Leases - Future Lease Payments under Non-Cancellable Leases (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Leases [Abstract]
2019	$ 6,258
2020	24,159
2021	22,135
2022	19,650
2023	17,462
Thereafter	99,334
Total undiscounted lease payments	188,998
Less: imputed interest	(76,633)
Total lease liabilities	112,365
2019	2,099
2020	7,598
2021	6,839
2022	6,708
2023	6,689
Thereafter	58,162
Total undiscounted lease payments	88,095
Less: imputed interest	(32,870)
Total lease liabilities	$ 55,225	$ 55,282