Stockholders' Equity - Schedule of Change in Stockholder's Equity (Detail) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 04, 2020	Jun. 29, 2019	Jul. 04, 2020	Jun. 29, 2019
BALANCES, beginning of period	$ 10,596,069	$ 10,502,666	$ 10,791,176	$ 10,201,968
Net earnings	133,153	412,277	187,532	943,070
Other comprehensive income (loss)	26,791	11,027	(37,870)	4,487
Stock options exercised		2,756		5,892
Stock option expense	1,864	3,800	2,139	4,112
Issuance of stock under award plans, net of forfeitures	11,618	29,554	27,807	48,269
Amortization of unearned compensation	500	400	900	1,000
Treasury stock value acquired		(124,681)	(39,499)	(197,511)
Cash dividends declared	(123,038)	(122,812)	(245,735)	(245,898)
Distributions to noncontrolling interests	(23,472)	(16,978)	(62,965)	(67,380)
Other		(1)		(1)
BALANCES, end of period	10,623,485	10,698,008	10,623,485	10,698,008
Common Stock [Member]
BALANCES, beginning of period	$ 152,061	$ 152,061	$ 152,061	$ 152,061
BALANCES, shares at beginning of period	380,154	380,154	380,154	380,154
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	$ 2,119,370	$ 2,083,339	$ 2,107,646	$ 2,073,715
Stock options exercised		575		808
Stock option expense	1,864	3,800	2,139	4,112
Issuance of stock under award plans, net of forfeitures	(14,827)	10,696	(3,778)	19,175
Amortization of unearned compensation	500	400	900	1,000
Other		(1)		(1)
BALANCES, end of period	2,106,907	2,098,809	2,106,907	2,098,809
Retained Earnings [Member]
BALANCES, beginning of period	11,012,690	10,714,279	11,115,056	10,337,445
Net earnings	108,881	386,483	129,212	888,289
Cash dividends declared	(123,038)	(122,812)	(245,735)	(245,898)
Other				(1,886)
BALANCES, end of period	10,998,533	10,977,950	10,998,533	10,977,950
Accumulated Other Comprehensive Income (Loss) [Member]
BALANCES, beginning of period	(367,627)	(308,787)	(302,966)	(304,133)
Other comprehensive income (loss)	26,791	11,027	(37,870)	4,487
Other				1,886
BALANCES, end of period	(340,836)	(297,760)	(340,836)	(297,760)
Treasury Stock (at cost) [Member]
BALANCES, beginning of period	$ (2,748,290)	$ (2,526,701)	$ (2,713,931)	$ (2,467,010)
BALANCES, shares at beginning of period	79,019	75,368	78,342	74,562
Stock options exercised		$ 2,181		$ 5,084
Stock options exercised (in shares)		(65)		(153)
Issuance of stock under award plans, net of forfeitures	$ 26,445	$ 18,858	$ 31,585	$ 29,094
Issuance of stock under award plans, net of forfeitures, shares	(760)	(556)	(908)	(862)
Treasury stock value acquired		$ (124,681)	$ (39,499)	$ (197,511)
Treasury stock acquired (in shares)		2,250	825	3,450
BALANCES, end of period	$ (2,721,845)	$ (2,630,343)	$ (2,721,845)	$ (2,630,343)
BALANCES, shares at end of period	78,259	76,997	78,259	76,997
Total Nucor Stockholders' Equity [Member]
BALANCES, beginning of period	$ 10,168,204	$ 10,114,191	$ 10,357,866	$ 9,792,078
Net earnings	108,881	386,483	129,212	888,289
Other comprehensive income (loss)	26,791	11,027	(37,870)	4,487
Stock options exercised		2,756		5,892
Stock option expense	1,864	3,800	2,139	4,112
Issuance of stock under award plans, net of forfeitures	11,618	29,554	27,807	48,269
Amortization of unearned compensation	500	400	900	1,000
Treasury stock value acquired		(124,681)	(39,499)	(197,511)
Cash dividends declared	(123,038)	(122,812)	(245,735)	(245,898)
Other		(1)		(1)
BALANCES, end of period	10,194,820	10,300,717	10,194,820	10,300,717
Noncontrolling Interests [Member]
BALANCES, beginning of period	427,865	388,475	433,310	409,890
Net earnings	24,272	25,794	58,320	54,781
Distributions to noncontrolling interests	(23,472)	(16,978)	(62,965)	(67,380)
BALANCES, end of period	$ 428,665	$ 397,291	$ 428,665	$ 397,291