Stock-Based Compensation - Summary of Nucor's RSU Activity (Detail) - Restricted Stock Units [Member] shares in Thousands	6 Months Ended
	Jul. 04, 2020 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unvested at beginning of year, Shares | shares	1,776
Granted, Shares | shares	1,246
Vested, Shares | shares	(1,089)
Canceled, Shares | shares	(17)
Unvested at end of year, Shares | shares	1,916
Unvested at beginning of year, Grant Date Fair Value | $ / shares	$ 52.60
Granted, Grant Date Fair Value | $ / shares	42.46
Vested, Grant Date Fair Value | $ / shares	50.13
Canceled, Grant Date Fair Value | $ / shares	51.33
Unvested at end of year, Grant Date Fair Value | $ / shares	$ 47.42