Organization and Description of Business - Additional Information (Details) $ in Thousands	1 Months Ended	6 Months Ended
	Oct. 31, 2018	Jun. 30, 2019 USD ($)	Dec. 31, 2018 USD ($)	Jun. 30, 2018 USD ($)	Dec. 31, 2017 USD ($)
Organization and Description of Business [Line Item]
Reverse stock split description		The Company effected a 11.0634-for-1 reverse split of its outstanding common stock and redeemable convertible preferred stock.
Accumulated deficit		$ (139,436)	$ (122,911)
Cash and cash equivalents		90,342	$ 61,051	$ 8,734	$ 13,406
Working capital		$ 89,200
Common Stock
Organization and Description of Business [Line Item]
Reverse stock split conversion ratio	11.0634