Leases Maturity of Lease Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Total lease obligations	$ 627	$ 845
Current operating lease liabilities	(353)	0
Finance lease, current maturities of long-term debt	(85)
Noncurrent operating lease liabilities	978	$ 0
Finance lease, long-term debt less current maturities	542
Operating Lease
2020	392
2021	257
2022	141
2023	113
2024	92
Thereafter	661
Total lease payments	1,656
Less imputed interest	(325)
Total lease obligations	1,331
Current operating lease liabilities	(353)
Noncurrent operating lease liabilities	978
Finance Lease
2020	107
2021	102
2022	98
2023	94
2024	90
Thereafter	230
Total lease payments	721
Less imputed interest	(94)
Total lease obligations	627
Finance lease, current maturities of long-term debt	(85)
Finance lease, long-term debt less current maturities	$ 542