Stockholders' Equity - Schedule of Change in Stockholder's Equity (Detail) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 03, 2021	Jul. 04, 2020	Jul. 03, 2021	Jul. 04, 2020
BALANCES, beginning of period	$ 11,861,723	$ 10,596,069	$ 11,231,861	$ 10,791,176
Net earnings	1,571,459	133,153	2,558,973	187,532
Other comprehensive income (loss)	29,831	26,791	45,132	(37,870)
Stock options exercised	21,276		$ 128,800
Stock options exercised (in shares)			2,554
Stock option expense	2,575	1,864	$ 2,908	2,139
Issuance of stock under award plans, net of forfeitures	(18,338)	11,618	(2,736)	27,807
Amortization of unearned compensation	(1,100)	500	800	900
Treasury stock value acquired	(614,286)		(916,145)	(39,499)
Cash dividends declared	(120,088)	(123,038)	(242,746)	(245,735)
Distributions to noncontrolling interests	(23,401)	(23,472)	(97,196)	(62,965)
BALANCES, end of period	12,709,651	10,623,485	12,709,651	10,623,485
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	$ 2,160,909	$ 2,119,370	$ 2,121,288	$ 2,107,646
Stock options exercised	5,337		35,825
Stock option expense	2,575	1,864	2,908	2,139
Issuance of stock under award plans, net of forfeitures	(50,566)	(14,827)	(43,666)	(3,778)
Amortization of unearned compensation	(1,100)	500	800	900
BALANCES, end of period	2,117,155	2,106,907	2,117,155	2,106,907
Retained Earnings [Member]
BALANCES, beginning of period	12,163,626	11,012,690	11,343,852	11,115,056
Net earnings	1,506,868	108,881	2,449,300	129,212
Cash dividends declared	(120,088)	(123,038)	(242,746)	(245,735)
BALANCES, end of period	13,550,406	10,998,533	13,550,406	10,998,533
Accumulated Other Comprehensive Income (Loss) [Member]
BALANCES, beginning of period	(103,560)	(367,627)	(118,861)	(302,966)
Other comprehensive income (loss)	29,831	26,791	45,132	(37,870)
BALANCES, end of period	(73,729)	(340,836)	(73,729)	(340,836)
Treasury Stock (at cost) [Member]
BALANCES, beginning of period	$ (2,925,796)	$ (2,748,290)	$ (2,709,675)	$ (2,713,931)
BALANCES, shares at beginning of period	80,912	79,019	77,909	78,342
Stock options exercised	$ 15,939		$ 92,975
Stock options exercised (in shares)	(419)		(2,554)
Issuance of stock under award plans, net of forfeitures	$ 32,228	$ 26,445	$ 40,930	$ 31,585
Issuance of stock under award plans, net of forfeitures, shares	(799)	(760)	(1,041)	(908)
Treasury stock value acquired	$ (614,286)		$ (916,145)	$ (39,499)
Treasury stock acquired (in shares)	6,765		12,145	825
BALANCES, end of period	$ (3,491,915)	$ (2,721,845)	$ (3,491,915)	$ (2,721,845)
BALANCES, shares at end of period	86,459	78,259	86,459	78,259
Total Nucor Stockholders' Equity [Member]
BALANCES, beginning of period	$ 11,447,240	$ 10,168,204	$ 10,788,665	$ 10,357,866
Net earnings	1,506,868	108,881	2,449,300	129,212
Other comprehensive income (loss)	29,831	26,791	45,132	(37,870)
Stock options exercised	21,276		128,800
Stock option expense	2,575	1,864	2,908	2,139
Issuance of stock under award plans, net of forfeitures	(18,338)	11,618	(2,736)	27,807
Amortization of unearned compensation	(1,100)	500	800	900
Treasury stock value acquired	(614,286)		(916,145)	(39,499)
Cash dividends declared	(120,088)	(123,038)	(242,746)	(245,735)
BALANCES, end of period	12,253,978	10,194,820	12,253,978	10,194,820
Noncontrolling Interests [Member]
BALANCES, beginning of period	414,483	427,865	443,196	433,310
Net earnings	64,591	24,272	109,673	58,320
Distributions to noncontrolling interests	(23,401)	(23,472)	(97,196)	(62,965)
BALANCES, end of period	$ 455,673	$ 428,665	$ 455,673	$ 428,665