Stock-Based Compensation (Tables)

9 Months Ended

Sep. 30, 2018

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 Contractual Life (Years)		Aggregate Intrinsic Value
											(In thousands)
Balance at December 31, 2017		969,783			8,592,747		$	3.69		7.4	$	47,864
Additional options authorized		8,326,158			—
Options granted		(5,716,505	)		5,716,505			8.66
Options exercised		—			(1,607,108	)		2.22
Options canceled		801,933			(801,933	)		6.00
RSUs granted		(1,767,542	)		—
Balance at September 30, 2018		2,613,827			11,900,211		$	6.12		7.3	$	39,509
Vested and exercisable at September 30, 2018					4,731,731		$	3.57		5.1	$	27,404
Vested and expected to vest at September 30, 2018					11,397,852		$	6.06		7.2	$	38,576

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

	Nine Months Ended September 30,
	2018		2017
Expected term (in years)		6.0		6.0
Expected volatility%	60.4%		66.9%
Risk-free interest rate%	2.8%		2.1%
Expected dividend yield%		0.0%		0.0%

Summary of Restricted Stock Units

	RSUs
	Number of Shares			Weighted Average Grant Date Fair Value
Unvested at December 31, 2017		—		$	—
RSUs granted		1,767,542			9.65
RSUs vested		(20,109	)		10.31
Unvested at September 30, 2018		1,747,433		$	9.64
Vested and unreleased		130,889
Outstanding at September 30, 2018		1,878,322

Summary of Stock-Based Compensation Expense

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

	Three Months Ended September 30,				Nine Months Ended September 30,
	2018		2017		2018		2017
Research and development	$	511	$	221	$	1,061	$	602
Selling and marketing		234		70		555		193
General and administrative		6,434		693		8,436		1,971
Total stock-based compensation expense	$	7,179	$	984	$	10,052	$	2,766