Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2017

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Summary of Stock Option Plans Activity

A summary of activity under Nucor’s stock option plans is as follows (shares in thousands):

Year Ended December 31,	2017						2016						2015
	Shares			Weighted - Average Exercise Price			Shares			Weighted - Average Exercise Price			Shares			Weighted - Average Exercise Price
Number of shares under option:
Outstanding at beginning of year		3,591			$	45.32		3,092			$	43.51		2,422			$	42.39
Granted		698			$	59.07		899			$	48.80		700			$	47.59
Exercised		(183	)		$	38.56		(400	)		$	39.19		(10	)		$	42.34
Canceled		—				—		—				—		(20	)		$	50.63
Outstanding at end of year		4,106			$	47.96		3,591			$	45.32		3,092			$	43.51
Options exercisable at end of year		1,809			$	43.39		1,557			$	40.80		1,531			$	39.35

Summary of Stock Options Outstanding

The following table summarizes information about stock options outstanding at December 31, 2017 (shares in thousands):

	Options Outstanding
Exercise Price	Options Outstanding		Options Exercisable		Weighted- Average Remaining Contractual Life
$35.76		426		426		4.4 years
$42.34		442		442		3.4 years
$44.51		506		506		5.4 years
$47.59		700		—		7.4 years
$48.80		899		—		8.4 years
$50.63		435		435		6.4 years
$59.07		698		—		9.4 years
$35.76 - $59.07		4,106		1,809		6.9 years

Schedule of Grant Date Fair Value Black-Scholes Option-Pricing Model Assumptions

The fair value was estimated using the Black-Scholes option-pricing model with the following assumptions:

	2017			2016			2015
Exercise price	$	59.07		$	48.80		$	47.59
Expected dividend yield		2.56	%		3.07	%		3.13	%
Expected stock price volatility		26.53	%		26.14	%		33.32	%
Risk-free interest rate		2.02	%		1.67	%		1.86	%
Expected life (in years)		6.5			6.5			6.5

Summary of Nucor's RSU Activity

A summary of Nucor’s RSU activity is as follows (shares in thousands):

Year Ended December 31,	2017					2016					2015
	Shares			Grant Date Fair Value		Shares			Grant Date Fair Value		Shares			Grant Date Fair Value
Restricted stock units:
Unvested at beginning of year		1,040		$	48.47		1,031		$	47.93		1,012		$	45.98
Granted		721		$	59.07		723		$	48.80		790		$	47.59
Vested		(677	)	$	53.17		(681	)	$	48.09		(756	)	$	44.99
Canceled		(13	)	$	50.21		(33	)	$	46.44		(15	)	$	46.61
Unvested at end of year		1,071		$	52.62		1,040		$	48.47		1,031		$	47.93
Shares reserved for future grants (stock options and RSUs)		7,259					8,706					10,349

Summary of Nucor's Restricted Stock Activity under AIP and LTIP

A summary of Nucor’s restricted stock activity under the AIP and the LTIP is as follows (shares in thousands):

	2017					2016					2015
Year Ended December 31,	Shares			Grant Date Fair Value		Shares			Grant Date Fair Value		Shares			Grant Date Fair Value
Restricted stock awards and units:
Unvested at beginning of year		67		$	45.77		63		$	48.07		65		$	48.20
Granted		172		$	60.62		123		$	44.03		136		$	47.07
Vested		(148	)	$	51.72		(116	)	$	45.16		(138	)	$	47.15
Canceled		—			—		(3	)	$	45.75		—			—
Unvested at end of year		91		$	54.50		67		$	45.77		63		$	48.07
Shares reserved for future grants		683					855					975