Leases - Maturities of Lease Liabilities, Topic 842 (Details) $ in Millions	Dec. 31, 2019 USD ($)
Finance Leases
2020	$ 148
2021	449
2022	325
2023	183
2024	69
Thereafter	10
Total lease payments	1,184
Less: imputed interest	(70)
Total payments	1,114
Real Estate
Operating Leases
2020	115
2021	398
2022	321
2023	240
2024	182
Thereafter	305
Total lease payments	1,561
Less: imputed interest	(147)
Total payments	1,414
Equipment
Operating Leases
2020	31
2021	84
2022	38
2023	15
2024	9
Thereafter	14
Total lease payments	191
Less: imputed interest	(10)
Total payments	$ 181