Summary of Significant Accounting Policies (Schedule of Right-of-use Assets and Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Summary of Significant Accounting Policies [Abstract]
Operating lease right-of-use assets, net	$ 2,369,358	$ 2,567,507
Financing lease right-of-use assets, net	4,202	4,710
Right-of-use assets, net	2,373,560	2,572,217
Current operating lease liabilities	234,605	245,665
Current financing lease liabilities	1,432	1,350
Current lease liabilities	236,037	247,015
Long-term operating lease liabilities	2,092,353	2,276,858
Long-term financing lease liabilities	2,010	2,542
Long-term lease liabilities	$ 2,094,363	$ 2,279,400