Stockholders' Equity (Tables)

12 Months Ended

Dec. 31, 2015

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Schedule of Common Stock Reserved for Future Issuance

The following shares of common stock were reserved for future issuance as of December 31, 2015:

	Total Shares Reserved
2014 Equity Incentive Plan		3,916,362
2014 Employee Stock Purchase Plan		432,898
Total reserved shares of common stock		4,349,260

Summary of RSU Activity and Restricted Stock Award

The following is a summary of RSAs and RSUs activity under our 2014 EIP:

	RSAs					RSUs
	Shares			Weighted Average Grant Date Fair Value		Shares			Weighted Average Grant Date Fair Value
Unvested as of December 31, 2014		112,740		$	0.40		619,303		$	4.64
Granted		—			—		87,600		$	25.15
Forfeited		—			—		(2,645	)	$	8.59
Vested		(64,423	)	$	0.40		(276,653	)	$	6.12
Unvested as of December 31, 2015		48,317		$	0.40		427,605		$	7.86
Vested and unreleased							24,835
Outstanding as of December 31, 2015		—			—		452,440

Summary of Stock Option Activity

The following is a summary of option activity under our 2014 EIP:

	Number of shares			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (Years)		Aggregate Intrinsic Value (in thousands)
Outstanding as of December 31, 2014		623,936		$	13.69
Granted		2,610,174		$	28.95
Exercised		(23,822	)	$	18.44
Forfeited or expired		(72,759	)	$	37.11
Outstanding as of December 31, 2015		3,137,529		$	25.81		6.42	$	12,978
Vested and expected to vest as of December 31, 2015		3,137,529		$	25.81		6.42	$	12,978
Exercisable as of December 31, 2015		276,909		$	17.75		5.75	$	2,470

Summary of Options Estimated with Weighted Average

The fair value of each option issued was estimated at the date of grant using the Black-Scholes valuation model. The following table summarizes the weighted-average assumptions

	Year Ended December 31, 2015						Year Ended December 31, 2014
	Employees			Consultants			Employees			Consultants
Assumptions:
Expected term (years)		4.5			7.0		4.5				7.0
Expected volatility		72.4	%		71.5	%		65.7	%		65.8	%
Risk-free interest rate		1.6	%		2.0	%		1.6	%		2.2	%
Expected dividend yield		0.0	%		0.0	%		0.0	%		0.0	%
Weighted-average estimated grant date fair value per share	$	16.63		$	27.82		$	7.29		$	8.61

Schedule of Stock-based Compensation, Related to Employee and Nonemployee Awards

Total stock-based compensation expense related to all employee and non-employee awards was as follows:

	Year ended December 31,
	2015		2014		2013
			(in thousands)
Research and development	$	4,822	$	3,258	$	251
General and administrative		5,429		6,843		1,462
Total stock-based compensation	$	10,251	$	10,101	$	1,713