Leases Future minimum lease payments (Details) $ in Millions	Dec. 31, 2018 USD ($)
Leases, Operating [Abstract]
2019	$ 43
2020	34
2021	25
2022	23
2023	21
Later years	130
Minimum lease commitments	276
Leases, Capital [Abstract]
2019	42
2020	42
2021	40
2022	32
2023	23
Later years	88
Minimum lease commitments	267
Less amounts representing interest	(100)
Present value of net minimum lease obligations	$ 167