Condensed Consolidated Statements of Earnings - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 29, 2018	Sep. 30, 2017	Sep. 29, 2018	Sep. 30, 2017
Income Statement [Abstract]
Net sales	$ 6,742,202	$ 5,170,117	$ 18,771,395	$ 15,160,065
Costs, expenses and other:
Cost of products sold	5,452,052	4,591,153	15,588,249	13,111,226
Marketing, administrative and other expenses	234,081	172,792	651,422	519,429
Equity in earnings of unconsolidated affiliates	(13,634)	(7,743)	(34,157)	(29,801)
Impairment of assets	110,000		110,000
Interest expense, net	37,201	43,310	103,766	131,495
Costs, expenses and other, total	5,819,700	4,799,512	16,419,280	13,732,349
Earnings before income taxes and noncontrolling interests	922,502	370,605	2,352,115	1,427,716
Provision for income taxes	216,215	104,500	552,101	442,239
Net earnings	706,287	266,105	1,800,014	985,477
Earnings attributable to noncontrolling interests	29,631	11,255	86,026	50,680
Net earnings attributable to Nucor stockholders	$ 676,656	$ 254,850	$ 1,713,988	$ 934,797
Net earnings per share:
Basic	$ 2.13	$ 0.79	$ 5.37	$ 2.91
Diluted	$ 2.13	$ 0.79	$ 5.35	$ 2.90
Average shares outstanding:
Basic	315,913	320,096	317,928	320,253
Diluted	316,798	320,763	318,882	321,045