Leases - Future Minimum Lease Payments (Details) $ in Thousands	Jun. 30, 2019 USD ($)
Operating leases
Remainder of 2019	$ 889
2020	1,815
2021	1,863
2022	1,914
2023	1,970
2024	1,340
Total undiscounted cash flows	9,791
Less: amount representing interest	(2,396)
Present value of lease liabilities	7,395
Finance leases
Remainder of 2019	12
2020	24
2021	14
2022	3
2023	0
2024	0
Total undiscounted cash flows	53
Less: amount representing interest	(13)
Present value of lease liabilities	$ 40