Commitments and Contingencies - Future Minimum Payments Under Leases (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Capital Leases
2019	$ 252
2020	61
2021	0
2022	0
2023	0
Total minimum lease payments	313
Less: amount representing interest	(10)
Present value of capital lease obligations	303
Less: current portion	(242)
Long-term portion of capital leases	61	$ 302
Operating leases
2019	3,280
2020	712
2021	490
2022	41
2023	0
Total minimum lease payments	4,523
Total future minimum sublease rentals to be received under noncancellable subleases	$ 900