Stock Incentive Plan (Tables)

6 Months Ended

Jun. 30, 2014

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary of Assumptions to Apply Black-Scholes Option-Pricing Model

The Company used the following assumptions to apply the Black-Scholes option-pricing model:  

	Three Months Ended June 30,		Six Months Ended June 30,
	2013	2014(1)	2013	2014
Expected dividend yield	0.00%	—%	0.00%	0.00%
Risk-free interest rate	0.89%	—%	0.87% - 0.89%	1.48%
Expected term (in years)	6.25	—	6.25	6.25
Volatility	55%	—%	55%	55%

(1) There were no stock options granted during the three months ended June 30, 2014.

Summary of Stock Option Activity

The following table summarizes stock option activity, including performance-based options (shares and intrinsic value in thousands):

	Number of shares			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (Years)		Aggregate Intrinsic Value
Outstanding at January 1, 2014		2,389		$	26.85		6.4	$	22,330
Granted		35			41.03
Exercised		(500	)		20.62			$	11,037
Forfeited		(75	)		33.36
Outstanding at June 30, 2014		1,849		$	28.54		6.3	$	33,444
Exercisable at December 31, 2013		1,451		$	23.45		5.4	$	17,855
Exercisable at June 30, 2014		1,332		$	26.72		5.7	$	26,522

Summary of Assumptions Used in Monte Carlo Simulation Model

The assumptions used in the Monte Carlo simulation model include (but are not limited to) the following:

	August 2013 Grant			May 2014 Grant
Risk-free interest rate		0.62	%		0.78	%
Volatility		54	%		54	%

Schedule of Restricted Stock Unit Activity

The following table summarizes restricted stock unit activity (shares in thousands):

	Number of shares Underlying Restricted Stock Units			Weighted Average Grant Date Fair Value
Unvested as of January 1, 2014		1,192		$	28.47
Restricted stock units granted		610			44.38
Restricted stock units vested		(303	)		26.88
Restricted stock units forfeited		(101	)		26.46
Unvested as of June 30, 2014		1,398		$	35.90

Schedule of Stock Based Compensation Allocated to Expense

The Company recognized stock based compensation expense within the accompanying condensed consolidated statements of operations as summarized in the following table (in thousands):

	Three Months Ended June 30,				Six Months Ended June 30,
	2013		2014		2013		2014
Cost of revenue	$	181	$	274	$	384	$	509
Research and development		1,045		1,008		2,062		1,784
Sales and marketing		2,146		2,796		4,227		4,857
General and administrative		1,745		2,635		3,609		5,001
	$	5,117	$	6,713	$	10,282	$	12,151