7Baggers

ALLETE, Inc
(NYSE:ALE) 

ALE stock logo

ALLETE, Inc. operates as an energy company. The company operates through Regulated Operations, ALLETE Clean Energy, and Corporate and Other segments. It generates electricity from coal-fired, biomass co-fired / natural gas, hydroelectric, wind, and solar. The company provides regulated utility elect...

Founded: 1906
Full Time Employees: 1,322
Sector: Utilities
Industry: Utilities-Diversified

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Quarterly
Annual
    Unit: USD2025-09-30 2025-06-30 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 2021-06-30 2021-03-31 2020-12-31 2020-09-30 2020-06-30 2020-03-31 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 2014-12-31 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 2008-03-31 
                                                                         
      millions except per share amounts
                                                                         
      operating revenue
                                      365.6 -998,198,660.3 349,600,000 314,800,000 333,800,000 -1,105,798,513.6 462,500,000 323,300,000 320,000,000 -846,098,863.2 288,900,000 260,700,000 296,500,000 -750,398,981.6 251,000,000 235,600,000 263,800,000 -705,199,038.8 248,800,000 216,400,000 240,000,000 -688,999,071.8 226,900,000 219,900,000 242,200,000 -668,899,093 224,100,000 211,200,000 233,600,000 -550,699,233.3 178,800,000 167,000,000 204,900,000 201,700,000 205,300,000 
      contracts with customers – utility
    320.2 305.1 332.8 314.1 310.5 279.8 338.3 319.2 314.3 292.2 312.6 299 322.6 308.7 329 339.7 304.8 290.4 293 266.1 255.1 200.8 265.3 256.3 254.1 249.8 282.2 270.2 261.3 257.8 270.2                                       
      contracts with customers – non-utility
    53.3 53.8 65.9 49.5 95.4 73.5 63.7 82.3 63.2 239.9 251 125.5 64.5 62.1 51.7 56.5 37.7 42.3 43.4 51.5 35.9 39.6 43.5 45.4 31.3 37.7 72.1 172.4 80.7 80.4 82                                       
      other – non-utility
    1.5 1.4 1.5 1.2 1.3 1.2 1.3 1.2 1.3 1.3 1.3 1.3 1.2 2.3 2.8 2.8 2.9 2.9 2.8 2.8 2.9 2.8 2.8 2.9 2.9 2.9 2.9 5.7 5.9                                       
      total operating revenue
    375 360.3 400.2 364.8 407.2 354.5 403.3 402.7 378.8 533.4 564.9 425.8 388.3 373.1 383.5 399 345.4 335.6 339.2 320.4 293.9 243.2 311.6 304.6 288.3 290.4 357.2 448.3 348 344.1 358.2 337.9 362.5 353.3                          -668,899,093 224,100,000 211,200,000 233,600,000       
      operating expenses
                                                                         
      fuel, purchased power and gas – utility
    120.4 113.3 123 120.3 116.5 107.3 133.5 132.1 124.9 107.3 118.6 128.1 136.8 143.2 137.4 173 140.1 128.9 120.4 106.9 93.4 69.3 89 94.8 98.2 87.9 109.8 106.9 103.2 96.5 100.9 113.7 93.5 93.1                                    
      transmission services – utility
    19.2 19.3 19 20.7 19.6 1.6 22.7 21.9 22.7 23.5 20.1 19.2 19.3 18.3 19.9 19.2 19.2 19.2 17.7 17.2 14.9 16.4 18.5 14 18.3 19.2 18.3 16.8 17.9 16.8 18.4 18.1 18.9 17.6                                    
      cost of sales – non-utility
    26 24.3 24.9 26 47 31.8 24.4 36.8 33 193.2 210.5 85.9 38.4 41.5 17 21 15.2 15.8 16.8 18.1 15.4 16.3 16.9 18.8 14.7 16.5 30.6 109.4 38.7 37 32.9 41.7 36.1 38.4                                    
      operating and maintenance
    90.7 96.6 93 74.9 92.7 102.1 91.7 91.1 83.6 84.9 85.7 80.8 83.2 79.6 75.3 59.1 66.7 67.1 66.3 70.1 61.9 59 61 63.3 58.1 66.7 76.2 86.9 80.3 86.8 86.5 91.7 80 84.9 83.3 -240,899,665.9 80,800,000 82,000,000 78,100,000 -246,399,666.5 81,300,000 85,400,000 79,700,000 -340,599,543.8 105,700,000 115,100,000 119,800,000 -311,199,587.1 102,700,000 103,800,000 104,700,000 -294,799,602.9 98,700,000 96,200,000 99,900,000 -276,299,618.8 90,500,000 95,700,000 90,100,000 -262,899,634.4 89,800,000 85,400,000 87,700,000 -224,699,691.1 67,500,000 76,700,000 80,500,000 73,400,000 74,600,000 
      depreciation and amortization
    72.5 73.2 69.7 69.7 70.8 66 65 63.6 63.1 62.8 62.3 60.8 58.7 61 61.7 58.3 57.5 57.9 58 56.5 53.4 54.5 53.4 50.4 49.5 50.2 51.9 52.2 51.5 56.1 45.8 26 50.9 50.1 50.5 -145,699,804.2 48,900,000 48,700,000 48,100,000 -123,499,830 43,200,000 41,300,000 39,000,000                           
      taxes other than income taxes
    16.6 15.6 17.6 15.1 15.3 16.3 18.7 14.1 15.5 8.2 19.4 17.3 18.5 15.8 18.8 18.4 15.6 18.5 18 15.2 13.3 15 12.6 13.5 12.5 13.7 13.6 14.1 13.1 14.4 16.3 14.2 14.1 14.2 14.4 -40,599,946.2 12,500,000 14,300,000 13,800,000 -38,499,948.6 12,300,000 13,400,000 12,800,000                           
      total operating expenses
    345.4 342.3 347.2 326.7 361.9 325.1 356 359.6 342.8 479.9 516.6 392.1 354.9 359.4 330.1 349 314.3 307.4 297.2 284 252.3 230.5 251.4 254.8 251.3 254.2 300.4 384.3 304.7 307.6 300.8 304.7 293.5 298.3 293 -835,798,883.8 296,200,000 272,600,000 267,000,000 -924,698,724.3 377,300,000 283,800,000 263,600,000 -708,799,052 228,100,000 232,500,000 248,200,000 -643,199,135.7 212,600,000 211,200,000 219,400,000 -597,899,194 203,200,000 193,100,000 201,600,000 -573,199,221.8 188,000,000 193,800,000 191,400,000 -555,799,228.8 188,800,000 179,500,000 187,500,000       
      operating income
    29.6 18 53 38.1 45.3 29.4 47.3 43.1 36 53.5 48.3 33.7 33.4 13.7 53.4 50 31.1 28.2 42 36.4 41.6 12.7 60.2 49.8 37 36.2 56.8 64 43.3 36.5 57.4 33.2 69 55 72.6 -162,399,776.5 53,400,000 42,200,000 66,800,000 -181,099,789.3 85,200,000 39,500,000 56,400,000 -137,299,811.2 60,800,000 28,200,000 48,300,000 -107,199,845.9 38,400,000 24,400,000 44,400,000 -107,299,844.8 45,600,000 23,300,000 38,400,000 -115,799,850 38,900,000 26,100,000 50,800,000 -113,099,864.2 35,300,000 31,700,000 46,100,000 -72,199,894 25,400,000 15,700,000 31,100,000 33,800,000 41,300,000 
      yoy
    -34.66% -38.78% 12.05% -11.60% 25.83% -45.05% -2.07% 27.89% 7.78% 290.51% -9.55% -32.60% 7.40% -51.42% 27.14% 37.36% -25.24% 122.05% -30.23% -26.91% 12.43% -64.92% 5.99% -22.19% -14.55% -0.82% -1.05% 92.77% -37.25% -33.64% -20.94% -100.00% -100.00% -100.00% -100.00% -10.33% -37.32% 6.84% 18.44% 31.90% 40.13% 40.07% 16.77% 28.08% 58.33% 15.57% 8.78% -0.09% -15.79% 4.72% 15.63% -7.34% 17.22% -10.73% -24.41% 2.39% 10.20% -17.67% 10.20% 56.65% 38.98% 101.91% 48.23% -313.61% -38.50%     
      qoq
    64.44% -66.04% 39.11% -15.89% 54.08% -37.84% 9.74% 19.72% -32.71% 10.77% 43.32% 0.90% 143.80% -74.34% 6.80% 60.77% 10.28% -32.86% 15.38% -12.50% 227.56% -78.90% 20.88% 34.59% 2.21% -36.27% -11.25% 47.81% 18.63% -36.41% 72.89% -51.88% 25.45% -24.24% -100.00% -404.12% 26.54% -36.83% -136.89% -312.56% 115.70% -29.96% -141.08% -325.82% 115.60% -41.61% -145.06% -379.17% 57.38% -45.05% -141.38% -335.31% 95.71% -39.32% -133.16% -397.69% 49.04% -48.62% -144.92% -420.40% 11.36% -31.24% -163.85% -384.25% 61.78% -49.52% -7.99% -18.16%  
      other income
                                                                         
      interest expense
    -25.6 -23.1 -21.4 -20.9 -20.3 -20.1 -20.4 -19.9 -20.5 -21.1 -19.3 -19.9 -18.4 -18.6 -18.3 -17.3 -17.3 -17.4 -17.1 -17.7 -16.3 -15.9 -15.7 -12.225 -16.1 -16.3 -16.5 -12.9 -17.6 -17.1 -16.9 -12.625 -16.6 -16.7 -17.2 -13,250,000 -18,700,000 -17,400,000 -16,900,000 -12,250,000 -17,700,000 -16,200,000 -15,100,000 -9,875,000 -13,200,000 -13,500,000 -12,800,000 -9,450,000 -12,700,000 -12,800,000 -12,300,000 33,399,954.5 -12,300,000 -10,100,000 -11,000,000 32,599,956.4 -10,900,000 -11,000,000 -10,700,000 28,099,960.8 -9,700,000 -9,500,000 -8,900,000 25,399,966.2 -8,300,000 -8,400,000 -8,700,000 -7,500,000 -6,300,000 
      equity earnings
    5.6 5.9 8.5 5.1 5.9 5.5 5.6 4.7 5.4 5.6 2.3 5.3 5.5 5.7 4.4 5.1 4.8 5.4 5.1 6.4 5.2 6.4 4.9 4.8 5.6                                           
      other
    5.3 5.2 4.6 5.5 5.9 8.6 9.7 68.7 2.5 4.1 2.3 12.1 2.6 1.8 3.3 2.275 2.9 5.2 3.65 4.2 7.4 2.1 1.4 2.2 2.1 0.4 0.8 0.6 0.6 -2,799,996.1 1,200,000 600,000 1,000,000 -3,499,995.3 1,700,000 700,000 1,100,000 -5,999,991.4 2,100,000 1,900,000 2,000,000 -7,499,990.7 3,300,000 1,500,000 2,700,000 -3,399,994 1,500,000 1,200,000 700,000 -2,299,995.6 500,000 1,000,000 800,000 -3,799,995.4 600,000 2,200,000 1,000,000 -3,799,998.2 800,000 1,900,000 1,100,000 2,800,000 4,600,000 
      total other expense
    -14.7 -12 -10.8   -8.3 -6.3   -13.2 -9.2 -8.3 -13.8 -1.2 -10.8 -9 -11.9 -10.5 -9         -8.225 -12.2 -10.6 -10.1 -7.8 -9.9 -10.8 -10.5 -8,800,000 -11,400,000 -12,700,000 -11,100,000 -7,850,000 -10,500,000 -10,800,000 -10,100,000 -4,475,000 -5,800,000 -6,400,000 -5,700,000 -3,800,000 -4,500,000 -6,300,000 -4,400,000 15,699,979.9 -5,900,000 -4,100,000 -5,700,000 16,599,979.2 -5,700,000 -5,400,000 -5,500,000 -2,725,000 -4,600,000 -2,900,000        
      income before income taxes
    14.9 42.2 24.425 35.6 21.1 41 42.075 88.9 40.3 39.1 18.675 19.6 12.5 42.6 17.475 19.2 17.7 33 23.1 33.3 8.4 50.7 32.9 28.8 29.4 73.4 26.075 31.1 25.9 47.3                 23,000,000 33,900,000 18,100,000 40,000,000                27,700,000   
      income tax expense
    1.6 -0.6 7.5 -3.6 2.9 1.4 7.5 19.3 -0.4 1.5         -6.95 -5.5 -8.5 -13.8 -1.075 -2.4  2.9 -2.175 0.4 -5.4 -3.7 -19.9 14.2 7.3 13.1 -15,699,980.2 1,700,000 4,700,000 9,300,000 -26,999,974.7 14,400,000 6,400,000 6,200,000 -27,099,963.3 13,400,000 4,900,000 8,800,000 -20,299,971.3 8,700,000 4,100,000 7,500,000 -23,399,962 10,300,000 4,800,000 8,300,000 -24,699,964.4 12,700,000 3,800,000 8,200,000 -40,499,955.7 11,200,000 9,400,000 19,900,000 -21,499,969.2 6,500,000 4,200,000 10,800,000 8,400,000 16,100,000 
      net income
    13.3 6.6 34.7 32.3 32.7 19.7 37 31 69.6 40.7 37.6 37.2 26.8 20.8 46.5 48.6 24.1 21.7 43.4 41.4 38.8 16.9 64.5 49.6 31.2 34.2 70.5 61.1 30.7 31.3 51 41.4 44.9 36.9 49 -111,499,844.2 40,300,000 24,800,000 46,400,000 -122,699,858.5 60,300,000 22,300,000 40,100,000 -92,299,874.5 41,600,000 16,900,000 33,800,000 -71,699,895.3 25,200,000 14,000,000 32,500,000 -68,199,902.9 29,400,000 14,400,000 24,400,000 -74,499,906.4 20,500,000 16,900,000 37,100,000 -61,699,925.2 19,500,000 19,400,000 22,800,000 -41,999,939.3 15,800,000 9,300,000 16,900,000 24,700,000 26,300,000 
      yoy
    -59.33% -66.50% -6.22% 4.19% -53.02% -51.60% -1.60% -16.67% 159.70% 95.67% -19.14% -23.46% 11.20% -4.15% 7.14% 17.39% -37.89% 28.40% -32.71% -16.53% 24.36% -50.58% -8.51% -18.82% 1.63% 9.27% 38.24% 47.58% -31.63% -15.18% 4.08% -100.00% -100.00% -100.00% -100.00% -9.13% -33.17% 11.21% 15.71% 32.94% 44.95% 31.95% 18.64% 28.73% 65.08% 20.71% 4.00% 5.13% -14.29% -2.78% 33.20% -8.46% 43.41% -14.79% -34.23% 20.75% 5.13% -12.89% 62.72% 46.90% 23.42% 108.60% 34.91% -270.04% -39.92%     
      qoq
    101.52% -80.98% 7.43% -1.22% 65.99% -46.76% 19.35% -55.46% 71.01% 8.24% 1.08% 38.81% 28.85% -55.27% -4.32% 101.66% 11.06% -50.00% 4.83% 6.70% 129.59% -73.80% 30.04% 58.97% -8.77% -51.49% 15.38% 99.02% -1.92% -38.63% 23.19% -7.80% 21.68% -24.69% -100.00% -376.67% 62.50% -46.55% -137.82% -303.48% 170.40% -44.39% -143.45% -321.87% 146.15% -50.00% -147.14% -384.52% 80.00% -56.92% -147.65% -331.97% 104.17% -40.98% -132.75% -463.41% 21.30% -54.45% -160.13% -416.41% 0.52% -14.91% -154.29% -365.82% 69.89% -44.97% -31.58% -6.08%  
      net loss attributable to non-controlling interest
    -13.8 -25.3 -21.4 -18.3 -12.3 -13.3 -13.7 -20.5 -16.3 -10.8 -20.6 -14.5 -6.9 -16.8 -19.8 -13.3 -3.5 -6.2 -8.4 -5.7 -1.9 -3.2 -1.8                                               
      net income attributable to allete
    27.1 31.9 56.1 50.6 45 33 50.7 51.5 85.9 51.5 58.2 51.7 33.7 37.6 66.3 61.9 27.6 27.9 51.8 47.1 40.7 20.1 66.3         41.4 44.9 36.9 49 -110,999,844.7 40,300,000 24,800,000 45,900,000 -122,799,858.9 60,400,000 22,500,000 39,900,000 -91,899,875.2 41,600,000 16,800,000 33,500,000     -68,199,902.9 29,400,000 14,400,000 24,400,000 -74,699,906.2 20,500,000 17,000,000 37,200,000 -61,999,924.7 19,600,000 19,400,000 23,000,000 -42,299,939 16,000,000 9,400,000    
      average shares of common stock
                                                                         
      basic
    58.1 58 57.9  57.8 57.7 57.6  57.4 57.3 57.3 0.4 57.1 56.1 53.3 0.1 52.4 52.2 52.1 0.1 51.9 51.8 51.7  51.7 51.6 51.6  51.4 51.3 51.2 0.1 51 50.9 50.2 -49,299,950.7 49,400,000 49,300,000 49,200,000 -47,999,951.7 48,800,000 48,600,000 46,900,000 -42,099,957.1 42,900,000 42,100,000 41,400,000 -39,399,960.3 39,800,000 39,400,000 38,900,000 -37,299,962.4 37,700,000 37,300,000 36,800,000 -35,099,964.7 35,600,000 35,000,000 34,600,000 -34,099,965.8 34,400,000 34,100,000 33,800,000 -31,799,967.8 32,800,000 31,800,000 30,900,000 29,100,000 28,100,000 
      diluted
    58.2 58.1 58  57.9 57.8 57.7  57.5 57.4 57.3 0.4 57.2 56.1 53.3 0.2 52.5 52.3 52.2  52 51.9 51.8  51.8 51.7 51.7  51.6 51.5 51.4 0.1 51.2 51.1 50.4 -49,399,950.5 49,500,000 49,500,000 49,200,000 -48,099,951.6 48,900,000 48,700,000 47,100,000 -42,299,956.9 42,900,000 42,300,000 41,600,000 -39,499,960.2 39,900,000 39,600,000 39,000,000 -37,299,962.4 37,800,000 37,400,000 36,900,000 -35,199,964.6 35,700,000 35,100,000 34,700,000 -34,199,965.7 34,500,000 34,200,000 33,800,000 -31,899,967.8 32,900,000 31,800,000 31,000,000 29,300,000 28,100,000 
      basic earnings per share of common stock
    0.47 0.55 0.97 0.88 0.78 0.57 0.88 0.9 1.5 0.9 1.02 0.9 0.59 0.67 1.24 1.18 0.53 0.53 0.99 0.91 0.78 0.39 1.28 0.96 0.6 0.66 1.37 1.19 0.59 0.61 0.81 0.88 0.73 0.97 0.9 0.82 0.5 0.93 0.36 1.24 0.46 0.85 0.73 0.97 0.4 0.81 0.82 0.63 0.36 0.83 0.76 0.78 0.39 0.66 0.53 0.57 0.49 1.07 0.38 0.57 0.57 0.68       
      diluted earnings per share of common stock
    0.46 0.55 0.97 0.87 0.78 0.57 0.88 0.89 1.49 0.9 1.02 0.9 0.59 0.67 1.24 1.18 0.53 0.53 0.99 0.9 0.78 0.39 1.28 0.96 0.6 0.66 1.37 1.19 0.59 0.61 0.99 0.81 0.88 0.72 0.97 0.89 0.81 0.5 0.93 0.37 1.23 0.46 0.85 0.73 0.97 0.4 0.8 0.82 0.63 0.35 0.83 0.75 0.78 0.39 0.66 0.53 0.57 0.48 1.07 0.38 0.56 0.57 0.68       
      total other income
       -9.4 -9.7   -4.6 52.9           -5.525 -8.3 -4.3 -9.5 0.4 -8.2 -6.8 16.6                                    -3,400,000       
      income tax benefit
               -11.8 -7.2 -8.3 -3.9 -7.6 -4.9 -4 -10.4       -4.8                                            
      gain on sale of u.s. water services
                            0.5 20.1                                           
      equity earnings in atc
                               4.5 4.3 4.7 5.2 5.9 5.3 6.1 -14,999,981.5 6,100,000 4,100,000 4,800,000 -14,099,983.7 5,500,000 4,700,000 3,900,000 -15,599,980.4 5,300,000 5,200,000 5,100,000 -15,099,979.7 4,900,000 5,000,000 5,200,000 -14,299,980.6 4,900,000 4,800,000 4,600,000 -13,699,981.6 4,700,000 4,600,000 4,400,000 -13,399,982.1 4,500,000 4,400,000 4,500,000 -12,899,982.5 4,400,000 4,300,000 4,200,000 4,200,000 2,900,000 
      dividends per share of common stock
                               0.42 0.56 0.56 0.56 0.535 0.535 0.535 0.535 0.52 0.52 0.52 0.52 0.505 0.505 0.505 0.505 0.49 0.49 0.49 0.49 0.475 0.475 0.475 0.475 0.46 0.46 0.46 0.46 0.445 0.445 0.445 0.445 0.44 0.44 0.44 0.44 0.44 0.44 0.44 0.44 0.43 0.41 
      utility
                                   239.7 277.6 264.9                                    
      non-utility
                                   98.2 84.9 88.4                                    
      income before non-controlling interest and income taxes
                                   21.5 59.1 44.2 62.1 -127,199,824.4 42,000,000 29,500,000 55,700,000 -149,699,833.2 74,700,000 28,700,000 46,300,000 -119,399,837.8 55,000,000 21,800,000 42,600,000     -91,599,864.9 39,700,000 19,200,000 32,700,000 -99,199,870.8 33,200,000 20,700,000 45,300,000 -102,199,880.9 30,700,000 28,800,000 42,700,000 -63,499,908.5 22,300,000 13,500,000    
      less: non-controlling interest in subsidiaries
                                       -499,999.5   500,000 100,000.4 -100,000 -200,000 200,000 -399,999.3  100,000 300,000         199,999.8  -100,000 -100,000 299,999.5 -100,000  -200,000 299,999.7 -200,000 -100,000    
      fuel and purchased power
                                      93 -245,999,667.1 91,000,000 78,100,000 76,900,000 -242,899,671.9 76,800,000 80,100,000 86,000,000 -268,699,643.9 88,900,000 83,600,000 96,200,000 -245,699,665.2 80,500,000 78,700,000 86,500,000 -228,699,691.3 79,500,000 72,100,000 77,100,000 -229,799,693.4 74,800,000 76,000,000 79,000,000 -233,099,674.9 79,000,000 74,300,000 79,800,000 -199,399,720.5 69,800,000 56,800,000 72,800,000 81,000,000 77,700,000 
      transmission services
                                      16.6 -49,499,934.8 16,600,000 16,100,000 16,800,000 -40,099,945.9 13,900,000 11,300,000 14,900,000                           
      cost of sales
                                      35.2 -113,099,855.3 46,400,000 33,400,000 33,300,000 -233,299,697.7 149,800,000 52,300,000 31,200,000                           
      depreciation
                                               -99,499,864.3 33,500,000 33,800,000 32,200,000 -86,299,883.4 29,400,000 28,700,000 28,200,000 -74,399,899.8 25,000,000 24,800,000 24,600,000 -67,099,909.6 22,700,000 22,100,000 22,300,000 -59,799,919.5 20,000,000 19,800,000 20,000,000 -46,799,935.3 16,100,000 15,500,000 15,200,000 13,500,000 11,700,000 
      prior year rate refunds
                                                                   7,599,992.4  -2,300,000 -5,300,000   
      basic and diluted earnings per share of common stock
                                                                   0.333 0.49 0.29 0.55 0.85 0.93 
      income before minority interest and income taxes
                                                                       33,300,000 42,500,000 
      minority interest
                                                                       200,000 100,000 
    Balance Sheets:
    Quarterly
    Annual
      Unit: USD2025-09-30 2025-06-30 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 2021-06-30 2021-03-31 2020-12-31 2020-09-30 2020-06-30 2020-03-31 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 2014-12-31 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 2008-12-31 2008-09-30 2008-06-30 2008-03-31 2007-12-31 2007-09-30 
                                                                               
        millions
                                                                               
        assets
                                                                               
        current assets
                                                                               
        cash and cash equivalents
      78,700,000 55,400,000 92,000,000 32,800,000 101,900,000 37,500,000 32,000,000 71,900,000 125,500,000 47,900,000 29,900,000 36,400,000 42,100,000 74,600,000 60,100,000 45,100,000 59,000,000 62,500,000 159,000,000 44,300,000 79,000,000 25,700,000 67,000,000 69,300,000 100,300,000 203,100,000 353,300,000 69,100,000 128,000,000 121,900,000 98,500,000 98,900,000 104,400,000 84,200,000 81,800,000 27,500,000 107,200,000 91,900,000 97,000,000 97,000,000 103,000,000 60,600,000 72,100,000 145,800,000 150,500,000 83,600,000 44,600,000 97,300,000 164,500,000 145,000,000 77,300,000 80,800,000 104,300,000 8,600,000 118,200,000 101,100,000 135,100,000 79,400,000 52,700,000 44,900,000 92,300,000 45,300,000 32,500,000 25,700,000 54,300,000 72,400,000 98,000,000 102,000,000 78,100,000 99,100,000 76,200,000 23,300,000 61,400,000 
        accounts receivable
      146,100,000 129,700,000 143,200,000 148,100,000 136,800,000 133,000,000 142,200,000 137,200,000 119,600,000 123,200,000 120,300,000 137,900,000 120,500,000 116,200,000 118,400,000 123,700,000 110,200,000 105,200,000 113,500,000 111,900,000 92,000,000 85,800,000 99,400,000 96,400,000 85,100,000 87,400,000 98,900,000 144,400,000 129,400,000 132,400,000 128,200,000 135,100,000 136,700,000 120,100,000 122,800,000 122,500,000 108,100,000 113,600,000 124,800,000 121,200,000 110,700,000 103,900,000 111,800,000 103,000,000 82,400,000 78,900,000 97,400,000 96,300,000 79,900,000 78,700,000 86,200,000 89,000,000 73,200,000 66,700,000 76,700,000 79,700,000 75,800,000 71,900,000 91,500,000 99,500,000 112,100,000 107,900,000 119,000,000 118,500,000    76,300,000    79,500,000  
        inventories – net
      184,900,000 178,200,000 171,100,000 154,600,000 166,600,000 184,300,000 182,700,000 175,400,000 180,300,000 194,300,000 346,900,000 455,900,000 472,200,000 355,800,000 196,600,000 97,700,000 89,600,000 88,100,000 74,000,000 74,200,000 74,800,000 82,000,000 79,000,000 72,800,000 84,600,000 78,200,000 73,800,000 86,700,000 154,800,000 145,400,000 143,100,000 95,900,000 102,600,000 103,400,000 110,500,000 104,200,000                                      
        prepayments and other
      75,300,000 89,600,000 71,600,000 99,700,000 78,100,000 77,400,000 76,300,000 83,600,000 77,800,000 80,800,000 72,600,000 87,800,000 87,400,000 113,400,000 105,400,000 24,800,000 19,900,000 23,500,000 31,900,000 24,500,000 19,300,000 29,500,000 29,400,000 31,000,000 26,100,000 28,600,000 30,400,000 34,100,000 27,200,000 24,300,000 33,800,000 37,600,000 44,200,000 38,800,000 45,500,000 40,300,000 38,900,000 38,400,000 41,500,000 35,700,000 42,500,000 36,500,000 88,500,000 82,000,000 29,300,000 32,200,000 33,400,000 35,100,000 29,200,000 26,200,000 28,100,000 33,600,000 23,800,000 25,500,000 22,900,000 27,100,000 22,800,000 20,600,000 24,500,000 28,600,000 26,700,000 21,900,000 19,400,000 24,300,000 24,500,000 25,700,000 19,700,000 24,300,000 16,900,000 27,200,000 29,600,000 39,100,000 25,400,000 
        total current assets
      485,000,000 452,900,000 477,900,000 435,200,000 483,400,000 432,200,000 433,200,000 468,100,000 503,200,000 446,200,000 569,700,000 718,000,000 722,200,000 660,000,000 480,500,000 291,300,000 278,700,000 279,300,000 378,400,000 254,900,000 265,100,000 223,000,000 274,800,000 269,500,000 296,100,000 397,300,000 556,400,000 334,300,000 439,400,000 424,000,000 403,600,000 367,500,000 387,900,000 346,500,000 360,600,000 294,500,000 361,600,000 354,300,000 379,300,000 371,000,000 403,300,000 330,600,000 390,000,000 418,800,000 357,800,000 293,500,000 269,400,000 307,000,000 369,000,000 320,900,000 255,900,000 273,200,000 278,000,000 170,100,000 290,000,000 277,000,000 302,800,000 233,200,000 224,800,000 239,700,000 294,000,000 232,200,000 222,600,000 225,500,000    252,300,000    214,500,000  
        property, plant and equipment – net
      5,528,800,000 5,324,000,000 5,255,500,000 5,181,500,000 5,112,800,000 5,079,500,000 5,009,100,000 5,013,400,000 4,996,800,000 4,973,900,000 4,979,300,000 5,004,000,000 5,011,000,000 5,027,100,000 5,078,300,000 5,100,200,000 5,053,100,000 5,021,600,000 4,930,600,000 4,840,800,000 4,697,500,000 4,644,500,000 4,496,300,000 4,377,000,000 4,210,700,000 4,062,900,000 3,940,500,000 3,904,400,000 3,846,500,000 3,809,300,000 3,786,100,000 3,822,400,000 3,746,300,000 3,745,600,000 3,745,300,000 3,741,200,000 3,644,500,000 3,631,300,000 3,642,300,000 3,669,100,000 3,639,100,000 3,451,500,000 3,319,200,000 3,286,400,000    2,576,500,000    2,347,600,000    1,982,700,000    1,805,600,000    1,622,700,000    1,387,300,000    1,104,500,000  
        regulatory assets
      360,400,000 363,000,000 364,600,000 371,700,000 386,100,000 394,700,000 409,000,000 425,400,000 443,300,000 454,500,000 469,100,000 441,000,000 447,100,000 470,900,000 464,200,000 511,800,000 502,900,000 491,900,000 472,700,000 480,900,000 427,900,000 424,700,000 423,800,000 420,500,000 393,100,000 391,200,000 385,100,000 389,500,000 370,600,000 374,500,000 376,000,000 384,700,000 310,600,000 324,500,000 320,900,000 359,600,000 358,900,000 359,100,000 367,100,000 372,000,000 353,300,000 359,600,000 358,000,000 357,300,000 277,100,000 270,800,000 267,000,000 263,800,000 340,300,000 337,500,000 336,600,000 340,300,000 334,600,000 336,900,000 339,300,000 345,900,000 286,900,000 290,200,000 288,500,000 310,200,000 282,500,000 287,800,000 287,900,000 293,200,000          
        equity investments
      357,700,000 350,500,000 344,000,000 340,100,000 337,900,000 336,000,000 333,100,000 331,200,000 329,700,000 327,500,000 323,900,000 322,700,000 320,300,000 322,000,000 320,600,000 318,000,000 317,800,000 317,800,000 301,500,000 301,200,000 291,800,000 267,100,000 225,700,000 197,600,000 183,300,000 160,200,000 154,800,000 161,100,000                                              
        goodwill and intangible assets – net
      155,200,000 155,300,000 155,300,000 155,300,000 155,300,000 155,400,000 155,400,000 155,400,000 155,500,000 155,500,000 155,500,000 155,600,000 155,800,000 151,100,000          1,000,000 1,000,000 1,100,000 1,100,000 223,300,000 224,700,000 225,800,000 224,500,000 225,900,000 228,900,000 210,800,000 212,000,000 213,400,000 211,400,000 212,700,000 213,900,000 215,200,000 212,900,000 213,400,000 214,300,000                               
        other non-current assets
      265,800,000 267,500,000 269,000,000 270,500,000 261,700,000 263,500,000 264,800,000 262,900,000 216,300,000 210,300,000 207,000,000 204,300,000 201,600,000 207,900,000 212,400,000 213,700,000 179,700,000 182,700,000 191,300,000 206,800,000 196,200,000 201,100,000 198,900,000 217,200,000 191,600,000 163,800,000 180,900,000 103,300,000 104,400,000 105,000,000 109,000,000 107,700,000 103,000,000 104,800,000 105,200,000 106,500,000 106,500,000 98,900,000 68,600,000 80,700,000 83,700,000 78,700,000 61,600,000 62,800,000 74,400,000 75,400,000 74,700,000 68,600,000 42,900,000 43,900,000 44,500,000 41,500,000 40,400,000 39,100,000 38,300,000 39,200,000 35,200,000 35,700,000 35,900,000 34,300,000 33,600,000 33,400,000            
        total assets
      7,152,900,000 6,913,200,000 6,866,300,000 6,754,300,000 6,737,200,000 6,661,300,000 6,604,600,000 6,656,400,000 6,644,800,000 6,567,900,000 6,704,500,000 6,845,600,000 6,858,000,000 6,839,000,000 6,556,000,000 6,435,000,000 6,332,200,000 6,293,300,000 6,274,500,000 6,084,600,000 5,878,500,000 5,760,400,000 5,619,500,000 5,482,800,000 5,275,800,000 5,176,500,000 5,218,800,000 5,165,000,000 5,163,300,000 5,114,700,000 5,072,100,000 5,080,000,000 4,978,500,000 4,931,500,000 4,941,900,000 4,906,400,000 4,874,800,000 4,857,600,000 4,872,700,000 4,907,100,000 4,931,800,000 4,673,000,000 4,580,100,000 4,360,800,000 4,067,900,000 3,895,600,000 3,749,200,000 3,476,800,000 3,463,900,000 3,350,900,000 3,251,300,000 3,253,400,000 3,138,100,000 2,962,200,000 2,906,600,000 2,876,000,000 2,754,400,000 2,645,500,000 2,613,400,000 2,609,100,000 2,579,100,000 2,447,800,000 2,416,000,000 2,393,100,000 2,255,100,000 2,217,600,000 2,168,900,000 2,134,800,000 1,847,600,000 1,788,800,000 1,715,800,000 1,644,200,000 1,646,500,000 
        liabilities, redeemable non-controlling interest and equity
                                                                               
        liabilities
                                                                               
        current liabilities
                                                                               
        accounts payable
      116,700,000 124,000,000 106,000,000 113,600,000 110,800,000 94,100,000 84,200,000 102,200,000 112,300,000 89,300,000 84,900,000 103,000,000 124,300,000 134,800,000 75,900,000 111,000,000 101,900,000 100,000,000 107,000,000 110,000,000 79,000,000 86,100,000 164,400,000 165,200,000 143,500,000 150,400,000 134,400,000 149,800,000 131,800,000 105,000,000 88,100,000 136,300,000 75,300,000 61,000,000 59,200,000 74,000,000 72,600,000 64,800,000 58,800,000 88,800,000 125,000,000 94,800,000 98,900,000 134,100,000 92,700,000 93,200,000 78,100,000 99,900,000 84,300,000 52,100,000 53,300,000 90,500,000 57,400,000 78,300,000 51,500,000 71,800,000 44,100,000 44,400,000 48,200,000 75,400,000 66,500,000 56,000,000 36,400,000 62,100,000 54,800,000 59,000,000 51,900,000 75,700,000 58,500,000 69,200,000 57,900,000 72,700,000 52,000,000 
        accrued taxes
      56,900,000 43,300,000 64,900,000 54,600,000 60,200,000 47,200,000 62,900,000 51,000,000 63,500,000 50,400,000 81,400,000 69,100,000 69,500,000 52,700,000 78,500,000 65,100,000 67,400,000 53,000,000 75,200,000 59,400,000 60,000,000 48,500,000 63,000,000 50,800,000 53,400,000 41,300,000 60,300,000 51,400,000 53,900,000 42,000,000 60,500,000 50,000,000 51,800,000 39,100,000 56,100,000 46,500,000 36,700,000 37,700,000 52,200,000 44,000,000 34,800,000 34,900,000 47,400,000 38,700,000 30,900,000 30,900,000 42,900,000 34,800,000 26,100,000 26,400,000 36,200,000 30,200,000 22,500,000 22,600,000 30,800,000 26,400,000 20,300,000 19,800,000 27,800,000 22,000,000 18,000,000 16,800,000 25,000,000 20,600,000 15,900,000 15,800,000 17,700,000 12,900,000 16,400,000 15,700,000 27,400,000 14,800,000 13,800,000 
        accrued interest
      26,100,000 25,300,000 19,000,000 23,400,000 19,100,000 21,700,000 16,300,000 21,100,000 16,200,000 21,300,000 14,900,000 20,500,000 15,100,000 20,300,000 15,300,000 20,100,000 15,300,000 19,500,000 15,300,000 19,800,000 15,800,000 18,000,000 15,100,000 18,100,000 15,000,000 17,700,000 14,900,000 17,900,000 15,500,000 18,000,000 14,600,000 17,600,000 14,600,000 17,500,000 14,800,000 17,600,000 14,800,000 17,800,000 14,900,000 18,600,000 14,500,000 17,700,000 14,500,000 18,000,000 14,800,000 17,400,000 15,200,000 15,700,000 14,900,000 15,900,000 14,100,000 15,600,000 14,200,000 12,800,000 11,300,000 12,800,000 13,000,000 12,800,000 13,600,000 13,400,000 12,300,000 12,700,000 9,700,000 11,100,000 9,900,000 12,000,000 10,000,000 8,900,000 8,900,000 9,600,000 6,000,000 7,800,000 5,900,000 
        long-term debt due within one year
      138,100,000 63,600,000 94,200,000 94,700,000 41,800,000 42,100,000 17,200,000 111,400,000 111,000,000 106,700,000 176,400,000 272,600,000 308,600,000 390,500,000 278,100,000 214,200,000 377,400,000 362,600,000 298,500,000 203,700,000 404,500,000 509,700,000 323,000,000 212,900,000 212,700,000 27,700,000 14,300,000 57,500,000 56,600,000 56,700,000 106,200,000 64,100,000 64,100,000 117,700,000 162,600,000 187,700,000 186,600,000 64,500,000 14,800,000 36,300,000 49,100,000 118,000,000 122,300,000 100,700,000 85,300,000 10,800,000 11,100,000 27,200,000 37,700,000 37,900,000 41,200,000 84,500,000 67,300,000 67,400,000 5,500,000 5,400,000 12,800,000 12,900,000 13,000,000 13,400,000 1,600,000 1,600,000 1,600,000 5,200,000 12,000,000 13,000,000 14,000,000 10,400,000 17,200,000 14,800,000 12,800,000 11,800,000 29,400,000 
        other
      75,400,000 81,700,000 96,500,000 117,900,000 102,500,000 92,500,000 80,200,000 91,900,000 110,500,000 112,600,000 106,800,000 251,000,000 188,500,000 110,700,000 108,800,000 133,000,000 84,000,000 60,400,000 78,900,000 66,700,000 70,700,000 65,400,000 57,600,000 60,400,000 58,700,000 59,500,000 98,500,000 128,500,000 144,900,000 128,500,000 130,200,000 83,200,000 84,700,000 70,100,000 70,600,000 73,700,000 93,600,000 85,900,000 82,800,000 86,100,000 94,300,000 135,600,000 118,600,000 120,800,000 60,400,000 61,100,000 61,200,000 52,600,000 59,300,000 60,800,000 57,800,000 62,600,000 53,100,000 51,300,000 41,800,000 45,600,000 26,200,000 23,600,000 22,600,000 33,700,000 31,600,000 30,700,000 34,200,000 32,200,000 44,200,000 40,100,000 37,700,000 36,800,000 28,000,000 24,000,000 26,800,000 27,300,000 23,200,000 
        total current liabilities
      413,200,000 337,900,000 380,600,000 404,200,000 334,400,000 297,600,000 260,800,000 377,600,000 413,500,000 380,300,000 464,400,000 716,200,000 706,000,000 709,000,000 556,600,000 543,400,000 646,000,000 595,500,000 574,900,000 459,600,000 630,000,000 727,700,000 623,100,000 507,400,000 483,300,000 296,600,000 322,400,000 405,100,000 402,700,000 350,200,000 399,600,000 351,200,000 290,500,000 305,400,000 364,600,000 399,500,000 404,300,000 271,600,000 224,200,000 275,400,000 317,700,000 401,000,000 402,000,000 416,000,000 286,800,000 213,400,000 208,500,000 230,200,000 223,500,000 193,100,000 202,600,000 283,400,000 214,800,000 232,400,000 142,500,000 163,100,000 122,000,000 116,000,000 125,700,000 158,900,000 131,000,000 119,200,000 108,600,000 133,100,000    150,700,000    137,100,000  
        long-term debt
      2,098,900,000 1,931,800,000 1,832,800,000 1,704,700,000 1,743,700,000 1,746,000,000 1,772,400,000 1,679,900,000 1,686,100,000 1,685,900,000 1,755,500,000 1,648,200,000 1,653,000,000 1,595,600,000 1,669,400,000 1,763,200,000 1,649,400,000 1,664,600,000 1,652,400,000 1,593,200,000 1,608,000,000 1,381,000,000 1,399,900,000 1,400,900,000 1,404,900,000 1,505,900,000 1,525,000,000 1,428,500,000 1,461,700,000 1,462,200,000 1,396,500,000 1,439,200,000 1,444,600,000 1,401,400,000 1,370,200,000 1,370,400,000 1,358,900,000 1,498,900,000 1,551,300,000 1,568,700,000 1,549,000,000 1,272,400,000 1,253,800,000 1,272,800,000 1,289,200,000 1,316,800,000 1,202,500,000 1,083,000,000 1,064,200,000 1,064,700,000 975,100,000 933,600,000 947,600,000 808,400,000 856,500,000 857,900,000 844,400,000 770,700,000 771,000,000 771,600,000 784,200,000 709,600,000 710,100,000 695,800,000 628,400,000 627,200,000 627,100,000 588,300,000 537,200,000 538,500,000 470,300,000 410,900,000 409,000,000 
        deferred income taxes
      291,700,000 278,900,000 269,500,000 253,400,000 255,500,000 215,600,000 195,000,000 192,700,000 171,200,000 153,600,000 156,300,000 158,100,000 177,000,000 181,800,000 188,300,000 185,700,000 187,100,000 188,700,000 190,200,000 195,700,000 204,800,000 202,300,000 207,000,000 212,800,000 213,900,000 213,500,000 215,500,000 223,600,000 231,300,000 228,500,000 229,700,000 230,500,000 592,900,000 577,000,000 568,600,000 584,100,000 582,100,000 595,100,000 589,700,000  28,000,000 21,800,000 14,900,000 7,500,000 24,000,000 23,500,000 25,100,000 19,000,000 30,700,000 435,500,000 430,900,000 423,800,000 400,000,000 388,000,000 383,400,000 373,600,000 373,000,000 353,800,000 341,900,000 325,200,000 321,000,000 276,900,000 266,500,000 253,100,000 217,500,000 199,300,000 182,200,000 169,600,000 165,800,000 152,600,000 148,500,000 144,200,000 137,300,000 
        regulatory liabilities
      593,500,000 586,700,000 580,600,000 570,500,000 562,100,000 561,000,000 564,000,000 574,000,000 549,300,000 538,000,000 526,400,000 526,100,000 527,400,000 532,600,000 533,400,000 536,100,000 509,500,000 514,900,000 517,900,000 524,800,000 547,100,000 569,600,000 566,400,000 560,300,000 510,400,000 508,800,000 504,100,000 512,100,000 512,300,000 516,000,000 516,000,000 532,000,000 111,500,000 125,800,000 125,000,000 125,800,000 122,900,000 94,600,000 102,200,000 105,000,000 105,800,000 104,800,000 101,200,000 94,200,000 103,100,000 100,100,000 89,900,000 81,000,000 68,700,000 63,100,000 59,200,000 60,100,000 54,800,000 49,300,000 45,300,000 43,500,000 44,600,000 43,400,000 45,400,000 43,600,000 46,000,000 46,500,000 47,200,000 47,100,000          
        defined benefit pension and other postretirement benefit plans
      99,600,000 99,400,000 99,200,000 118,200,000 134,500,000 135,000,000 135,400,000 160,800,000 164,200,000 173,600,000 173,800,000 179,700,000 171,900,000 174,600,000 177,200,000 179,500,000 207,600,000 210,700,000 212,500,000 225,800,000 157,500,000 159,500,000 161,400,000 172,800,000 162,400,000 163,900,000 165,200,000 177,300,000 173,600,000 175,200,000 175,200,000 191,800,000 195,200,000 195,800,000 195,100,000 210,900,000 197,700,000 204,500,000 205,700,000 206,800,000 189,600,000 190,000,000 190,400,000 190,900,000 116,800,000 117,000,000 117,200,000 133,400,000 216,000,000 216,200,000 216,300,000 228,200,000 254,000,000 253,800,000 254,000,000 253,500,000 217,100,000 222,900,000                
        other non-current liabilities
      312,100,000 311,400,000 314,800,000 312,800,000 314,400,000 310,500,000 268,000,000 264,300,000 263,800,000 268,000,000 270,400,000 269,000,000 268,800,000 286,500,000 287,600,000 280,800,000 278,100,000 277,000,000 280,200,000 285,300,000 285,500,000 288,100,000 288,700,000 293,000,000 293,100,000 282,800,000 287,900,000 262,600,000 265,600,000 274,400,000 257,800,000 267,100,000 301,100,000 309,100,000 316,900,000 322,700,000 335,900,000 340,800,000 347,100,000 349,000,000 352,700,000 353,900,000 302,300,000 265,000,000 231,600,000 234,500,000 229,300,000 127,200,000 129,100,000 129,300,000 126,700,000 123,300,000 109,400,000 110,600,000 111,100,000 105,100,000 101,900,000 100,900,000 317,300,000 324,800,000 312,800,000 324,000,000            
        total liabilities
      3,809,000,000 3,546,100,000 3,477,500,000 3,363,800,000 3,344,600,000 3,265,700,000 3,195,600,000 3,249,300,000 3,248,100,000 3,199,400,000 3,346,800,000 3,497,300,000 3,504,100,000 3,480,100,000 3,412,500,000 3,488,700,000 3,477,700,000 3,451,400,000 3,428,100,000 3,284,400,000 3,432,900,000 3,328,200,000 3,246,500,000 3,147,200,000 3,068,000,000 2,971,500,000 3,020,100,000 3,009,200,000 3,047,200,000 3,006,500,000 2,974,800,000 3,011,800,000 2,935,800,000 2,914,500,000 2,940,400,000 3,013,400,000 3,001,800,000 3,005,500,000 3,020,200,000 3,084,700,000 3,108,400,000 2,894,600,000 2,809,200,000 2,749,600,000 2,537,200,000 2,478,100,000 2,341,800,000 2,133,900,000 2,176,400,000 2,101,900,000 2,010,800,000 2,052,400,000 1,980,600,000 1,842,500,000 1,792,800,000 1,796,700,000 1,703,000,000 1,607,700,000 1,601,300,000 1,624,100,000 1,595,000,000 1,476,200,000 1,458,800,000 1,454,100,000 1,340,000,000 1,332,800,000 1,310,500,000 1,307,700,000 1,047,900,000 1,029,600,000 964,400,000 901,600,000 922,000,000 
        commitments, guarantees and contingencies
                                                                               
        redeemable non-controlling interest
      700,000 800,000 500,000 400,000 700,000 900,000 500,000 500,000                                                                  
        equity
                                                                               
        allete equity
                                                                               
        common stock without par value, 80.0 shares authorized, 58.1 and 57.9 shares issued and outstanding
      1,839,000,000                                                                         
        accumulated other comprehensive loss
      -18,100,000 -18,100,000 -18,100,000 -18,100,000 -21,000,000 -20,900,000 -20,900,000 -20,500,000 -24,500,000 -24,400,000 -24,300,000 -24,400,000 -23,800,000 -23,900,000 -24,000,000 -23,800,000 -29,900,000 -30,300,000 -30,700,000 -31,100,000 -23,100,000 -23,300,000            -27,300,000 -27,700,000  -23,700,000 -24,200,000 -24,700,000  -20,600,000 -20,200,000 -20,600,000  -16,100,000 -16,300,000 -16,800,000  -21,300,000 -21,000,000 -21,600,000  -26,700,000 -27,600,000 -27,500,000  -22,700,000 -21,300,000 -21,900,000 -23,200,000 -23,200,000 -23,900,000 -23,600,000 -24,000,000 -30,400,000 -31,600,000 -33,600,000 -33,000,000 -8,800,000 -7,700,000 -9,100,000 -4,500,000 -7,500,000 
        retained earnings
      1,031,000,000 1,046,300,000 1,056,700,000 1,042,900,000 1,033,100,000 1,028,800,000 1,036,500,000 1,026,400,000 1,013,900,000 966,900,000 954,200,000 934,800,000 929,200,000 932,600,000 932,000,000 900,200,000 873,400,000 878,800,000 883,800,000 864,800,000 849,900,000 841,300,000 853,200,000 818,800,000 799,500,000 798,600,000 794,800,000 754,600,000 722,300,000 720,400,000 717,800,000 689,400,000 675,300,000 657,800,000 648,000,000 625,900,000 607,300,000 592,800,000 593,500,000 573,300,000 578,800,000 543,000,000 545,100,000 530,100,000 518,600,000 497,700,000 501,400,000 489,100,000 474,100,000 467,900,000 472,600,000 459,600,000 447,600,000 434,900,000 438,300,000 431,600,000 427,700,000 422,600,000 420,900,000 399,900,000 402,200,000 396,900,000 393,200,000 385,400,000 381,500,000 380,000,000 384,100,000 380,900,000 369,400,000 357,500,000 359,700,000 350,400,000 338,100,000 
        total allete equity
      2,851,900,000 2,861,900,000 2,866,000,000 2,848,000,000 2,831,200,000 2,821,700,000 2,823,000,000 2,809,600,000 2,786,600,000 2,734,100,000 2,715,500,000 2,691,900,000 2,682,600,000 2,680,400,000 2,449,300,000 2,413,100,000 2,340,000,000 2,322,600,000 2,320,700,000 2,294,600,000 2,281,000,000 2,265,700,000 2,271,100,000 2,231,900,000            1,893,000,000 1,873,000,000 1,852,100,000 1,849,800,000 1,820,200,000 1,821,700,000 1,776,600,000 1,768,900,000 1,609,400,000 1,529,200,000 1,416,000,000 1,402,500,000         1,079,300,000 1,051,400,000 1,029,000,000 1,003,200,000 976,000,000 974,900,000 962,300,000 947,900,000 929,500,000          
        non-controlling interest in subsidiaries
      491,300,000 504,400,000 522,300,000 542,100,000 560,700,000 573,000,000 585,500,000 597,000,000 610,100,000 634,400,000 642,200,000 656,400,000 671,300,000 678,500,000 694,200,000 533,200,000 514,500,000 519,300,000 525,700,000 505,600,000 164,600,000 166,500,000 101,900,000 103,700,000               2,700,000 2,200,000 1,700,000 1,800,000 2,000,000 1,800,000 1,500,000 1,500,000 4,900,000           8,800,000 8,900,000 9,000,000 9,200,000 9,300,000 9,300,000 9,500,000 9,500,000 9,600,000 9,700,000       
        total equity
      3,343,200,000 3,366,300,000 3,388,300,000 3,390,100,000 3,391,900,000 3,394,700,000 3,408,500,000 3,406,600,000 3,396,700,000 3,368,500,000 3,357,700,000 3,348,300,000 3,353,900,000 3,358,900,000 3,143,500,000 2,946,300,000 2,854,500,000 2,841,900,000 2,846,400,000 2,800,200,000 2,445,600,000 2,432,200,000 2,373,000,000 2,335,600,000            1,893,000,000 1,873,000,000 1,852,100,000 1,852,500,000 1,822,400,000 1,823,400,000 1,778,400,000 1,770,900,000 1,611,200,000 1,530,700,000 1,417,500,000 1,407,400,000 1,342,900,000 1,287,500,000 1,249,000,000 1,240,500,000 1,201,000,000 1,157,500,000 1,119,700,000 1,113,800,000 1,079,300,000 1,051,400,000 1,037,800,000 1,012,100,000 985,000,000 984,100,000 971,600,000 957,200,000 939,000,000 915,100,000 884,800,000 858,400,000       
        total liabilities, redeemable non-controlling interest and equity
      7,152,900,000 6,913,200,000 6,866,300,000 6,754,300,000 6,737,200,000 6,661,300,000 6,604,600,000 6,656,400,000                                                                  
        common stock without par value, 80.0 shares authorized, 58.0 and 57.9 shares issued and outstanding
       1,833,700,000 1,827,400,000                                                                       
        common stock without par value, 80.0 shares authorized, 57.9 and 57.6 shares issued and outstanding
         1,823,200,000                                                                      
        common stock without par value, 80.0 shares authorized, 57.8 and 57.6 shares issued and outstanding
          1,819,100,000 1,813,800,000                                                                    
        common stock without par value, 80.0 shares authorized, 57.7 and 57.6 shares issued and outstanding
            1,807,400,000                                                                   
        common stock without par value, 80.0 shares authorized, 57.6 and 57.2 shares issued and outstanding
             1,803,700,000                                                                  
        liabilities and equity
                                                                               
        common stock without par value, 80.0 shares authorized, 57.5 and 57.2 shares issued and outstanding
              1,797,200,000                                                                 
        total liabilities and equity
              6,644,800,000 6,567,900,000 6,704,500,000 6,845,600,000 6,858,000,000 6,839,000,000 6,556,000,000 6,435,000,000 6,332,200,000 6,293,300,000 6,274,500,000 6,084,600,000 5,878,500,000 5,760,400,000 5,619,500,000 5,482,800,000            4,906,400,000 4,874,800,000 4,857,600,000 4,872,700,000 4,907,100,000 4,931,800,000 4,673,000,000 4,580,100,000 4,360,800,000 4,067,900,000 3,895,600,000 3,749,200,000 3,476,800,000 3,463,900,000 3,350,900,000 3,251,300,000 3,253,400,000 3,138,100,000 2,962,200,000 2,906,600,000 2,876,000,000 2,754,400,000 2,645,500,000 2,613,400,000 2,609,100,000 2,579,100,000 2,447,800,000 2,416,000,000 2,393,100,000 2,255,100,000 2,217,600,000 2,168,900,000       
        common stock without par value, 80.0 shares authorized, 57.4 and 57.2 shares issued and outstanding
               1,791,600,000                                                                
        common stock without par value, 80.0 shares authorized, 57.3 and 57.2 shares issued and outstanding
                1,785,600,000                                                               
        common stock without par value, 80.0 shares authorized, 57.2 and 53.2 shares issued and outstanding
                 1,781,500,000 1,777,200,000                                                             
        common stock without par value, 80.0 shares authorized, 57.1 and 53.2 shares issued and outstanding
                   1,771,700,000                                                            
        common stock without par value, 80.0 shares authorized, 53.3 and 53.2 shares issued and outstanding
                    1,541,300,000                                                           
        common stock without par value, 80.0 shares authorized, 53.2 and 52.1 shares issued and outstanding
                     1,536,700,000                                                          
        common stock without par value, 80.0 shares authorized, 52.6 and 52.1 shares issued and outstanding
                      1,496,500,000                                                         
        common stock without par value, 80.0 shares authorized, 52.3 and 52.1 shares issued and outstanding
                       1,474,100,000                                                        
        common stock without par value, 80.0 shares authorized, 52.2 and 52.1 shares issued and outstanding
                        1,467,600,000                                                       
        common stock without par value, 80.0 shares authorized, 52.1 and 51.7 shares issued and outstanding
                         1,460,900,000                                                      
        common stock without par value, 80.0 shares authorized, 52.0 and 51.7 shares issued and outstanding
                          1,454,200,000                                                     
        common stock without par value, 80.0 shares authorized, 51.9 and 51.7 shares issued and outstanding
                           1,447,700,000                                                    
        common stock without par value, 80.0 shares authorized, 51.8 and 51.7 shares issued and outstanding
                            1,441,700,000                                                   
        allete’s equity
                                                                               
        common stock without par value, 80.0 shares authorized, 51.7 and 51.5 shares issued and outstanding
                             1,436,700,000 1,435,100,000 1,433,300,000                                                
        liabilities and shareholders’ equity
                                                                               
        shareholders’ equity
                                                                               
        total shareholders’ equity
                              2,207,800,000 2,205,000,000 2,198,700,000 2,155,800,000 2,116,100,000 2,108,200,000 2,097,300,000 2,068,200,000 2,042,700,000 2,017,000,000 2,001,500,000                                 827,100,000    742,600,000  
        total liabilities and shareholders’ equity
                              5,275,800,000 5,176,500,000 5,218,800,000 5,165,000,000 5,163,300,000 5,114,700,000 5,072,100,000 5,080,000,000 4,978,500,000 4,931,500,000 4,941,900,000                                 2,134,800,000    1,644,200,000  
        common stock without par value, 80.0 shares authorized, 51.6 and 51.5 shares issued and outstanding
                                1,431,100,000                                               
        other investments
                                 49,100,000 51,700,000 52,500,000 52,800,000 53,100,000 55,800,000 56,200,000 57,700,000 55,600,000 58,100,000 72,300,000 72,900,000 74,600,000 113,500,000 115,000,000 114,700,000 114,400,000 116,400,000 116,700,000 116,400,000 146,300,000 142,900,000 140,200,000 138,600,000 143,500,000 139,700,000 136,000,000 135,700,000 132,300,000 129,500,000 129,000,000 128,100,000 126,000,000 134,400,000 131,600,000 132,600,000 130,500,000 138,800,000 135,600,000 127,300,000 136,900,000      
        common stock without par value, 80.0 shares authorized, 51.5 and 51.1 shares issued and outstanding
                                 1,428,500,000                                              
        investment in atc
                                  126,000,000 123,600,000 120,100,000 118,700,000 146,000,000 143,100,000 140,200,000 135,600,000 133,800,000 129,000,000 128,600,000 124,500,000 126,000,000 124,200,000 122,300,000 121,100,000 120,700,000 118,800,000 116,600,000 114,600,000 112,700,000 111,200,000 109,000,000 107,300,000 105,500,000 102,600,000 100,500,000 98,900,000 97,900,000 96,300,000 94,800,000 93,300,000 92,000,000 91,100,000 90,300,000 88,400,000 85,100,000 82,100,000 79,700,000 76,900,000      
        common stock without par value, 80.0 shares authorized, 51.4 and 51.1 shares issued and outstanding
                                  1,421,100,000 1,415,400,000                                            
        common stock without par value, 80.0 shares authorized, 51.3 and 51.1 shares issued and outstanding
                                    1,407,400,000                                           
        common stock without par value, 80.0 shares authorized, 51.1 and 49.6 shares issued and outstanding
                                     1,401,400,000                                          
        common stock without par value, 80.0 shares authorized, 51.0 and 49.6 shares issued and outstanding
                                      1,394,300,000 1,386,500,000                                        
        notes payable
                                        1,300,000   900,000 700,000 1,600,000   300,000 3,700,000 2,700,000    1,200,000    300,000  1,600,000 1,100,000 5,600,000 2,500,000 500,000 1,000,000 1,000,000 1,400,000 1,700,000 1,900,000 5,300,000 6,000,000 6,000,000 6,000,000 6,000,000 6,000,000    
        common stock without par value, 80.0 shares authorized, 50.9 and 49.6 shares issued and outstanding
                                        1,381,200,000                                       
        common stock without par value, 80.0 shares authorized, 49.6 and 49.1 shares issued and outstanding
                                         1,295,300,000                                      
        inventories
                                          107,400,000 110,400,000 116,000,000 117,100,000 119,100,000 107,800,000 102,700,000 80,500,000 71,600,000 75,300,000 68,900,000 59,300,000 64,700,000 71,000,000 64,300,000 69,800,000 76,700,000 69,300,000 72,200,000 69,100,000 69,100,000 61,300,000 56,100,000 60,000,000 62,900,000 57,100,000 51,700,000 57,000,000 54,400,000 53,600,000 49,800,000 49,700,000 59,900,000 53,700,000 49,700,000 49,500,000 48,600,000 
        common stock without par value, 80.0 shares authorized, 49.5 and 49.1 shares outstanding
                                          1,289,400,000                                     
        common stock without par value, 80.0 shares authorized, 49.4 and 49.1 shares outstanding
                                           1,283,500,000                                    
        common stock without par value, 80.0 shares authorized, 49.3 and 49.1 shares outstanding
                                            1,281,000,000                                   
        common stock without par value, 80.0 shares authorized, 49.1 and 45.9 shares outstanding
                                             1,271,400,000                                  
        unearned esop shares
                                              -1,400,000 -3,300,000 -5,300,000  -8,600,000 -10,500,000 -12,500,000  -15,100,000 -17,200,000 -19,200,000  -22,800,000 -24,900,000 -27,000,000  -30,300,000 -32,400,000 -34,600,000 -36,800,000 -38,200,000 -40,500,000 -42,900,000 -45,300,000 -46,900,000 -48,300,000 -51,300,000 -54,900,000 -58,500,000 -60,400,000 -62,100,000 -64,500,000 -66,100,000 
        common stock without par value, 80.0 shares authorized, 49.0 and 45.9 shares outstanding
                                              1,264,900,000                                 
        common stock without par value, 80.0 shares authorized, 48.9 and 45.9 shares outstanding
                                               1,257,100,000                                
        common stock without par value, 80.0 shares authorized, 48.8 and 45.9 shares outstanding
                                                1,249,700,000                               
        common stock without par value, 80.0 shares authorized, 45.9 and 41.4 shares outstanding
                                                 1,107,600,000                              
        property, plant and equipment - net
                                                  3,121,500,000 3,020,400,000 2,905,100,000  2,456,100,000 2,397,200,000 2,366,700,000  2,239,900,000 2,177,500,000 2,002,800,000  1,902,100,000 1,861,100,000 1,841,300,000  1,742,600,000 1,671,700,000 1,649,100,000  1,530,500,000 1,481,700,000 1,435,200,000  1,292,400,000 1,224,300,000 1,153,100,000  1,033,800,000 
        common stock without par value, 80.0 shares authorized, 44.5 and 41.4 shares outstanding
                                                  1,035,300,000                             
        common stock without par value, 80.0 shares authorized, 42.6 and 41.4 shares outstanding
                                                   945,100,000                            
        common stock without par value, 80.0 shares authorized, 42.4 and 41.4 shares outstanding
                                                    930,400,000                           
        commitments and contingencies
                                                                               
        common stock without par value, 80.0 shares authorized, 41.4 and 39.4
                                                                               
        shares outstanding
                                                     885,200,000    784,700,000    705,600,000    636,100,000    613,400,000  575,100,000 549,500,000  497,600,000 469,800,000 462,900,000  460,000,000 
        common stock without par value, 80.0 shares authorized, 40.7 and 39.4 shares outstanding
                                                      849,800,000                         
        common stock without par value, 80.0 shares authorized, 40.1 and 39.4 shares outstanding
                                                       819,300,000                        
        common stock without par value, 80.0 shares authorized, 39.9 and 39.4 shares outstanding
                                                        808,700,000                       
        common stock without par value, 80.0 shares authorized, 39.4 and 37.5
                                                                               
        common stock without par value, 80.0 shares authorized, 38.8 and 37.5 shares outstanding
                                                          759,400,000                     
        common stock without par value, 80.0 shares authorized, 38.3 and 37.5 shares outstanding
                                                           737,300,000                    
        common stock without par value, 80.0 shares authorized, 38.1 and 37.5 shares outstanding
                                                            730,000,000                   
        short-term investments
                                                                 6,700,000            23,100,000 70,400,000 
        common stock without par value, 80.0 shares authorized, 37.5 and 35.8
                                                                               
        common stock without par value, 80.0 shares authorized, 36.8 and 35.8 shares outstanding
                                                              676,700,000                 
        common stock without par value, 80.0 shares authorized, 36.5 and 35.8 shares outstanding
                                                               660,100,000                
        common stock without par value, 80.0 shares authorized, 35.9 and 35.8 shares outstanding
                                                                638,800,000               
        common stock without par value, 80.0 shares authorized, 35.8 and 35.2
                                                                               
        common stock without par value, 80.0 shares authorized, 35.8 and 35.2 shares outstanding
                                                                  634,100,000             
        common stock without par value, 80.0 shares authorized, 35.7 and 35.2 shares outstanding
                                                                   629,800,000            
        other assets
                                                                    33,500,000 32,800,000 288,200,000 285,800,000 282,800,000 281,400,000 122,100,000 117,000,000 111,300,000 111,400,000 138,700,000 
        other liabilities
                                                                    326,400,000 325,000,000 352,000,000 360,400,000 363,900,000 389,300,000 199,500,000 187,200,000 202,700,000 200,100,000 237,100,000 
        common stock without par value, 80.0 shares authorized, 35.5 and 35.2 shares outstanding
                                                                    621,200,000           
        common stock without par value, 80.0 shares authorized, 35.2 and 32.6
                                                                               
        common stock without par value, 80.0 shares authorized, 34.9 and 32.6
                                                                               
        common stock without par value, 80.0 shares authorized, 34.1 and 32.6
                                                                               
        total allete’s equity
                                                                       875,200,000 848,700,000       
        common stock without par value, 43.3 shares authorized, 33.2 and 32.6
                                                                               
        deferred profit on sales of real estate
                                                                          800,000 2,700,000 2,700,000 2,700,000 5,300,000 
        minority interest
                                                                         9,800,000 9,600,000 9,300,000 9,300,000 9,300,000 9,000,000 
        common stock without par value, 43.3 shares authorized
                                                                               
        32.6 and 30.8 shares outstanding
                                                                         534,100,000      
        investments
                                                                          213,300,000 208,300,000 225,800,000 213,800,000 206,400,000 
        liabilities and shareholders' equity
                                                                               
        shareholders' equity
                                                                               
        common stock without par value, 43.3 shares authorized, 31.6 and 30.8
                                                                               
        total shareholders' equity
                                                                          799,700,000 759,200,000 751,400,000  724,500,000 
        total liabilities and shareholders' equity
                                                                          1,847,600,000 1,788,800,000 1,715,800,000  1,646,500,000 
        common stock without par value, 43.3 shares authorized, 31.0 and 30.8
                                                                               
        common stock without par value, 43.3 shares authorized, 30.8 and 30.8
                                                                               
        30.8 and 30.4 shares outstanding
                                                                             461,200,000  
        common stock without par value, 43.3 shares authorized, 30.8 and 30.4
                                                                               
      Cashflow Statements:
      Quarterly
      Annual
        Unit: USD2025-09-30 2025-06-30 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 2021-06-30 2021-03-31 2020-12-31 2020-09-30 2020-06-30 2020-03-31 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 2014-12-31 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 2008-12-31 2008-09-30 2008-06-30 2008-03-31 2007-12-31 
                                                                                
          millions
                                                                                
          operating activities
                                                                                
          net income
        13,300,000 6,600,000 34,700,000 32,300,000 32,700,000 19,700,000 37,000,000 31,000,000 69,600,000 40,700,000 37,600,000 37,200,000 26,800,000 20,800,000 46,500,000 48,600,000 24,100,000 21,700,000 43,400,000 41,400,000 38,800,000 16,900,000 64,500,000 49,600,000 31,200,000 34,200,000 70,500,000 61,100,000 30,700,000 31,300,000 51,000,000 41,400,000 44,900,000 36,900,000 49,000,000 44,300,000 40,300,000 24,800,000 46,400,000 18,800,000 60,300,000 22,300,000 40,100,000 33,200,000 41,600,000 16,900,000 33,800,000 33,000,000 25,200,000 14,000,000 32,500,000 28,900,000 29,400,000 14,400,000 24,400,000 19,100,000 20,500,000 16,900,000 37,100,000 13,100,000 19,500,000 19,400,000 22,800,000 18,700,000 15,800,000 9,300,000 16,900,000 23,500,000 24,700,000 10,700,000 23,600,000 22,200,000 
          adjustments to reconcile net income to cash from operating activities:
                                                                                
          afudc – equity
        -1,300,000 -1,300,000 -1,400,000 -1,000,000 -1,500,000 -1,300,000 -1,200,000 -1,100,000 -1,100,000 -900,000 -500,000 -300,000 -700,000 -800,000 -900,000 -900,000 -600,000 -600,000 -500,000 -100,000 -400,000 -900,000 -500,000  -600,000 -700,000 -600,000  -400,000 -200,000 -300,000  -300,000 -200,000 -200,000                                      
          income from equity investments – net of dividends
        200,000 -400,000 1,900,000 -1,900,000 400,000   400,000 400,000   -1,400,000 3,200,000 200,000 400,000 400,000 700,000 100,000 1,000,000 -900,000 -100,000    -1,000,000 -1,000,000 -1,200,000  -900,000 100,000 -500,000  -1,300,000 -1,000,000 -1,500,000  -2,900,000 -2,900,000  -1,400,000                                
          gain on investments and property, plant and equipment
        -500,000 -600,000 -700,000             -100,000                                                         
          depreciation expense
        72,400,000 73,200,000 69,700,000 69,600,000 70,800,000 65,900,000 65,000,000 63,500,000 63,200,000 62,700,000 62,300,000 60,700,000 58,600,000 61,000,000 61,700,000 58,200,000 57,600,000 57,800,000 58,000,000 56,400,000 53,400,000 54,500,000 53,400,000 50,300,000 49,500,000 50,100,000 50,700,000 50,800,000 50,100,000 54,700,000 44,500,000 24,500,000 49,500,000 48,700,000 49,200,000 48,800,000 47,600,000 47,400,000 46,800,000 45,200,000 42,000,000 40,300,000 38,400,000 36,200,000 33,500,000 33,800,000 32,200,000 30,300,000 29,400,000 28,700,000 28,200,000 25,800,000 25,000,000 24,800,000 24,600,000 23,300,000 22,700,000 22,100,000 22,300,000 20,700,000 20,000,000 19,800,000 20,000,000 17,900,000 16,100,000   16,400,000     
          amortization of psas
        -1,500,000 -1,400,000 -1,500,000 -1,200,000 -1,300,000 -1,200,000 -1,300,000 -1,300,000 -1,300,000 -1,300,000 -1,300,000 -1,300,000 -1,200,000 -2,300,000 -2,800,000 -2,800,000 -2,900,000 -2,900,000 -2,800,000 -2,800,000 -2,900,000 -2,800,000 -2,800,000  -2,900,000 -2,900,000 -2,900,000  -6,000,000 -5,900,000 -6,000,000  -5,900,000 -5,900,000 -5,900,000                                      
          amortization of other intangible assets and other assets
        1,600,000 1,700,000 1,700,000 1,700,000 1,900,000 1,700,000 1,600,000 1,800,000 1,800,000 1,600,000 1,900,000 2,000,000 2,000,000 2,200,000 2,100,000 2,500,000 2,300,000 2,600,000 2,500,000 1,900,000 3,300,000 2,600,000 2,600,000 3,100,000 6,700,000 1,300,000 1,900,000 2,600,000 2,800,000 2,200,000 2,800,000 2,600,000 2,300,000 2,400,000 2,900,000 2,200,000 3,100,000 2,700,000 2,300,000 600,000                                 
          deferred income tax benefit
        600,000 -3,200,000 -300,000   -5,100,000 -2,900,000  14,200,000 -6,600,000 -6,300,000 -18,800,000 -7,400,000 -8,300,000 -4,000,000 -7,500,000 -5,000,000 -4,000,000 -10,400,000 -11,600,000 -5,600,000    -2,400,000                                                
          share-based and esop compensation expense
        2,200,000 2,300,000 1,700,000 1,100,000 1,800,000 2,000,000 1,700,000 3,000,000 1,900,000 1,600,000 800,000 700,000 1,500,000 1,400,000 1,300,000 1,300,000 1,500,000 1,400,000 1,700,000 1,400,000 1,600,000 1,400,000 1,700,000 1,400,000 1,600,000 1,500,000 1,800,000 1,700,000 1,800,000 1,600,000 1,700,000 1,600,000 1,700,000                                        
          defined benefit pension and other postretirement plan benefit
        -900,000 -800,000 -900,000  -3,400,000 -3,500,000 -3,400,000                                                                  
          fuel adjustment clause
        300,000 -3,600,000 4,400,000 -6,100,000 -1,300,000 3,100,000 4,900,000 -9,800,000 15,400,000 23,100,000 15,300,000 18,600,000 15,300,000                                                            
          bad debt expense
        500,000 300,000 300,000 400,000 400,000 300,000 100,000 500,000 400,000 300,000 500,000 600,000 400,000 400,000 300,000 300,000 200,000 400,000 1,100,000 500,000 700,000 400,000  300,000 -1,000,000 400,000 -400,000 800,000 400,000 300,000 300,000   -400,000 1,600,000 1,400,000 500,000 600,000 800,000 500,000 100,000 200,000 700,000 500,000 400,000 200,000 400,000 500,000 300,000 100,000 100,000 400,000 200,000 300,000 200,000 500,000 300,000 200,000 300,000 300,000 300,000 200,000 100,000 600,000 300,000 300,000 -200,000 400,000 300,000 200,000 200,000 
          provision (payments) for interim rate refund
                           -6,500,000                                                    
          changes in operating assets and liabilities
                                                                                
          accounts receivable
        -16,900,000 13,500,000 4,600,000 -14,800,000 -4,300,000 11,500,000 -5,500,000 -15,400,000 3,200,000 -3,300,000 17,300,000 -17,200,000 -5,000,000 3,300,000 4,900,000 -13,800,000 -4,900,000 7,900,000 -2,200,000 -21,000,000 -6,700,000 12,900,000 -3,400,000 -11,500,000 100,000 13,100,000 20,900,000  2,200,000 -4,600,000 6,300,000  -12,000,000 2,300,000 100,000  4,100,000 10,700,000 -4,200,000 -10,500,000 -5,700,000 9,500,000 7,800,000  -4,100,000 18,100,000 2,900,000  -1,700,000 7,200,000 2,700,000  -6,800,000 9,700,000 2,700,000 -4,200,000 -4,400,000 19,400,000 7,800,000 12,300,000 -4,500,000 10,700,000 -600,000          
          inventories
        -8,700,000 -9,500,000 -5,800,000 5,000,000 11,400,000 -1,600,000 -7,300,000 1,500,000 14,000,000 152,600,000 109,000,000 5,300,000 -93,200,000 -69,300,000 -98,900,000 -8,100,000 -1,500,000 -14,100,000 200,000 600,000 7,300,000 -3,100,000 -6,200,000  -6,400,000 -4,400,000 -5,100,000 68,100,000 -9,400,000 -2,900,000 -300,000 6,600,000 4,500,000 7,100,000 -6,300,000 3,600,000 3,000,000 5,600,000 1,100,000  -10,700,000 -4,600,000 -8,800,000  3,700,000 -6,400,000 -6,500,000 5,400,000 6,300,000 -6,700,000 5,500,000  -7,400,000 2,900,000 -3,100,000  -7,800,000 -5,200,000 3,900,000 2,800,000 -5,700,000 -5,500,000 5,400,000          
          prepayments and other
        14,900,000 -14,100,000 9,600,000 -8,500,000 -2,300,000 -6,400,000 6,700,000 -8,500,000 1,800,000 -12,200,000 11,000,000 -13,800,000 1,000,000 -1,300,000 -7,400,000 -8,400,000 6,200,000 3,000,000 -1,300,000 -7,900,000 5,500,000 -700,000 4,000,000 -7,000,000 4,000,000 400,000 2,900,000  2,900,000 4,000,000 -1,200,000  -2,200,000 2,500,000 1,800,000  100,000 -900,000 100,000 4,100,000 -4,600,000 4,900,000 -700,000 -4,000,000 1,800,000 4,800,000 2,200,000  -3,000,000 1,900,000 5,500,000  1,700,000 -2,600,000 4,200,000 -4,300,000 -2,200,000 3,900,000 4,100,000 -1,900,000 -4,800,000 -2,500,000 4,900,000          
          accounts payable
        2,800,000 -4,400,000 1,500,000 400,000 9,700,000 -2,400,000 -10,400,000 4,000,000 5,300,000 -2,600,000 -10,700,000 -9,300,000 -9,800,000 28,400,000 -10,600,000 11,000,000 5,200,000 7,400,000 -8,600,000 9,600,000 13,800,000 -6,100,000 -5,500,000  7,900,000 -5,700,000 -5,500,000 3,700,000 1,800,000 8,200,000 -100,000  10,000,000 -1,300,000 -11,300,000 5,900,000 -700,000 5,500,000 -4,200,000   -11,600,000 -14,000,000 12,100,000 9,800,000 -11,100,000 100,000 -2,800,000 14,000,000 900,000 -11,000,000  6,900,000 -300,000 -7,900,000  1,200,000 -5,000,000 -12,700,000 2,100,000 14,100,000 9,600,000 -20,000,000          
          other current liabilities
        9,700,000 -2,900,000 -17,100,000 12,600,000 16,300,000 -8,200,000 -19,800,000 10,300,000 -1,100,000 -24,600,000 -142,200,000 52,700,000 91,200,000 -26,700,000 -1,000,000 7,300,000 33,700,000 -36,500,000 23,500,000 4,200,000 21,000,000 -15,600,000 7,100,000  8,100,000 -14,000,000 -9,900,000 -14,500,000 22,500,000 -18,600,000 17,300,000 -900,000 15,500,000 -11,800,000 -1,000,000  -4,500,000 -19,400,000 900,000 5,900,000 -48,200,000 49,100,000 -1,700,000  -3,100,000 -11,300,000 1,600,000 10,200,000 -3,000,000 -5,100,000 -700,000 14,400,000   -900,000 19,800,000 5,700,000 -5,000,000 -5,100,000 7,200,000 1,700,000 -8,700,000 5,000,000          
          renewable tax credit sales
        4,900,000 9,800,000 12,500,000 2,700,000 35,900,000                                                                    
          cash contributions to defined benefit pension plans
        -19,100,000 -25,000,000 -10,800,000 -6,500,000     -10,300,000 -10,700,000  -10,400,000  -15,000,000  -1,700,000                                      
          changes in regulatory and other non-current assets
        100,000 -700,000 5,600,000 3,700,000 15,400,000 14,000,000 9,100,000 11,500,000 5,700,000 -900,000 -700,000 -3,900,000 11,100,000 14,900,000 2,000,000 29,300,000 -15,700,000 -25,000,000 -600,000 -7,500,000 -6,700,000 -5,400,000 -11,400,000  -6,400,000 -12,200,000 300,000 -500,000 1,400,000 2,000,000 3,800,000 9,600,000 17,400,000 -2,900,000 9,600,000  2,700,000 -23,800,000 2,800,000 6,800,000 3,400,000 -5,500,000 -4,100,000  -1,500,000 -7,500,000 -4,000,000  -5,500,000 -6,100,000 -1,900,000  -3,200,000 -3,900,000 2,100,000  15,700,000    5,500,000            
          changes in regulatory and other non-current liabilities
        9,700,000 3,200,000 3,800,000 -500,000 1,800,000 -300,000 5,600,000 1,600,000 -1,300,000 1,300,000 400,000 5,800,000 -2,700,000 -4,700,000 1,800,000 -7,600,000 1,400,000 -2,700,000 -6,100,000 -2,300,000 -15,900,000 2,400,000 6,300,000  -8,100,000 600,000 -7,000,000  -5,800,000 100,000 7,400,000  -18,300,000 -2,600,000 -2,600,000 3,300,000 10,700,000 -1,800,000 -1,100,000  -5,000,000 -1,000,000 7,500,000 -1,200,000 -1,600,000 5,700,000 -300,000  2,000,000 6,900,000 -4,300,000 -3,000,000 -3,100,000 1,200,000 5,700,000 -9,300,000 -4,500,000    -7,100,000            
          cash from operating activities
        103,400,000 39,400,000 110,200,000 89,800,000 190,800,000 116,400,000 60,100,000 65,300,000 188,400,000 239,200,000 92,400,000 140,100,000 89,100,000 -3,100,000 -4,800,000 54,300,000 103,500,000 17,200,000 88,500,000 55,900,000 99,400,000 55,700,000 88,800,000 73,100,000 81,200,000 16,100,000 79,100,000 135,000,000 103,700,000 73,100,000 121,300,000 95,700,000 122,800,000 85,700,000 98,700,000 94,200,000 91,600,000 53,000,000 93,200,000 85,500,000 72,300,000 110,500,000 71,800,000 57,700,000 86,000,000 51,200,000 74,900,000 50,500,000 77,800,000 52,900,000 58,200,000 44,100,000 67,400,000 59,600,000 68,500,000 56,600,000 55,100,000 60,900,000 69,100,000 40,700,000 79,500,000 51,800,000 56,700,000          
          capital expenditures
        -277,600,000 -108,300,000 -154,400,000 -124,600,000 -96,300,000 -73,400,000 -60,600,000 -87,100,000 -63,600,000 -50,500,000 -70,000,000 -68,500,000 -62,500,000 -32,200,000 -57,300,000 -89,000,000 -90,900,000 -159,000,000 -134,400,000 -177,000,000 -120,900,000 -265,600,000 -154,300,000 -185,300,000 -146,700,000 -89,300,000 -67,600,000 -45,300,000 -88,100,000 -49,200,000 -44,400,000 -36,700,000 -44,700,000 -32,400,000 -42,400,000 -67,700,000 -52,300,000 -88,200,000 -133,900,000 -117,700,000 -216,200,000 -66,700,000 -58,800,000 -69,800,000 -110,100,000 -167,900,000 -53,900,000 -65,200,000 -40,100,000 -51,500,000 -76,200,000 -93,200,000 -31,400,000 -48,100,000          
          free cash flows
        -174,200,000 -68,900,000 -44,200,000 -34,800,000 94,500,000 43,000,000 -500,000 -21,800,000 124,800,000 188,700,000 22,400,000 71,600,000 26,600,000 -35,300,000 -62,100,000 -34,700,000 12,600,000 -141,800,000 -45,900,000 -121,100,000 -21,500,000 -209,900,000 -65,500,000 73,100,000 -104,100,000 -130,600,000 -10,200,000 135,000,000 36,100,000 27,800,000 33,200,000 95,700,000 73,600,000 41,300,000 62,000,000 94,200,000 46,900,000 20,600,000 50,800,000 85,500,000 4,600,000 58,200,000 -16,400,000 57,700,000 -47,900,000 -66,500,000 -141,300,000 50,500,000 11,100,000 -5,900,000 -11,600,000 44,100,000 -42,700,000 -108,300,000 14,600,000 56,600,000 -10,100,000 20,800,000 17,600,000 -35,500,000 -13,700,000 20,400,000 8,600,000          
          investing activities
                                                                                
          proceeds from sale of available-for-sale securities
        500,000 1,100,000 1,400,000 300,000 300,000 1,400,000 500,000 300,000   500,000 500,000 700,000 500,000 3,100,000 700,000 1,400,000 1,200,000 6,000,000 4,700,000 1,200,000 900,000 900,000 5,200,000 3,300,000 2,700,000 900,000 2,100,000 3,900,000 3,300,000 4,900,000 4,200,000 700,000 300,000 2,200,000 5,400,000 300,000 1,100,000 1,000,000 500,000 200,000 300,000 600,000 2,100,000 600,000 1,100,000 6,900,000 200,000 7,900,000 300,000 200,000 500,000 500,000 400,000 200,000 200,000 7,000,000 100,000 -100,000 600,000 7,900,000 100,000 900,000 3,800,000 6,200,000 37,200,000 15,100,000 75,400,000 
          payments for purchase of available-for-sale securities
        -1,300,000 -100,000 -1,300,000 -500,000 -300,000 -100,000 -1,500,000 -400,000 -400,000   -700,000 -500,000 -800,000 -400,000 -600,000 -1,000,000 -1,400,000 -600,000 -1,500,000 -4,900,000 -1,200,000 -1,100,000  -5,200,000 -3,300,000 -2,600,000  -2,700,000 -4,500,000 -5,300,000  -4,300,000 -1,100,000 -500,000  -6,000,000 -900,000 -300,000  -300,000 -400,000 -400,000  -900,000 -2,700,000 -700,000  -1,400,000 -200,000 -1,200,000  -500,000 -200,000 -800,000  -400,000 -300,000 -900,000 -500,000 -400,000 -200,000 -1,200,000 -400,000 -900,000 -700,000 -200,000 300,000 -5,800,000 -27,300,000 -12,000,000 -28,100,000 
          payments for equity method investments
        -7,000,000 -5,800,000 -5,500,000  -1,900,000 -2,300,000 -1,600,000  -2,300,000 -3,500,000 -800,000  -1,200,000 -1,200,000 -2,700,000  -300,000                                                        
          additions to property, plant and equipment
        -277,600,000 -108,300,000 -154,400,000 -124,600,000 -96,300,000 -73,400,000 -60,600,000 -87,100,000 -63,600,000 -50,500,000 -70,000,000 -68,500,000 -62,500,000 -32,200,000 -57,300,000 -89,000,000 -90,900,000 -159,000,000 -134,400,000 -177,000,000 -120,900,000 -265,600,000 -154,300,000  -185,300,000 -146,700,000 -89,300,000  -67,600,000 -45,300,000 -88,100,000  -49,200,000 -44,400,000 -36,700,000  -44,700,000 -32,400,000 -42,400,000  -67,700,000 -52,300,000 -88,200,000  -133,900,000 -117,700,000 -216,200,000  -66,700,000 -58,800,000 -69,800,000  -110,100,000 -167,900,000 -53,900,000  -65,200,000 -40,100,000 -51,500,000 -76,200,000 -93,200,000 -31,400,000 -48,100,000 -118,400,000 -66,800,000 -58,700,000 -74,600,000 -91,100,000 -79,500,000 -70,900,000 -59,600,000 -73,500,000 
          other investing activities
        2,800,000 -400,000 -400,000 4,000,000 15,100,000 -200,000 1,500,000 5,600,000 -3,300,000 -2,400,000 -3,900,000 -3,400,000 -200,000 1,400,000 -200,000 -1,400,000 100,000 300,000 3,900,000  -300,000 -500,000 -200,000 -300,000 -800,000 12,200,000 1,800,000 4,300,000 1,200,000 200,000                                          
          cash from investing activities
        -282,600,000 -113,500,000 -160,200,000 -120,800,000 -83,100,000 -76,000,000 -60,800,000 -83,000,000 -69,300,000 -56,600,000 -74,700,000 -72,900,000 -63,900,000 -187,100,000 -60,100,000                                                          
          financing activities
                                                                                
          proceeds from issuance of common stock
        3,100,000 4,000,000 2,500,000 3,000,000 3,500,000 4,400,000 2,000,000 3,500,000 3,700,000 4,400,000 3,300,000 3,600,000 4,000,000 237,100,000 3,300,000 38,900,000 20,900,000 5,100,000 5,000,000 5,300,000 4,900,000 4,600,000 3,300,000 200,000 200,000 700,000 800,000 5,700,000 3,900,000 6,400,000 4,300,000 5,500,000 6,100,000 3,800,000 70,600,000 3,900,000 11,800,000 6,200,000 9,000,000 6,000,000 7,000,000 6,700,000 141,500,000 71,700,000 90,000,000 14,100,000 24,800,000 34,900,000 30,000,000 9,900,000 23,400,000 24,900,000 21,600,000 6,800,000 23,700,000 9,000,000 7,200,000 20,800,000 2,100,000 1,500,000 3,800,000 7,900,000 7,300,000 11,500,000 25,800,000 25,100,000 2,800,000      
          proceeds from issuance of short-term and long-term debt
        345,000,000 100,000,000 240,000,000 30,000,000 322,000,000 150,000,000 156,000,000 27,200,000 6,100,000 165,200,000 238,500,000 64,900,000 245,200,000 246,400,000 228,900,000 222,400,000 131,600,000 184,100,000 194,900,000                                                      
          repayments of short-term and long-term debt
        -101,700,000 -31,900,000 -111,800,000 -16,400,000 -324,000,000 -151,000,000 -158,000,000 -33,300,000 -1,900,000 -303,700,000 -227,800,000 -106,000,000 -269,400,000 -242,400,000 -259,200,000 -272,000,000 -131,600,000                                                        
          proceeds from non-controlling interest in subsidiaries – net
        2,200,000 7,900,000 2,000,000  1,400,000 2,700,000  3,200,000 6,700,000                                                              
          distributions to non-controlling interest
        -1,600,000 -200,000 -300,000 -600,000 -200,000 -200,000 -500,000                                                                 
          dividends on common stock
        -42,400,000 -42,300,000 -42,300,000 -40,800,000 -40,700,000 -40,700,000 -40,600,000 -39,000,000 -38,900,000 -38,800,000 -38,800,000 -37,300,000 -37,100,000 -37,000,000 -34,500,000 -33,200,000 -33,000,000 -32,900,000 -32,800,000 -32,200,000 -32,100,000 -32,000,000 -31,900,000  -30,300,000 -30,400,000 -30,300,000  -28,800,000 -28,700,000 -28,700,000  -27,400,000 -27,100,000 -26,900,000  -25,800,000 -25,500,000 -25,700,000  -24,500,000 -24,600,000 -24,900,000  -20,700,000 -20,600,000 -21,100,000  -19,000,000 -18,700,000 -19,500,000  -16,700,000 -17,800,000 -17,700,000  -15,500,000 -15,200,000 -16,200,000 -15,600,000 -14,400,000 -15,600,000 -15,200,000 -14,800,000 -14,500,000 -13,600,000 -13,600,000      
          other financing activities
        -2,100,000 100,000 -900,000 -1,000,000   -400,000 500,000 -1,400,000 -200,000 -800,000 -1,000,000 -700,000 -400,000 -2,000,000 -1,900,000 -500,000 -400,000 200,000 -2,200,000 -600,000 100,000  -200,000 100,000 -900,000  100,000 -400,000 -200,000  -200,000                                        
          cash from financing activities
        202,500,000 37,600,000 89,200,000  -40,400,000 -37,000,000 -38,400,000  -39,000,000 -171,100,000 -18,300,000 -75,600,000 -58,300,000 196,900,000 92,200,000 16,100,000 -14,000,000 47,900,000 154,200,000    80,100,000                 -7,000,000 133,200,000 -6,700,000 110,400,000 104,800,000 116,000,000 106,600,000 77,000,000 23,900,000 11,500,000 76,100,000 2,200,000 10,900,000    -4,600,000    -14,900,000   1,800,000          
          change in cash, cash equivalents and restricted cash
        23,300,000 -36,500,000 39,200,000 -55,800,000 67,300,000 3,400,000 -39,100,000 -51,800,000 80,100,000 11,500,000 -600,000 -8,400,000 -33,100,000 6,700,000 27,300,000 -17,700,000 -1,900,000 -109,700,000 111,800,000 -19,900,000 47,700,000 -41,500,000 -13,600,000 -42,700,000 -71,400,000 -158,600,000 286,200,000  8,700,000 16,900,000 5,800,000                                          
          cash, cash equivalents and restricted cash at beginning of period
        55,200,000 79,400,000 40,200,000 47,700,000 65,200,000 92,500,000 79,000,000 110,100,000                                          
          cash, cash equivalents and restricted cash at end of period
        23,300,000 -36,500,000 94,400,000 -55,800,000 67,300,000 3,400,000 40,300,000 -51,800,000 80,100,000 11,500,000 39,600,000 -8,400,000 -33,100,000 6,700,000 75,000,000 -17,700,000 -1,900,000 -109,700,000 177,000,000 -19,900,000 47,700,000 -41,500,000 78,900,000 -42,700,000 -71,400,000 -158,600,000 365,200,000 -62,500,000 8,700,000 16,900,000 115,900,000                                          
          provision for interim rate refund
          5,000,000  6,000,000 5,500,000 5,500,000  7,600,000 8,300,000 5,100,000                600,000 3,300,000 4,200,000 4,400,000 4,400,000                                          
          loss on investments and property, plant and equipment
            -400,000 400,000 -500,000  200,000 400,000 -900,000 700,000 1,300,000 100,000                                                          
          deferred income tax expense
           -8,600,000                   -13,800,000    2,600,000  400,000 -5,100,000 -4,400,000 -19,900,000 14,100,000 7,200,000 13,000,000 3,900,000 1,700,000 4,600,000 9,200,000 -1,400,000 14,200,000 6,200,000 6,100,000 7,500,000 11,600,000 4,800,000 8,800,000 8,200,000 8,800,000 4,300,000 7,300,000 14,100,000 10,300,000 4,800,000 8,300,000 11,200,000 12,800,000 3,700,000 8,100,000 1,000,000 41,900,000 11,300,000 11,800,000 36,300,000 14,900,000 13,500,000 10,500,000 20,400,000     
          defined benefit pension and other postretirement plan expense
                                                                                
          acquisitions of subsidiaries – net of cash and restricted cash acquired
                                                                                
          payments for equity investments
                          -1,000,000 -8,100,000 -24,400,000 -38,800,000 -27,800,000  -21,800,000 -4,100,000 -500,000                                              
          equity issuance costs
                                                                              
          proceeds from non-controlling interest in subsidiaries – net of issuance costs
                           346,700,000                                                    
          cash provided (used in) by financing activities
                                                                                
          defined benefit pension and postretirement benefit
                -800,000 -900,000 -800,000                                                              
          residential interim rate adjustment
                    -2,100,000                                                            
          acquisition of subsidiaries - net of cash & restricted cash acquired
                                                                               
          loss on impairment of assets
                                                                                
          defined benefit pension and other postretirement benefit expense
                                                                                
          payments for tax reform refund
                                                                               
          defined benefit pension and postretirement benefit expense
                    -800,000 -1,000,000 -400,000  1,100,000 1,100,000 1,100,000      -300,000 1,000,000 1,100,000  2,100,000 2,100,000 2,200,000  2,600,000 2,500,000 2,500,000  1,300,000 1,300,000 1,300,000  3,800,000 3,900,000 3,800,000  3,200,000 3,200,000 3,200,000  5,600,000 5,600,000 5,600,000  6,800,000 6,900,000 6,900,000                  
          proceeds from non-controlling interest in subsidiaries - net
                    1,600,000 154,100,000                                                          
          payments for interim rate refund
                                                                                
          gain on sale of u.s. water services
                                -500,000 -20,100,000                                              
          changes in fuel adjustment clause regulatory asset and liability
                                                                                
          return of capital from equity investments
                               8,300,000                                              
          proceeds from sale of u.s. water services – net of transaction costs and cash retained
                               2,500,000 1,900,000 -500,000 264,700,000                                              
          cash for investing activities
                       -88,100,000 -91,400,000 -174,800,000 -130,900,000 -179,600,000         -69,300,000 -49,500,000 -89,000,000  -67,000,000 -43,600,000 -41,100,000  -46,800,000 -31,300,000 -42,600,000  -163,100,000 -115,300,000 -255,900,000  -135,100,000 -118,800,000 -204,600,000  -69,800,000 -61,300,000 -63,900,000  -114,600,000 -170,500,000 -56,500,000  -67,900,000 -41,300,000 -45,700,000 -73,200,000 -95,500,000 -30,500,000 -51,700,000          
          acquisition-related contingent consideration payments
                                -3,800,000      -4,600,000 -15,100,000  -100,000 -100,000 -600,000                                  
          proceeds from non-controlling interest in subsidiaries
                        28,900,000                                                      
          realized and unrealized loss on investments and property, plant and equipment
                             -2,000,000 3,100,000                                                  
          realized and unrealized gain on investments and property, plant and equipment
                          -500,000                                                      
          repayments of long-term debt
                          -41,400,000 -281,200,000 -186,500,000 -19,500,000 -1,400,000  -16,300,000 -6,000,000 -43,800,000  -1,600,000 -56,000,000 -1,900,000  -56,600,000 -100,700,000 -26,300,000  -18,600,000 -5,500,000 -26,600,000  -78,400,000                                
          change in fair value of contingent consideration
                                        -400,000                                      
          provision (payments) for tax reform refund
                                                                                
          proceeds from issuance of long-term debt
                           65,000,000 310,000,000 187,400,000 110,000,000 1,900,000 100,000,000 100,000,000 2,900,000 700,000   45,300,000   2,600,000   84,500,000 225,000,000   160,000,000 115,000,000 100,000,000 19,800,000   5,000,000 160,000,000   6,400,000    75,000,000 80,000,000 66,700,000 1,400,000 400,000 42,900,000      
          cash (for) from financing activities
                                                                                
          cash from (for) investing activities
                             -304,900,000 -182,500,000   -139,100,000 185,100,000                                              
          cash from (for) financing activities
                                  22,000,000    -26,500,000      -29,500,000 -26,800,000 -50,600,000               1,300,000 5,100,000    -15,600,000              
          deferred fuel adjustment clause charge
                                                                                
          loss on sales of investments and property, plant and equipment
                                      -100,000                                          
          equity investments
                                                                                
          payments / provision for interim rate refund
                                                                               
          payments / provision for tax reform refund
                                -100,000 -100,000 -10,200,000                                              
          cash for financing activities
                                    -25,700,000    -35,600,000 -39,700,000 -3,300,000                                      
          gain on sales of investments and property, plant and equipment
                                  -1,700,000                                              
          impairment of goodwill
                                                                                
          provision for tax reform refund
                                   1,500,000 2,500,000 -800,000 7,500,000                                          
          acquisition of non-controlling interest
                                                   -6,000,000                          
          investment in atc
                                    -1,100,000 -2,300,000 -1,600,000  -1,600,000 -1,900,000 -3,100,000  -1,900,000 -400,000 -1,200,000  -400,000 -400,000 -400,000  -800,000 -1,100,000 -1,200,000  -700,000 -1,200,000 -400,000  -1,900,000 -1,200,000 -800,000  -600,000 -600,000 -800,000 -400,000 -1,200,000 -2,400,000 -1,900,000 -1,600,000 -1,900,000 -2,200,000     
          changes to other investments
                                      2,500,000 900,000 800,000 2,500,000 -1,200,000 1,900,000 400,000 1,900,000 200,000     1,900,000 500,000 600,000 30,000,000  -7,900,000 -1,600,000 -1,000,000  -2,300,000 -1,700,000 -1,500,000  -2,700,000 -500,000 -900,000 3,900,000 -2,000,000 1,200,000 -1,800,000 -200,000 -5,700,000 -1,200,000 6,400,000      
          changes in notes payable
                                          1,300,000  -900,000 200,000 -900,000  -300,000 -3,400,000 1,000,000           500,000 -4,500,000 3,100,000 2,000,000 -500,000 -400,000 -300,000 -200,000 -3,400,000        
          impairment of real estate
                                                                                
          acquisitions of subsidiaries – net of cash acquired
                                                -110,400,000 -47,500,000 -166,900,000                              
          proceeds from sale of property, plant and equipment
                                       100,000 500,000 600,000 100,000 500,000   100,000                                 
          changes in restricted cash
                                        -2,800,000 5,400,000 -6,900,000 4,900,000 4,100,000 3,800,000 -5,800,000 6,300,000 5,100,000 -2,100,000 -800,000  -7,400,000 6,000,000                          
          change in cash and cash equivalents
                                       -5,500,000 20,200,000 2,400,000 54,300,000  15,300,000    42,400,000 -11,500,000 -73,700,000 -4,700,000 66,900,000 39,000,000 -52,700,000 -67,200,000 19,500,000 67,700,000 -3,500,000  95,700,000 -109,600,000 17,100,000 -34,000,000 55,700,000 26,700,000 7,800,000 -47,400,000 47,000,000 12,800,000 6,800,000 -28,600,000 -18,100,000 -25,600,000 -4,000,000 23,900,000 -21,000,000 22,900,000 52,900,000 -38,100,000 
          cash and cash equivalents at beginning of period
                                       27,500,000 97,000,000 145,800,000 97,300,000 80,800,000 101,100,000 44,900,000 25,700,000 102,000,000 23,300,000 
          cash and cash equivalents at end of period
                                       -5,500,000 20,200,000 2,400,000 81,800,000 -79,700,000 15,300,000 -5,100,000 97,000,000 -6,000,000 42,400,000 -11,500,000 72,100,000 -4,700,000 66,900,000 39,000,000 44,600,000 -67,200,000 19,500,000 67,700,000 77,300,000 -23,500,000 95,700,000 -109,600,000 118,200,000 -34,000,000 55,700,000 26,700,000 52,700,000 -47,400,000 47,000,000 12,800,000 32,500,000 -28,600,000 -18,100,000 -25,600,000 98,000,000 23,900,000 -21,000,000 22,900,000 76,200,000 -38,100,000 
          loss on sales of property, plant and equipment
                                          100,000                                      
          share-based compensation expense
                                          700,000 600,000 700,000 700,000 600,000 500,000 800,000 700,000 600,000 600,000 300,000 600,000 800,000 600,000 500,000 700,000 600,000 400,000 500,000 500,000 700,000 -100,000 600,000 500,000 600,000              
          esop compensation expense
                                          1,100,000 900,000 700,000   1,700,000 2,400,000 2,500,000 2,400,000 2,400,000 2,200,000 2,300,000 2,200,000 2,400,000 2,000,000 2,000,000 2,000,000 2,200,000 1,800,000 1,900,000 1,800,000 2,100,000 1,700,000 1,700,000 1,900,000              
          allowance for funds used during construction – equity
                                            -500,000 -300,000 -900,000  -1,000,000 -700,000 -900,000  -2,100,000 -2,000,000 -1,800,000  -1,300,000 -1,000,000 -1,100,000                      
          amortization of power sales agreements
                                                                                
          construction costs for development project
                                                  -200,000                              
          cash in escrow for acquisition
                                                                               
          construction deposits received for development project
                                                                                
          amortization of power purchase agreements
                                            -5,600,000 -5,500,000 -5,600,000  -6,100,000 -6,100,000 -4,900,000                              
          debt issuance costs
                                                   -1,300,000 -900,000 -900,000            -700,000 -700,000 -100,000 -500,000      
          gain on sales of investments
                                                                                
          cash contributions to defined benefit pension and other postretirement plans
                                                                                
          gain on sale of investments
                                                        -1,400,000 -800,000                      
          amortization of intangible assets and other assets
                                                 2,100,000 800,000                              
          income from equity investments, net of dividends
                                                  -800,000  -1,100,000 -1,100,000 -800,000  -800,000 -1,000,000 -1,300,000  -1,000,000 -1,000,000 -700,000  -1,000,000    -800,000    300,000   -700,000 -1,400,000 -600,000 -400,000 -800,000 
          reductions of long-term debt
                                                  -2,000,000  -113,300,000 -1,000,000 -19,800,000       -1,700,000 -1,400,000     -800,000 -300,000 -500,000 -69,400,000 -6,100,000 -1,200,000 -1,300,000 -500,000      
          loss on sale of assets / investments
                                                                                
          other amortization
                                                                                
          proceeds from sale of assets
                                                       400,000 300,000 600,000     800,000 1,400,000        100,000 100,000   100,000 
          gains on sale of assets / investments
                                                                               
          amortization of debt issuance costs
                                                    300,000 200,000 300,000 200,000 300,000 200,000 300,000 300,000 200,000 300,000 200,000 200,000 200,000 300,000 200,000 200,000 200,000 300,000 200,000 200,000 300,000        
          cash contributions to defined benefit pension and other postretirement benefit plans
                                                        -10,800,000                      
          acquisition – net of cash acquired
                                                    -23,100,000                          
          gain on real estate foreclosure
                                                                              
          loss on sale of assets
                                                                                
          changes to restricted cash
                                                                                
          gain on sale of assets
                                                        -100,000 100,000 -200,000      -200,000 -700,000     -100,000    -100,000 -100,000   -100,000 
          payments for long-term debt
                                                        -700,000 -63,800,000 -1,700,000                      
          payments for notes payable
                                                                                
          proceeds from notes payable
                                                                                
          allowance for funds used during construction
                                                            -1,500,000 -1,100,000 -800,000  -600,000 -500,000 -600,000 -800,000 -1,300,000 -900,000 -1,200,000 -1,300,000 -1,600,000 -1,600,000 -1,300,000 -700,000 -600,000    
          proceeds from (for) notes payable
                                                            300,000                    
          loss from equity investments, net of dividends
                                                                                
          cash contributions to defined benefit pension and postretirement plans
                                                                                
          changes in defined benefit pension and other postretirement benefit plans
                                                                -5,800,000                
          payments on long-term debt
                                                                -1,300,000 -500,000 -1,000,000              
          operating revenue
                                                                  242,200,000            213,400,000  
          operating expenses
                                                                                
          fuel and purchased power
                                                                  79,000,000            86,300,000  
          operating and maintenance
                                                                  90,100,000            82,400,000  
          depreciation
                                                                  22,300,000           12,900,000 12,700,000 12,700,000 
          total operating expenses
                                                                  191,400,000              
          operating income
                                                                  50,800,000            32,000,000  
          other income
                                                                                
          interest expense
                                                                  -10,700,000            -6,700,000  
          equity earnings in atc
                                                                  4,400,000            3,400,000  
          other
                                                                  800,000       -3,200,000 -200,000 -1,300,000 -1,100,000 -11,600,000 8,600,000 -10,200,000 
          total other expense
                                                                  -5,500,000              
          income before non-controlling interest and income taxes
                                                                  45,300,000              
          income tax expense
                                                                  8,200,000            13,700,000  
          less: non-controlling interest in subsidiaries
                                                                  -100,000              
          net income attributable to allete
                                                                  37,200,000              
          average shares of common stock
                                                                                
          basic
                                                                  34,600,000            28,700,000  
          diluted
                                                                  34,700,000            28,700,000  
          basic earnings per share of common stock
                                                                  1,070,000              
          diluted earnings per share of common stock
                                                                  1,070,000              
          dividends per share of common stock
                                                                  445,000            430,000  
          regulatory and other assets
                                                                  -700,000    5,100,000          
          regulatory and other liabilities
                                                                  2,700,000    3,000,000          
          gain on sale of available-for-sale securities
                                                                                
          stock compensation expense
                                                                    500,000 600,000 500,000 500,000 500,000 500,000 600,000 500,000 500,000 200,000 600,000 500,000 
          (income) income from equity investments, net of dividends
                                                                      -400,000          
          loss (income) from equity investments, net of dividends
                                                                          300,000      
          other assets
                                                                        -2,700,000 -3,100,000 -1,200,000 8,200,000 -5,100,000 -5,800,000 200,000 700,000 
          other liabilities
                                                                        -3,900,000 900,000 -8,000,000 -9,500,000 4,200,000 -8,700,000 1,200,000 -8,800,000 
          depreciation and amortization
                                                                          15,400,000      
          loss from discontinued operations
                                                                                
          loss on impairment of investments
                                                                                
          minority interest
                                                                           200,000    300,000 
          net operating activities for discontinued operations
                                                                                
          changes to investments
                                                                           -5,400,000 1,600,000 200,000 3,500,000 -1,600,000 
          net investing activities from discontinued operations
                                                                                
          issuance of common stock
                                                                           35,900,000 27,300,000 6,800,000 1,100,000 700,000 
          issuance of long-term debt
                                                                                
          issuance of notes payable
                                                                                
          dividends on common stock and distributions to minority shareholders
                                                                             -12,800,000 -12,800,000 -9,900,000 
          net decrease in book overdrafts
                                                                                
          gain on sale of available for sale securities
                                                                               
          issuance of debt
                                                                            1,400,000 77,700,000 61,000,000  
          payments of long-term debt
                                                                            -200,000 -7,600,000 -600,000  
          deferred income taxes
                                                                             3,000,000 6,100,000 10,200,000 
          income before minority interest and income taxes
                                                                              37,300,000  
          basic and diluted earnings per share of common stock
                                                                              820,000  
          afudc-equity
                                                                              -1,000,000  
          afudc - equity
                                                                                
          net operating activities from (for) discontinued operations
                                                                                
          net increase in book overdrafts
                                                                                
          net financing activities for discontinued operations