Stock-based Compensation (Tables)

12 Months Ended

Dec. 31, 2017

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

Summary of Weighted Average Assumptions Used to Value Options

The following table summarizes the weighted-average assumptions used in the Black-Scholes option-pricing model to determine fair value of stock options:

	Year Ended December 31,
	2017		2016		2015
Volatility	86	%	52	%	40	%
Expected dividend yield	—		—		—
Risk-free rate	2.15	%	1.34	%	1.59	%
Expected term (in years)	6		6		5

The weighted-average grant date fair value of the options granted under the 2015 Equity Incentive Plan as calculated using the Black-Scholes option-pricing model was $3.11,  $1.63 and $2.76 per share for the years ended December 31, 2017, 2016 and 2015, respectively.

On April 1, 2017, our compensation committee granted 204,220 RSUs that do not begin vesting unless certain performance goals are met. All performance goals must be met in order for the shares to begin vesting. Vesting would begin on the one-year anniversary of the grant date. These performance goals relate to a) the price performance of our common stock one year from the grant date as compared to a threshold established by our compensation committee and b) revenue, gross profit and EBITDA performance relative to plan targets for fiscal 2017 established by our compensation committee.  As a result of these performance-based vesting conditions we valued these RSUs using Monte Carlo simulation techniques to establish a fair value per share of $0.81 at the time of grant.

Schedule of Employee Service Share-based Compensation for Stock Options, Restricted Stock Units and ESPP Shares

The weighted-average grant date fair value of the options granted under the 2015 Equity Incentive Plan as calculated using the Black-Scholes option-pricing model was $3.11,  $1.63 and $2.76 per share for the years ended December 31, 2017, 2016 and 2015, respectively.

On April 1, 2017, our compensation committee granted 204,220 RSUs that do not begin vesting unless certain performance goals are met. All performance goals must be met in order for the shares to begin vesting. Vesting would begin on the one-year anniversary of the grant date. These performance goals relate to a) the price performance of our common stock one year from the grant date as compared to a threshold established by our compensation committee and b) revenue, gross profit and EBITDA performance relative to plan targets for fiscal 2017 established by our compensation committee.  As a result of these performance-based vesting conditions we valued these RSUs using Monte Carlo simulation techniques to establish a fair value per share of $0.81 at the time of grant.

The following table presents the effects of stock-based compensation for stock options, RSUs, and ESPP (in thousands):

	Year Ended December 31,
	2017		2016		2015
Cost of revenue	$	112	$	81	$	19
Research and development		1,172		1,038		263
Sales and marketing		764		706		153
General and administrative		1,454		1,518		352
Total	$	3,502	$	3,343	$	787