Stock-Based Compensation (Summary Of Nucor's Restricted Stock Awards And Units Under AIP And LTIP) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2012
RSU [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unvested at beginning of year, Shares	962
Granted, Shares
Vested, Shares	(37)
Canceled, Shares	(6)
Unvested at March 31, 2012, Shares	919
Unvested at beginning of year, Grant Date Fair Value	$ 46.09
Granted, Grant Date Fair Value
Vested, Grant Date Fair Value	$ 50.69
Canceled, Grant Date Fair Value	$ 43.11
Unvested at March 31, 2012, Grant Date Fair Value	$ 45.92
Shares reserved for future grants (stock options and RSUs)	13,692
AIP And LTIP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unvested at beginning of year, Shares	94
Granted, Shares	122
Vested, Shares	(133)
Canceled, Shares
Unvested at March 31, 2012, Shares	83
Unvested at beginning of year, Grant Date Fair Value	$ 42.46
Granted, Grant Date Fair Value	$ 42.20
Vested, Grant Date Fair Value	$ 41.39
Canceled, Grant Date Fair Value
Unvested at March 31, 2012, Grant Date Fair Value	$ 43.80
Shares reserved for future grants (stock options and RSUs)	1,360