Condensed Consolidated Statements of Earnings - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 29, 2019	Jun. 30, 2018	Jun. 29, 2019	Jun. 30, 2018
Income Statement [Abstract]
Net sales	$ 5,895,986	$ 6,460,774	$ 11,992,610	$ 12,029,193
Costs, expenses and other:
Cost of products sold	5,120,492	5,294,184	10,321,224	10,136,197
Marketing, administrative and other expenses	208,980	234,381	389,719	417,341
Equity in earnings of unconsolidated affiliates	(1,138)	(10,943)	(4,044)	(20,523)
Interest expense, net	33,030	29,451	61,473	66,565
Costs, expenses and other, total	5,361,364	5,547,073	10,768,372	10,599,580
Earnings before income taxes and noncontrolling interests	534,622	913,701	1,224,238	1,429,613
Provision for income taxes	122,345	200,086	281,168	335,886
Net earnings	412,277	713,615	943,070	1,093,727
Earnings attributable to noncontrolling interests	25,794	30,462	54,781	56,395
Net earnings attributable to Nucor stockholders	$ 386,483	$ 683,153	$ 888,289	$ 1,037,332
Net earnings per share:
Basic	$ 1.26	$ 2.14	$ 2.89	$ 3.24
Diluted	$ 1.26	$ 2.13	$ 2.88	$ 3.23
Average shares outstanding:
Basic	305,461	318,467	306,017	318,941
Diluted	305,952	319,391	306,559	319,930