Leases, Remaining Minimum Lease Payments (Details) - USD ($) $ in Millions		Jun. 30, 2019	Dec. 31, 2018
Operating Leases
2019	[1]	$ 202
2020		314
2021		222
2022		180
2023		148
Thereafter		633
Total undiscounted lease payments		1,699
Less amount associated with discounting		353
Total lease liabilities		1,346
Finance Leases
2019	[1]	44
2020		86
2021		84
2022		85
2023		87
Thereafter		1,066
Total undiscounted lease payments		1,452
Less amount associated with discounting		671
Total lease liabilities		$ 781
Operating Leases
2019			$ 359
2020			245
2021			178
2022			146
2023			123
Thereafter			514
Total undiscounted lease payments			1,565
Capital Leases
2019			69
2020			65
2021			62
2022			64
2023			65
Thereafter			957
Total undiscounted lease payments			1,282
Less amount associated with discounting			676
Total lease liabilities			$ 606

[1] The amounts as of June 30, 2019 are for the remaining six months of 2019.