Leases - Maturity of Operating Lease Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Jan. 01, 2019
Leases [Abstract]
Remainder of 2019	$ 1,259
2020	4,197
2021	3,890
2022	3,609
2023	3,460
Thereafter	6,373
Total operating lease payments	22,788
Less: imputed interest	(3,335)
Total operating lease liabilities	$ 19,453	$ 22,500