Common Stock Reserved for Issuance (Tables)

12 Months Ended

Dec. 31, 2018

Equity [Abstract]

Schedule of Common Stock Reserved for Future Issuance

The common stock reserved for future issuance at December 31, 2018 and 2017 was as follows:

	December 31,
	2018		2017
Shares underlying outstanding stock options		11,603,708		8,592,747
Shares available for future stock option grants		1,908,626		969,783
Shares issuable upon settlement of restricted    stock units outstanding		1,857,741		149,636
ESPP shares available for issuance		1,780,020		1,103,481
Warrants to purchase common stock		4,426,244		3,393,755
Total shares of common stock reserved		21,576,339		14,209,402