Condensed Consolidated Statements of Earnings - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Oct. 01, 2016	Sep. 30, 2017	Oct. 01, 2016
Income Statement [Abstract]
Net sales	$ 5,170,117	$ 4,290,236	$ 15,160,065	$ 12,251,584
Costs, expenses and other:
Cost of products sold	4,591,153	3,608,000	13,111,226	10,669,103
Marketing, administrative and other expenses	172,792	169,223	519,429	440,679
Equity in earnings of unconsolidated affiliates	(7,743)	(14,168)	(29,801)	(30,232)
Interest expense, net	43,310	43,009	131,495	128,415
Costs, expenses and other, total	4,799,512	3,806,064	13,732,349	11,207,965
Earnings before income taxes and noncontrolling interests	370,605	484,172	1,427,716	1,043,619
Provision for income taxes	104,500	152,807	442,239	318,388
Net earnings	266,105	331,365	985,477	725,231
Earnings attributable to noncontrolling interests	11,255	25,918	50,680	88,599
Net earnings attributable to Nucor stockholders	$ 254,850	$ 305,447	$ 934,797	$ 636,632
Net earnings per share:
Basic	$ 0.79	$ 0.95	$ 2.91	$ 1.99
Diluted	$ 0.79	$ 0.95	$ 2.90	$ 1.99
Average shares outstanding:
Basic	320,096	319,737	320,253	319,444
Diluted	320,763	320,028	321,045	319,632
Dividends declared per share	$ 0.3775	$ 0.3750	$ 1.1325	$ 1.1250