CONSOLIDATED STATEMENTS OF INCOME (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Net sales
Unrelated parties	$ 1,830,117	$ 2,004,283	$ 3,735,192	$ 3,945,947
Related parties	79,686	75,448	156,651	149,753
Total net sales	1,909,803	2,079,731	3,891,843	4,095,700
Costs of goods sold	1,727,667	1,803,345	3,508,443	3,523,560
Gross profit	182,136	276,386	383,400	572,140
Selling, general and administrative expenses	61,235	63,631	125,619	128,772
Profit sharing	8,211	14,454	16,283	29,657
Amortization of intangible assets	8,991	10,082	17,983	20,166
Total selling, general and administrative expenses	78,437	88,167	159,885	178,595
Operating income	103,699	188,219	223,515	393,545
Interest expense, net of capitalized interest	41,106	44,812	82,218	88,158
Other expense (income), net	(1,892)	(5,745)	8,356	(10,312)
Income before income taxes	64,485	149,152	132,941	315,699
Income taxes	25,180	53,326	51,859	115,643
Net income	39,305	95,826	81,082	200,056
Net loss attributable to noncontrolling interests	5,167	2,884	9,065	4,557
Net income attributable to Steel Dynamics, Inc.	$ 44,472	$ 98,710	$ 90,147	$ 204,613
Basic earnings per share attributable to Steel Dynamics, Inc. stockholders (in dollars per share)	$ 0.20	$ 0.45	$ 0.41	$ 0.94
Weighted average common shares outstanding (in shares)	219,104	218,500	219,050	218,246
Diluted earnings per share attributable to Steel Dynamics, Inc. stockholders, including the effect of assumed conversions when dilutive (in dollars per share)	$ 0.20	$ 0.43	$ 0.40	$ 0.89
Weighted average common shares and share equivalents outstanding (in shares)	236,208	236,266	236,367	236,245
Dividends declared per share (in dollars per share)	$ 0.10	$ 0.10	$ 0.20	$ 0.20