Stock Based Awards (Tables)

6 Months Ended

Jun. 30, 2013

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,
	2012	2013	2012	2013
Expected dividend yield	0.00%	0.00%	0.00%	0.00%
Risk-free interest rate	0.77%	0.89%	0.77% - 0.87%	0.87% - 0.89%
Expected term (in years)	5.56 - 6.25	6.25	5.56 - 6.25	6.25
Volatility	55%	55%	55% - 60%	55%

Summary of Stock Option Activity

The following table summarizes stock option activity, including performance-based options:

	Number of shares			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (Years)		Aggregate Intrinsic Value
Outstanding at January 1, 2013		2,941,098		$	25.90		7.2	$	14,173,945
Granted		180,375			21.97
Exercised		(61,371	)		4.32			$	945,134
Forfeited		(113,495	)		33.69
Outstanding at June 30, 2013		2,946,607		$	25.84		6.9	$	15,785,517
Exercisable at December 31, 2012		1,361,728		$	17.16		5.6	$	13,090,809
Exercisable at June 30, 2013		1,708,298		$	21.31		5.9	$	14,338,894

Schedule of Restricted Stock Unit Activity

The following table summarizes restricted stock unit activity:

	Number of shares Underlying Restricted Stock Units			Weighted Average Grant Date Fair Value
Unvested as of January 1, 2013		782,805		$	31.14
Restricted stock units granted		519,370			22.41
Restricted stock units vested		(148,766	)		33.12
Restricted stock units forfeited		(18,605	)		29.46
Unvested as of June 30, 2013		1,134,804		$	26.91

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:

	Three Months Ended June 30,				Six Months Ended June 30,
	2012		2013		2012		2013
Cost of revenue	$	107,789	$	180,702	$	214,970	$	383,965
Research and development		574,452		1,044,848		1,156,167		2,061,654
Sales and marketing		900,724		2,145,877		1,850,669		4,226,797
General and administrative		1,505,606		1,745,657		2,851,201		3,609,339
	$	3,088,571	$	5,117,084	$	6,073,007	$	10,281,755