Stockholders' Equity - Schedule of Change in Stockholder's Equity (Detail) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 28, 2019	Sep. 29, 2018	Sep. 28, 2019	Sep. 29, 2018
BALANCES, beginning of period	$ 10,698,008	$ 9,735,424	$ 10,201,968	$ 9,084,788
Net earnings	293,587	706,287	1,236,657	1,800,014
Other comprehensive income (loss)	(16,006)	21,425	(11,519)	(19,926)
Stock options exercised		11,822	$ 5,892	24,102
Stock options exercised (in shares)			153
Stock option expense	275	312	$ 4,387	4,249
Issuance of stock under award plans, net of forfeitures	11,339	9,598	59,608	44,304
Amortization of unearned compensation	500	400	1,500	1,400
Treasury stock value acquired		(181,077)	(197,511)	(351,392)
Cash dividends declared	(122,809)	(120,406)	(368,707)	(363,624)
Distributions to noncontrolling interests	(3,861)	(9,364)	(71,241)	(49,494)
Other			(1)
BALANCES, end of period	10,861,033	10,174,421	10,861,033	10,174,421
Common Stock [Member]
BALANCES, beginning of period	$ 152,061	$ 152,061	$ 152,061	$ 151,960
BALANCES, shares at beginning of period	380,154	380,154	380,154	379,900
Stock options exercised				$ 84
Stock options exercised (in shares)				210
Issuance of stock under award plans, net of forfeitures				$ 17
Issuance of stock under award plans, net of forfeitures, shares				44
BALANCES, end of period	$ 152,061	$ 152,061	$ 152,061	$ 152,061
BALANCES, shares at end of period	380,154	380,154	380,154	380,154
Additional Paid-in Capital [Member]
BALANCES, beginning of period	$ 2,098,809	$ 2,051,383	$ 2,073,715	$ 2,021,339
Stock options exercised		4,572	808	14,675
Stock option expense	275	312	4,387	4,249
Issuance of stock under award plans, net of forfeitures	9,365	8,633	28,540	23,636
Amortization of unearned compensation	500	400	1,500	1,400
Other	(1)	(1)	(2)
BALANCES, end of period	2,108,948	2,065,299	2,108,948	2,065,299
Retained Earnings [Member]
BALANCES, beginning of period	10,977,950	9,257,822	10,337,445	8,463,709
Net earnings	275,031	676,656	1,163,320	1,713,988
Cash dividends declared	(122,809)	(120,406)	(368,707)	(363,624)
Other		1	(1,886)
BALANCES, end of period	11,130,172	9,814,073	11,130,172	9,814,073
Accumulated Other Comprehensive Loss [Member]
BALANCES, beginning of period	(297,760)	(296,032)	(304,133)	(254,681)
Other comprehensive income (loss)	(16,006)	21,425	(11,519)	(19,926)
Other			1,886
BALANCES, end of period	(313,766)	(274,607)	(313,766)	(274,607)
Treasury Stock [Member]
BALANCES, beginning of period	$ (2,630,343)	$ (1,791,827)	$ (2,467,010)	$ (1,643,291)
BALANCES, shares at beginning of period	76,997	63,810	74,562	61,931
Stock options exercised		$ 7,250	$ 5,084	$ 9,343
Stock options exercised (in shares)		(256)	(153)	(334)
Issuance of stock under award plans, net of forfeitures	$ 1,974	$ 965	$ 31,068	$ 20,651
Issuance of stock under award plans, net of forfeitures, shares	(58)	(34)	(920)	(754)
Treasury stock value acquired		$ (181,077)	$ (197,511)	$ (351,392)
Treasury stock acquired (in shares)		2,701	3,450	5,378
Other	$ 1		$ 1
BALANCES, end of period	$ (2,628,368)	$ (1,964,689)	$ (2,628,368)	$ (1,964,689)
BALANCES, shares at end of period	76,939	66,221	76,939	66,221
Total Nucor Stockholders' Equity [Member]
BALANCES, beginning of period	$ 10,300,717	$ 9,373,407	$ 9,792,078	$ 8,739,036
Net earnings	275,031	676,656	1,163,320	1,713,988
Other comprehensive income (loss)	(16,006)	21,425	(11,519)	(19,926)
Stock options exercised		11,822	5,892	24,102
Stock option expense	275	312	4,387	4,249
Issuance of stock under award plans, net of forfeitures	11,339	9,598	59,608	44,304
Amortization of unearned compensation	500	400	1,500	1,400
Treasury stock value acquired		(181,077)	(197,511)	(351,392)
Cash dividends declared	(122,809)	(120,406)	(368,707)	(363,624)
Other			(1)
BALANCES, end of period	10,449,047	9,792,137	10,449,047	9,792,137
Noncontrolling Interest [Member]
BALANCES, beginning of period	397,291	362,017	409,890	345,752
Net earnings	18,556	29,631	73,337	86,026
Distributions to noncontrolling interests	(3,861)	(9,364)	(71,241)	(49,494)
BALANCES, end of period	$ 411,986	$ 382,284	$ 411,986	$ 382,284