Leases (Components of Lease Expense) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Leases [Abstract]
Operating lease cost	$ 41,559
Amortization of leased assets	5,240
Interest on lease liabilities	933
Total finance lease cost	6,173
Short-term lease cost	8,927
Variable lease cost	5,416
Net lease cost	62,075
Rent expense		$ 43,600	$ 48,100
Operating cash flows for operating leases	39,870
Operating cash flows for finance leases	893
Financing cash flows for finance leases	$ 6,574
Operating leases, Weighted average remaining lease term	4 years 8 months 12 days
Finance leases, Weighted average remaining lease term	3 years 7 months 6 days
Operating lease, Weighted average discount rate	4.20%
Finance lease, Weighted average discount rate	4.60%