Leases - Operating and Finance Lease Liability Reconciliation (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Leases [Abstract]
Total operating lease liabilities	$ 46,762	$ 44,833
Total finance lease liabilities	28,687	30,437
Gross lease liabilities	75,449	75,270
Imputed interest - operating leases	(5,784)	(5,734)
Imputed interest - finance leases	(1,895)	(2,003)
Imputed interest	(7,679)	(7,737)
Present value of operating leases	40,978	39,099
Present value of finance leases	26,792	28,434
Present value of lease liabilities	$ 67,770	$ 67,533
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	Accrued expenses and other	Accrued expenses and other
Finance Lease, Liability, Current, Statement of Financial Position [Extensible List]		Accrued expenses and other
Current portion of operating lease liabilities	$ (4,841)	$ (4,586)
Current portion of finance lease liabilities	(9,862)	(10,374)
Current portion of lease liabilities	(14,703)	(14,960)
Total long-term operating lease liabilities	36,137	34,513
Total long-term finance lease liabilities	16,930	18,060
Total long-term lease liabilities	$ 53,067	$ 52,573
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	Total long-term lease liabilities	Total long-term lease liabilities
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	Total long-term lease liabilities	Total long-term lease liabilities