Stockholders' Equity (Tables)

6 Months Ended

Jun. 30, 2016

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 June 30, 2016:

	Total Shares Reserved
2014 Equity Incentive Plan		9,247,174
2014 Employee Stock Purchase Plan		663,667
Total reserved shares of common stock		9,910,841

Summary of RSU Activity and Restricted Stock Award

The following is a summary of RSA and RSU 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, 2015		48,317		$	0.40		427,605		$	7.86
Granted		—					642,697		$	15.78
Forfeited		—					(44,333	)	$	11.83
Vested		(32,211	)	$	0.40		(103,400	)	$	6.31
Unvested as of June 30, 2016		16,106		$	0.40		922,569		$	13.36
Vested and unreleased							23,582
Outstanding as of June 30, 2016							946,151

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, 2015		3,137,529		$	25.81
Granted		462,600		$	19.99
Exercised		(2,444	)	$	11.82
Forfeited or expired		(173,586	)	$	25.39
Outstanding as of June 30, 2016		3,424,099		$	25.12		6.04	$	7,120
Vested and expected to vest as of June 30, 2016		3,424,099		$	25.12		6.04	$	7,120
Exercisable as of June 30, 2016		702,649		$	22.36		5.60	$	2,451

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

	Six months ended June 30, 2016						Six months ended June 30, 2015
	Employees			Consultants			Employees			Consultants
Assumptions:
Expected term (years)		4.5			6.9			4.5			6.9
Expected volatility		68.9	%		66.1	%		71.2	%		70.1	%
Risk-free interest rate		1.4	%		1.7	%		1.3	%		1.6	%
Expected dividend yield		0.0	%		0.0	%		0.0	%		0.0	%
Fair Value:
Weighted-average estimated grant date fair    value per share	$	11.04		$	11.57		$	15.31		$	16.66
Options granted		453,600			9,000			800,099			2,000
Total estimated grant date fair value	$	5,006,000		$	104,000		$	12,248,000		$	33,000

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:

	Three months ended June 30,				Six months ended June 30,
	2016		2015		2016		2015
	(in thousands)				(in thousands)
Research and development	$	2,434	$	1,251	$	4,681	$	2,540
General and administrative		2,701		1,318		5,179		2,513
Total stock-based compensation expense	$	5,135	$	2,569	$	9,860	$	5,053