Leases - Operating and Finance Lease Liability Reconciliation (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Leases [Abstract]
Gross lease liabilities - operating leases	$ 36,048	$ 31,963
Gross lease liabilities - finance leases	28,787	28,875
Gross lease liabilities	64,835	60,838
Imputed interest - operating leases	(6,449)	(6,128)
Imputed interest - finance leases	(1,997)	(1,896)
Imputed interest	(8,446)	(8,024)
Present value of operating leases	29,599	25,835
Present value of finance leases	26,790	26,979
Present value of lease liabilities	56,389	52,814
Current portion of operating lease liabilities	(3,530)	(3,139)
Current portion of finance lease liabilities	(10,061)	(9,884)
Current portion of lease liabilities	(13,591)	(13,023)
Total long-term operating lease liabilities	26,069	22,696
Total long-term finance lease liabilities	16,729	17,095
Total long-term lease liabilities	$ 42,798	$ 39,791