Leases - Maturities of Lease Liabilities (Details) $ in Millions	Jun. 30, 2019 USD ($)
Operating Leases
2019	$ 288
2020	456
2021	367
2022	319
2023	274
Thereafter	895
Total lease payments	2,599
Less: interest	(644)
Total	1,955
Less: current portion	(488)
Long-term portion	1,467
Finance Leases
2019	22
2020	36
2021	25
2022	23
2023	20
Thereafter	179
Total lease payments	305
Less: interest	(85)
Total	220
Less: current portion	(32)
Long-term portion	$ 188