Employee Benefit Plans (Tables)

12 Months Ended

Dec. 31, 2017

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

Schedule of Stock-Based Compensation Expense

Stock-based compensation expense related to stock options, RSUs, ESPP purchase rights, and stock options under ASC 718 for the years ended December 31, 2017, 2016, and 2015 is summarized as follows (in thousands):

	2017			2016			2015
RSUs	$	21,887		$	28,952		$	29,671
ESPP purchase rights		4,645			2,795			4,003
Employee stock options		—			79			397
Total stock-based compensation		26,532			31,826			34,071
Income tax benefit		(8,188	)		(10,342	)		(9,436	)
Stock-based compensation expense, net of tax	$	18,344		$	21,484		$	24,635

Schedule of ESPP Purchase Rights and Underlying Weighted Average Assumptions

Stock options were not granted during the years ended December 31, 2017, 2016, and 2015. The estimated weighted average fair value per share of ESPP purchase rights issued and the assumptions used to estimate fair value for the years ended December 31, 2017, 2016, and 2015 are as follows:

	2017			2016			2015
Weighted average fair value per share	$	12.09		$	10.69		$	10.28
Expected volatility		24% - 28	%		22% - 32	%		19% - 28	%
Risk-free interest rate		0.7% - 1.3	%		0.4% - 0.8	%		0.1% - 0.7	%
Expected term (in years)		0.5 - 2.0			0.5 - 2.0			0.5 - 2.0

Schedule of Stock Options Outstanding and Exercisable

Stock options outstanding and exercisable, including performance-based and market-based options, as of December 31, 2017, 2016, and 2015 and activity for each of the years then ended are summarized as follows (in thousands, except weighted average exercise price and remaining contractual term):

	Shares			Weighted average exercise price		Weighted average remaining contractual term (years)		Aggregate intrinsic value
Options outstanding at January 1, 2015		566		$	13.67
Options exercised		(124	)		15.35
Options outstanding at December 31, 2015		442		$	13.20
Options forfeited and expired		(12	)		10.77
Options exercised		(115	)		11.64
Options outstanding at December 31, 2016		315		$	13.86		1.46	$	9,480
Options exercised		(165	)		12.45
Options outstanding at December 31, 2017		150		$	15.43		1.27	$	2,116
Options vested and expected to vest at December 31, 2017		150		$	15.43		1.27	$	2,116
Options exercisable at December 31, 2017		150		$	15.43		1.27	$	2,116

Schedule of Non-Vested RSUs

Non-vested RSUs, including performance-based and market-based RSUs, as of December 31, 2017, 2016, and 2015, and activity for each of the years then ended, are summarized as follows (shares in thousands):

	Shares			Weighted average grant date fair value
Non-vested at January 1, 2015		2,003		$	35.91
Restricted stock granted		1,104			41.61
Restricted stock vested		(925	)		32.39
Restricted stock forfeited		(368	)		39.08
Non-vested at December 31, 2015		1,814		$	40.53
Restricted stock granted		1,359			43.35
Restricted stock vested		(787	)		38.34
Restricted stock forfeited		(303	)		39.54
Non-vested at December 31, 2016		2,083		$	43.34
Restricted stock granted		1,467			35.89
Restricted stock vested		(761	)		42.74
Restricted stock forfeited		(510	)		41.51
Non-vested at December 31, 2017		2,279		$	39.16

Schedule of Performance-Based and Market-Based RSUs and Stock Options

Performance-based and Market-based RSUs and Stock Options

Performance-based and market-based RSUs included in the tables above as of December 31, 2017, 2016, and 2015, and activity for each of the years then ended, are summarized below (in thousands):

	Performance-based						Market-based
	RSUs			Stock Options			RSUs
Non-vested at January 1, 2015		852			16			34
Granted		569			—			18
Vested		(284	)		—			(3	)
Forfeited		(217	)		—			(26	)
Non-vested at December 31, 2015		920			16			23
Granted		821			—			—
Vested		(226	)		(4	)		—
Forfeited		(250	)		(12	)		—
Non-vested at December 31, 2016		1,265			—			23
Granted		675			—			—
Vested		(284	)		—			—
Forfeited		(447	)		—			—
Non-vested at December 31, 2017		1,209			—			23

Schedule of Weighted Average Grant Date Fair Value Per Share of Performance-Based and Market-Based RSUs and Assumptions Used to Estimate Fair Value

The estimated grant date fair value per share of performance-based and market-based RSUs granted and the assumptions used to estimate grant date fair value for the years ended December 31, 2017, 2016, and 2015 are as follows:

	Performance-based				Market-based
	RSUs				RSUs
	Short-term		Long-term
Year ended December 31, 2017 Grants
Grant date fair value per share	$	47.18	$	33.43
Service period (years)		1.0		2.0 - 3.0
Year ended December 31, 2016 Grants
Grant date fair value per share	$	39.79	$	45.76
Service period (years)		1.0		2.0 - 3.0
Year ended December 31, 2015 Grants
Grant date fair value per share	$	38.77	$	42.82	$	33.84
Service period (years)		1.0		2.0 - 3.0
Derived service period (years)						1.60
Implied volatility						30.0	%
Risk-free interest rate						1.7	%