess of fair value of acquired net assets over cost
                                                                                
          undistributed equity in (earnings) income from unconsolidated affiliates, after-tax
                                                                                
          net change in ceded unearned insurance and reinsurance premiums
                                                                                
          net cash from discontinued operations
                                                                                
          repurchase of debt
                                                                                
          issuance of debt, net of debt issuance costs
                                                                                
          net change in cash from discontinued operations
                                                                                
          cash reclassified to assets held for sale
                                                                                
          see notes to consolidated financial statements.
                                                                                
          net (income) income from discontinued operations
                                                    -500,000                            
          net income on sale of discontinued operation
                                                                                
          gain on sale of subsidiary - essentia
                                                  -23,000,000                            
          cash reclassified from assets held for sale
                                                     2,000,000                         
          net income tax payments to national governments
                                                  6,900,000 -6,200,000 -2,200,000 6,900,000 -4,700,000 -8,700,000  18,900,000 -14,500,000 -10,800,000                     
          less: beginning net income and lae reserves for onebeacon’s runoff business
                                                                                
          loss and lae reserves acquired - american fuji
                                                    21,300,000                            
          net (gain) income from discontinued operations
                                                                                
          less: beginning net income and lae reserves for onebeacon's runoff business
                                                                                
          plus: ending net income and lae reserves for onebeacon's runoff business
                                                                                
          sale of unconsolidated affiliates
                                                                                
          cash dividends paid to onebeacon ltd.’s noncontrolling common shareholders
                                                     -5,000,000                           
          less: beginning net income and lae reserves for autoone and onebeacon's runoff business
                                                                                
          plus: ending net income and lae reserves for autoone and onebeacon's runoff business
                                                                                
          loss and lae reserve balances for onebeacon's run-off business prior to september 30, 2012 and autoone prior to september 30, 2011 were not classified as held for sale. adjustment is to present loss and lae reserve activities from continuing operations.
                                                                                
          less: beginning net income and lae reserves for autoone
                                                                                
          plus: ending net income and lae reserves for autoone
                                                                                
          net income on sale of discontinued operation - autoone
                                                        1,000,000                        
          net gain on sale of discontinued operation - esurance
                                                                                
          net cash (used for) provided from operations — continuing operations
                                                                                
          net cash (used for) provided from operations — discontinued operations
                                                                                
          net cash provided from (used for) investing activities — discontinued operations
                                                                                
          repayment of debt
                                                                                
          settlement of interest rate swap associated with mortgage note
                                                                                
          capital lease obligation
                                                                                
          net cash provided from financing activities — discontinued operations
                                                                                
          net increase in cash during year
                                                                                
          net decrease in cash from discontinued operations
                                                                                
          currency
                                                                                
          swedish kronor
                                                                                
          british pound
                                                                                
          canadian dollar
                                                                                
          contribution to discontinued operations
                                                                                
          sales of consolidated and unconsolidated affiliates
                                                                                
          net cash provided from (used for) investing activities - discontinued operations
                                                         165,800,000                       
          cash dividends paid on sirius group preference shares
                                                                                
          loss and lae reserves acquired — central national
                                                                                
          loss and lae reserves sold — onebeacon personal lines
                                                                                
          cash dividends paid on white mountains re group, ltd. preference shares
                                                                                
          net increase in cash during the period
                                                          40,100,000 6,800,000       -83,500,000 134,200,000  -9,500,000 -41,600,000 58,300,000 -13,400,000 27,300,000  18,700,000     
          cash reclassified to assets held for personal lines transaction
                                                                                
          net change in ceded reinsurance premiums receivable
                                                                                
          sales of trust account investments
                                                                                
          issuance of debt
                                                                    175,800,000 475,000,000 394,400,000 417,400,000 15,000,000     
          redemption of mandatorily redeemable preferred stock
                                                                                
          cash dividends paid to mandatorily redeemable preferred shareholders
                                                                                
          cash exchanged with berkshire hathaway inc. for the company’s common shares
                                                                                
          settlement of interest rate swap
                                                                                
          net decrease in cash during the period
                                                                                
          net (income tax payments to) income tax receipts from national governments
                                                                                
          net (income tax payments to) tax receipts from national governments
                                                                                
          assets held for sale:
                                                                                
          fixed maturity investments, at fair value
                                                                                
          short-term investments, at amortized cost
                                                                                
          reinsurance recoverable on unpaid losses
                                                                                
          reinsurance recoverable on paid losses
                                                                                
          premiums receivable
                                                                                
          deferred acquisition costs
                                                                                
          net deferred tax asset
                                                                                
          total assets held for sale
                                                                                
          liabilities held for sale:
                                                                                
          loss and lae reserves
                                                                                
          unearned premiums
                                                                                
          total liabilities held for sale
                                                                                
          net assets held for sale
                                                                                
          net change in fixed maturity investments held for collateral under onebeacon’s securities lending program
                                                                                
          net change in short-term investments held for collateral under onebeacon’s securities lending program
                                                                                
          net change in onebeacon’s securities lending payable
                                                                   46,900,000             
          proceeds from option exercises
                                                               500,000      300,000 100,000         
          net cash (used for) provided from financing activities
                                                                                
          net (tax payments to) tax receipts from national governments
                                                               -5,100,000                 
          loss and lae reserves acquired-central national
                                                               17,600,000                 
          net change in loss reserves
                                                                                
          deferred income tax provision
                                                                                
          undistributed equity in earnings (losses) from unconsolidated affiliates, after-tax
                                                                                
          net change in loss and lae reserves
                                                                                
          net change in reserves for structured contracts
                                                                                
          issuance of wmre preference shares, net of issuance costs
                                                                                
          interest rate swap agreements associated with wmre senior notes
                                                                                
          company’s common shares repurchased and retired
                                                                                
          net cash (used for) financing activities
                                                                                
          swedish krona
                                                                                
          net income - white mountains and noncontrolling interests
                                                                 192,700,000               
          excess of fair value of acquired assets over cost
                                                                                
          maturities of trust account investments
                                                                     302,200,000 3,400,000 26,900,000 6,900,000       
          cash dividends paid to preferred shareholders
                                                                                
          net receipts from (payments to) national governments
                                                                 14,100,000 -7,400,000 20,600,000             
          loss and lae reserves acquired - helicon
                                                                       13,700,000         
          distributions of other long-term investments
                                                                  10,200,000 10,300,000             
          noncontrolling interest
                                                                   6,700,000             
          net realized investment losses
                                                                    421,800,000 129,000,000 4,900,000 13,000,000         
          net unrealized investment losses
                                                                    108,300,000 320,900,000 54,200,000 105,000,000         
          gain on sale of shares through initial public offering of onebeacon ltd.
                                                                                
          minority interest
                                                                        26,400,000 19,000,000       
          undistributed equity in (losses) earnings from unconsolidated affiliates, after-tax
                                                                                
          net change in funds held by ceding reinsurers
                                                                                
          sales of common equity securities and other investments
                                                                              129,300,000 131,700,000 
          sale of agri renewal rights
                                                                                
          purchases of trust account assets
                                                                                
          purchases of common equity securities and other investments
                                                                                
          interest rate swap agreements
                                                                                
          cash dividends paid to onebeacon ltd.’s minority common shareholders
                                                                                
          cash dividends paid on wmre preference shares
                                                                                
          sales of other investments
                                                                     7,200,000 2,300,000 34,900,000 57,400,000 27,600,000  26,600,000 10,600,000 12,700,000   
          sale of shares of onebeacon ltd.
                                                                        16,700,000       
          purchases of other investments
                                                                                
          issuance of white mountains re group, ltd. preference shares, net of issuance costs
                                                                                
          cash dividends paid on white mountains re group ltd. preference shares
                                                                                
          net payments to national governments
                                                                     -27,000,000           
          net realized investment gains
                                                                                
          purchases of unconsolidated affiliates
                                                                                
          interest rate swap agreement
                                                                                
          net federal income taxes (paid) received
                                                                                
          total incurred loss and lae
                                                                         613,300,000       
          gain on sale of shares of onebeacon insurance group, ltd.
                                                                                
          undistributed equity in earnings from unconsolidated insurance affiliates, after-tax
                                                                                
          net federal income tax receipts
                                                                                
          sales of renewal rights
                                                                                
          carrying value of net liability for weather derivative contracts at january 1, 2006
                                                                                
          net consideration received during the year for new contracts
                                                                                
          net payments made on contracts settled during the year
                                                                                
          net decrease in fair value on settled and unsettled contracts
                                                                                
          carrying value of net liability for weather derivative contracts at december 31, 2006
                                                                                
          net cash from (used for) operations
                                                                                
          sales of consolidated affiliate, net of cash sold
                                                                                
          sale of renewal rights
                                                                                
          net federal income taxes received
                                                                           17,500,000   
          net change in insurance and reinsurance balances receivable
                                                                                
          net decrease in short-term investments
                                                                                
          maturities of fixed maturity investments
                                                                              -125,700,000 272,100,000 
          proceeds from issuances of debt
                                                                                
          repayments of debt
                                                                                
          dividends paid on mandatorily redeemable preferred stock of subsidiaries
                                                                                
          dividends paid on common shares
                                                                                
          charges (credits) to reconcile net income to cash flows used for operations:
                                                                                
          net cash used for operations
                                                                                
          sales of consolidated affiliates, net of cash sold
                                                                                
          sale of montpelier common shares
                                                                                
          purchases of consolidated affiliates, net of cash acquired
                                                                                
          investment in unconsolidated insurance affiliate
                                                                                
          proceeds from exercise of warrants to acquire common shares
                                                                                
          net income taxes paid
                                                                                
          excess of fair value of acquired net assets over cost - sierra group
                                                                                
          sale of consolidated affiliate, net of cash sold
                                                                                
          charges (credits) to reconcile net income to cash flows from operations:
                                                                                
          cumulative effect of changes in accounting principles
                                                                                
          loss on early extinguishment of debt
                                                                                
          dividends on preferred stock subject to mandatory redemption
                                                                                
          share appreciation expense for series b warrants
                                                                                
          amortization of deferred credits and other benefits
                                                                                
          undistributed equity in earnings from unconsolidated insurance affiliates, after tax
                                                                                
          net income tax receipts
                                                                                
          net cash from operating activities
                                                                                
          net decrease (increase) in short-term investments
                                                                                
          proceeds from sales of subsidiaries and affiliates, net of cash acquired
                                                                                
          proceeds from issuances of common shares and convertible preference shares
                                                                                
          proceeds from issuances of preferred stock of subsidiaries
                                                                                
          proceeds from the issuance of warrants
                                                                                
          dividends paid on convertible preference shares
                                                                                
          common shares repurchased and retired
                                                                                
          basic earnings
                                                                                
          net income from continuing operations
                                                                                
          redemption value adjustment and dividends on convertible preference shares
                                                                                
          net income from continuing operations available to common shareholders
                                                                                
          extraordinary income items
                                                                                
          net income available to common shareholders
                                                                                
          diluted earnings
                                                                                
          other effects on diluted earnings
                                                                                
          adjusted net income available to common shareholders
                                                                                
          earnings
                                                                                
          average outstanding dilutive options and warrants to acquire common shares
                                                                                
          diluted earnings per share denominator