Stockholders' Equity (Tables)

12 Months Ended

Dec. 31, 2014

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary of Equity Incentive Plan Activity

Equity Incentive Plan activity under the 2000 Plan and the 2009 Plan is summarized as follows:

Equity Incentive Plan activity	Shares Available for Grant
Balance at December 31, 2013		2,004,464
Authorized		3,000,000
Granted		(2,773,500	)
Forfeited		470,980
Expired		6,580
Balance at December 31, 2014		2,708,524

Summary of Stock Option Activity under the Company's Equity-Based Plans

The following table summarizes stock option activity under the Company’s equity-based plans for the year ended December 31, 2014:

Stock Options activity	Number of Shares			Weighted Average Exercise Price		Weighted- Average Remaining Contractual Term (Years)		Aggregate Intrinsic Value (in thousands)
Balance at December 31, 2013		6,281,148		$	1.74	8.55		$	53,373
Granted		2,748,500			13.02
Exercised		(1,712,278	)		1.28
Forfeited		(417,980	)		5.33
Expired		(6,580	)		0.50
Balance at December 31, 2014		6,892,810		$	6.13		8.22	$	173,338
Exercisable at December 31, 2014		1,735,148		$	1.20		7.09	$	52,195
Vested and expected to vest at December 31, 2014		6,600,369		$	6.01		8.19	$	166,806

Summary of Restricted Stock Unit Activity under the Company's Equity-Based Plans

The following table summarizes restricted stock unit activity under the Company’s equity-based plans for the year ended December 31, 2014:

Restricted Stock Unit activity	Number of Units			Weighted-Average Grant Date Fair Value
Nonvested at December 31, 2013		40,000		$	13.21
Granted		25,000			28.59
Vested		(4,250	)		13.21
Forfeited		(53,000	)		20.46
Nonvested at December 31, 2014		7,750		$	13.21

Summary of Significant Assumptions Used to Estimate Fair Value of Stock Options under Black-Scholes Model

The fair value of stock-based awards is estimated on the date of grant using the Black-Scholes option-pricing model with the following weighted-average assumptions:

	Year Ended December 31,
Stock Option:	2014			2013			2012
Expected term (in years)		6.05		6.04			6.04
Expected volatility		58	%		48	%		46	%
Risk-free interest rate		1.80	%		1.26	%		1.01	%
Expected dividend yield		0	%		0	%		0	%

Summary of Significant Assumptions Used to Estimate Fair Value of Employee Stock Purchase Plans under Black-Scholes Model

The fair value of stock-based awards is estimated on the date of grant using the Black-Scholes option-pricing model with the following weighted-average assumptions:

	Year Ended December 31,
ESPP:	2014			2013	2012
Expected term (in years)		0.50		n/a	n/a
Expected volatility	33-58%			n/a	n/a
Risk-free interest rate	0.06-0.07%			n/a	n/a
Expected dividend yield		0	%	n/a	n/a

Computation of Basic and Diluted Net Income per Share Attributable to Common Stock

The following table sets forth the computation of the Company’s basic and diluted net income per share attributable to common stock for the years ended December 31, 2014, 2013 and 2012 (in thousands, except per share data):

	Year Ended December 31,
	2014			2013			2012
Numerator (basic)
Net income	$	15,497		$	13,147		$	31,832
Less net income allocated to participating securities		(2,224	)		(9,926	)		(25,312	)
Net income attributable to common stock	$	13,273		$	3,221		$	6,520
Denominator (basic)
Weighted average shares of common stock outstanding		56,161			12,353			9,805
Basic EPS	$	0.24		$	0.26		$	0.66
Numerator (diluted)
Net income	$	15,497		$	13,147		$	31,832
Less net income allocated to participating securities		(2,114	)		(9,303	)		(23,974	)
Net income attributable to common stock	$	13,383		$	3,844		$	7,858
Denominator (diluted)
Weighted average shares of common stock		56,161			12,353			9,805
Dilutive effect of stock options and restricted stock units		3,406			3,379			2,671
Weighted average shares of common stock outstanding		59,567			15,732			12,476
Diluted EPS	$	0.22		$	0.24		$	0.63
Common stock equivalents excluded from income per    diluted share because of their anti-dilutive effect		526			1,389			2,947