Leases - Maturities of Lease Liabilities (Details) $ in Millions	Dec. 31, 2019 USD ($)
Operating Leases
2020	$ 276
2021	231
2022	199
2023	166
2024	113
Thereafter	437
Total lease payments	1,422
Less: interest	(319)
Total	1,103
Less: current portion	(249)
Noncurrent operating lease liabilities	854
Finance Leases
2020	21
2021	17
2022	18
2023	18
2024	18
Thereafter	154
Total lease payments	246
Less: interest	(75)
Total	171
Less: current portion	(11)
Long-term portion	$ 160