Commitments and Contingencies - Future Minimum Annual Lease Payments (Details) $ in Thousands	Jun. 30, 2018 USD ($)
Commitments And Contingencies Disclosure [Abstract]
Operating leases Remainder of 2018	$ 829
Operating leases 2019	1,665
Operating leases 2020	1,688
Operating leases 2021	1,009
Total Operating leases	5,191
Capital leases Remainder of 2018	38
Capital leases 2019	37
Capital leases 2020	37
Capital leases 2021	37
Capital leases 2022 and thereafter	37
Total Capital leases	186
Less: amount representing interest	(24)
Present value of minimum lease payments	162
Current portion of capital leases	(38)
Capital leases, less current portion	$ 124