Stock Plans and Stock-Based Compensation (Tables)

9 Months Ended

Sep. 30, 2016

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Schedule of Assumptions Used in Determining Fair Value of Stock Option Grants

The fair value of stock option grants is determined using the Black-Scholes option pricing model with the following weighted average assumptions. In addition, the fair value per share on grant date is presented below: 

	Three Months Ended September 30,				Nine  Months Ended September 30,
	2016		2015		2016		2015
Employee Stock Options:
Fair value per share on grant date	$8.94 - $9.02		$5.06 - $7.76		$8.51 - $9.02		$5.06 - $7.76
Expected term (in years)	5.99 - 6.11		5.52 - 6.15		5.29 - 6.11		5.52 - 6.15
Expected volatility	70%		60%		70%		60%
Risk-free interest rate	1.21% - 1.25%		1.47% - 1.94%		1.21% - 1.86%		1.47% - 1.94%
Dividend rate		0%		0%		0%		0%

⁽¹⁾ The expected term represents the period that the stock-based compensation awards are expected to be outstanding. Since the Company did not have sufficient historical information to develop reasonable expectations about future exercise behavior, the Company used the simplified method to compute expected term, which reflects the average of the time-to-vesting and the contractual life;

⁽²⁾ The expected volatility of the Company’s common stock on the date of grant is based on the volatilities of publicly traded peer companies that are reasonably comparable to the Company’s own operations;

⁽³⁾ The risk-free interest rate is based on the U.S. Treasury yield curve in effect at the time of grant for zero coupon U.S. Treasury notes with maturities approximately equal to the expected term of the options; and

⁽⁴⁾ The expected dividend yield is assumed to be zero as the Company has never paid dividends and has no current plans to pay any dividends on the Company’s common stock.

Schedule of Stock Option Activity

A summary of activities under the 2008 Option Plan and the 2016 Option Plan is shown as follows for the years ended December 31, 2014 and 2015 and the nine months ended September 30, 2016:

	Stock options outstanding			Weighted average exercise price
Outstanding at December 31, 2014		699,662		$	2.24
Granted		1,190,317			12.19
Exercised		(37,559	)		1.32
Forfeited/canceled		(30,698	)		7.76
Outstanding at December 31, 2015		1,821,722			8.68
Granted		241,590			14.66
Exercised		(161,336	)		4.34
Forfeited/canceled		(55,123	)		8.29
Outstanding at September 30, 2016		1,846,853		$	9.89

Schedule of Stock Options Outstanding and Options Exercisable and Vested

Stock options outstanding, and options exercisable and vested are as follows:

Outstanding as of September 30, 2016		Remaining contractual life (years)		Weighted average exercise price		Exercisable as of June 30, 2016		Remaining contractual life (years)		Weighted average exercise price
	1,846,853		8.17	$	9.89		722,492		7.20	$	6.07

Outstanding as of December 31, 2015	Remaining contractual life (years)		Weighted average exercise price		Exercisable as of December 31, 2015		Remaining contractual life (years)		Weighted average exercise price
1,821,722		8.62	$	8.68		472,463		6.88	$	1.90

Schedule of Vested and Nonvested Stock Option Activity

Vested and nonvested stock option activity was as follows:

	Vested				Nonvested
	Options outstanding		Weighted average exercise price		Options outstanding		Weighted average exercise price
Outstanding at September 30, 2016		722,492	$	6.07		1,124,361	$	12.24
Outstanding at December 31, 2015		472,463	$	1.90		1,349,259	$	10.87

Schedule of Stock-Based Compensation Expense

The Company recorded the total stock-based compensation expense as follows (in thousands):

	Three Months Ended September 30,				Nine Months Ended September 30,
	2016		2015		2016		2015
Cost of revenue	$	46	$	46	$	135	$	103
Sales and marketing		211		98		503		200
Research and development		87		79		263		213
General and administrative		415		319		1,264		384
Total	$	759	$	542	$	2,165	$	900