Stock-Based Compensation - Summary of Nucor's RSU Activity (Detail) - Restricted Stock Units [Member] shares in Thousands	9 Months Ended
	Oct. 03, 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	(1,140)
Canceled, Shares | shares	(22)
Unvested at end of year, Shares | shares	1,860
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	50.14
Canceled, Grant Date Fair Value | $ / shares	50.17
Unvested at end of year, Grant Date Fair Value | $ / shares	$ 47.34