Leases (Future Minimum Payments) (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Operating
2019 (October 1 through December 31)	$ 56
2020	170
2021	174
2022	143
2023	130
2024 and thereafter	672
Total minimum payments	1,345
Less amounts representing interest	266
Present value of minimum payments	1,079
Finance
2019 (October 1 through December 31)	4
2020	12
2021	11
2022	7
2023	2
2024 and thereafter	2
Total minimum payments	38
Less amounts representing interest	3
Present value of minimum payments	$ 35	$ 43