Summary of Significant Accounting Policies (Components of Lease Cost, Lease Term, and Discount Rate) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Summary of Significant Accounting Policies [Abstract]
Amortization of right-of-use assets	$ 1,485	$ 1,275
Interest on finance lease liabilities	135	115
Total finance lease cost	1,620	1,390
Operating lease cost	260,619	266,681
Variable lease cost	42,654	38,477
Total lease cost	$ 304,893	$ 306,548
Weighted Average Remaining Lease Term Operating leases	16 years 1 month 6 days	16 years 7 months 6 days
Weighted Average Remaining Lease Term Finance leases	2 years 8 months 12 days	3 years 3 months 18 days
Weighted Average Discount Rate: Operating leases	5.90%	6.10%
Weighted Average Discount Rate: Finance leases	3.40%	3.60%
Cash paid for amounts included in measurement of lease liabilities: Cash flows from operating leases	$ 237,747	$ 237,758
Cash paid for amounts included in measurement of lease liabilities: Cash flows from finance leases	$ 1,485	$ 1,275