Employee Stock and Benefit Plans (Tables)

12 Months Ended

Dec. 31, 2016

Share-based Compensation [Abstract]

Schedule of shares reserved for future issuance

The Company had reserved shares of common stock for future issuance as of December 31, 2016 as follows:

Options and RSUs outstanding under equity incentive plans
2000 Equity Incentive Plan	2,718,517
2012 Equity Incentive Plan	5,396,496
Shares available for future grants under an equity incentive plan
2012 Equity Incentive Plan	1,425,230
Total shares reserved for future issuance	9,540,243

Stock-based employee compensation

Stock-based compensation included in the consolidated statements of operations is as follows:

	Year Ended December 31,
	2016		2015		2014
	(in thousands)
Cost of revenues	$	1,858	$	1,250	$	757
Research and development	5,678		4,936		2,470
Sales and marketing	4,870		3,867		2,407
General and administrative	7,743		7,441		4,915
Total stock-based employee compensation	$	20,149	$	17,494	$	10,549

Fair value assumptions of options granted to employees

The fair value of each option granted to employees is estimated on the date of grant using the Black-Scholes option-pricing model based on the following assumptions:

	Year Ended December 31,
	2016	2015	2014
Expected term (in years)	5.0 to 5.9	4.9 to 5.9	5.3 to 5.9
Volatility	45% to 49%	45% to 48%	48% to 52%
Risk-free interest rate	1.1% to 1.3%	1.3% to 1.7%	1.5% to 1.7%
Dividend yield	—	—	—

Stock option activity

A summary of the Company’s stock option activity is as follows:

	Outstanding Shares		Weighted Average Exercise Price		Weighted Average Remaining Contractual Life (Years)	Aggregate Intrinsic Value
						(in thousands)
Balance as of December 31, 2013	7,039,093		$	7.17	6.5	$	112,312
Granted	2,744,150		$	26.16
Exercised	(1,216,710	)	$	6.28
Canceled	(961,126	)	$	16.91
Balance as of December 31, 2014	7,605,407		$	12.93	6.5	$	188,743
Granted	1,526,450		$	39.50
Exercised	(807,846	)	$	12.50
Canceled	(744,953	)	$	27.67
Balance as of December 31, 2015	7,579,058		$	16.88	5.9	$	131,345
Granted	2,120,633		$	26.64
Exercised	(1,399,157	)	$	10.83
Canceled	(772,854	)	$	31.57
Balance as of December 31, 2016	7,527,680		$	19.25	6.0	$	101,717
Vested and expected to vest—December 31, 2016	7,008,375		$	18.43	5.7	$	99,875
Exercisable—December 31, 2016	5,137,869		$	14.49	4.6	$	91,928

Schedule of exercise price range, outstanding and vested

The followingtable summarizes the outstanding and vested stock options at December 31, 2016:

	Outstanding				Exercisable
Exercise Price	Number of Shares	Weighted Average Exercise Price Per Share		Weighted Average Remaining Contractual Life (Years)	Number of Shares	Weighted Average Exercise Price Per Share
$1.90 - $1.90	938,282	$	1.90	0.07	938,282	$	1.90
$2.10 - $2.80	161,970	$	2.73	2.21	161,970	$	2.73
$3.80 - $3.80	1,057,235	$	3.80	2.92	1,057,235	$	3.80
$4.10 - $12.68	841,480	$	8.50	4.87	835,654	$	8.49
$13.50 - $25.17	1,126,929	$	22.19	7.74	592,323	$	20.13
$25.56 - $25.56	1,064,551	$	25.56	9.28	146,263	$	25.56
$26.86 - $30.58	1,065,841	$	28.78	7.37	968,961	$	28.74
$31.67 - $37.28	905,161	$	35.41	8.88	220,324	$	36.55
$40.68 - $40.89	225,661	$	40.82	7.55	154,011	$	40.79
$52.14 - $52.14	140,570	$	52.14	7.46	62,846	$	52.14
	7,527,680	$	19.25	5.96	5,137,869	$	14.49

Summary of the Company’s RSUs and RSAs activity

A summary of the Company’s RSUs and RSAs activity is as follows:

	Number of Shares		Weighted-Average Grant Date Fair Value Per Share
Balance as of December 31, 2014	—		$	—
Granted	60,000		$	37.28
Vested	(12,500	)	$	37.28
Cancelled	—		$	—
Balance as of December 31, 2015	47,500		$	37.28
Granted	681,350		$	28.52
Vested	(39,998	)	$	27.49
Cancelled	(101,519	)	$	31.12
Balance as of December 31, 2016	587,333		$	28.85
Expected to vest as of December 31, 2016	409,789		$	28.81