Commitments and Contingencies - Schedule of Maturity of Company's Operating Lease Liabilities (Details) $ in Thousands	Sep. 30, 2019 USD ($)
Commitments And Contingencies Disclosure [Abstract]
2019 (remaining three months)	$ 1,389
2020	5,647
2021	5,332
2022	5,460
2023	5,570
Thereafter	35,836
Total undiscounted lease payments	59,234
Present value adjustment	25,414
Total net lease liability	33,820
Net lease liability - current	1,700
Net lease liability - non-current	32,120
Total net lease liability	$ 33,820