Leases - Operating and Finance Lease Liability Reconciliation (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Leases [Abstract]
Gross lease liabilities - operating leases	$ 42,014	$ 31,963
Gross lease liabilities - finance leases	29,801	28,875
Gross lease liabilities	71,815	60,838
Imputed interest - operating leases	(6,759)	(6,128)
Imputed interest - finance leases	(2,051)	(1,896)
Imputed interest	(8,810)	(8,024)
Present value of operating leases	35,255	25,835
Present value of finance leases	27,750	26,979
Present value of lease liabilities	63,005	52,814
Current portion of operating lease liabilities	(4,156)	(3,139)
Current portion of finance lease liabilities	(10,260)	(9,884)
Current portion of lease liabilities	(14,416)	(13,023)
Total long-term operating lease liabilities	31,099	22,696
Total long-term finance lease liabilities	17,490	17,095
Total long-term lease liabilities	$ 48,589	$ 39,791