Leases (Summary of Lease Costs) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Leases [Abstract]
Operating lease costs	$ 31,785	$ 33,184
Finance lease costs:
Amortization of leased assets	2,299	2,472
Interest on lease liabilities	2,617	2,513
Short term lease costs	240	3,309
Variable lease costs	1,487	1,068
Total net lease costs	$ 38,428	$ 42,546