CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Net sales
Unrelated parties	$ 1,945,983	$ 1,987,635	$ 3,949,956	$ 3,753,516
Related parties	59,024	82,126	102,486	146,327
Total net sales	2,005,007	2,069,761	4,052,442	3,899,843
Costs of goods sold	1,833,264	1,846,990	3,693,657	3,513,768
Gross profit	171,743	222,771	358,785	386,075
Selling, general and administrative expenses	82,660	73,463	159,010	143,505
Profit sharing	5,031	10,469	9,629	15,864
Amortization of intangible assets	6,493	6,934	12,816	13,869
Operating income	77,559	131,905	177,330	212,837
Interest expense, net of capitalized interest	37,163	30,050	80,250	60,619
Other expense (income), net	(1,212)	(1,754)	14,980	(2,385)
Income before income taxes	41,608	103,609	82,100	154,603
Income taxes	16,283	37,268	29,821	54,564
Net income	25,325	66,341	52,279	100,039
Net loss attributable to noncontrolling interests	6,225	5,962	10,032	10,843
Net income attributable to Steel Dynamics, Inc.	$ 31,550	$ 72,303	$ 62,311	$ 110,882
Basic earnings per share attributable to Steel Dynamics, Inc. stockholders (in dollars per share)	$ 0.13	$ 0.32	$ 0.26	$ 0.49
Weighted average common shares outstanding (in shares)	241,900	226,220	241,718	224,615
Diluted earnings per share attributable to Steel Dynamics, Inc. stockholders, including the effect of assumed conversions when dilutive (in dollars per share)	$ 0.13	$ 0.31	$ 0.26	$ 0.48
Weighted average common shares and share equivalents outstanding (in shares)	243,491	242,048	243,179	241,721
Dividends declared per share (in dollars per share)	$ 0.1375	$ 0.1150	$ 0.2750	$ 0.2300