Common Stock (Tables)

3 Months Ended

Mar. 31, 2017

Stockholders Equity Note [Abstract]

Schedule of Common Stock Reserved for Issuance

	March 31,	December 31,
	2017	2016
Options outstanding	8,778,134	9,835,992
Unvested restricted stock units outstanding	11,558,974	10,474,975
Unvested early exercised stock options	1,534	2,471
Shares available for grant under the 2014 Equity Incentive Plan and 2015 Inducement Plan	6,306,437	4,199,415
Shares available for purchase under the Employee Stock Purchase Plan	673,449	575,974
Total	27,318,528	25,088,827