Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2016

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary of Company's Stock Option Activity and Related Information

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

				Options Outstanding
	Shares Available for Grant			Number of Stock Options Outstanding			Weighted- Average Exercise Price		Weighted- Average Remaining ContractualLife (Years)		Aggregate Intrinsic Value
											(In thousands)
Balance at December 31, 2015		3,166,968			6,053,672		$	2.13		7.6	$	20,605
Granted (unaudited)		(794,496	)		794,496			4.53
Exercised (unaudited)		—			(157,174	)		0.70
Cancelled (unaudited)		211,454			(211,454	)		4.27
Balance at June 30, 2016 (unaudited)		2,583,926			6,479,540		$	2.39		7.4	$	13,211
Vested and exercisable at June 30, 2016 (unaudited)					3,736,516		$	1.38		6.4	$	10,669
Vested and expected to vest at June 30, 2016 (unaudited)					6,228,743		$	2.34		7.4	$	12,950

Schedule of Weighted-Average Assumptions Used in Black-Scholes Option-Pricing Model to Estimate Fair Value of Employee Stock Option at Grant Date

The fair value of employee stock option was estimated at the date of grant using a Black-Scholes option-pricing model with the following weighted-average assumptions:  

	Six Months Ended June 30,
	2016		2015
	(Unaudited)
Expected term (in years)		6.0		6.0
Expected volatility%		69.7%		52.3%
Risk-free interest rate%		1.3%		1.6%
Expected dividend yield%		0.0%		0.0%

Summary of Stock-Based Compensation Expense

Total stock-based compensation expense recognized in the Company’s condensed consolidated statements of operations is classified as follows (in thousands):

	Three Months Ended June 30,				Six Months Ended June 30,
	2016		2015		2016		2015
	(Unaudited)
Research and development	$	235	$	25	$	356	$	48
Selling and marketing		14		5		38		10
General and administrative		440		44		851		90
Total stock-based compensation expense	$	689	$	74	$	1,245	$	148