Commitments and Contingencies - Future Minimum Lease Payments (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Future minimum capital leases:
2019 (remaining 3 months)	$ 12
2020	51
2021	51
2022	4
Total minimum lease payments	118
Less: amount representing interest	(7)
Present value of capital lease obligation	111
Less: current portion	46
Non-current portion	65	$ 100
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2019 (remaining 3 months)	1,717
2020	5,734
2021	5,716
2022	7,311
2023	7,012
Thereafter	77,226
Total minimum lease payments	$ 104,716