Leases (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($) item
Leases
Operating lease option to extend	true
Lease expenses:
Lease cost	$ 3,229
Short-term lease cost	217
Sublease income	(32)
Total lease cost	3,414
Cash payments for operating leases	3,846
Right-of-use assets obtained in exchange for lease obligations	$ 58,598
Remaining lease term (in year)	6 years 3 months 18 days
Discount rate (as a percent)	4.60%
Operating lease liabilities
2020	$ 15,683
2021	14,993
2022	13,397
2023	11,941
2024	10,343
Thereafter	21,999
Total lease payments	88,356
Less imputed interest	(11,983)
Total	$ 76,373
Number of operating leases not yet commenced. | item	1
Lease expense from leases not yet commenced	$ 1,500
Minimum
Leases
Remaining operating lease term	1 year
Maximum
Leases
Remaining operating lease term	10 years
Operating lease renewal term	5 years