Leases, Remaining Minimum Lease Payments (Details) - USD ($) $ in Millions		Mar. 31, 2019	Dec. 31, 2018
Operating Leases
2019	[1]	$ 273
2020		267
2021		191
2022		157
2023		131
Thereafter		576
Total undiscounted lease payments		1,595
Less amount associated with discounting		335
Total lease liabilities		1,260
Finance Leases
2019	[1]	51
2020		65
2021		63
2022		64
2023		65
Thereafter		939
Total undiscounted lease payments		1,247
Less amount associated with discounting		641
Total lease liabilities		$ 606
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 March 31, 2019 are for the remaining nine months of 2019.