Stockholders' Equity (Details 3) - USD ($) $ / shares in Units, $ in Millions	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Dec. 31, 2014
Weighted-average assumptions:
Estimated annual forfeiture rate (as a percent)	9.00%	7.00%
Shares Available for Grant
Balance at the end of the period (in shares)	997,830
Shares of common stock reserved for issuance
Stock options outstanding (in shares)			4,657,949
Shares available for future grant under 2013 Plan (in shares)	997,830		997,830
Employee stock purchase plan			225,806
Warrants outstanding (in shares)			27,839
Total shares of common stock reserved for issuance			5,909,424
2013 plan
Shares Available for Grant
Balance at the beginning of the period (in shares)	829,364
Authorized (in shares)			1,569,646
Granted (in shares)	(1,554,960)
Forfeitures/Expirations (in shares)	153,780
Balance at the end of the period (in shares)	997,830
Shares of common stock reserved for issuance
Shares available for future grant under 2013 Plan (in shares)	829,364		997,830	829,364
Stock options
Equity Incentive Plans
Intrinsic value of options exercisable			$ 13.5
Per share price of Company's closing stock price (in dollars per share)			$ 10.35
Weighted average exercise price (in dollars per share)			$ 2.96
Per-share weighted-average grant date fair value of options granted (in dollars per share)	$ 4.37	$ 4.50
Weighted-average assumptions:
Unrecognized compensation expense			$ 9.5
Weighted average remaining period for recognition of unrecognized compensation expense	2 years 10 months 24 days
Shares of common stock reserved for issuance
Stock options outstanding (in shares)			4,657,949	3,574,450
Stock options | Weighted-average
Weighted-average assumptions:
Expected term of options (in years)	6 years 2 months 19 days	5 years 10 months 13 days
Risk-free interest rate (as a percent)	1.69%	1.82%
Expected volatility (as a percent)	69.00%	76.00%
Dividend yield (as a percent)	0.00%	0.00%