Leases - Leases, Liability, Maturity (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Jan. 01, 2019
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
2019 (excluding the six months ended June 30, 2019)	$ 1,859
2020	3,153
2021	3,101
2022	3,094
2023	3,043
Thereafter	11,204
Total future minimum lease payments	25,454
Less imputed interest	(5,654)
Total	$ 19,800	$ 20,800