Leases - Operating and Finance Lease Liability Reconciliation (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Leases [Abstract]
Gross lease liabilities - operating leases	$ 33,654
Gross lease liabilities - finance leases	28,147
Gross lease liabilities	61,801
Imputed interest - operating leases	(6,570)
Imputed interest - finance leases	(1,828)
Imputed interest	(8,398)
Present value of operating leases	27,084
Present value of finance leases	26,319
Present value of lease liabilities	53,403
Current portion of operating lease liabilities	(3,279)
Current portion of finance lease liabilities	(9,824)
Current portion of lease liabilities	(13,103)
Total long-term operating lease liabilities	23,805
Total long-term finance lease liabilities	16,495
Total long-term lease liabilities	$ 40,300	$ 39,791