Commitments and Contingencies - Schedule of Future Minimum Lease Payments under 2017 Sublease and Lease (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2019 USD ($)
Commitments And Contingencies Disclosure [Abstract]
2019	$ 335
2020	655
2021	675
2022	727
2023	483
Thereafter	1,327
Total future minimum lease payments	4,202
Less interest	(981)
Total lease liability	$ 3,221
Weighted average lease term	6 years 6 months
Weighted average discount rate	8.10%