Leases (Lease Expense and Cash Outflows from Operating and Finance Leases) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Leases [Abstract]
Operating lease cost	$ 37,498	$ 37,817
Short-term lease cost	1,261	1,379
Variable lease cost	2,838	3,149
Amortization	111	224
Interest on lease liabilities	14	15
Total lease cost	41,722	42,584
Cash paid for amounts included in measurement of lease liabilities:
Operating cash flows from operating leases	26,235	37,684
Operating cash flows from finance leases	14	15
Financing cash flows from finance leases	102	217
Right-of-use assets obtained in exchange for lease obligations:
Operating leases	16,275	41,776
Finance leases	$ 60	$ 159