Right-of-Use ("ROU") Assets and Lease Liabilities - Lease Cost (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Operating leases:
Lease cost	$ 8,790	$ 8,052
Variable lease cost	1,260	1,053
Operating lease cost	10,050	9,105
Finance leases:
Amortization of ROU assets	601	668
Interest on lease liabilities	91	124
Finance lease cost	692	792
Total lease cost	10,742	9,897
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	7,335	6,618
Financing cash flows from finance leases	678	654
Right-of-use-assets obtained in exchange for lease obligations:
Finance leases	20	185
Operating leases	$ 10,152	$ 120,555
Operating Leases
Weighted average remaining lease term (years)	5 years 3 months 3 days		5 years 3 months 25 days
Weighted average discount rate	4.30%		4.40%
Finance Leases
Weighted average remaining lease term (years)	5.20%		5.20%
Weighted average discount rate	3 years 14 days		3 years 3 months 3 days