7Baggers

Steel Dynamics, Inc
(NASDAQ:STLD) 

STLD stock logo

Steel Dynamics, Inc., together with its subsidiaries, operates as a steel producer and metal recycler in the United States. It operates through three segments: Steel Operations, Metals Recycling Operations, and Steel Fabrication Operations. The Steel Operations segment offers hot and cold roll, and ...

Founded: 1993
Full Time Employees: 8,385
Sector: Basic Materials
Industry: Steel

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Quarterly
Annual
    Unit: USD2026-03-31 2025-12-31 2025-09-30 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 2015-09-30 2015-06-30 2015-03-31 2014-09-30 2014-06-30 2014-03-31 2013-09-30 2013-06-30 2013-03-31 2012-09-30 2012-06-30 2012-03-31 2011-09-30 2011-06-30 2011-03-31 2010-09-30 2010-06-30 2010-03-31 2009-06-30 2009-03-31 2008-09-30 2008-06-30 2008-03-31 2007-09-30 2007-06-30 2007-03-31 2006-12-31 2006-09-30 2006-06-30 2006-03-31 2005-12-31 
                                                                            
      net sales
                                                                            
      yoy
                                                                            
      qoq
                                                                            
      unrelated parties
    5,185,334,000 12,903,185,000 4,651,398,000 4,340,798,000 4,241,499,000 12,656,997,000 4,162,651,000 4,443,994,000 4,496,819,000 13,706,451,000 4,408,861,000 4,930,422,000 4,745,353,000  5,438,747,000 5,964,503,000 5,410,801,000  5,081,476,000 4,453,556,000 3,537,625,000 2,595,959,000 2,327,224,000 2,092,964,000 2,571,544,000 2,347,003,000 2,523,279,000 2,766,364,000 2,814,486,000 2,899,584,000 3,220,891,000 3,083,822,000 2,597,312,000 2,298,130,000 2,399,116,000 2,347,304,000 2,319,663,000 1,869,596,000 2,060,596,000 1,978,984,000 1,698,004,000 1,901,415,000 1,945,983,000 2,003,973,000 2,276,747,000 1,987,635,000 1,765,881,000 1,838,464,000 1,735,420,000 1,728,401,000 1,624,561,000 1,830,117,000 1,905,075,000 1,976,296,000 2,004,283,000 1,941,664,000 1,520,346,000 1,570,093,000 1,496,082,000 773,137,000 787,810,000 2,479,655,000 2,289,121,000 1,814,083,000 1,104,076,000 850,443,000 824,385,000 774,813,000 854,299,000 758,186,000 608,618,000  
      related parties
    19,524,000 445,181,000 176,817,000 224,325,000 127,696,000 541,778,000 178,964,000 188,640,000 197,184,000 501,808,000 178,196,000 151,208,000 147,853,000  212,960,000 248,375,000 159,101,000  6,812,000 11,752,000 6,972,000 5,286,000 3,608,000 1,341,000 3,556,000 3,193,000 3,566,000 4,151,000 2,949,000 4,308,000 2,656,000 6,703,000 6,563,000 38,349,000 44,266,000 43,416,000 48,553,000 41,000,000 40,714,000 44,918,000 43,297,000 49,508,000 59,024,000 43,462,000 62,269,000 82,126,000 64,201,000 73,274,000 65,920,000 67,295,000 68,829,000 79,686,000 76,965,000 67,159,000 75,448,000 74,305,000 63,818,000 62,706,000 59,708,000 19,021,000 26,840,000 84,288,000 114,818,000 88,122,000 52,517,000 60,805,000 41,289,000 64,987,000 57,563,000 63,061,000 57,260,000  
      total net sales
    5,204,858,000 13,348,366,000 4,828,215,000 4,565,123,000 4,369,195,000 13,198,775,000 4,341,615,000 4,632,634,000 4,694,003,000 14,208,259,000 4,587,057,000 5,081,630,000 4,893,206,000  5,651,707,000 6,212,878,000 5,569,902,000  5,088,288,000 4,465,308,000 3,544,597,000 2,601,245,000 2,330,832,000 2,094,305,000 2,575,100,000 2,350,196,000 2,526,845,000 2,770,515,000 2,817,435,000 2,903,892,000 3,223,547,000 3,090,525,000 2,603,875,000 2,336,479,000 2,443,382,000 2,390,720,000 2,368,216,000 1,910,596,000 2,101,310,000 2,023,902,000 1,741,301,000 1,950,923,000 2,005,007,000 2,047,435,000 2,339,016,000 2,069,761,000 1,830,082,000 1,911,738,000 1,801,340,000 1,795,696,000 1,693,390,000 1,909,803,000 1,982,040,000 2,043,455,000 2,079,731,000 2,015,969,000 1,584,164,000 1,632,799,000 1,555,790,000 792,158,000 814,650,000 2,563,943,000 2,403,939,000 1,902,205,000 1,156,593,000 911,248,000 865,674,000 839,800,000 911,862,000 821,247,000 665,878,000  
      costs of goods sold
    4,441,635,000 11,714,063,000 4,070,335,000 3,946,655,000 3,882,651,000 11,001,406,000 3,736,398,000 3,857,797,000 3,713,205,000 11,114,395,000 3,635,038,000 3,774,772,000 3,837,084,000  4,187,278,000 4,329,536,000 3,787,389,000  3,487,659,000 3,265,616,000 2,744,331,000 2,158,992,000 2,038,017,000 1,809,874,000 2,159,871,000 2,033,787,000 2,167,006,000 2,349,349,000 2,383,865,000 2,382,657,000 2,537,466,000 2,438,443,000 2,140,459,000 2,015,655,000 2,046,864,000 1,998,202,000 1,896,062,000 1,600,654,000 1,692,807,000 1,643,519,000 1,505,265,000 1,722,197,000 1,833,264,000 1,860,393,000 2,050,504,000 1,846,990,000 1,666,778,000 1,714,546,000 1,653,648,000 1,619,432,000 1,536,989,000 1,727,667,000 1,780,776,000 1,844,212,000 1,803,345,000 1,720,215,000 1,444,632,000 1,440,815,000 1,345,308,000 723,321,000 855,277,000 2,118,737,000 1,924,284,000 1,554,896,000 928,142,000 694,666,000 649,271,000 610,654,000 667,058,000 624,692,000 506,391,000  
      gross profit
    763,223,000 1,634,303,000 757,880,000 618,468,000 486,544,000 2,197,369,000 605,217,000 774,837,000 980,798,000 3,093,864,000 952,019,000 1,306,858,000 1,056,122,000  1,464,429,000 1,883,342,000 1,782,513,000  1,600,629,000 1,199,692,000 800,266,000 442,253,000 292,815,000 284,431,000 415,229,000 316,409,000 359,839,000 421,166,000 433,570,000 521,235,000 686,081,000 652,082,000 463,416,000 320,824,000 396,518,000 392,518,000 472,154,000 309,942,000 408,503,000 380,383,000 236,036,000 228,726,000 171,743,000 187,042,000 288,512,000 222,771,000 163,304,000 197,192,000 147,692,000 176,264,000 156,401,000 182,136,000 201,264,000 199,243,000 276,386,000 295,754,000 139,532,000 191,984,000 210,482,000 68,837,000  445,206,000 479,655,000 347,309,000 228,451,000 216,582,000 216,403,000 229,146,000 244,804,000 196,555,000 159,487,000  
      yoy
    56.87% -25.62% 25.22% -20.18% -50.39% -28.98% -36.43% -40.71% -7.13%  -34.99% -30.61% -40.75%  -8.51% 56.99% 122.74%  446.63% 321.79% 92.73% 39.77% -18.63% -32.47% -4.23% -39.30% -47.55% -35.41% -6.44% 62.47% 73.03% 66.13% -1.85% 3.51% -2.93% 3.19% 100.03% 35.51% 137.86% 103.37% -18.19% 2.67% 5.17% -5.15% 95.35% 26.38% 4.41% 8.27% -26.62% -11.53% -43.41% -38.42% 44.24% 3.78% 31.31% 329.64%  -56.88% -56.12% -80.18%  105.56% 121.65% 51.57% -6.68% 10.19% 35.69%      
      qoq
    -53.30% 115.64% 22.54% 27.11% -77.86% 263.07% -21.89% -21.00% -68.30% 224.98% -27.15% 23.74%   -22.24% 5.66%   33.42% 49.91% 80.95% 51.03% 2.95% -31.50% 31.23% -12.07% -14.56% -2.86% -16.82% -24.03% 5.21% 40.71% 44.45% -19.09% 1.02% -16.87% 52.34% -24.13% 7.39% 61.15% 3.20% 33.18% -8.18% -35.17% 29.51% 36.41% -17.19% 33.52% -16.21% 12.70% -14.13% -9.50% 1.01% -27.91% -6.55% 111.96% -27.32% -8.79% 205.77%   -7.18% 38.11% 52.03% 5.48% 0.08% -5.56% -6.40% 24.55% 23.24%   
      gross margin %
    Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% NaN% Infinity% Infinity% Infinity% NaN% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% NaN% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity%  
      selling, general and administrative expenses
    175,220,000 564,464,000 200,844,000 198,010,000 181,808,000 496,427,000 167,692,000 160,016,000 159,507,000 442,725,000 145,896,000 141,209,000 144,309,000  132,627,000 118,377,000 152,015,000  157,526,000 154,379,000 149,781,000 137,018,000 118,235,000 109,299,000 112,898,000 111,968,000 107,242,000 106,250,000 111,038,000 106,564,000 102,614,000 101,031,000 106,431,000 96,209,000 97,056,000 98,433,000 102,933,000 94,110,000 95,185,000 96,853,000 87,530,000 82,371,000 82,660,000 76,350,000 80,240,000 73,463,000 70,042,000 67,553,000 65,356,000 65,262,000 62,984,000 61,235,000 64,384,000 72,876,000 63,631,000 65,141,000 54,679,000 55,957,000 57,160,000 48,559,000 57,320,000 67,459,000 86,557,000 65,340,000 54,524,000 48,922,000 45,092,000 53,872,000 46,224,000 42,407,000 28,375,000  
      profit sharing
    42,198,000 80,597,000 42,389,000 30,706,000 22,695,000 130,460,000 34,444,000 48,053,000 62,652,000 207,620,000 64,413,000 90,990,000 69,575,000  105,122,000 139,742,000 128,469,000  113,880,000 82,140,000 48,848,000 19,404,000 11,778,000 9,092,000 21,454,000 13,633,000 17,848,000 22,871,000 23,677,000 41,684,000 45,304,000 42,335,000 26,662,000 21,595,000 21,175,000 21,308,000 27,231,000 19,563,000 22,255,000 20,176,000 9,291,000 9,008,000 5,031,000 4,598,000 12,865,000 10,469,000 5,395,000 8,469,000 4,779,000 6,643,000 3,954,000 8,211,000 8,072,000 7,428,000 14,454,000 15,203,000 4,562,000 7,827,000 9,444,000   30,800,000 26,897,000 18,507,000         
      amortization of intangible assets
    7,801,000 21,013,000 6,890,000 6,897,000 6,897,000 22,882,000 7,644,000 7,645,000 7,664,000 25,888,000 8,160,000 10,924,000 6,878,000  6,836,000 7,160,000 7,162,000  7,178,000 7,438,000 7,438,000 7,672,000 6,946,000 7,190,000 7,191,000 8,847,000 6,704,000 7,013,000 7,013,000 7,434,000 6,591,000 6,829,000 6,926,000 7,073,000 7,272,000 7,424,000 7,424,000 7,406,000 7,208,000 7,232,000 7,250,000 6,318,000 6,493,000 6,323,000 6,764,000 6,934,000 6,935,000 7,897,000 8,051,000 8,127,000 8,848,000 8,991,000  10,154,000 10,082,000  11,291,000 11,565,000  13,994,000 15,698,000 10,765,000 8,120,000 11,530,000         
      operating income
    538,004,000 968,229,000 507,757,000 382,855,000 275,144,000 1,547,600,000 395,437,000 559,123,000 750,975,000 2,417,631,000 733,550,000 1,063,735,000 835,360,000  1,219,844,000 1,618,063,000 1,494,867,000  1,322,045,000 955,735,000 594,199,000 258,750,000 155,856,000 158,850,000 273,686,000 181,961,000 228,045,000 285,032,000 291,842,000 365,553,000 531,572,000 501,887,000 323,397,000 195,947,000 271,015,000 265,353,000 334,566,000 56,024,000 283,855,000 256,122,000 131,965,000 131,029,000 77,559,000 99,771,000 188,643,000 131,905,000 80,932,000 113,273,000 69,198,000 96,232,000 72,721,000 103,699,000 119,816,000 108,785,000 188,219,000 205,326,000 69,000,000 116,635,000 132,297,000 6,284,000  336,182,000 358,081,000 251,932,000 173,927,000 167,660,000 171,311,000 175,274,000 198,580,000 154,148,000 131,112,000  
      yoy
    95.54% -37.44% 28.40% -31.53% -63.36% -35.99% -46.09% -47.44% -10.10%  -39.87% -34.26% -44.12%  -7.73% 69.30% 151.58%  748.25% 501.66% 117.11% 42.20% -31.66% -44.27% -6.22% -50.22% -57.10% -43.21% -9.76% 86.56% 96.14% 89.14% -3.34% 249.76% -4.52% 3.60% 153.53% -57.24% 265.99% 156.71% -30.05% -0.66% -4.17% -11.92% 172.61% 37.07% 11.29% 9.23% -42.25% -11.54% -61.36% -49.50% 73.65% -6.73% 42.27% 3167.44%  -65.31% -63.05% -97.51%  100.51% 109.02% 43.74% -12.41% 8.77% 30.66%      
      qoq
    -44.43% 90.69% 32.62% 39.15% -82.22% 291.36% -29.28% -25.55% -68.94% 229.58% -31.04% 27.34%   -24.61% 8.24%   38.33% 60.84% 129.64% 66.02% -1.88% -41.96% 50.41% -20.21% -19.99% -2.33% -20.16% -31.23% 5.91% 55.19% 65.04% -27.70% 2.13% -20.69% 497.18% -80.26% 10.83% 94.08% 0.71% 68.94% -22.26% -47.11% 43.01% 62.98% -28.55% 63.69% -28.09% 32.33% -29.87% -13.45% 10.14% -42.20% -8.33% 197.57% -40.84% -11.84% 2005.30%   -6.12% 42.13% 44.85% 3.74% -2.13% -2.26% -11.74% 28.82% 17.57%   
      operating margin %
    Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% NaN% Infinity% Infinity% Infinity% NaN% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% NaN% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity%  
      interest expense, net of capitalized interest
    33,241,000 56,470,000 13,573,000 17,381,000 12,131,000 39,276,000 17,071,000 12,719,000 11,978,000 58,069,000 18,415,000 20,767,000 22,507,000  25,347,000 25,667,000 16,669,000  12,704,000 14,898,000 17,269,000 20,206,000 18,950,000 27,702,000 28,019,000 32,322,000 31,339,000 32,321,000 31,122,000 31,652,000 31,560,000 31,512,000 31,896,000 32,380,000 34,177,000 33,869,000 33,973,000 36,149,000 36,199,000 36,646,000 37,043,000 37,084,000 37,163,000 43,087,000 31,904,000 30,050,000 30,569,000 30,970,000 31,465,000 34,629,000 41,490,000 41,106,000 41,112,000 44,702,000 44,812,000 43,346,000 44,286,000 43,448,000 37,515,000              
      other income
    -8,450,000                        -2,589,000 -424,000 -4,545,000 -4,249,000    -5,035,000          239,000  16,192,000 22,072,000      24,010,000  10,248,000       786,000             
      income before income taxes
    513,213,000 979,125,000 513,846,000 387,866,000 280,654,000 1,574,856,000 408,025,000 565,112,000 765,781,000 2,464,344,000 754,599,000 1,074,316,000 847,789,000  1,208,472,000 1,596,417,000 1,457,730,000  1,302,565,000 930,798,000 566,859,000 220,817,000 133,360,000 103,045,000 248,256,000 150,063,000 201,251,000 256,960,000 267,063,000 341,285,000 507,115,000 475,410,000 295,964,000 161,352,000 234,312,000 235,319,000 304,252,000 2,820,000 243,305,000 221,294,000 96,714,000 93,706,000 41,608,000 40,492,000 134,667,000 103,609,000 50,994,000 84,155,000 38,979,000 62,649,000 7,221,000 64,485,000 68,456,000 67,606,000 149,152,000 166,547,000 30,929,000 76,708,000 97,863,000   307,078,000 339,507,000 229,931,000 159,927,000 148,939,000 164,780,000 168,391,000 192,109,000 147,398,000 123,657,000  
      income tax expense
    113,108,000 195,740,000 109,920,000 86,675,000 62,975,000 345,794,000 87,131,000 133,422,000 178,281,000 576,794,000 174,817,000 258,139,000 203,456,000  289,997,000 381,765,000 350,376,000  302,406,000 218,595,000 128,104,000 23,867,000 29,083,000 24,280,000 57,420,000 26,344,000 48,643,000 60,214,000 62,236,000 71,433,000 109,209,000 112,838,000 70,489,000 -141,819,000 83,300,000 82,372,000 105,586,000    35,396,000                                
      net income
    400,105,000 783,385,000 403,926,000 301,191,000 217,679,000 1,229,062,000 320,894,000 431,690,000 587,500,000 1,887,550,000 579,782,000 816,177,000 644,333,000  918,475,000 1,214,652,000 1,107,354,000  1,000,159,000 712,203,000 438,755,000 196,950,000 104,277,000 78,765,000 190,836,000 123,719,000 152,608,000 196,746,000 204,827,000 269,852,000 397,906,000 362,572,000 225,475,000 303,171,000 151,012,000 152,947,000 198,666,000 3,832,000 154,413,000 140,443,000 61,318,000 58,867,000 25,325,000 26,954,000 87,657,000 66,341,000 33,698,000 51,090,000 23,273,000 41,252,000 6,105,000 39,305,000 41,777,000 39,857,000 95,826,000 104,230,000 15,355,000 46,797,000 63,389,000   193,008,000 210,494,000 142,557,000 100,591,000 93,942,000 102,164,000 105,066,000 118,723,000 96,869,000 76,049,000  
      yoy
    83.81% -36.26% 25.88% -30.23% -62.95% -34.89% -44.65% -47.11% -8.82%  -36.88% -32.81% -41.81%  -8.17% 70.55% 152.39%  859.14% 804.21% 129.91% 59.19% -31.67% -59.97% -6.83% -54.15% -61.65% -45.74% -9.16% -10.99% 163.49% 137.06% 13.49% 7811.56% -2.20% 8.90% 223.99% -93.49% 509.73% 421.05% -30.05% -11.27% -24.85% -47.24% 276.65% 60.82% 451.97% 29.98% -44.29% 3.50% -93.63% -62.29% 172.07% -14.83% 51.17%   -75.75% -69.89%   105.45% 106.04% 35.68% -15.27% -3.02% 34.34%      
      qoq
    -48.93% 93.94% 34.11% 38.36% -82.29% 283.01% -25.67% -26.52% -68.87% 225.56% -28.96% 26.67%   -24.38% 9.69%   40.43% 62.32% 122.77% 88.87% 32.39% -58.73% 54.25% -18.93% -22.43% -3.95% -24.10% -32.18% 9.75% 60.80% -25.63% 100.76% -1.27% -23.01% 5084.39% -97.52% 9.95% 129.04% 4.16% 132.45% -6.04% -69.25% 32.13% 96.87% -34.04% 119.52% -43.58% 575.71% -84.47% -5.92% 4.82% -58.41% -8.06% 578.80% -67.19% -26.17%    -8.31% 47.66% 41.72% 7.08% -8.05% -2.76% -11.50% 22.56% 27.38%   
      net income margin %
    Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% NaN% Infinity% Infinity% Infinity% NaN% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% NaN% NaN% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity% Infinity%  
      net loss attributable to noncontrolling interests
    3,331,000                         -2,294,000 -1,560,000 -2,444,000 -499,000 152,000 469,000 -123,000 2,076,000 1,562,000 2,246,000 986,000 2,151,000 16,180,000 2,984,000                                  
      net income attributable to steel dynamics, inc.
    403,436,000 781,910,000 403,685,000 298,726,000 217,151,000 1,219,332,000 317,802,000 427,998,000 584,041,000 1,873,687,000 577,195,000 812,107,000 637,310,000  914,325,000 1,209,554,000 1,103,931,000  990,763,000 702,291,000 430,507,000 187,843,000 100,143,000 75,496,000 187,340,000 121,425,000 151,048,000 194,302,000 204,328,000 270,004,000 398,375,000 362,449,000 227,551,000 304,733,000 153,258,000 153,933,000 200,817,000 20,012,000 157,397,000 141,969,000 62,737,000 60,617,000 31,550,000 30,761,000 91,173,000 72,303,000 38,579,000 57,486,000 28,958,000 48,215,000 12,833,000 44,472,000 45,675,000 43,304,000 98,710,000 105,903,000 18,741,000 49,207,000 64,969,000 -15,991,000 -87,862,000            
      basic earnings per share attributable to steel
                                                                            
      dynamics, inc. stockholders
    2.79 0.688 2.75 2.01 1.45 0.515 2.06 2.73 3.68 0.873 3.49 4.83 3.71  5.07 6.49 5.74  4.89                                                      
      weighted-average common shares outstanding
    144,797 147,806 146,947 148,387 150,262 155,420 154,061 156,856 158,666 166,552 165,170 168,009 171,597 183,393 180,264 186,442 192,158 205,115 202,450 209,647 211,015 211,140 210,366 210,343 213,254 219,639 217,873 221,505 224,058 233,923 234,208 235,617 236,623 240,132 239,066 241,343 242,943 243,576 243,761 243,655 243,202 242,074 241,900 241,535 240,087 226,220 223,011 220,926 220,471 219,995 219,191 219,104 218,996 218,674 218,500 217,992 216,881 216,635 216,284 189,848 182,000 195,347 190,351 189,039 89,741 93,429 96,316 93,931 49,843 48,231 43,517  
      diluted earnings per share attributable to steel
                                                                            
      dynamics, inc. stockholders, including the effect
                                                                            
      of assumed conversions when dilutive
    2.78 0.685 2.74 2.01 1.44 0.513 2.05 2.72 3.67 0.868 3.47 4.81 3.7  5.03 6.44 5.71  4.85                                                      
      weighted-average common shares and share equivalents outstanding
    145,321 148,404 147,600 148,960 150,809 156,136 154,810 157,579 159,354 167,431 166,105 168,865 172,479 184,622 181,613 187,740 193,241 206,615 204,167 211,246 212,254 212,345 211,926 211,378 214,024 220,748 219,109 222,519 224,962 235,193 235,649 236,945 237,723 241,781 240,880 243,021 244,546 245,298 245,682 245,392 244,608 243,822 243,491 242,867 242,244 242,048 241,394 239,001 221,736 238,087 220,044 236,208 236,526 235,759 236,266 236,224 234,543 234,600 234,659 189,848 182,000 196,859 200,345 199,317 94,929 98,781 101,637 105,774 54,893 54,883 50,336  
      dividends declared per share
    0.53 1.5 0.5 0.5 0.5 1.38 0.46 0.46 0.46 1.275 0.425 0.425 0.425  0.34 0.34 0.34  0.26 0.26 0.26 0.25 0.25 0.25 0.25 0.24 0.24 0.24 0.24 0.188 0.188 0.188 0.188 0.155 0.155 0.155 0.155 0.14 0.14 0.14 0.14 0.138 0.138 0.138 0.115 0.115 0.115 0.11 0.11 0.11 0.1 0.1 0.1 0.1 0.1 0.1 0.075 0.075 0.075 0.075 0.1 0.1 0.1 0.1 0.15 0.15 0.15 -0.2 0.3 0.2 0.2  
      other expense
     -67,366,000 -19,662,000 -22,392,000 -17,641,000 -66,532,000 -29,659,000 -18,708,000 -26,784,000 -104,782,000 -39,464,000 -31,348,000 -34,936,000  -13,975,000 -4,021,000 20,468,000  6,776,000 10,039,000 10,071,000 17,727,000 3,546,000 28,103,000     -6,343,000 -7,384,000 -7,103,000  -4,463,000 2,215,000 2,526,000 -3,835,000 -3,659,000 17,055,000 4,351,000                           11,523,000       
      net income attributable to noncontrolling interests
     -1,475,000 -241,000 -2,465,000 -528,000 -9,730,000 -3,092,000 -3,692,000 -3,459,000 -13,863,000 -2,587,000 -4,070,000 -7,023,000  -4,150,000 -5,098,000 -3,423,000  -9,396,000 -9,912,000 -8,248,000 -2,724,750 -4,134,000 -3,269,000 -3,496,000               1,526,000 1,419,000 1,750,000 6,225,000 3,807,000 3,516,000 5,962,000 4,881,000 6,396,000 5,685,000 6,963,000 6,728,000 5,167,000 3,898,000 3,447,000 2,884,000 1,673,000 3,386,000 2,410,000 1,580,000              
      basic earnings per share attributable to steel dynamics, inc.
                                                                            
      stockholders
                       3.35                                                     
      diluted earnings per share attributable to steel dynamics, inc.
                                                                            
      stockholders, including the effect of assumed conversions
                                                                            
      when dilutive
                       3.32 2.03 0.88 0.47 0.36 0.88 0.57 0.69 0.87 0.91 1.18 1.69 1.53 0.96 1.27 0.64 0.63 0.82 0.08 0.64                                  
      basic earnings per share attributable to steel dynamics,
                                                                            
      inc. stockholders
                        2.04 0.89 0.48 0.36 0.88 0.57 0.69 0.88 0.91 1.18 1.7 1.54 0.96 1.27 0.64 0.64 0.83 0.08 0.65                                  
      income taxes
                                         51,284,750 88,892,000 80,851,000  34,839,000 16,283,000 13,538,000 47,010,000 37,268,000 17,296,000 33,065,000 15,706,000 21,397,000 1,116,000 25,180,000 26,679,000 27,749,000 53,326,000 62,317,000 15,574,000 29,911,000 34,474,000   114,070,000 129,013,000 87,374,000 59,336,000 54,997,000 62,616,000 63,325,000 73,386,000 50,529,000 47,608,000  
      other income (income)
                                                                            
      basic earnings per share attributable to steel dynamics, inc. stockholders
                                           0.58 0.26 0.25 0.13 0.13 0.38 0.32 0.17 0.26 0.13 0.22 0.06 0.2 0.21 0.2 0.45 0.49 0.09 0.23 0.3 -0.08 -0.48            
      diluted earnings per share attributable to steel dynamics, inc. stockholders, including the effect of assumed conversions when dilutive
                                           0.58 0.26 0.25 0.13 0.13 0.38 0.31 0.17 0.25 0.13 0.21 0.06 0.2 0.2 0.19 0.43 0.46 0.09 0.22 0.29 -0.08 -0.48            
      impairment charges
                                                    308,000  7,894,000                      
      total selling, general and administrative expenses
                                                99,869,000 90,866,000 82,372,000 83,919,000 78,494,000 80,032,000 83,680,000 78,437,000 81,448,000 90,458,000 88,167,000 90,428,000 70,532,000 75,349,000 78,185,000 62,553,000 72,976,000 109,024,000 121,574,000 95,377,000         
      amortization of intangibles
                                                        8,992,000   10,084,000   11,581,000              
      interest expense, net capitalized interest
                                                               37,043,000 36,251,000 37,446,000 35,475,000 29,807,000         
      basic earnings per share
                                                                 0.99 1.11 0.75 1.12 1.01 1.06 -1.96 2.38 2.01 1.75  
      diluted earnings per share, including the effect of assumed conversions
                                                                 0.98 1.05 0.72   1.01      
      other income, net other income
                                                                            
      interest expense
                                                                    14,602,000 7,198,000 7,246,000 8,498,000 7,445,000 8,025,000 8,136,000  
      other (income) expense
                                                                            
      diluted earnings per share, including effect of assumed conversions
                                                                    1.06 0.95  1.373 2.17 1.78 1.52  
    Balance Sheets:
    Quarterly
    Annual
      Unit: USD2026-03-31 2025-12-31 2025-09-30 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 2015-09-30 2015-06-30 2015-03-31 2014-09-30 2014-06-30 2014-03-31 2013-09-30 2013-06-30 2013-03-31 2012-09-30 2012-06-30 2012-03-31 2011-09-30 2011-06-30 2011-03-31 2010-09-30 2010-06-30 2010-03-31 2009-06-30 2009-03-31 2008-09-30 2008-06-30 2008-03-31 2007-09-30 2007-06-30 2007-03-31 2006-12-31 2006-09-30 2006-06-30 2006-03-31 2005-12-31 
                                                                              
        assets
                                                                              
        current assets
                                                                              
        cash and equivalents
      556,527,000 769,878,000 770,356,000 458,048,000 1,186,917,000 589,464,000 1,015,210,000 829,980,000 1,039,421,000 1,400,887,000 1,765,467,000 1,475,356,000 1,604,943,000 1,628,417,000 1,420,497,000 1,007,085,000 1,189,528,000 1,243,868,000 1,095,701,000 1,113,744,000 1,245,165,000 1,368,618,000 1,267,618,000 1,496,458,000 1,235,478,000 1,381,460,000 1,146,007,000 972,561,000 791,444,000 828,220,000 884,315,000 720,445,000 985,824,000 1,028,649,000 1,101,964,000 908,843,000 966,826,000 841,483,000 1,051,489,000 1,052,666,000 976,951,000 473,790,000 419,401,000 160,982,000 159,591,000 357,490,000 342,919,000 370,056,000 243,753,000 477,861,000 287,120,000 420,938,000 357,809,000 456,694,000 277,691,000 160,810,000 270,118,000 191,593,000 225,506,000 18,217,000 16,067,000 22,135,000 115,405,000 58,889,000 10,811,000 12,212,000 28,332,000 29,373,000 20,843,000 53,948,000 195,705,000 65,518,000 
        accounts receivable
      2,050,980,000  1,697,298,000 1,606,114,000 1,647,704,000  1,500,685,000 1,695,840,000 1,665,424,000  1,807,313,000 2,079,949,000 2,072,619,000  2,255,206,000 2,573,539,000 2,285,245,000  1,886,759,000 1,565,317,000 1,360,535,000  915,223,000 841,593,000 995,324,000  983,515,000 1,069,061,000 1,141,038,000  1,224,477,000 1,175,795,000 983,457,000  897,838,000 866,716,000 860,676,000  752,232,000 758,145,000 654,177,000 757,110,000 772,309,000 741,309,000 1,013,503,000 852,440,000 760,654,000 722,867,000 725,105,000 703,896,000 656,517,000 660,351,000 737,531,000 764,715,000 797,577,000 828,514,000 599,108,000 577,380,000 615,624,000 340,426,000 335,715,000 1,032,734,000 1,147,277,000 817,799,000 446,131,000 399,699,000 383,632,000  360,196,000 322,478,000 229,124,000 202,878,000 
        accounts receivable-related parties
      5,454,000 2,411,000 64,663,000 94,861,000 73,097,000 54,230,000 64,272,000 79,552,000 73,636,000 73,245,000 74,736,000 63,015,000 54,355,000 79,769,000 78,788,000 87,176,000 78,423,000 5,049,000 6,036,000 5,707,000 5,928,000 3,937,000 3,619,000 2,463,000 3,084,000 2,958,000 3,431,000 3,818,000 2,357,000 3,536,000 3,713,000 4,388,000 4,198,000 22,422,000 25,179,000 20,178,000 22,471,000 26,219,000 27,227,000 35,858,000 35,024,000 41,915,000 44,213,000 28,432,000 45,165,000 58,356,000 50,446,000 50,006,000 48,022,000 49,405,000 56,233,000 55,089,000 51,643,000 51,153,000 51,824,000 55,423,000 55,837,000 50,928,000 34,108,000 24,310,000 26,124,000 89,914,000 87,333,000 82,117,000 45,326,000 42,425,000 38,346,000  43,003,000 31,813,000 31,771,000 38,830,000 
        inventories
      3,908,120,000 3,738,516,000 3,195,660,000 3,260,899,000 3,099,054,000 3,113,733,000 3,044,887,000 3,073,637,000 3,027,143,000 2,894,632,000 2,941,634,000 3,044,009,000 2,988,852,000 3,129,964,000 3,376,532,000 3,647,061,000 3,516,815,000 3,531,130,000 2,894,970,000 2,481,832,000 2,217,534,000 1,843,548,000 1,609,216,000 1,567,017,000 1,644,538,000 1,689,043,000 1,767,020,000 1,802,759,000 1,867,700,000 1,859,168,000 1,853,862,000 1,787,109,000 1,600,058,000 1,519,347,000 1,487,516,000 1,418,732,000 1,361,550,000 1,275,211,000 1,275,575,000 1,175,716,000 1,066,823,000 1,321,397,000 1,292,069,000 1,453,242,000 1,664,212,000 1,320,871,000 1,332,101,000 1,192,032,000 1,168,499,000 1,170,159,000 1,209,079,000 1,252,153,000 1,270,941,000 1,158,848,000 1,195,194,000 1,186,168,000 1,008,309,000 1,017,874,000 900,889,000 738,470,000 833,074,000 1,356,992,000 1,201,640,000 894,759,000 744,534,000 726,236,000 626,218,000 569,317,000 557,726,000 528,683,000 381,505,000 398,684,000 
        other current assets
      274,089,000 293,117,000 351,428,000 231,100,000 190,297,000 163,131,000 173,179,000 141,635,000 138,557,000 162,790,000 138,605,000 122,025,000 127,022,000 195,371,000 99,210,000 90,144,000 79,624,000 209,591,000 104,106,000 98,509,000 67,744,000 74,363,000 59,219,000 39,043,000 45,351,000 76,012,000 50,818,000 61,248,000 52,628,000 72,730,000 50,110,000 39,927,000 38,705,000 91,509,000 59,648,000 37,188,000 33,442,000 83,197,000 30,121,000 28,072,000 41,258,000 28,744,000 32,004,000 34,846,000 29,263,000 23,216,000 24,363,000 25,126,000 33,028,000 24,056,000 24,107,000 15,816,000 15,029,000 18,646,000 15,164,000 18,913,000 21,451,000 14,844,000 12,091,000 22,017,000 35,725,000 61,977,000 67,566,000 62,522,000 27,264,000 31,493,000 10,593,000 15,167,000 14,705,000 21,853,000 13,300,000 13,307,000 
        total current assets
      6,795,170,000 6,484,171,000 6,079,405,000 5,690,599,000 6,216,705,000 5,431,338,000 6,443,576,000 6,239,011,000 6,597,436,000 6,787,826,000 7,228,599,000 7,396,055,000 7,562,560,000 7,638,018,000 7,813,444,000 7,756,010,000 7,149,635,000 6,901,023,000 5,987,572,000 5,265,109,000 4,896,906,000 4,258,447,000 3,854,895,000 4,016,120,000 4,142,968,000 4,253,025,000 4,020,320,000 4,023,601,000 4,028,890,000 4,032,657,000 4,131,477,000 3,817,664,000 3,652,242,000 3,508,342,000 3,572,145,000 3,251,657,000 3,244,965,000 2,929,675,000 3,136,644,000 3,050,457,000 2,774,233,000 2,651,795,000 2,591,392,000 2,452,225,000 2,930,136,000 2,630,186,000 2,528,354,000 2,385,315,000 2,242,089,000 2,448,941,000 2,262,224,000 2,458,344,000 2,526,857,000 2,496,227,000 2,373,859,000 2,277,120,000 2,010,022,000 1,910,116,000 1,934,753,000 1,301,531,000 1,366,811,000 2,575,775,000 2,627,538,000 1,927,542,000 1,290,146,000 1,226,553,000 1,100,732,000 1,036,197,000 1,014,739,000 976,121,000 858,355,000 725,733,000 
        property, plant and equipment
      8,549,876,000 8,569,466,000 8,493,550,000 8,465,478,000 8,322,652,000 8,117,988,000 7,825,869,000 7,433,564,000 7,063,990,000 6,734,218,000 6,313,366,000 5,783,622,000 5,491,201,000 5,373,665,000 5,146,606,000 4,886,555,000 4,827,962,000 4,751,430,000 4,654,192,000 4,526,892,000 4,340,411,000 4,105,569,000 3,862,375,000 3,587,450,000 3,327,605,000 3,135,886,000 3,031,731,000 2,947,243,000 2,936,893,000 2,945,767,000 2,901,658,000 2,909,033,000 2,657,937,000 2,675,904,000 2,708,777,000 2,729,721,000 2,760,544,000 2,787,215,000 2,928,226,000 2,885,844,000 2,914,186,000 3,013,659,000 3,047,401,000 3,085,587,000 3,420,654,000 2,177,007,000 2,197,503,000 2,241,067,000 2,232,852,000 2,232,413,000 2,213,703,000 2,208,660,000 2,199,509,000 2,168,444,000 2,176,314,000 2,187,698,000 2,214,105,000 2,237,927,000 2,240,375,000 2,144,360,000 2,108,657,000 1,997,495,000 1,916,403,000 1,720,276,000 1,358,204,000 1,249,178,000 1,161,914,000 1,136,703,000 1,118,533,000 1,113,709,000 990,506,000 999,969,000 
        intangible assets
      323,489,000 331,290,000 206,549,000 213,439,000 220,336,000 227,234,000 234,806,000 242,450,000 250,095,000 257,759,000 265,845,000 274,005,000 260,629,000 267,507,000 276,586,000 281,022,000 288,183,000 295,345,000 302,522,000 309,700,000 317,139,000 324,577,000 306,574,000 313,520,000 320,711,000  249,598,000 256,302,000 263,315,000  236,563,000 243,154,000 249,983,000  263,357,000 269,129,000 276,553,000  291,814,000 265,476,000 272,528,000 353,561,000 358,402,000 364,620,000 406,318,000 372,819,000 379,488,000 393,531,000 401,104,000 408,832,000 425,034,000 433,559,000 442,277,000 460,206,000 469,719,000 479,480,000 500,021,000 511,002,000 522,245,000 557,194,000 551,489,000 625,537,000 636,649,000 488,436,000 198,678,000 14,110,000 11,973,000  12,478,000 12,335,000   
        goodwill
      477,471,000 477,471,000 477,471,000 477,471,000 477,471,000 477,471,000 477,471,000 477,471,000 477,471,000 477,471,000 477,471,000 477,471,000 502,067,000 502,067,000 451,594,000 452,341,000 453,088,000 453,835,000 454,683,000 455,530,000 456,378,000 457,226,000 474,520,000 451,220,000 452,068,000 452,915,000 540,913,000 526,462,000 530,716,000 429,645,000 502,900,000 508,275,000 386,045,000 386,893,000 388,518,000 390,129,000 391,740,000 393,351,000 399,867,000 394,275,000 395,872,000 740,243,000 741,898,000 743,528,000 727,128,000 728,751,000 730,360,000 733,650,000 735,281,000 736,912,000 740,192,000 741,817,000 743,441,000 746,737,000 748,383,000 750,029,000 753,355,000 753,355,000 756,624,000 780,321,000 812,161,000 781,555,000 789,580,000 518,759,000 200,637,000 48,490,000 30,966,000 30,966,000 30,966,000 30,720,000   
        other assets
      574,213,000 557,382,000 708,055,000 701,651,000 693,264,000 681,202,000 678,099,000 668,761,000 637,758,000 651,146,000 643,675,000 620,244,000 403,303,000 378,727,000 359,468,000 335,286,000 337,769,000 129,601,000 137,016,000 130,100,000 117,062,000 119,743,000 119,192,000 100,031,000 101,571,000 106,038,000 100,685,000 104,306,000 97,419,000 25,166,000 25,770,000 26,395,000 26,606,000 10,745,000 10,848,000 12,121,000 12,387,000 11,454,000 11,440,000 14,069,000 15,220,000 63,662,000 68,099,000 70,636,000 75,790,000 57,979,000 59,564,000 97,726,000 101,353,000 106,076,000 106,927,000 101,194,000 104,549,000 111,104,000 110,461,000 111,830,000 112,386,000 112,813,000 117,578,000 84,474,000 70,744,000 66,838,000 65,763,000 154,732,000 40,993,000 30,963,000 29,785,000 25,223,000 26,316,000 27,053,000 30,619,000 30,397,000 
        total assets
      16,720,219,000 16,419,780,000 15,965,030,000 15,548,638,000 15,930,428,000 14,935,233,000 15,659,821,000 15,061,257,000 15,026,750,000 14,908,420,000 14,928,956,000 14,551,397,000 14,219,760,000 14,159,984,000 14,047,698,000 13,711,214,000 13,056,637,000 12,531,234,000 11,535,985,000 10,687,331,000 10,127,896,000 9,265,562,000 8,617,556,000 8,468,341,000 8,344,923,000 8,275,765,000 7,943,247,000 7,857,914,000 7,857,233,000 7,703,563,000 7,798,368,000 7,504,521,000 6,972,813,000 6,855,732,000 6,960,737,000 6,670,130,000 6,704,035,000 6,423,732,000 6,787,562,000 6,629,676,000 6,391,642,000 6,842,541,000 6,826,763,000 6,735,838,000 7,578,283,000 5,985,202,000 5,913,857,000 5,874,305,000 5,735,910,000 5,956,574,000 5,775,516,000 5,971,380,000 6,043,627,000 6,003,481,000 5,900,453,000 5,827,605,000 5,610,459,000 5,545,805,000 5,582,122,000 4,881,812,000 4,926,079,000 6,054,879,000 6,043,589,000 4,821,612,000 3,095,301,000 2,575,886,000 2,341,392,000 2,247,017,000 2,208,803,000 2,164,473,000 1,881,619,000 1,757,687,000 
        liabilities and equity
                                                                              
        current liabilities
                                                                              
        accounts payable
      1,366,020,000 1,223,776,000 1,201,459,000 1,216,907,000 1,252,529,000 972,645,000 1,074,501,000 1,205,679,000 1,174,060,000 1,078,645,000 1,049,317,000 1,039,149,000 1,126,795,000 1,007,304,000 1,153,299,000 1,365,608,000 1,202,033,000 1,266,833,000 1,208,499,000 1,167,102,000 1,113,250,000 760,536,000 702,991,000 696,845,000 602,875,000 509,687,000 518,909,000 516,109,000 582,284,000 536,743,000 595,286,000 657,496,000 544,419,000 473,765,000 512,290,000 467,611,000 514,788,000 382,126,000 427,790,000 450,945,000 407,405,000 378,594,000 438,363,000 367,267,000 621,579,000 422,761,000 401,539,000 411,201,000 355,678,000 401,407,000 364,380,000 381,250,000 462,492,000 453,232,000 443,693,000 437,531,000 356,042,000 354,550,000 380,284,000 225,753,000 239,355,000 644,263,000 757,590,000 473,150,000 320,276,000 212,239,000 218,156,000 145,938,000 192,730,000 167,920,000 178,501,000 111,067,000 
        accounts payable-related parties
      13,474,000 7,582,000 13,306,000 10,276,000 5,157,000 7,267,000 5,315,000 7,729,000 9,533,000 9,685,000 10,858,000 9,435,000 12,171,000 9,934,000 11,848,000 15,206,000 11,525,000 13,722,000 11,938,000 16,502,000 21,422,000 8,919,000 12,690,000 5,087,000 9,285,000 3,657,000 9,720,000 9,047,000 9,183,000 14,011,000 15,742,000 18,305,000 18,199,000 15,683,000 16,393,000 16,392,000 16,170,000 13,070,000 10,046,000 10,322,000 6,170,000 7,776,000 8,335,000 9,695,000 18,542,000 17,930,000 15,629,000 15,205,000 8,652,000 9,225,000 12,833,000 11,924,000 9,765,000 9,107,000 12,166,000 15,883,000 10,289,000 8,786,000 10,028,000 1,693,000 4,559,000 8,532,000 14,682,000 21,551,000 5,288,000 6,079,000 7,316,000  1,966,000 1,766,000 1,614,000 4,475,000 
        income taxes payable
      135,202,000 67,315,000 3,088,000 2,069,000 43,249,000 3,783,000 6,248,000 6,070,000 150,103,000 5,524,000 30,343,000 39,177,000 129,082,000 6,520,000 41,121,000 36,976,000 229,360,000 13,746,000 80,167,000 80,520,000 52,969,000 2,386,000 827,000 25,411,000 17,806,000 2,014,000 2,074,000 3,032,000 26,896,000 7,468,000 10,872,000 38,273,000 14,564,000 3,696,000 5,596,000 5,589,000 80,741,000 5,593,000 35,733,000 43,367,000 9,960,000 14,246,000 2,411,000 5,116,000 26,949,000 19,448,000 23,531,000 7,649,000 2,862,000 13,438,000 12,014,000 2,164,000 14,383,000 14,844,000 11,531,000 19,640,000 5,431,000 2,008,000 30,723,000   31,614,000 63,728,000 98,479,000 31,739,000 26,365,000 85,347,000 30,497,000 33,846,000    
        accrued payroll and benefits
      225,703,000 361,494,000 302,245,000 233,395,000 173,318,000 373,216,000 334,859,000 277,307,000 209,782,000 469,143,000 405,556,000 321,303,000 209,522,000 610,558,000 545,311,000 428,758,000 275,621,000 539,812,000 406,538,000 276,232,000 182,044,000 201,778,000 177,935,000 148,055,000 124,181,000 208,287,000 181,785,000 148,747,000 114,575,000 264,542,000 228,911,000 170,470,000 113,001,000 195,909,000 171,508,000 138,360,000 106,733,000 164,543,000 143,986,000 112,625,000 81,246,000 95,150,000 78,201,000 66,427,000 107,484,000 74,155,000 57,384,000 79,589,000 65,698,000 59,488,000          37,157,000 39,492,000            
        accrued expenses
      408,196,000 427,432,000 435,199,000 354,974,000 373,258,000 366,682,000 389,360,000 343,525,000 329,490,000 309,312,000 336,242,000 293,102,000 296,524,000 340,646,000 323,331,000 300,663,000 270,178,000 278,549,000 258,551,000 200,849,000 176,422,000 178,618,000 171,307,000 154,243,000 167,718,000 175,405,000 162,692,000 151,161,000 141,239,000 146,613,000 136,111,000 130,234,000 112,975,000 125,138,000 128,701,000 118,337,000 109,400,000 113,556,000 112,521,000 105,378,000 97,567,000 102,510,000 97,215,000 87,302,000 113,851,000 86,486,000 87,715,000 82,157,000 80,209,000 80,257,000 166,845,000 168,928,000 186,247,000 203,191,000 173,440,000 199,211,000 193,919,000 165,842,000 202,961,000 81,025,000 91,547,000 274,886,000 247,934,000 184,329,000  92,401,000 79,114,000 94,024,000     
        current maturities of long-term debt
      22,124,000 34,655,000 1,429,000 1,460,000 418,947,000 426,990,000 882,013,000 815,642,000 425,696,000 459,987,000 86,061,000 56,869,000 46,452,000 57,334,000 22,951,000 37,130,000 68,390,000 97,174,000 55,056,000 93,505,000 81,226,000 86,894,000 82,229,000 73,926,000 70,106,000 89,356,000 82,150,000 72,131,000 80,958,000 24,234,000 14,776,000 18,266,000 9,646,000 28,795,000 182,661,000 19,971,000 2,965,000 3,632,000 16,155,000 18,047,000 22,770,000 31,584,000 35,075,000 30,727,000 131,858,000 61,761,000 343,722,000 335,341,000 324,241,000 231,582,000 30,114,000 439,912,000 439,633,000 1,210,000 1,552,000 1,216,000 8,438,000 6,341,000 6,333,000 1,049,000 65,450,000 65,203,000   55,683,000 699,000 95,693,000 80,686,000 30,772,000 649,000 1,072,000 2,156,000 
        total current liabilities
      2,170,719,000 2,122,254,000 1,956,726,000 1,819,081,000 2,266,458,000 2,150,583,000 2,692,296,000 2,655,952,000 2,298,664,000 2,332,296,000 1,918,377,000 1,759,035,000 1,820,546,000 2,032,296,000 2,131,396,000 2,201,872,000 2,090,646,000 2,227,369,000 2,054,289,000 1,852,245,000 1,661,189,000 1,258,787,000 1,175,628,000 1,115,426,000 1,031,720,000 1,006,698,000 1,005,275,000 925,736,000 1,003,090,000 1,019,137,000 1,049,665,000 1,058,586,000 860,740,000 868,519,000 1,066,529,000 795,892,000 881,447,000 712,815,000 794,113,000 779,224,000 673,046,000 677,858,000 698,588,000 618,334,000 1,041,540,000 713,223,000 951,431,000 954,202,000 869,849,000 814,687,000 605,399,000 1,019,449,000 1,121,868,000 717,467,000 670,846,000 689,644,000 595,452,000 554,298,000 640,011,000 488,389,000 729,650,000 1,674,710,000 1,395,509,000 1,009,980,000 672,778,000 580,402,000 501,429,000 399,490,000 372,889,000 273,246,000 244,228,000 207,177,000 
        long-term debt
      4,178,669,000 4,176,508,000 3,781,026,000 3,779,559,000 3,777,132,000 2,804,017,000 2,801,871,000 2,212,802,000 2,612,246,000 2,611,069,000 3,009,010,000 3,010,829,000 3,014,358,000 3,013,241,000 3,012,120,000 3,011,116,000 3,010,109,000 3,008,702,000 3,019,175,000 3,016,486,000 3,016,200,000 3,015,782,000 2,636,615,000 2,636,722,000 2,646,012,000 2,644,988,000 2,355,243,000 2,355,917,000 2,354,427,000 2,352,489,000 2,351,979,000 2,352,127,000 2,353,703,000 2,353,145,000 2,351,483,000 2,354,337,000 2,353,744,000 2,353,194,000 2,570,837,000 2,573,186,000 2,575,528,000                                
        deferred income taxes
      1,042,980,000 1,004,375,000 1,105,134,000 957,564,000 918,435,000 902,186,000 943,154,000 928,321,000 923,745,000 944,768,000 961,117,000 941,491,000 898,112,000 889,103,000 856,650,000 853,407,000 856,790,000 854,905,000 722,220,000 652,059,000 602,185,000 536,288,000 512,503,000 503,034,000 489,248,000 484,169,000 468,248,000 457,784,000 447,087,000 435,838,000 398,814,000 375,719,000 314,736,000 305,949,000 461,399,000 459,639,000 454,426,000 448,375,000 450,159,000 433,116,000 416,260,000 28,839,000 31,396,000 33,414,000 18,402,000 17,813,000 17,871,000 25,228,000 23,682,000 23,564,000 28,229,000 26,917,000 26,089,000 21,652,000 21,114,000 21,007,000 24,786,000 21,678,000 21,585,000 32,179,000 26,631,000 12,023,000 8,317,000 11,456,000    13,964,000    6,516,000 
        other liabilities
      194,449,000 186,232,000 151,819,000 148,384,000 134,509,000 133,201,000 143,200,000 143,968,000 144,336,000 180,760,000 182,161,000 175,073,000 180,321,000 129,539,000 112,327,000 95,929,000 120,918,000 120,087,000 117,367,000 136,189,000 113,125,000 106,479,000 94,011,000 73,237,000 72,004,000 75,055,000 70,126,000 70,196,000 63,171,000 8,870,000 11,833,000 18,330,000 20,257,000 21,811,000 20,305,000 20,781,000 19,711,000 20,649,000 20,751,000 19,544,000 19,302,000 16,405,000 16,147,000 15,936,000 24,922,000 22,356,000 22,843,000 22,898,000 20,324,000 19,947,000 18,564,000 81,795,000 82,613,000 77,391,000 63,794,000 62,944,000 62,145,000 61,594,000 60,957,000 67,095,000 65,759,000 63,027,000 44,003,000 39,705,000         
        total liabilities
      7,586,817,000 7,489,369,000 6,994,705,000 6,704,588,000 7,096,534,000 5,989,987,000 6,580,521,000 5,941,043,000 5,978,991,000 6,068,893,000 6,070,665,000 5,886,428,000 5,913,337,000 6,064,179,000 6,112,493,000 6,162,324,000 6,078,463,000 6,211,063,000 5,913,051,000 5,656,979,000 5,392,699,000 4,917,336,000 4,418,757,000 4,328,419,000 4,238,984,000 4,210,910,000 3,898,892,000 3,809,633,000 3,867,775,000 3,816,334,000 3,812,291,000 3,804,762,000 3,549,436,000 3,549,424,000 3,899,716,000 3,630,649,000 3,709,328,000 3,535,033,000                                   
        commitments and contingencies
                                                                              
        redeemable noncontrolling interests
      141,226,000 141,226,000 141,226,000 141,226,000 171,212,000 171,212,000 171,212,000 171,212,000 171,212,000 171,212,000 171,212,000 171,212,000 186,205,000 181,503,000 172,403,000 168,303,000 227,914,000 211,414,000 186,814,000 176,414,000 163,614,000 158,614,000 155,414,000 152,414,000 151,014,000 143,614,000 143,614,000 139,930,000 139,930,000 111,240,000 111,240,000 111,240,000 111,240,000 111,240,000 111,240,000 111,240,000 111,240,000 111,240,000 126,340,000 126,340,000 126,340,000 126,340,000 125,972,000 126,340,000 126,340,000 124,180,000 121,834,000 110,054,000 104,734,000                        
        equity
                                                                              
        common stock voting, 0.0025 par value; 900,000,000 shares authorized;
                                                                              
        268,694,600 and 268,644,427 shares issued; and 144,443,460 and 144,940,102
                                                                              
        shares outstanding, as of march 31, 2026 and december 31, 2025, respectively
      653,000                                                                        
        treasury stock
                                                                              
        as of march 31, 2026 and december 31, 2025, respectively
      -8,088,699,000                                                                        
        additional paid-in capital
      1,237,939,000 1,248,634,000 1,243,261,000 1,229,809,000 1,218,235,000 1,229,819,000 1,220,089,000 1,207,771,000 1,197,176,000 1,217,610,000 1,214,894,000 1,204,134,000 1,194,079,000 1,212,566,000 1,219,947,000 1,213,481,000 1,204,023,000 1,218,933,000 1,219,438,000 1,210,833,000 1,202,945,000 1,207,392,000 1,200,228,000 1,191,614,000 1,183,776,000 1,181,012,000 1,175,512,000 1,167,505,000 1,160,139,000 1,160,048,000 1,156,556,000 1,149,367,000 1,142,871,000 1,141,534,000 1,147,463,000 1,141,050,000 1,135,892,000 1,132,749,000 1,132,365,000 1,125,519,000 1,115,008,000 1,104,832,000 1,099,669,000 1,088,605,000 1,075,593,000 1,058,921,000 1,092,281,000 1,060,780,000 1,050,470,000 1,045,973,000 1,033,857,000 1,033,086,000 1,031,043,000 1,023,295,000 1,019,061,000 1,010,698,000 988,972,000 983,780,000 978,090,000 958,558,000 544,971,000 538,445,000 583,756,000 562,847,000 392,269,000 386,935,000 375,887,000 367,772,000 419,430,000 414,792,000 421,648,000 405,900,000 
        retained earnings
      16,015,823,000 15,689,042,000 15,495,603,000 15,165,119,000 14,940,418,000 14,798,082,000 14,660,426,000 14,413,148,000 14,056,868,000 13,545,590,000 13,189,468,000 12,681,894,000 11,940,621,000 11,375,765,000 10,799,863,000 9,945,710,000 8,800,883,000 7,761,417,000 6,721,734,000 5,783,184,000 5,134,398,000 4,758,969,000 4,624,019,000 4,576,629,000 4,553,882,000 4,419,296,000 4,349,523,000 4,250,419,000 4,109,034,000 3,958,320,000 3,730,662,000 3,376,163,000 3,057,904,000 2,874,693,000 2,606,831,000 2,490,373,000 2,373,718,000 2,210,459,000 2,224,963,000 2,101,729,000 1,993,910,000 2,250,901,000 2,223,599,000 2,225,354,000 2,300,660,000 2,237,147,000 2,192,413,000 2,149,389,000 2,116,262,000 2,111,597,000 2,049,011,000 2,058,108,000 2,035,569,000 2,003,486,000 1,982,051,000 1,905,207,000 1,829,659,000 1,827,194,000 1,794,247,000 1,682,208,000 1,714,310,000 1,921,240,000 1,746,544,000 1,555,860,000 1,348,576,000 1,261,085,000 1,180,700,000 1,093,271,000 1,002,668,000 898,522,000 811,581,000 744,344,000 
        accumulated other comprehensive loss
      -858,000 -598,000 -1,328,000                            -42,000 -105,000                                         
        total steel dynamics, inc. equity
      9,164,858,000 8,957,182,000 8,995,142,000 8,864,052,000 8,824,710,000 8,934,287,000 9,081,502,000 9,130,773,000 9,072,408,000 8,866,666,000 8,893,535,000 8,707,983,000 8,336,637,000 8,130,357,000 7,971,156,000 7,588,348,000 6,964,354,000 6,304,641,000 5,607,926,000 5,020,114,000 4,728,792,000 4,345,164,000 4,201,183,000 4,145,250,000 4,113,526,000 4,075,834,000 4,056,641,000 4,064,490,000 4,008,111,000 3,935,071,000 4,033,768,000 3,746,981,000 3,470,719,000 3,351,574,000 3,104,725,000 3,080,939,000 3,035,179,000 2,927,020,000 2,965,917,000 2,835,837,000 2,717,209,000 2,959,896,000 2,927,413,000 2,918,077,000 2,978,084,000 2,897,897,000 2,568,795,000 2,492,437,000 2,448,999,000 2,439,133,000 2,363,025,000 2,371,349,000 2,346,224,000 2,301,568,000 2,275,899,000 2,190,691,000                 
        noncontrolling interests
      -172,682,000 -167,997,000 -166,043,000 -161,228,000 -162,028,000 -160,253,000 -173,414,000 -181,771,000 -195,861,000 -198,351,000 -206,456,000 -214,226,000 -216,419,000 -216,055,000 -208,354,000 -207,761,000 -214,094,000 -195,884,000 -171,806,000 -166,176,000 -157,209,000 -155,552,000 -157,798,000 -157,742,000 -158,601,000 -154,593,000 -155,900,000 -156,139,000 -158,583,000 -159,082,000 -158,931,000 -158,462,000 -158,582,000 -156,506,000 -154,944,000 -152,698,000 -151,712,000 -149,561,000 -140,555,000                  12,037,000 13,618,000 13,417,000 13,953,000 14,274,000            
        total equity
      8,992,176,000 8,789,185,000 8,829,099,000 8,702,824,000 8,662,682,000 8,774,034,000 8,908,088,000 8,949,002,000 8,876,547,000 8,668,315,000 8,687,079,000 8,493,757,000 8,120,218,000 7,914,302,000 7,762,802,000 7,380,587,000 6,750,260,000 6,108,757,000 5,436,120,000 4,853,938,000 4,571,583,000 4,189,612,000 4,043,385,000 3,987,508,000 3,954,925,000 3,921,241,000 3,900,741,000 3,908,351,000 3,849,528,000 3,775,989,000 3,874,837,000 3,588,519,000 3,312,137,000 3,195,068,000 2,949,781,000 2,928,241,000 2,883,467,000 2,777,459,000 2,825,362,000 2,698,266,000 2,581,166,000 2,829,445,000 2,798,728,000 2,796,753,000 2,911,649,000 2,835,030,000 2,512,496,000 2,447,734,000 2,410,737,000 2,406,590,000 2,339,054,000 2,354,136,000 2,332,561,000 2,282,666,000 2,257,194,000 2,173,400,000                 
        total liabilities and equity
      16,720,219,000 16,419,780,000 15,965,030,000 15,548,638,000 15,930,428,000 14,935,233,000 15,659,821,000 15,061,257,000 15,026,750,000 14,908,420,000 14,928,956,000 14,551,397,000 14,219,760,000 14,159,984,000 14,047,698,000 13,711,214,000 13,056,637,000 12,531,234,000 11,535,985,000 10,687,331,000 10,127,896,000 9,265,562,000 8,617,556,000 8,468,341,000 8,344,923,000 8,275,765,000 7,943,247,000 7,857,914,000 7,857,233,000 7,703,563,000 7,798,368,000 7,504,521,000 6,972,813,000 6,855,732,000 6,960,737,000 6,670,130,000 6,704,035,000 6,423,732,000 6,787,562,000 6,629,676,000 6,391,642,000 6,842,541,000 6,826,763,000 6,735,838,000 7,578,283,000 5,985,202,000 5,913,857,000 5,874,305,000 5,735,910,000 5,956,574,000 5,775,516,000 5,971,380,000 6,043,627,000 6,003,481,000 5,900,453,000 5,827,605,000                 
        short-term investments
         39,577,000 19,636,000 147,811,000 645,343,000 418,367,000 653,255,000 721,210,000 500,844,000 611,701,000 714,769,000 628,215,000 583,211,000 351,005,000        69,546,000 219,193,000 262,174,000 69,529,000 114,154,000 173,723,000 228,783,000                                           
        as of december 31, 2025 and 2024, respectively
       1,680,249,000                                                                       
        common stock voting, .0025 par value; 900,000,000 shares authorized;
                                                                              
        268,644,427 and 268,377,165 shares issued; and 144,940,102 and 151,117,153
                                                                              
        shares outstanding, as of december 31, 2025 and 2024, respectively
       653,000                                                                       
        268,417,974 and 268,377,165 shares issued; and 146,156,096 and 151,117,153
                                                                              
        shares outstanding, as of september 30, 2025 and december 31, 2024, respectively
        652,000                                                                      
        as of september 30, 2025 and december 31, 2024, respectively
        -7,743,046,000                                                                      
        268,417,974 and 268,377,165 shares issued; and 147,788,364 and 151,117,153
                                                                              
        shares outstanding, as of june 30, 2025 and december 31, 2024, respectively
         652,000                                                                     
        as of june 30, 2025 and december 31, 2024, respectively
         -7,532,706,000                                                                     
        accumulated other comprehensive income
         1,178,000   -445,000 -1,428,000 -13,000 421,000 -494,000 1,027,000 1,800,000 889,000 -2,748,000 -4,999,000 9,296,000 -2,091,000 10,583,000 32,344,000 5,667,000 1,902,000 95,000 216,000 30,000 -7,000 39,000 78,000 130,000 301,000                                           
        268,417,974 and 268,377,165 shares issued; and 149,380,035 and 151,117,153
                                                                              
        shares outstanding, as of march 31, 2025 and december 31, 2024, respectively
          652,000                                                                    
        as of march 31, 2025 and december 31, 2024, respectively
          -7,334,595,000                                                                    
        as of december 31, 2024 and 2023, respectively
           1,362,969,000                                                                   
        268,377,165 and 268,112,991 shares issued; and 151,117,153 and 160,018,100
                                                                              
        shares outstanding, as of december 31, 2024 and 2023, respectively
           652,000                                                                   
        268,142,204 and 268,112,991 shares issued; and 153,042,184 and 160,018,100
                                                                              
        shares outstanding, as of september 30, 2024 and december 31, 2023, respectively
            651,000                                                                  
        as of september 30, 2024 and december 31, 2023, respectively
            -6,799,219,000                                                                  
        268,142,204 and 268,112,991 shares issued; and 155,617,909 and 160,018,100
                                                                              
        shares outstanding, as of june 30, 2024 and december 31, 2023, respectively
             651,000                                                                 
        as of june 30, 2024 and december 31, 2023, respectively
             -6,489,369,000                                                                 
        268,142,204 and 268,112,991 shares issued; and 157,878,760 and 160,018,100
                                                                              
        shares outstanding, as of march 31, 2024 and december 31, 2023, respectively
              651,000                                                                
        as of march 31, 2024 and december 31, 2023, respectively
              -6,182,274,000                                                                
        as of december 31, 2023, and december 31, 2022, respectively
               1,535,062,000                                                               
        268,112,991 and 267,762,488 shares issued; and 160,018,100 and 172,936,163
                                                                              
        shares outstanding, as of december 31, 2023, and december 31, 2022, respectively
               651,000                                                               
        267,772,737 and 267,762,488 shares issued; and 163,489,456 and 172,936,163
                                                                              
        shares outstanding, as of september 30, 2023 and december 31, 2022, respectively
                650,000                                                              
        as of september 30, 2023 and december 31, 2022, respectively
                -5,510,983,000                                                              
        267,772,737 and 267,762,488 shares issued; and 166,383,336 and 172,936,163
                                                                              
        shares outstanding, as of june 30, 2023 and december 31, 2022, respectively
                 650,000                                                             
        as of june 30, 2023 and december 31, 2022, respectively
                 -5,179,722,000                                                             
        267,772,737 and 267,762,488 shares issued; and 170,170,375 and 172,936,163
                                                                              
        shares outstanding, as of march 31, 2023 and december 31, 2022, respectively
                  650,000                                                            
        as of march 31, 2023 and december 31, 2022, respectively
                  -4,800,513,000                                                            
        as of december 31, 2022, and december 31, 2021, respectively
                   1,976,282,000                                                           
        267,762,488 and 267,224,622 shares issued; and 172,936,163 and 194,997,922
                                                                              
        shares outstanding, as of december 31, 2022, and december 31, 2021, respectively
                   650,000                                                           
        accrued interest
                    33,535,000 17,531,000 33,539,000 17,533,000 33,540,000 17,535,000 33,856,000 19,656,000 27,649,000 11,859,000 39,749,000 18,292,000 47,945,000 25,509,000 47,955,000 25,526,000 47,967,000 25,542,000 47,936,000 25,533,000 49,380,000 29,632,000 50,650,000 30,295,000 47,882,000 38,540,000 47,928,000 47,998,000 38,988,000 51,800,000 21,277,000 30,682,000 21,911,000 23,060,000 32,509,000 19,290,000          27,656,000 58,191,000         9,810,000  8,952,000 
        267,228,549 and 267,224,622 shares issued; and 176,563,632 and 194,997,922
                                                                              
        shares outstanding, as of september 30, 2022 and december 31, 2021, respectively
                    649,000                                                          
        as of september 30, 2022 and december 31, 2021, respectively
                    -4,046,555,000                                                          
        267,224,622 and 267,224,622 shares issued; and 182,610,729 and 194,997,922
                                                                              
        shares outstanding, as of june 30, 2022 and december 31, 2021, respectively
                     649,000                                                         
        as of june 30, 2022 and december 31, 2021, respectively
                     -3,566,493,000                                                         
        267,224,622 and 267,224,622 shares issued; and 189,247,115 and 194,997,922
                                                                              
        shares outstanding, as of march 31, 2022 and december 31, 2021, respectively
                      649,000                                                        
        as of march 31, 2022 and december 31, 2021, respectively
                      -3,050,497,000                                                        
        as of december 31, 2021, and december 31, 2020, respectively
                       1,911,385,000                                                       
        267,224,622 and 266,618,566 shares issued; and 194,997,922 and 210,914,264
                                                                              
        shares outstanding, as of december 31, 2021, and december 31, 2020, respectively
                       649,000                                                       
        as of december 31, 2021, and december 31, 2020 respectively
                       -2,674,267,000                                                       
        266,618,566 shares issued; and 199,778,688 and 210,914,264
                                                                              
        shares outstanding, as of september 30, 2021 and december 31, 2020, respectively
                        648,000                                                      
        as of september 30, 2021 and december 31, 2020, respectively
                        -2,344,477,000                                                      
        266,618,566 shares issued; and 205,307,447 and 210,914,264
                                                                              
        shares outstanding, as of june 30, 2021 and december 31, 2020, respectively
                         648,000                                                     
        as of june 30, 2021 and december 31, 2020, respectively
                         -2,006,895,000                                                     
        266,618,566 shares issued; and 211,218,956 and 210,914,264
                                                                              
        shares outstanding, as of march 31, 2021 and december 31, 2020, respectively
                          648,000                                                    
        as of march 31, 2021 and december 31, 2020, respectively
                          -1,614,866,000                                                    
        december 31, 2020, and december 31, 2019, respectively
                           967,981,000                                                   
        266,618,566 and 266,072,787 shares issued; and 210,914,264 and 214,502,639
                                                                              
        shares outstanding, as of december 31, 2020, and december 31, 2019, respectively
                           648,000                                                   
        as of december 31, 2020, and december 31, 2019 respectively
                           -1,623,747,000                                                   
        266,072,787 and 266,072,787 shares issued; and 210,366,497 and 214,502,639
                                                                              
        shares outstanding, as of september 30, 2020 and december 31, 2019, respectively
                            646,000                                                  
        as of september 30, 2020 and december 31, 2019, respectively
                            -1,623,805,000                                                  
        266,072,787 and 266,072,787 shares issued; and 210,364,813 and 214,502,639
                                                                              
        shares outstanding, as of june 30, 2020 and december 31, 2019, respectively
                             646,000                                                 
        as of june 30, 2020 and december 31, 2019, respectively
                             -1,623,855,000                                                 
        266,079,627 and 266,072,787 shares issued; and 210,338,959 and 214,502,639
                                                                              
        shares outstanding, as of march 31, 2020 and december 31, 2019, respectively
                              646,000                                                
        as of march 31, 2020 and december 31, 2019, respectively
                              -1,624,808,000                                                
        accounts receivable, net of related allowances of 15,867 and 17,495 as of
                                                                              
        december 31, 2019, and december 31, 2018, respectively
                               841,378,000                                               
        intangible assets, net of accumulated amortization of 322,611 and 294,449 as of
                                                                              
        266,072,787 and 265,822,402 shares issued; and 214,502,639 and 225,272,174
                                                                              
        shares outstanding, as of december 31, 2019, and december 31, 2018, respectively
                               646,000                                               
        as of december 31, 2019, and december 31, 2018 respectively
                               -1,525,113,000                                               
        265,553,499 and 265,822,402 shares issued; and 215,740,572 and 225,272,174
                                                                              
        shares outstanding, as of september 30, 2019 and december 31, 2018, respectively
                                645,000                                              
        as of september 30, 2019 and december 31, 2018, respectively
                                -1,469,078,000                                              
        265,553,499 and 265,822,402 shares issued; and 219,797,547 and 225,272,174
                                                                              
        shares outstanding, as of june 30, 2019 and december 31, 2018, respectively
                                 645,000                                             
        as of june 30, 2019 and december 31, 2018, respectively
                                 -1,354,157,000                                             
        265,552,825 and 265,822,402 shares issued; and 222,931,285 and 225,272,174
                                                                              
        shares outstanding, as of march 31, 2019 and december 31, 2018, respectively
                                  645,000                                            
        as of march 31, 2019 and december 31, 2018, respectively
                                  -1,261,837,000                                            
        accounts receivable, net of related allowances of 17,495 and 15,036 as of
                                                                              
        december 31, 2018, and december 31, 2017, respectively
                                   1,040,220,000                                           
        intangible assets, net of accumulated amortization of 294,449 and 269,868 as of
                                                                              
        265,822,402 and 265,003,133 shares issued; and 225,272,174 and 237,396,839
                                                                              
        shares outstanding, as of december 31, 2018, and december 31, 2017, respectively
                                   645,000                                           
        as of december 31, 2018, and december 31, 2017 respectively
                                   -1,184,243,000                                           
        short term investments
                                    115,000,000 90,000,000 40,000,000                                        
        265,117,573 and 265,003,133 shares issued; and 233,422,108 and 237,396,839
                                                                              
        shares outstanding, as of september 30, 2018 and december 31, 2017, respectively
                                    644,000                                          
        as of september 30, 2018 and december 31, 2017, respectively
                                    -854,052,000                                          
        265,006,573 and 265,003,133 shares issued; and 235,096,384 and 237,396,839
                                                                              
        shares outstanding, as of june 30, 2018 and december 31, 2017, respectively
                                     644,000                                         
        as of june 30, 2018 and december 31, 2017 respectively
                                     -779,088,000                                         
        265,080,663 and 265,003,133 shares issued; and 236,095,748 and 237,396,839
                                                                              
        shares outstanding, as of march 31, 2018 and december 31, 2017, respectively
                                      644,000                                        
        as of march 31, 2018 and december 31, 2017 respectively
                                      -730,700,000                                        
        accounts receivable, net of related allowances of 15,036 and 14,413 as of
                                                                              
        december 31, 2017, and december 31, 2016, respectively
                                       846,415,000                                       
        restricted cash
                                       16,939,000 17,092,000 17,373,000 17,846,000 18,060,000 19,571,000 19,555,000 19,603,000 19,621,000 19,571,000 19,242,000 18,257,000 18,460,000 18,588,000 23,016,000 23,231,000 23,400,000 27,436,000 27,806,000 26,994,000 20,763,000 21,717,000 21,448,000 20,570,000 20,592,000 10,547,000 13,932,000 16,217,000 7,679,000 7,656,000 11,867,000 6,643,000 6,592,000 6,022,000 5,702,000 5,771,000 4,535,000 2,139,000 1,588,000 
        intangible assets, net of accumulated amortization of 269,868 and 294,676 as of
                                                                              
        265,003,133 and 264,130,544 shares issued; and 237,396,839 and 243,785,485
                                                                              
        shares outstanding, as of december 31, 2017, and december 31, 2016, respectively
                                       644,000                                       
        as of december 31, 2017, and december 31, 2016 respectively
                                       -665,297,000                                       
        264,161,359 and 264,130,544 shares issued; and 236,951,784 and 243,785,485
                                                                              
        shares outstanding, as of september 30, 2017 and december 31, 2016, respectively
                                        641,000                                      
        as of september 30, 2017 and december 31, 2016 respectively
                                        -650,210,000                                      
        264,161,359 and 264,130,544 shares issued; and 239,872,874 and 243,785,485
                                                                              
        shares outstanding, as of june 30, 2017 and december 31, 2016, respectively
                                         641,000                                     
        as of june 30, 2017 and december 31, 2016 respectively
                                         -551,125,000                                     
        264,135,545 and 264,130,544 shares issued; and 242,110,745 and 243,785,485
                                                                              
        shares outstanding, as of march 31, 2017 and december 31, 2016, respectively
                                          641,000                                    
        as of march 31, 2017 and december 31, 2016 respectively
                                          -475,072,000                                    
        accounts receivable, net of related allowances of 14,413 and 9,765 as of
                                                                              
        december 31, 2016, and 2015, respectively
                                           703,565,000                                   
        intangible assets, net of accumulated amortization of 294,676 and 265,940 as of
                                                                              
        264,130,544 and 262,937,139 shares issued; and 243,785,485 and 243,089,514
                                                                              
        shares outstanding, as of december 31, 2016, and december 31, 2015, respectively
                                           641,000                                   
        as of december 31, 2016, and december 31, 2015 respectively
                                           -416,829,000                                   
        263,396,348, and 262,937,139 shares issued; and 243,770,777, and 243,089,514
                                                                              
        shares outstanding, as of september 30, 2016 and december 31, 2015, respectively
                                            640,000                                  
        as of september 30, 2016 and december 31, 2015 respectively
                                            -392,051,000                                  
        common stock voting, .0025 par value; 900,000,000 shares authorized; 263,370,594, and 262,937,139 shares issued; and 243,745,023, and 243,089,514 shares outstanding, as of june 30, 2016 and december 31, 2015, respectively
                                             639,000                                 
        net sales
                                                                              
        unrelated parties
                                             1,978,984,000 1,698,004,000 1,901,415,000 1,945,983,000 2,003,973,000 2,276,747,000 1,987,635,000 1,765,881,000 1,838,464,000 1,735,420,000  1,624,561,000 1,830,117,000 1,905,075,000 1,976,296,000 2,004,283,000 1,941,664,000                 
        related parties
                                             44,918,000 43,297,000 49,508,000 59,024,000 43,462,000 62,269,000 82,126,000 64,201,000 73,274,000 65,920,000  68,829,000 79,686,000 76,965,000 67,159,000 75,448,000 74,305,000                 
        total net sales
                                             2,023,902,000 1,741,301,000 1,950,923,000 2,005,007,000 2,047,435,000 2,339,016,000 2,069,761,000 1,830,082,000 1,911,738,000 1,801,340,000  1,693,390,000 1,909,803,000 1,982,040,000 2,043,455,000 2,079,731,000 2,015,969,000                 
        costs of goods sold
                                             1,643,519,000 1,505,265,000 1,722,197,000 1,833,264,000 1,860,393,000 2,050,504,000 1,846,990,000 1,666,778,000 1,714,546,000 1,653,648,000  1,536,989,000 1,727,667,000 1,780,776,000 1,844,212,000 1,803,345,000 1,720,215,000                 
        gross profit
                                             380,383,000 236,036,000 228,726,000 171,743,000 187,042,000 288,512,000 222,771,000 163,304,000 197,192,000 147,692,000  156,401,000 182,136,000 201,264,000 199,243,000 276,386,000 295,754,000                 
        selling, general and administrative expenses
                                             96,853,000 87,530,000 82,371,000 82,660,000 76,350,000 80,240,000 73,463,000 70,042,000 67,553,000 65,356,000  62,984,000 61,235,000 64,384,000 72,876,000 63,631,000 65,141,000                 
        profit sharing
                                             20,176,000 9,291,000 9,008,000 5,031,000 4,598,000 12,865,000 10,469,000 5,395,000 8,469,000 4,779,000  3,954,000 8,211,000 8,072,000 7,428,000 14,454,000 15,203,000                 
        amortization of intangible assets
                                             7,232,000 7,250,000 6,318,000 6,493,000 6,323,000 6,764,000 6,934,000 6,935,000 7,897,000 8,051,000  8,848,000 8,991,000  10,154,000 10,082,000                  
        operating income
                                             256,122,000 131,965,000 131,029,000 77,559,000 99,771,000 188,643,000 131,905,000 80,932,000 113,273,000 69,198,000  72,721,000 103,699,000 119,816,000 108,785,000 188,219,000 205,326,000                 
        interest expense, net of capitalized interest
                                             36,646,000 37,043,000 37,084,000 37,163,000 43,087,000 31,904,000 30,050,000 30,569,000 30,970,000 31,465,000  41,490,000 41,106,000 41,112,000 44,702,000 44,812,000 43,346,000                 
        other income (income)
                                                                              
        income before income taxes
                                             221,294,000 96,714,000 93,706,000 41,608,000 40,492,000 134,667,000 103,609,000 50,994,000 84,155,000 38,979,000  7,221,000 64,485,000 68,456,000 67,606,000 149,152,000 166,547,000                 
        income taxes
                                             80,851,000  34,839,000 16,283,000 13,538,000 47,010,000 37,268,000 17,296,000 33,065,000 15,706,000  1,116,000 25,180,000 26,679,000 27,749,000 53,326,000 62,317,000                 
        net income
                                             140,443,000 61,318,000 58,867,000 25,325,000 26,954,000 87,657,000 66,341,000 33,698,000 51,090,000 23,273,000  6,105,000 39,305,000 41,777,000 39,857,000 95,826,000 104,230,000                 
        net income attributable to noncontrolling interests
                                             1,526,000 1,419,000 1,750,000 6,225,000 3,807,000 3,516,000 5,962,000 4,881,000 6,396,000 5,685,000  6,728,000 5,167,000 3,898,000 3,447,000 2,884,000 1,673,000                 
        net income attributable to steel dynamics, inc.
                                             141,969,000 62,737,000 60,617,000 31,550,000 30,761,000 91,173,000 72,303,000 38,579,000 57,486,000 28,958,000  12,833,000 44,472,000 45,675,000 43,304,000 98,710,000 105,903,000                 
        basic earnings per share attributable to steel dynamics, inc. stockholders
                                             580 260 250 130 130 380 320 170 260 130  60 200 210 200 450 490                 
        weighted-average common shares outstanding
                                             243,655,000 243,202,000 242,074,000 241,900,000 241,535,000 240,087,000 226,220,000 223,011,000 220,926,000 220,471,000  219,191,000 219,104,000 218,996,000 218,674,000 218,500,000 217,992,000                 
        diluted earnings per share attributable to steel dynamics, inc. stockholders, including the effect of assumed conversions when dilutive
                                             580 260 250 130 130 380 310 170 250 130  60 200 200 190 430 460                 
        weighted-average common shares and share equivalents outstanding
                                             245,392,000 244,608,000 243,822,000 243,491,000 242,867,000 242,244,000 242,048,000 241,394,000 239,001,000 221,736,000  220,044,000 236,208,000 236,526,000 235,759,000 236,266,000 236,224,000                 
        dividends declared per share
                                             140 140 137.5 137.5 137.5 115 115 115 110 110  100 100 100 100 100 100                 
        common stock voting, .0025 par value; 900,000,000 shares authorized; 263,142,777, and 262,937,139 shares issued; and 243,500,764, and 243,089,514 shares outstanding, as of march 31, 2016 and december 31, 2015, respectively
                                              639,000                                
        other income
                                               239,000  16,192,000 22,072,000  -631,000    24,010,000  10,248,000                    
        income tax expense
                                              35,396,000                                
        senior term loan
                                               228,125,000 231,250,000 234,375,000 189,062,000 199,375,000                           
        senior notes
                                               2,350,000,000 2,350,000,000 2,350,000,000 2,700,000,000 1,500,000,000 1,500,000,000 1,500,000,000 1,500,000,000 1,500,000,000                       
        other long-term debt
                                               37,694,000 38,324,000 39,069,000 40,932,000 42,753,000 45,341,000 46,744,000 40,493,000 41,093,000 35,491,000 36,224,000 36,707,000 41,550,000 40,293,000 40,780,000 71,938,000 64,179,000 62,364,000 42,392,000 30,314,000 15,884,000 17,785,000 16,085,000 16,536,000 16,750,000 16,836,000  17,368,000 17,887,000 17,807,000  
        total long-term debt
                                               2,615,819,000 2,619,574,000 2,623,444,000 2,929,994,000 1,742,128,000 1,755,028,000 1,773,619,000 1,774,243,000 2,069,214,000 2,173,925,000 1,928,097,000 1,932,019,000 2,379,050,000                   
        common stock voting, .0025 par value; 900,000,000 shares authorized; 261,938,768, and 261,420,126 shares issued; and 242,090,224, and 241,449,423 shares outstanding, as of september 30, 2015 and december 31, 2014, respectively
                                               636,000                               
        common stock voting, .0025 par value; 900,000,000 shares authorized; 261,904,809, and 261,420,126 shares issued; and 242,055,377, and 241,449,423 shares outstanding, as of june 30, 2015 and december 31, 2014, respectively
                                                636,000                              
        common stock voting, .0025 par value; 900,000,000 shares authorized; 261,539,685 and 261,420,126 shares issued; and 241,688,172 and 241,449,423 shares outstanding, as of march 31, 2015 and december 31, 2014, respectively
                                                 635,000                             
        common stock voting, .0025 par value; 900,000,000 shares authorized; 260,332,348 and 258,840,350 shares issued; and 240,365,196 and 222,867,408 shares outstanding, as of september 30, 2014 and december 31, 2013, respectively
                                                  649,000                            
        impairment charges
                                                      308,000  7,894,000                      
        total selling, general and administrative expenses
                                                  99,869,000 90,866,000 82,372,000 83,919,000 78,494,000  83,680,000 78,437,000 81,448,000 90,458,000 88,167,000 90,428,000                 
        common stock voting, .0025 par value; 900,000,000 shares authorized; 259,588,037 and 258,840,350 shares issued; and 239,620,885 and 222,867,408 shares outstanding, as of june 30, 2014 and december 31, 2013, respectively
                                                   647,000                           
        term note
                                                    209,687,000 226,875,000 233,750,000 240,625,000                       
        common stock voting, .0025 par value; 900,000,000 shares authorized; 259,046,646 and 258,840,350 shares issued; and 223,173,055 and 222,867,408 shares outstanding, as of march 31, 2014 and december 31, 2013, respectively
                                                    646,000                          
        investments in short-term commercial paper
                                                         9,998,000 64,982,000                    
        convertible senior notes
                                                       287,496,000                       
        common stock voting, .0025 par value; 900,000,000 shares authorized; 257,314,197 and 255,592,901 shares issued; and 221,349,383 and 219,522,655 shares outstanding, as of september 30, 2013 and december 31, 2012, respectively
                                                     641,000                         
        common stock voting, .0025 par value; 900,000,000 shares authorized; 256,630,645 and 255,592,901 shares issued; and 220,665,831 and 219,522,655 shares outstanding, as of june 30, 2013 and december 31, 2012, respectively
                                                      640,000                        
        redeemable noncontrolling interest
                                                       99,414,000 93,774,000 77,424,000 73,924,000 64,364,000 54,294,000 54,294,000                 
        common stock voting, .0025 par value; 900,000,000 shares authorized; 256,333,083 and 255,592,901 shares issued; and 220,333,057 and 219,522,655 shares outstanding, as of march 31, 2013 and december 31, 2012, respectively
                                                       639,000                       
        income taxes receivable
                                                        939,000 17,082,000 2,833,000 24,519,000 15,295,000 6,285,000 30,413,000 35,819,000 124,950,000 125,912,000 93,475,000            
        accrued profit sharing
                                                        19,213,000 15,271,000 9,348,000 35,883,000 28,464,000 16,163,000 21,333,000 16,771,000 9,682,000 56,000 56,000 75,212,000 44,767,000 19,994,000 42,363,000 27,619,000 15,803,000 46,341,000 34,426,000 20,752,000   
        term loan
                                                        250,938,000 254,375,000 257,812,000                    
        7 3/8% senior notes due 2012
                                                                              
        5.125% convertible senior notes due 2014
                                                        287,496,000                      
        6 ¾% senior notes due 2015
                                                        500,000,000                      
        7 ¾% senior notes due 2016
                                                                              
        6 1/8% senior notes due 2019
                                                        400,000,000                      
        7 5/8% senior notes due 2020
                                                        350,000,000                      
        6 3/8% senior notes due 2022
                                                        350,000,000                      
        common stock voting, .0025 par value; 900,000,000 shares authorized; 255,299,134 and 255,052,811 shares issued; and 219,228,888 and 218,873,720 shares outstanding, as of september 30, 2012 and december 31, 2011, respectively
                                                        636,000                      
        7 3/8% senior notes, due 2012
                                                           700,000,000 700,000,000 700,000,000 700,000,000 700,000,000 700,000,000 700,000,000 700,000,000 700,000,000 700,000,000 700,000,000         
        5.125% convertible senior notes, due 2014
                                                         287,498,000 287,500,000 287,500,000 287,500,000 287,500,000 287,500,000 287,500,000 287,500,000 287,500,000             
        6 ¾% senior notes, due 2015
                                                         500,000,000 500,000,000 500,000,000 500,000,000 500,000,000 500,000,000 500,000,000 500,000,000 500,000,000  500,000,000  500,000,000         
        7 ¾% senior notes, due 2016
                                                         500,000,000 500,000,000 500,000,000 500,000,000 500,000,000 500,000,000 500,000,000 500,000,000 500,000,000  500,000,000           
        7 5/8% senior notes, due 2020
                                                         350,000,000 350,000,000 350,000,000 350,000,000 350,000,000                 
        common stock voting, .0025 par value; 900,000,000 shares authorized; 255,225,325 and 255,052,811 shares issued; and 219,154,966 and 218,873,720 shares outstanding, as of june 30, 2012 and december 31, 2011, respectively
                                                         636,000                     
        common stock voting, .0025 par value; 900,000,000 shares authorized; 255,171,906 and 255,052,811 shares issued; and 219,074,339 and 218,873,720 shares outstanding, as of march 31, 2012 and december 31, 2011, respectively
                                                          636,000                    
        amortization of intangibles
                                                          8,992,000   10,084,000                 
        common stock voting, .0025 par value; 900,000,000 shares authorized; 255,029,406 and 254,002,799 shares issued; and 218,690,315 and 217,574,826 shares outstanding, as of september 30, 2011 and december 31, 2010, respectively
                                                           636,000                   
        common stock voting, .0025 par value; 900,000,000 shares authorized; 254,987,769 and 254,002,799 shares issued; and 218,648,678 and 217,574,826 shares outstanding, as of june 30, 2011 and december 31, 2010, respectively
                                                            636,000                  
        common stock voting, .0025 par value; 900,000,000 shares authorized; 254,642,621 and 254,002,799 shares issued; and 218,303,530 and 217,574,826 shares outstanding, as of march 31, 2011 and december 31, 2010, respectively
                                                             635,000                 
        liabilities and stockholders’ equity
                                                                              
        senior secured revolving credit facility, due 2012
                                                                 114,000,000 231,000,000 575,000,000           
        7 5/8% notes, due 2020
                                                              350,000,000 350,000,000 350,000,000              
        stockholders’ equity
                                                                              
        common stock voting, .0025 par value; 900,000,000 shares authorized; 253,422,407 and 252,589,627 shares issued; and 216,994,434 and 215,999,801 shares outstanding, as of september 30, 2010 and december 31, 2009, respectively
                                                              632,000                
        total steel dynamics, inc. stockholders’ equity
                                                              2,091,639,000 2,083,981,000 2,044,478,000 1,910,530,000 1,524,670,000            
        total stockholders’ equity
                                                              2,103,676,000 2,097,599,000 2,057,895,000 1,924,483,000 1,538,944,000 1,739,394,000 1,987,552,000 1,616,057,000 1,079,959,000 1,184,155,000 1,225,106,000 1,231,108,000 1,172,573,000 1,224,936,000 971,522,000 879,868,000 
        total liabilities and stockholders’ equity
                                                              5,610,459,000 5,545,805,000 5,582,122,000 4,881,812,000 4,926,079,000 6,054,879,000 6,043,589,000 4,821,612,000 3,095,301,000 2,575,886,000 2,341,392,000 2,247,017,000 2,208,803,000 2,164,473,000 1,881,619,000 1,757,687,000 
        common stock voting, .0025 par value; 900,000,000 shares authorized; 253,233,868 and 252,589,627 shares issued; and 216,805,895 and 215,999,801 shares outstanding, as of june 30, 2010 and december 31, 2009, respectively
                                                               631,000               
        common stock voting, .0025 par value; 900,000,000 shares authorized; 252,908,444 and 252,589,627 shares issued; and 216,437,175 and 215,999,801 shares outstanding, as of march 31, 2010 and december 31, 2009, respectively
                                                                630,000              
        senior secured term a loan
                                                                    536,000,000 552,100,000         
        common stock voting, .0025 par value; 900,000,000 shares authorized; 251,398,691 and 218,733,363 shares issued; and 214,808,597 and 181,820,012 shares outstanding, as of june 30, 2009 and december 31, 2008, respectively
                                                                 626,000             
        other accumulated comprehensive loss
                                                                              
        senior secured term a loan, due 2012
                                                                  487,700,000 519,900,000           
        6 3/4% senior notes, due 2015
                                                                  500,000,000  500,000,000          
        7 3/4% senior notes, due 2016
                                                                  500,000,000  500,000,000          
        common stock voting, .0025 par value; 900,000,000 shares authorized; 218,771,002 and 218,733,363 shares issued; and 182,130,997 and 181,820,012 shares outstanding, as of march 31, 2009 and december 31, 2008, respectively
                                                                  545,000            
        4.0% convertible subordinated notes
                                                                              
        minority interest
                                                                   8,939,000 12,304,000 11,513,000 976,000 869,000 1,043,000 1,424,000 1,814,000 1,747,000 1,357,000 1,118,000 
        common stock voting, .0025 par value; 900,000,000 shares authorized; 218,636,669 and 217,770,922 shares issued; and 183,115,409 and 190,324,402 shares outstanding, as of september 30, 2008 and december 31, 2007, respectively
                                                                   544,000           
        other accumulated comprehensive income
                                                                    5,011,000          
        senior secured revolving credit facility
                                                                    201,000,000 147,000,000 97,000,000 215,000,000       
        other current maturities of long-term debt
                                                                    65,808,000 65,477,000         
        4.0% convertible subordinated notes, due 2012
                                                                    16,000,000 37,250,000         
        common stock voting, .0025 par value; 900,000,000 shares authorized; 218,551,353 and 217,770,922 shares issued; and 198,191,407 and 190,324,402 shares outstanding, as of june 30, 2008 and december 31, 2007, respectively
                                                                    544,000          
        common stock voting, .0025 par value; 400,000,000 shares authorized; 218,161,133 and 217,770,922 shares issued; and 188,849,999 and 190,324,402 shares outstanding, as of march 31, 2008 and december 31, 2007, respectively
                                                                     543,000         
        deferred taxes
                                                                      16,080,000 14,488,000 13,611,000  18,266,000 17,346,000 6,950,000  
        other accrued expenses
                                                                      120,429,000    79,149,000 72,349,000 63,041,000 80,527,000 
        senior secured term a loan facility
                                                                      495,000,000        
        9 ½% senior unsecured notes
                                                                              
        6 ¾% senior unsecured notes
                                                                      500,000,000        
        subordinated convertible 4.0% notes
                                                                      37,250,000 37,500,000 37,500,000  79,995,000 79,995,000 110,000,000  
        unamortized bond premium
                                                                        3,350,000 3,772,000 4,194,000 4,615,000 5,037,000 5,459,000 
        common stock voting, .005 par value; 200,000,000 shares authorized: 108,578,346 and 107,865,486 shares issued, and 87,242,960 and 96,983,303 shares outstanding, as of september 30, 2007 and december 31, 2006, respectively
                                                                      541,000        
        91¤2% senior unsecured notes
                                                                              
        63¤4% senior unsecured notes
                                                                       500,000,000       
        common stock voting, .005 par value; 200,000,000 shares authorized; 108,408,426 and 107,865,486 shares issued, and 91,923,320 and 96,983,303 shares outstanding, as of june 30, 2007 and december 31, 2006, respectively
                                                                       540,000       
        senior unsecured 9½% notes
                                                                        300,000,000 300,000,000    300,000,000 
        common stock voting, .005 par value; 200,000,000 shares authorized; 108,082,420 and 107,865,486 shares issued, and 94,510,185 and 96,983,303 shares outstanding, as of march 31, 2007 and december 31, 2006, respectively
                                                                        538,000      
        accounts receivable, net of related allowances of 6,863 and 5,727 as of december 31, 2006 and 2005, respectively
                                                                         355,011,000     
        accounts receivable—related parties
                                                                         53,365,000     
        intangible assets, net of accumulated amortization of 1,874 as of december 31, 2006
                                                                         12,226,000     
        accounts payable—related parties
                                                                         2,004,000     
        convertible subordinated 4.0% notes
                                                                         37,500,000    115,000,000 
        other secured debt
                                                                         16,920,000    17,960,000 
        common stock voting, .005 par value; 200,000,000 shares authorized; 107,865,486 and 106,111,440 shares issued; and 96,983,303 and 86,367,978 shares outstanding, as of december 31, 2006 and 2005, respectively
                                                                         537,000     
        current assets:
                                                                              
        current liabilities:
                                                                              
        senior unsecured 9 ½% notes
                                                                          300,000,000 300,000,000   
        stockholders’ equity:
                                                                              
        common stock voting, .01 par value...
                                                                          537,000 536,000 534,000 529,000 
        senior unsecured 9.5% notes
                                                                            300,000,000  
        long-term debt:
                                                                              
      Cashflow Statements:
      Quarterly
      Annual
        Unit: USD2026-03-31 2025-09-30 2025-06-30 2025-03-31 2024-09-30 2024-06-30 2024-03-31 2023-09-30 2023-06-30 2023-03-31 2022-09-30 2022-06-30 2022-03-31 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 2015-09-30 2015-06-30 2015-03-31 2014-06-30 2014-03-31 2013-09-30 2013-06-30 2013-03-31 2012-09-30 2012-06-30 2012-03-31 2011-09-30 2011-06-30 2011-03-31 2010-09-30 2010-06-30 2010-03-31 2009-06-30 2009-03-31 2008-09-30 2008-06-30 2008-03-31 2007-09-30 2007-06-30 2007-03-31 2006-12-31 2006-09-30 2006-06-30 2006-03-31 
                                                                         
          operating activities:
                                                                         
          net income
        400,105,000 403,926,000 301,191,000 217,679,000 320,894,000 431,690,000 587,500,000 579,782,000 816,177,000 644,333,000 918,475,000 1,214,652,000 1,107,354,000 1,000,159,000 712,203,000 438,755,000 466,551,000 25,512,000 -112,071,000 190,836,000 525,292,000 -44,138,000 -8,081,000 204,827,000 857,899,000 35,334,000 137,097,000 225,475,000 654,784,000 -1,935,000 -45,719,000 198,666,000 205,593,000 13,970,000 79,125,000 61,318,000 33,542,000 -1,629,000 26,954,000 32,643,000 33,698,000 27,817,000 -17,979,000 41,252,000 -33,200,000 -2,472,000 41,777,000 -55,969,000 -8,404,000 104,230,000 -31,442,000 -18,172,000 64,969,000   -17,486,000 67,937,000 142,557,000 6,649,000 -8,222,000 102,164,000 277,984,000 21,854,000 20,820,000 76,049,000 
          adjustments to reconcile net income to net cash from
                                                                         
          depreciation and amortization
        159,280,000 138,487,000 132,865,000 133,756,000 121,052,000 117,053,000 115,252,000 107,418,000 110,970,000 107,694,000 98,714,000 95,701,000 87,546,000 87,407,000 87,047,000 86,919,000 244,037,000 3,031,000 -1,538,000 80,259,000 241,612,000 -1,441,000 737,000 80,174,000 235,815,000 2,263,000 2,985,000 76,135,000 223,789,000 1,409,000 -1,256,000 75,057,000 221,919,000 -605,000 810,000 73,985,000 -62,000 1,451,000 72,822,000 873,000 57,568,000 1,376,000 -235,000 57,061,000 3,451,000 -70,000 55,572,000 -295,000 1,511,000 54,746,000 1,880,000 -874,000 56,272,000 802,000 56,963,000 7,777,000 -5,630,000 53,212,000 875,000 3,713,000 29,265,000 84,196,000 178,000 5,521,000 24,917,000 
          equity-based compensation
        17,451,000 14,238,000 14,063,000 17,040,000 12,828,000 13,013,000 15,612,000 12,044,000 11,678,000 16,078,000 12,093,000 11,069,000 16,519,000 9,917,000 9,808,000 17,040,000 46,112,000 -34,000 -8,324,000 17,844,000 38,790,000 -239,000 -6,228,000 15,308,000 35,339,000 -63,000 -4,800,000 12,841,000 29,322,000 495,000 -4,923,000 11,303,000 25,732,000 -1,312,000 -1,169,000 8,405,000 -1,025,000 -2,186,000 8,543,000 -1,068,000 5,768,000 171,000 -2,409,000 4,753,000 -1,864,000 -3,521,000 6,123,000 21,000 102,000 3,710,000 297,000 560,000 2,769,000 -5,266,000 8,579,000 539,000 -1,175,000 3,929,000 -315,000 -137,000 2,269,000     
          deferred income taxes
        32,669,000 147,570,000 39,129,000 16,249,000 14,832,000 4,577,000 -21,024,000 19,625,000 43,380,000 9,008,000 3,990,000 -2,636,000 2,632,000 71,008,000 50,722,000 66,744,000 37,420,000 -4,246,000 8,707,000 5,927,000 40,410,000 -239,000 -541,000 12,091,000 37,928,000 11,906,000 2,448,000 9,545,000 -139,183,000 -3,565,000 -867,000 7,716,000 35,368,000 164,000 1,227,000 17,087,000 -3,237,000 -350,000 16,717,000   -951,000 -123,000 10,935,000 23,999,000 1,437,000 9,197,000 -1,910,000 -3,907,000 12,935,000 -7,682,000 1,949,000 8,468,000 -1,898,000 7,695,000          128,000 
          other adjustments
        -2,293,000 -7,986,000 -890,000 -4,195,000 -10,523,000 -6,403,000 18,705,000 -12,163,000 1,541,000 -10,006,000 -12,409,000 -640,000 11,157,000 -781,000 -1,472,000 -662,000 13,737,000 12,509,000 4,992,000 -264,000 2,529,000 -552,000 -1,292,000 728,000 -1,557,000 457,000 -175,000 30,000 5,866,000 8,245,000 61,000 -104,000                                  
          changes in certain assets and liabilities:
                                                                         
          accounts receivable
        -373,774,000 -60,985,000 19,825,000 -303,602,000 210,435,000 -36,332,000 -130,753,000 260,915,000 -16,971,000 -70,922,000 326,731,000 -297,047,000 -447,234,000 -321,771,000 -204,561,000 -394,545,000 -53,649,000 -212,623,000 308,424,000 -154,072,000 152,172,000 15,009,000 131,686,000 -61,062,000 -97,849,000 115,441,000 -44,647,000 -118,818,000 -102,931,000 -32,377,000 149,618,000 -153,364,000 -136,001,000      133,084,000      -71,044,000   -1,003,000       141,093,000           
          inventories
        -174,427,000 64,501,000 -163,417,000 13,810,000 28,169,000 -46,645,000 -133,025,000 102,376,000 -55,158,000 141,112,000 270,628,000 -130,552,000 14,315,000 -412,952,000 -264,935,000 -374,588,000 -112,360,000 -115,757,000 33,016,000 44,505,000 182,387,000 -29,462,000 25,472,000 39,469,000 -176,328,000 20,427,000 -9,601,000 -80,711,000 -175,598,000 -9,663,000 29,197,000 -86,819,000 -39,562,000   82,567,000  -3,825,000 164,999,000    -30,688,000 32,348,000 24,218,000         -97,801,000 193,097,000   9,575,000       17,179,000 
          other assets
        21,001,000 -34,551,000 7,789,000 -32,115,000 -11,851,000 1,973,000 -12,176,000 -13,423,000 -4,923,000 7,842,000 -15,789,000 -12,887,000 19,402,000 -20,361,000 -4,285,000 5,828,000 2,347,000 -15,031,000 12,678,000 -1,541,000 13,696,000 -7,253,000 6,991,000 301,000 2,954,000 -5,799,000 -525,000 -105,000 13,422,000 -14,652,000 3,305,000 2,113,000 11,359,000 -9,919,000 9,867,000 746,000  2,878,000 4,508,000 -7,014,000 7,359,000  3,425,000 3,358,000   2,963,000 -683,000 -1,067,000 3,382,000   940,000  17,825,000   2,633,000       3,020,000 
          accounts payable
        156,905,000 -4,817,000 -5,267,000 248,600,000 -13,852,000 -27,251,000 29,499,000 -57,532,000 -114,013,000 117,312,000 -264,313,000 187,521,000 -75,971,000 48,726,000 63,155,000 360,681,000 181,864,000 -68,878,000 17,927,000 51,596,000 -87,556,000 59,595,000 -61,690,000 3,206,000 52,787,000 -63,802,000 -17,413,000 66,332,000 51,175,000 90,332,000 -179,254,000 133,809,000 155,692,000 -102,903,000 -58,927,000 112,659,000    8,344,000 5,041,000   38,988,000   34,902,000  -91,425,000 94,175,000   118,217,000    135,150,000 114,515,000   77,341,000    60,079,000 
          income taxes receivable/payable
        74,432,000 -65,070,000 -82,710,000 42,815,000 -12,971,000 -145,676,000 165,664,000 -7,105,000 -85,486,000 189,247,000 8,269,000 -203,352,000 341,905,000 -353,000 27,551,000 59,593,000 59,678,000 -35,120,000 -44,392,000 52,385,000 -18,388,000 42,721,000 -86,278,000 49,850,000 57,598,000 -53,706,000 -41,383,000 63,962,000 -20,960,000 64,658,000 -173,906,000 96,319,000 -6,500,000 -41,809,000 20,395,000 13,993,000   16,265,000  19,393,000      17,392,000   45,439,000 -51,587,000 23,283,000 37,133,000             
          accrued expenses
        -163,033,000 127,295,000 39,033,000 -197,434,000 100,840,000 76,562,000 -280,037,000 121,762,000 100,611,000 -417,915,000 149,766,000 140,023,000 -258,657,000 169,817,000 111,997,000 -3,574,000 -69,904,000 76,417,000 55,310,000 -76,194,000 -138,856,000 48,728,000 179,144,000 -163,339,000 -9,557,000 31,949,000 124,112,000 -76,751,000 -26,228,000 42,193,000 64,303,000 -44,247,000 29,475,000 15,794,000                19,218,000   55,796,000   36,180,000 39,397,000 844,000 9,301,000   11,770,000 -753,000   
          net cash from operating activities
        148,316,000 722,608,000 301,611,000 152,603,000 759,853,000 382,561,000 355,217,000 1,113,699,000 807,806,000 733,783,000 1,496,155,000 1,001,852,000 818,968,000 630,816,000 587,230,000 262,191,000 835,242,000 -334,220,000 274,729,000 211,281,000 952,088,000 82,729,000 179,920,000 181,553,000 995,029,000 94,407,000 148,098,000 177,935,000 513,458,000 145,140,000 -159,441,000 240,449,000 656,429,000 38,368,000 -130,927,000 288,899,000 -144,834,000 74,505,000 234,707,000   150,551,000 3,005,000 29,710,000 16,764,000 79,181,000 21,421,000 56,466,000 162,060,000 3,937,000 70,069,000 -53,391,000 72,742,000 -143,029,000 214,695,000 21,944,000 -158,305,000 213,596,000   148,435,000 265,396,000   136,032,000 
          capital expenditures
        -137,979,000 -165,692,000 -288,331,000 -305,506,000 -621,355,000 -419,166,000 -374,310,000 -558,361,000 -358,280,000 -226,319,000 -241,229,000 -164,142,000 -159,330,000 -214,629,000 -277,206,000 -309,863,000 -870,408,000 -17,931,000 -92,181,000 -217,535,000 -297,814,000 -69,011,000 -30,684,000 -54,436,000 -168,722,000 -15,465,000 -4,597,000 -50,606,000 -122,140,000 479,000 -1,597,000 -41,677,000 -138,386,000       
          free cash flows
        10,337,000 556,916,000 13,280,000 -152,903,000 138,498,000 -36,605,000 -19,093,000 555,338,000 449,526,000 507,464,000 1,254,926,000 837,710,000 659,638,000 416,187,000 310,024,000 -47,672,000 -35,166,000 -352,151,000 182,548,000 -6,254,000 654,274,000 13,718,000 149,236,000 127,117,000 826,307,000 78,942,000 143,501,000 127,329,000 391,318,000 145,619,000 -161,038,000 198,772,000 518,043,000 38,368,000 -130,927,000 288,899,000 -144,834,000 74,505,000 234,707,000   150,551,000 3,005,000 29,710,000 16,764,000 79,181,000 21,421,000 56,466,000 162,060,000 3,937,000 70,069,000 -53,391,000 72,742,000 -143,029,000 214,695,000 21,944,000 -158,305,000 213,596,000   148,435,000 265,396,000   136,032,000 
          investing activities:
                                                                         
          purchases of property, plant and equipment
        -137,979,000 -165,692,000 -288,331,000 -305,506,000 -621,355,000 -419,166,000 -374,310,000 -558,361,000 -358,280,000 -226,319,000 -241,229,000 -164,142,000 -159,330,000 -214,629,000 -277,206,000 -309,863,000 -870,408,000 -17,931,000 -92,181,000 -217,535,000 -297,814,000 -69,011,000 -30,684,000 -54,436,000 -168,722,000 -15,465,000 -4,597,000 -50,606,000 -122,140,000 479,000 -1,597,000 -41,677,000 -138,386,000                                 
          purchases of short-term investments
          -29,571,000 -10,000,000 -430,826,000 -63,180,000 -205,873,000 -170,887,000 -165,052,000 -356,777,000 -283,188,000 -351,510,000        -149,359,000 -361,275,000 14,581,000 212,000 -49,677,000                                          
          proceeds from maturities of short-term investments
         39,571,000 9,614,000 137,811,000 204,543,000 298,314,000 272,994,000 282,592,000 267,969,000 271,107,000 49,794,000       -80,103,000 -42,692,000 192,340,000  -29,526,000 4,297,000 104,737,000                                          
          other investing activities
        -1,087,000 5,593,000 2,592,000 -1,064,000 -4,357,000 -25,554,000 14,255,000 -5,891,000 -217,905,000 2,343,000 4,113,000 4,817,000 410,000 1,024,000 1,859,000 390,000 2,254,000 -423,000 285,000 518,000 3,010,000 1,833,000 549,000 364,000 6,331,000 -81,000 428,000 229,000 30,941,000 -1,306,000 -24,531,000 26,918,000 7,111,000 301,000 -1,848,000 3,054,000 2,909,000 -857,000 1,663,000 -26,570,000 28,884,000 -19,000 -33,071,000 33,934,000 -23,000   -1,195,000   -41,000 473,000 504,000    1,495,000 1,329,000 108,000       
          net cash from investing activities
        -139,066,000 -120,528,000 -305,696,000 -178,759,000 -851,995,000 -209,586,000 -292,934,000 -452,547,000 -473,268,000 -309,646,000 -518,148,000 -510,835,000 -381,400,000 -213,605,000 -275,347,000 -309,473,000 -676,525,000 -157,469,000 14,771,000 -174,036,000 -466,231,000 -85,817,000 67,786,000 -92,424,000 -762,583,000 368,274,000 -410,578,000 -90,377,000 -91,873,000 -6,345,000 -26,128,000 -14,759,000 -145,561,000        4,043,000                         
          financing activities:
                                                                         
          issuance of current and long-term debt
        599,469,000 407,965,000 484,278,000 1,405,943,000 1,185,657,000 580,613,000 379,268,000 345,563,000 327,132,000 393,910,000 348,286,000 382,868,000 319,779,000 343,007,000 419,464,000 297,441,000 2,227,542,000 -803,960,000 883,513,000 216,261,000 1,445,732,000 3,008,000 3,988,000 121,234,000 335,566,000 -14,530,000 31,513,000 93,058,000 169,826,000 398,982,000   460,992,000 -50,744,000 43,203,000 20,452,000 7,058,000 10,848,000 50,093,000 20,492,000 43,453,000 9,494,000 -409,229,000 409,261,000   289,969,000   5,126,000 23,426,000 -542,548,000 544,550,000 234,626,000 237,059,000 399,100,000 568,900,000 218,000,000        
          repayment of current and long-term debt
        -612,359,000 -408,291,000 -902,605,000 -432,527,000 -527,977,000 -590,053,000 -413,939,000 -316,511,000 -321,143,000 -405,279,000 -363,060,000 -414,719,000 -349,272,000 -382,489,000 -408,565,000 -304,284,000 -1,871,616,000 797,903,000 -868,057,000 -235,757,000 -1,144,164,000 13,887,000 -18,604,000 -115,271,000 -340,452,000 3,050,000 -5,055,000 -113,034,000 -315,001,000 -259,916,000 -33,568,000 -1,429,000 -718,994,000                                 
          dividends paid
        -72,470,000 -73,894,000 -74,690,000 -69,514,000 -71,584,000 -72,624,000 -68,008,000 -70,713,000 -72,323,000 -58,798,000 -62,088,000 -64,344,000 -50,699,000 -53,380,000 -54,916,000 -52,729,000 -156,656,000 -8,000 -1,103,000 -51,481,000 -147,520,000 752,000 -11,264,000 -42,239,000 -124,832,000 187,000 -7,471,000 -36,797,000 -108,385,000 347,000 -3,397,000 -34,130,000 -101,643,000                                 
          purchases of treasury stock
        -115,087,000 -210,388,000 -200,048,000 -250,138,000 -309,901,000 -309,064,000 -298,059,000 -331,318,000 -380,206,000 -353,997,000 -481,676,000 -517,024,000 -389,190,000 -337,616,000 -393,198,000     -106,529,000 -233,658,000 -21,814,000 -8,828,000 -84,308,000 -448,604,000 -25,820,000 20,124,000 -69,269,000 -153,157,000 -22,272,000 -15,557,000 -61,256,000                                  
          other financing activities
        -22,312,000 -5,056,000 -31,718,000 -30,469,000 1,177,000 8,778,000 -23,108,000 1,953,000 -17,579,000 -23,449,000 -6,057,000 -60,241,000 -22,527,000 -4,776,000 -6,094,000 -16,598,000 -35,513,000 7,176,000 -2,611,000 -6,152,000 -26,034,000 -1,515,000 5,708,000 -5,720,000   2,036,000 -5,180,000 -20,823,000   -3,532,000                                  
          net cash from financing activities
        -222,759,000 -289,664,000 -724,783,000 623,295,000 277,372,000 -382,350,000 -423,846,000 -371,026,000 -464,119,000 -447,613,000 -564,595,000 -673,460,000 -491,909,000 -435,254,000 -443,309,000 -76,170,000 57,228,000 1,111,000 118,271,000 -183,658,000 -105,644,000 -5,682,000 -29,000,000 -126,304,000 -596,823,000 -33,969,000 41,147,000 -131,222,000  112,309,000 2,243,000 -100,347,000 -395,240,000           83,646,000         173,936,000      47,287,000      13,440,000 
          increase in cash, cash equivalents, and restricted cash
        -213,509,000 312,416,000  597,139,000 185,230,000   290,126,000   413,412,000    -131,426,000   -490,578,000    -8,770,000    428,712,000                                        
          cash, cash equivalents, and restricted cash at beginning of period
        775,272,000 463,281,000 1,192,149,000 595,010,000 835,526,000 1,044,901,000 1,406,464,000 1,480,862,000 1,610,443,000 1,633,919,000 1,012,585,000 1,195,028,000 1,249,369,000 1,119,244,000 1,250,670,000 1,374,122,000  261,358,000 -146,413,000 1,387,397,000  181,531,000 -37,175,000 834,423,000  -264,997,000 -43,664,000 1,035,085,000                                      
          cash, cash equivalents, and restricted cash at end of period
        561,763,000 775,697,000 463,281,000 1,192,149,000 1,020,756,000 835,526,000 1,044,901,000 1,770,988,000 1,480,862,000 1,610,443,000 1,425,997,000 1,012,585,000 1,195,028,000 1,101,201,000 1,119,244,000 1,250,670,000  -229,220,000 261,358,000 1,240,984,000  172,761,000 181,531,000 797,248,000  163,715,000 -264,997,000 991,421,000                                      
          supplemental disclosure information:
                                                                         
          cash paid for interest
        26,000,000 25,645,000 34,737,000 28,477,000 9,102,000 41,037,000 9,327,000 9,848,000 41,781,000 9,596,000 9,214,000 41,114,000 9,168,000 9,174,000 41,727,000 11,315,000 102,994,000 -51,071,000 50,883,000 8,785,000 125,435,000 -44,866,000 45,375,000 8,606,000 115,391,000 -44,583,000 44,597,000 8,629,000 121,851,000 -40,446,000 41,327,000 12,649,000 124,454,000 -18,869,000 18,808,000 26,286,000 -21,849,000 8,456,000 40,094,000 -18,825,000 39,663,000 22,492,000 -32,149,000 49,732,000 -20,394,000 44,054,000 18,753,000 -56,116,000 55,937,000 15,110,000 -56,977,000 68,224,000 3,769,000 55,466,000 11,984,000 -49,352,000 45,949,000 11,385,000 2,544,000 -14,320,000 16,339,000  12,845,000 -12,097,000 14,268,000 
          cash paid for income taxes
        4,491,000 22,192,000 124,753,000 3,717,000 81,742,000 273,323,000 28,390,000 160,178,000 308,055,000 4,703,000 276,948,000 580,454,000 9,948,000 222,691,000 146,002,000 2,142,000 6,517,000 42,470,000 912,000 518,000 125,731,000 -54,722,000 82,677,000 1,839,000 168,627,000 39,807,000 81,040,000 -1,045,000  -58,993,000 150,562,000 1,554,000                                  
          business combinations, net of cash acquired
                                                                         
          increase in cash and equivalents, and restricted cash
                                                                         
          cash and equivalents, and restricted cash at beginning of period
                                                                         
          cash and equivalents, and restricted cash at end of period
                                                                         
          decrease in cash, cash equivalents, and restricted cash
          -728,868,000   -209,375,000 -361,563,000  -129,581,000 -23,476,000  -182,443,000 -54,341,000 -18,043,000  -123,452,000    -146,413,000    -37,175,000                                          
          investments in unconsolidated affiliates
                    -222,480,000                                                     
          asset impairment charges
                                                                         
          business combination
                  -47,638,000                                                       
          ​
                   2,022,000                                                      
          other comprehensive income - net unrealized gain on cash
                                                                         
          flow hedging derivatives, net of income tax of (4,465), 8,332,
                                                                         
          (908), and 9,508 for the three and six-month periods ended
                                                                         
          june 30, 2022 and 2021, respectively
                   -14,295,000                                                      
          comprehensive income
                   1,200,357,000                                         64,969,000   -29,269,000 76,470,000 140,796,000        
          comprehensive income attributable to noncontrolling interests
                   -5,098,000                                                      
          comprehensive income attributable to steel dynamics, inc.
                   1,195,259,000                                       -30,466,000    -87,524,000           
          acquisition of business, net of cash acquired
                                    -674,000    -14,286,000                                 
          acquisition of business, net of cash and restricted cash acquired
                        -1,000,000       -93,412,000  358,820,000                                        
          proceeds from maturities of short term investments
                                30,000,000                                         
          asset impairment charge
                                                                         
          purchases of short term investments
                                 15,000,000 -10,000,000 -40,000,000                                      
          increase in cash and equivalents
                                   -43,664,000 -5,955,000 251,104,000 -183,326,000 125,343,000 115,628,000 -76,892,000 -174,204,000 249,919,000 -204,030,000       101,944,000    62,122,000     216,498,000    26,113,000 30,403,000        
          proceeds from exercise of stock options, including related tax effect
                                          791,000 2,892,000   1,753,000 5,611,000 2,905,000 4,948,000 -4,637,000 7,614,000 242,000 -756,000 1,097,000 -4,167,000     3,454,000             
          net cash provided used in financing activities
                                                                         
          cash and equivalents at beginning of period
                                    -67,360,000 -57,983,000 125,343,000 841,483,000 -325,634,000 75,715,000 249,919,000 727,032,000 258,419,000 -200,381,000 361,363,000 -52,237,000 395,156,000 -234,108,000 101,944,000 375,917,000 63,129,000 -32,952,000 390,761,000 116,881,000 -25,703,000 186,513,000 -33,913,000 216,498,000 9,008,000 -166,000 16,233,000 56,516,000 30,403,000 28,486,000 -16,120,000 -1,041,000 29,373,000  -141,757,000 130,187,000 65,518,000 
          cash and equivalents at end of period
                                    -73,315,000 193,121,000 -57,983,000 966,826,000 -210,006,000 -1,177,000 75,715,000 976,951,000 54,389,000 258,419,000 160,982,000 14,571,000 342,919,000 126,303,000 -234,108,000 477,861,000 -133,818,000 63,129,000 357,809,000 179,003,000 116,881,000 160,810,000 78,525,000 -33,913,000 225,506,000 2,150,000 16,067,000 -93,270,000 56,516,000 58,889,000 -1,401,000 -16,120,000 28,332,000  -33,105,000 -141,757,000 195,705,000 
          cash paid (refunded) for income taxes
                                                                         
          adjustments to reconcile net income to net cash provided by
                                                                         
          loss on disposal of assets
                                         -874,000                                
          stock option exercise proceeds, including related tax effect
                                                                         
          cash paid for federal and state income taxes
                                               40,865,000 2,143,000 -24,338,000   -37,673,000           -6,584,000 159,135,000 1,387,000 -80,581,000 131,349,000 468,000  -33,944,000 93,189,000 1,176,000 
          adjustments to reconcile net income to net cash from operating activities:
                                                                         
          debt issuance cost
                                                                         
          distributions to noncontrolling investors
                                                                         
          cash paid (received) for federal and state income taxes
                                          26,866,000 699,000 -5,874,000 25,585,000 -18,539,000     11,165,000   -955,000 -48,052,000 58,935,000 1,520,000 41,985,000 -28,987,000 -13,010,000             
          metals recycling segment:
                                                                         
          steel segment:
                                           142,783,000                              
          fabrication segment:
                                           1,925,000                              
          (gain) loss on disposal of assets
                                              4,985,000                           
          debt issuance costs
                                                                         
          contributions from noncontrolling investors
                                                5,370,000 -11,000 4,875,000 411,000 11,203,000 -4,389,000 9,506,000 9,850,000 1,053,000 417,000                
          butler flat roll division, structural and rail division, and engineered bar division
                                           95,000,000                              
          roanoke bar division
                                           29,041,000                              
          columbus flat roll division
                                           19,682,000                              
          (gain) loss on disposal of property, plant and equipment
                                               815,000 2,641,000 1,151,000          -406,000 956,000     14,000        
          accrued expenses and liabilities
                                            21,964,000     -10,796,000                        
          exercise of stock options proceeds, including related tax effect
                                            -4,904,000                             
          loss on disposal of property, plant and equipment
                                                                  13,000      46,000 
          omnisource — metals recycling/ferrous resources segment
                                             -1,630,000 455,097,000  556,611,000 -1,631,000 -1,631,000 563,163,000 -1,625,000 -1,624,000 569,692,000 -1,646,000                  
          the techs — steel segment
                                             142,783,000  142,783,000 142,783,000 142,783,000 142,783,000                
          butler flat roll division, structural and rail division, and engineered bar division — metals recycling and ferrous resources segment
                                                                         
          roanoke bar division — steel segment
                                             29,041,000  29,041,000 29,041,000 29,041,000 29,041,000                
          columbus flat roll division — steel segment
                                             19,682,000                           
          new millennium building systems — fabrication segment
                                             1,925,000  1,925,000 1,925,000 1,925,000 1,925,000                
          decrease in cash and equivalents
                                                                         
          butler flat roll division, structural and rail division, and engineered bar division — metals recycling/ferrous resources segment
                                              95,000,000                           
          impairment charges
                                                                         
          proceeds from maturity of short-term commercial paper
                                                    -44,986,000                     
          omnisource – metals recycling/ferrous resources segment
                                                                         
          the techs – steel segment
                                                                         
          roanoke bar division – steel segment
                                                                         
          new millennium building systems – fabrication segment
                                                                         
          gain on disposal of property, plant and equipment
                                                                         
          (gain)loss on disposal of property, plant and equipment
                                                                         
          issuance of common stock (net of expenses) and proceeds from exercise of stock options, including related tax effect
                                                         8,296,000 -1,418,000     -8,248,000 3,100,000 7,177,000        
          omnisource — metal recycling/ferrous resources segment
                                                         576,280,000                
          adjustments to reconcile net income to net cash from operating activities
                                                                         
          investment in direct financing lease
                                                                         
          contribution from noncontrolling investors
                                                          -806,000               
          net income attributable to steel dynamics, inc.
                                                          -30,466,000 -15,762,000 64,969,000 71,871,000 -87,862,000           
          unrealized gain on interest rate swap, net of tax
                                                             -95,000 338,000           
          reversal of unrealized loss on interest rate swap, net of tax
                                                                         
          adjustments to reconcile net income attributable to steel dynamics, inc. to net cash from operating activities:
                                                                         
          noncontrolling interests
                                                                         
          contribution from noncontrolling investor
                                                              5,000,000           
          adjustments to reconcile net income attributable to steel dynamics, inc. to net cash from operating activities
                                                                         
          income taxes payable
                                                                 72,608,000   54,850,000 3,814,000    
          acquisition of businesses, net of cash acquired
                                                                         
          purchase of securities
                                                                         
          purchase of treasury stock
                                                                         
          cash paid for federal and state income taxes, net of refunds
                                                             57,086,000 -55,430,000           
          unrealized gain on available-for-sale securities, net of tax
                                                                         
          operating activities
                                                                         
          changes in certain assets and liabilities
                                                                         
          investing activities
                                                                         
          purchases of securities
                                                                         
          financing activities
                                                                         
          unrealized loss on available-for-sale securities, net of tax
                                                                         
          unamortized bond premium
                                                                         
          minority interest
                                                                317,000 475,000    238,000 -321,000 150,000 239,000 
          sales of securities
                                                                         
          reversal of unrealized gain upon sale of available-for-sale securities, net of tax
                                                                         
          debt issue costs
                                                                         
          net cash provided by operating activities
                                                                         
          purchase of property, plant and equipment
                                                                         
          purchase of short-term investments
                                                                         
          maturities of short-term investments
                                                                       -4,675,000 9,375,000 
          issuance of long-term debt
                                                                  -54,000,000       
          repayment of long-term debt
                                                                         
          issuance of common stock (net of expenses) and proceeds and tax benefits from exercise of stock options
                                                                  -4,847,000 1,773,000 7,187,000 23,865,000 -3,896,000 -7,219,000 15,753,000 
          issuance (purchase) of treasury stock
                                                                       -8,471,000 8,664,000 
          adjustments to reconcile net income to net cash provided by operating activities:
                                                                         
          issuance of debt
                                                                    145,000,000     
          repayment of debt
                                                                         
          increase (decrease) in cash and equivalents
                                                                        130,187,000 
          repayments of long-term debt
                                                                         
          cash and equivalents at beginning of year
                                                                         
          cash and equivalents at end of year
                                                                         
          maturities/sales of short-term investments
                                                                         
          intangible asset amortization
                                                                         
          gain from debt extinguishment