Operating Leases - Schedule of Future Minimum Lease Payments (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Operating Leases, After Adoption of 842:
Remainder of 2019	$ 2,751
2020	6,064
2021	6,202
2022	6,325
2023	6,504
Thereafter	17,765
Total future minimum lease payments	45,611
Less: imputed interest	(11,150)
Total	$ 34,461
Operating Leases, Before Adoption of 842:
2019		$ 5,526
2020		5,560
2021		5,593
2022		5,708
2023		5,869
Thereafter		13,458
Total future minimum lease payments		41,714
2019		$ 5,526

Amount of lessee's undiscounted obligation for lease payments for operating lease.

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