Leases (Summary of Lease Cost) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Leases [Abstract]
Operating lease cost	$ 8,285	$ 8,258	$ 24,758	$ 24,268
Financing lease cost, Amortization of leased assets	12	13	37	37
Financing lease, Interest on lease liabilities	13	19	43	59
Variable lease cost	3,494	3,470	10,399	10,177
Short-term lease cost	145	197	531	679
Net lease cost	$ 11,949	$ 11,957	$ 35,768	$ 35,220