CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Net sales
Unrelated parties	$ 3,537,625	$ 2,571,544
Related parties	6,972	3,556
Total net sales	3,544,597	2,575,100
Costs of goods sold	2,744,331	2,159,871
Gross profit	800,266	415,229
Selling, general and administrative expenses	149,781	112,898
Profit sharing	48,848	21,454
Amortization of intangible assets	7,438	7,191
Operating income	594,199	273,686
Interest expense, net of capitalized interest	17,269	28,019
Other (income) expense, net	10,071	(2,589)
Income before income taxes	566,859	248,256
Income tax expense	128,104	57,420
Net income	438,755	190,836
Net income attributable to noncontrolling interests	(8,248)	(3,496)
Net income attributable to Steel Dynamics, Inc.	$ 430,507	$ 187,340
Basic earnings per share attributable to Steel Dynamics, Inc. stockholders (in dollars per share)	$ 2.04	$ 0.88
Weighted average common shares outstanding (in shares)	211,015	213,254
Diluted earnings per share attributable to Steel Dynamics, Inc. stockholders, including the effect of assumed conversions when dilutive (in dollars per share)	$ 2.03	$ 0.88
Weighted average common shares and share equivalents outstanding (in shares)	212,254	214,024
Dividends declared per share (in dollars per share)	$ 0.26	$ 0.25