Leases (Maturity of Lease Liabilities) (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Operating leases
2020	$ 105
2021	192
2022	158
2023	124
2024	90
Thereafter	132
Total	801
Less amount representing interest	(95)
Present value of lease liabilities	706
Finance leases
2020	28
2021	58
2022	33
2023	22
2024	3
Thereafter	5
Total	149
Less amount representing interest	(9)
Present value of lease liabilities	$ 140	$ 127