CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Net sales
Unrelated parties	$ 1,901,415	$ 2,276,747	$ 5,851,371	$ 6,030,408
Related parties	49,508	62,269	151,994	208,451
Total net sales	1,950,923	2,339,016	6,003,365	6,238,859
Costs of goods sold	1,722,197	2,050,504	5,415,854	5,564,272
Gross profit	228,726	288,512	587,511	674,587
Selling, general and administrative expenses	82,371	80,240	241,381	223,745
Profit sharing	9,008	12,865	18,637	28,729
Amortization of intangible assets	6,318	6,764	19,134	20,633
Operating income	131,029	188,643	308,359	401,480
Interest expense, net of capitalized interest	37,084	31,904	117,334	92,523
Other expense, net	239	22,072	15,219	19,687
Income before income taxes	93,706	134,667	175,806	289,270
Income taxes	34,839	47,010	64,660	101,574
Net income	58,867	87,657	111,146	187,696
Net loss attributable to noncontrolling interests	1,750	3,516	11,782	14,359
Net income attributable to Steel Dynamics, Inc.	$ 60,617	$ 91,173	$ 122,928	$ 202,055
Basic earnings per share attributable to Steel Dynamics, Inc. stockholders (in dollars per share)	$ 0.25	$ 0.38	$ 0.51	$ 0.88
Weighted average common shares outstanding (in shares)	242,074	240,087	241,836	229,772
Diluted earnings per share attributable to Steel Dynamics, Inc. stockholders, including the effect of assumed conversions when dilutive (in dollars per share)	$ 0.25	$ 0.38	$ 0.51	$ 0.85
Weighted average common shares and share equivalents outstanding (in shares)	243,822	242,244	243,393	241,895
Dividends declared per share (in dollars per share)	$ 0.1375	$ 0.1150	$ 0.4125	$ 0.3450