Commitments and Contingencies - Minimum Required Payments (Details) $ in Thousands	Dec. 31, 2018 USD ($)
Operating Leases
2019	$ 4,516
2020	3,619
2021	3,430
2022	3,138
2023	1,133
Thereafter	748
Operating Leases	16,584
Unconditional Purchase Obligations
2019	29,153
2020	8,597
2021	6,951
2022	7,110
2023	5,614
Thereafter	44,058
Unconditional Purchase Obligations	$ 101,483