Stock-based Compensation

9 Months Ended

Sep. 30, 2019

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 11.8 million shares of common stock as of September 30, 2019. 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, 2019, 5.5 million 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 Company's initial public offering, 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, 2019 and 2018:

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2019		2018		2019		2018
	(in thousands)
Cost of revenues	$	577	$	625	$	1,674	$	1,888
Research and development	2,831		1,937		7,875		5,754
Sales and marketing	1,459		1,163		3,590		3,669
General and administrative	3,516		3,033		12,024		11,361
Total stock-based compensation	$	8,383	$	6,758	$	25,163	$	22,672

As of September 30, 2019, the Company had $12.6 million of total unrecognized stock-based compensation cost related to unvested options that it expects to recognize over a weighted-average period of 2.2 years, and $46.3 million of unrecognized stock-based compensation cost related to unvested RSUs that it expects to recognize over a weighted-average period of 2.3 years. Compensation cost is recognized 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)
Balance as of December 31, 2018	3,429,309		$	31.79	6.4	$	149,935
Granted	260,175		$	90.72
Exercised	(412,910	)	$	26.67
Canceled	(120,799	)	$	67.98
Balance as of September 30, 2019	3,155,775		$	35.93	6.0	$	130,529
Vested and expected to vest - September 30, 2019	3,010,578		$	33.96	5.9	$	129,358
Exercisable - September 30, 2019	2,464,112		$	27.60	5.4	$	118,835

Restricted Stock

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

	Outstanding RSUs		Weighted Average Grant Date Fair Value Per Share
Balance as of December 31, 2018	1,226,883		$	55.71
Granted	233,088		$	83.41
Vested	(329,561	)	$	52.92
Canceled	(128,132	)	$	63.04
Balance as of September 30, 2019	1,002,278		$	62.16
Outstanding and expected to vest - September 30, 2019	763,526		$	60.77