Stock-based Compensation

9 Months Ended

Sep. 30, 2017

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

Stock-based Compensation

Stock-based Compensation

Equity Incentive Plans

2012 Equity Incentive Plan

Under the 2012 Equity Incentive Plan (the "2012 Plan"), the Company is authorized to grant to eligible participants incentive stock options (“ISOs”), non-statutory stock options (“NSOs”), stock appreciation rights ("SARs"), restricted stock awards ("RSAs"), restricted stock units ("RSUs"), performance units and performance shares equivalent to up to 9,861,234 shares of common stock. Options may be granted with an exercise price that is at least equal to the fair market value of the Company's stock at the date of grant and are exercisable when vested. As of September 30, 2017, 2,325,200 shares were available for grant under the 2012 Plan.

2000 Equity Incentive Plan

Under the 2000 Equity Incentive Plan (the "2000 Plan"), the Company was authorized to grant to eligible participants either ISOs or NSOs. The 2000 Plan was terminated in connection with the closing of the initial public offering ("IPO"), and accordingly, no shares are currently available for grant under the 2000 Plan. The 2000 Plan continues to govern outstanding awards granted thereunder.

Stock-based compensation

The following table shows a summary of the stock-based compensation expense included in the condensed consolidated statements of operations for the three and nine months ended September 30, 2017 and 2016.

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2017		2016		2017		2016
	(in thousands)
Cost of revenues	$	532	$	516	$	1,569	$	1,318
Research and development	1,503		1,585		4,229		4,373
Sales and marketing	1,231		821		3,444		3,459
General and administrative	4,477		2,181		9,280		5,972
Total stock-based compensation	$	7,743	$	5,103	$	18,522	$	15,122

As of September 30, 2017, the Company had $18.2 million of total unrecognized compensation cost related to unvested option awards that it expects to recognize over a weighted-average period of 2.5 years, and $31.9 million of unrecognized compensation cost related to unvested RSUs that it expects to recognize over a weighted-average period of 2.8 years. Compensation cost is recognized on a straight-line basis over the service period. Forfeitures are estimated at the time of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates.

Stock Option Plan Activity

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

	Outstanding Options		Weighted Average Exercise Price		Weighted Average Remaining Contractual Life (Years)	Aggregate Intrinsic Value
						(in thousands)
December 31, 2016	7,527,680		$	19.25	6.0	$	101,717
Granted	338,725		$	38.40
Exercised	(2,364,523	)	$	10.38
Canceled	(347,573	)	$	33.72
September 30, 2017	5,154,309		$	23.60	6.6	$	145,402
Vested and expected to vest - September 30, 2017	4,852,064		$	23.05	6.5	$	139,543
Exercisable - September 30, 2017	3,458,555		$	19.94	5.6	$	110,203

Restricted Stock

A summary of the Company’s RSU and RSA activity is as follows:

	Outstanding RSUs and RSAs		Weighted Average Grant Date Fair Value Per Share
December 31, 2016	587,333		$	28.85
Granted	934,439		$	38.53
Released	(239,222	)	$	32.15
Canceled	(106,522	)	$	31.80
September 30, 2017	1,176,028		$	35.60
Outstanding and expected to vest - September 30, 2017	1,010,848		$	35.58