Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2020

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary of Assumptions Used to Estimate the Fair Value of Stock Options

The fair value of each option was estimated using the Black-Scholes model on the date of grant for the periods presented using the following assumptions:

	Three Months Ended March 31,
	2020	2019
Expected life (in years)	6.02	6.02
Risk-free interest rate	0.96%	2.66%
Volatility	50%	50%
Dividend yield	—	—

Summary of Stock Option and Restricted Stock Units Award Activity

A summary of the Company’s stock option and RSU award activity under the 2013 Plan is as follows:

				RSUs Outstanding					Options Outstanding
	Shares Available for Grant			Number of Shares			Weighted Average Grant Date Fair Value		Number of Shares			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (Years)		Aggregate Intrinsic Value (in thousands)
Balance as of December 31, 2019		6,036,180			5,022,675		$	10.66		8,600,441		$	11.40		5.16	$	8,811
Increase in shares authorized		3,574,847		—			—		—			—		—		—
Options granted		(1,150,178	)	—			—			1,150,178		$	8.95	—		—
Options exercised	—			—			—			(58,017	)	$	8.07	—		$	140
Options canceled or expired		387,626		—			—			(387,626	)	$	12.77	—		—
RSUs granted		(1,356,389	)		1,356,389		$	9.04	—			—		—		—
RSUs vested	—				(656,922	)	$	11.11	—			—		—		—
RSUs canceled or expired		319,534			(319,534	)	$	11.14	—			—		—		—
RSUs vested and withheld for    taxes		240,969		—			—		—			—		—		—
Balance as of March 31, 2020		8,052,589			5,402,608		$	10.17		9,304,976		$	11.06		5.45	$	1,078
Vested and exercisable as of    March 31, 2020										5,344,446		$	12.45		3.65	$	1,078

Summary of Assumptions Used to Estimate the Fair Value of Employee Stock Purchase Plan

The fair value of the option feature is estimated using the Black-Scholes model for the period presented based on the following assumptions:

	Three Months Ended March 31,
	2020	2019
Expected life (in years)	0.50	0.50
Risk-free interest rate	1.59%	2.50%
Volatility	55%	35%
Dividend yield	—	—

Schedule of Stock Based Compensation Expense

The following table sets forth the total stock-based compensation expense resulting from stock options, RSUs and ESPP included in the Company’s condensed consolidated statements of operations (in thousands):

	Three Months Ended March 31,
	2020		2019
Cost of revenues	$	435	$	602
Sales and marketing		1,402		1,738
Research and development		881		1,366
General and administrative		4,808		4,342
Total stock-based compensation    expense	$	7,526	$	8,048