Condensed Consolidated Statements of Earnings - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jul. 01, 2017	Jun. 30, 2018	Jul. 01, 2017
Income Statement [Abstract]
Net sales	$ 6,460,774	$ 5,174,769	$ 12,029,193	$ 9,989,948
Costs, expenses and other:
Cost of products sold	5,294,184	4,465,144	10,136,197	8,520,073
Marketing, administrative and other expenses	234,381	170,211	417,341	346,637
Equity in earnings of unconsolidated affiliates	(10,943)	(13,302)	(20,523)	(22,058)
Interest expense, net	29,451	44,580	66,565	88,185
Costs, expenses and other, total	5,547,073	4,666,633	10,599,580	8,932,837
Earnings before income taxes and noncontrolling interests	913,701	508,136	1,429,613	1,057,111
Provision for income taxes	200,086	166,412	335,886	337,739
Net earnings	713,615	341,724	1,093,727	719,372
Earnings attributable to noncontrolling interests	30,462	18,676	56,395	39,425
Net earnings attributable to Nucor stockholders	$ 683,153	$ 323,048	$ 1,037,332	$ 679,947
Net earnings per share:
Basic	$ 2.14	$ 1.00	$ 3.24	$ 2.12
Diluted	$ 2.13	$ 1.00	$ 3.23	$ 2.11
Average shares outstanding:
Basic	318,467	320,439	318,941	320,332
Diluted	319,391	321,226	319,930	321,186
Dividends declared per share	$ 0.3800	$ 0.3775	$ 0.7600	$ 0.7550