Summary of Significant Accounting Policies - Estimated Future Lease Payments (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Leases, Operating [Abstract]
2021	$ 380,607
2022	362,970
2023	334,893
2024	307,039
2025	281,487
Thereafter	1,687,706
Total minimum lease payments	3,354,702
Less amounts representing interest or imputed interest	(1,059,865)
Present value of lease obligations	2,294,837
Lessee, Finance Sublease, Description [Abstract]
2021	(6,208)
2022	(5,752)
2023	(5,222)
2024	(3,771)
2025	(1,661)
Thereafter	(6,229)
Total minimum lease payments	(28,843)
Finance Lease, Liability, Payment, Due [Abstract]
2021	62,669
2022	54,499
2023	45,557
2024	38,051
2025	32,261
Thereafter	268,542
Total minimum lease payments	501,579
Less amounts representing interest or imputed interest	(135,268)
Present value of lease obligations	$ 366,311	$ 367,182