CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Net sales
Unrelated parties	$ 18,376,743	$ 9,587,691	$ 10,451,132
Related parties	32,107	13,791	13,859
Total net sales	18,408,850	9,601,482	10,464,991
Costs of goods sold	13,046,426	8,166,754	8,934,007
Gross profit	5,362,424	1,434,728	1,530,984
Selling, general and administrative expenses	643,976	477,450	436,498
Profit sharing	388,111	61,728	78,029
Amortization of intangible assets	29,232	28,999	29,577
Asset impairment charges		19,409
Operating income	4,301,105	847,142	986,880
Interest expense, net of capitalized interest	57,209	94,877	127,104
Other (income) expense, net	34,826	46,787	(15,561)
Income before income taxes	4,209,070	705,478	875,337
Income tax expense	962,256	134,650	197,437
Net income	3,246,814	570,828	677,900
Net income attributable to noncontrolling interests	(32,748)	(20,006)	(6,797)
Net income attributable to Steel Dynamics, Inc.	$ 3,214,066	$ 550,822	$ 671,103
Basic earnings per share attributable to Steel Dynamics, Inc. stockholders (in dollars per share)	$ 15.67	$ 2.61	$ 3.06
Weighted average common shares outstanding (in shares)	205,115	211,140	219,639
Diluted earnings per share attributable to Steel Dynamics, Inc. stockholders, including the effect of assumed conversions when dilutive (in dollars per share)	$ 15.56	$ 2.59	$ 3.04
Weighted average common shares and share equivalents outstanding (in shares)	206,615	212,345	220,748
Dividends declared per share (in dollars per share)	$ 1.04	$ 1.00	$ 0.96