Consolidated Statements of Earnings - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Statement [Abstract]
Net sales (Notes 23 and 25)	$ 20,139,658	$ 22,588,858	$ 25,067,279
Costs, expenses and other:
Cost of products sold (Notes 6, 13 and 20)	17,911,708	19,909,773	20,771,871
Marketing, administrative and other expenses (Note 6)	615,041	711,248	860,722
Equity in losses (earnings) of unconsolidated subsidiaries	10,533	(3,311)	(40,240)
Losses and impairments of assets (Notes 7, 8, 9, 14, 19, 20 and 25)	613,640	66,916	110,000
Interest expense, net (Notes 6, 18 and 19)	153,198	121,425	135,535
Costs, expenses and other, total	19,304,120	20,806,051	21,837,888
Earnings before income taxes and noncontrolling interests	835,538	1,782,807	3,229,391
Provision for income taxes (Notes 19 and 25)	(490)	411,897	748,307
Net earnings	836,028	1,370,910	2,481,084
Earnings attributable to noncontrolling interests	114,558	99,767	120,317
Net earnings attributable to Nucor stockholders	$ 721,470	$ 1,271,143	$ 2,360,767
Net earnings per share (Note 21):
Basic	$ 2.37	$ 4.14	$ 7.44
Diluted	$ 2.36	$ 4.14	$ 7.42