Stockholders' Equity - (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended		12 Months Ended
	Aug. 31, 2019	Feb. 28, 2018	Dec. 31, 2019	Dec. 31, 2018
Common stock reserved
Dividends on common stock			$ 0.00
Reserved shares of common stock for future issuance			2,809,928	2,360,840
Net proceeds				$ 24,524
Number of shares sold		3,772,447
Sale of common stock
Offering price		$ 7.00
Proceeds from stock offering, net of offering costs		$ 24,500
Offering costs		$ 1,900
Common stock warrants
Common stock reserved
Reserved shares of common stock for future issuance			27,836	27,836
Options issued and outstanding
Common stock reserved
Reserved shares of common stock for future issuance			1,931,903	1,475,299
Shares available for future option grants
Common stock reserved
Reserved shares of common stock for future issuance			638,227	764,145
RSUs subject to future vesting
Common stock reserved
Reserved shares of common stock for future issuance			211,962	93,560
At-the-Market Sales Agreement
Common stock reserved
Maximum amount of shares for offering	$ 25,000
Maximum commission percentage	3.00%
Net proceeds	$ 4,700
Number of shares sold	888,987
Shares available for future issuance	$ 19,900