Right-of-Use ("ROU") Assets and Lease Liabilities - Lease Cost (Details) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019 USD ($)	Sep. 30, 2019 USD ($)
Operating leases:
Lease cost	$ 8,335	$ 24,469
Variable lease cost	527	2,852
Operating lease cost	8,862	27,321
Finance leases:
Amortization of ROU assets	615	2,044
Interest on lease liabilities	106	347
Finance lease cost	721	2,391
Total lease cost	$ 9,583	29,712
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases		20,035
Financing cash flows from finance leases		2,002
Right-of-use-assets obtained in exchange for lease obligations:
Finance leases		203
Operating leases		$ 136,204
Operating Leases
Weighted average remaining lease term (years)	5 years 3 months 20 days	5 years 3 months 20 days
Weighted average discount rate	4.60%	4.60%
Finance Leases
Weighted average remaining lease term (years)	5.20%	5.20%
Weighted average discount rate	3 years 5 months 20 days	3 years 5 months 20 days