Stock-based Compensation (Tables)

9 Months Ended

Sep. 30, 2015

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

Schedule of Stock-Based Compensation Expense

Stock-based compensation expense related to stock options, ESPP purchases, and RSUs under ASC 718 for the three and nine months ended September 30, 2015 and 2014 is summarized as follows (in thousands):

	Three Months Ended September 30,						Nine Months Ended September 30,
	2015			2014			2015			2014
Stock-based compensation expense by type of award:
Employee stock options	$	329		$	37		$	385		$	191
RSUs		8,209			7,853			24,485			22,784
ESPP		990			1,144			3,217			2,176
Total stock-based compensation expense		9,528			9,034			28,087			25,151
Income tax effect		(2,787	)		(2,553	)		(7,451	)		(6,998	)
Stock-based compensation expense, net of tax	$	6,741		$	6,481		$	20,636		$	18,153

Schedule of ESPP Purchase Rights and Underlying Weighted Average Assumptions

Stock options were not granted during the three and nine months ended September 30, 2015 and 2014. ESPP purchase rights and the underlying weighted average assumptions for the three and nine months ended September 30, 2015 and 2014 are as follows:

	Three Months Ended September 30,						Nine Months Ended September 30,
	2015			2014			2015			2014
Weighted average fair value per share	$	11.35		$	11.42		$	10.28		$	11.12
Expected volatility		19% - 25	%		25% - 27	%		19% - 28	%		25% - 28	%
Risk-free interest rate		0.1% - 0.7	%		0.1% - 0.5	%		0.1% - 0.7	%		0.1% - 0.5	%
Expected term (in years)		0.5 - 2.0			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 September 30, 2015 and activity for the nine months ended September 30, 2015 are summarized below (in thousands, except weighted average exercise price and remaining contractual term):

	Shares outstanding			Weighted average exercise price			Weighted average remaining contractual term (years)		Aggregate intrinsic value
Options outstanding at January 1, 2015		567		$	13.67
Options exercised		(116	)		(15.59	)
Options outstanding at September 30, 2015		451		$	13.18			2.35	$	13,584
Options vested and expected to vest at September 30, 2015		450		$	13.18			2.35	$	13,549
Options exercisable at September 30, 2015		417		$	13.12			2.34	$	12,578

Schedule of Non-Vested RSUs

Non-vested RSUs, including performance-based and market-based RSUs, as of September 30, 2015 and activity during the nine months ended September 30, 2015 are summarized below (shares in thousands):

Non-vested shares	Shares			Weighted average grant date fair value
Non-vested at January 1, 2015		2,003		$	35.91
Restricted stock granted		1,034			41.29
Restricted stock vested		(857	)		(32.03	)
Restricted stock forfeited		(357	)		(39.10	)
Non-vested at September 30, 2015		1,823		$	39.73

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

Performance-based and market-based RSUs and stock options included in the tables above as of September 30, 2015 and activity for the nine months ended September 30, 2015 are summarized below (in thousands):

	Performance-based					Market-based
	RSUs			Stock Options		RSUs
Non-vested at January 1, 2015		852			16		34
Granted		562			—		18
Vested		(284	)		—		—
Forfeited		(214	)		—		(26	)
Non-vested at September 30, 2015		916			16		26

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

Performance-based stock options and market-based stock options were not granted during the nine months ended September 30, 2015. The weighted average 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 nine months ended September 30, 2015 are as follows:

	Performance-based				Market-based
	RSUs				RSUs
	Short-term		Long-term
Nine months ended September 30, 2015 Grants
Grant date fair value per share	$	38.77	$	42.76	$	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	%
Nine months ended September 30, 2014 Grants
Grant date fair value per share	$	40.18	$	41.11	$	32.10
Service period (years)		1.0		3.0 - 4.0
Derived service period (years)						1.53
Implied volatility						35.0	%
Risk-free interest rate						2.3	%