Leases - Operating Lease Minimum Payments (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Operating Lease Liabilities, Payments Due
2019	$ 3,925
2020	4,801
2021	4,179
2022	2,103
2023	953
Thereafter	5,054
Total undiscounted rental payments	21,015
Less imputed interest	3,087
Total lease liabilities	$ 17,928
Operating Leases Liabilities, Before Adoption
2019		$ 4,921
2020		4,801
2021		4,179
2022		2,103
2023		953
Thereafter		5,054
Total undiscounted rental payments		22,011
Less imputed interest		3,289
Total lease liabilities		$ 18,722