Lease Classification (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2019 USD ($)
Lease Classification
Short-term lease cost	$ 135
Operating lease cost	19,361
Total lease expense	$ 19,496
Weighted-average remaining lease term - operating leases	4 years
Weighted-average discount rate - operating leases	3.94%
Operating cash flows for operating leases	$ 19,091