Leases - Maturities (Details) $ in Thousands	Mar. 31, 2019 USD ($)
Maturities of leases
2019 (excluding the three months ended March 31, 2019)	$ 3,288
2020	3,936
2021	3,657
2022	3,267
2023	2,879
Thereafter	8,617
Total lease payments	25,644
Less: imputed interest	(4,087)
Total operating lease liabilities	$ 21,557