CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME
Net income	$ 152,608	$ 397,906	$ 554,181	$ 985,953
Other comprehensive income (loss) - net unrealized gain (loss) on cash flow hedging derivatives, net of income tax expense (benefit)	(39)	63	(262)	(42)
Comprehensive income	152,569	397,969	553,919	985,911
Comprehensive (income) loss attributable to noncontrolling interests	(1,560)	469	(4,503)	2,422
Comprehensive income attributable to Steel Dynamics, Inc.	$ 151,009	$ 398,438	$ 549,416	$ 988,333