Leases Future Minimum Lease Payments (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Leases, Operating [Abstract]
2019		$ 43
2020		34
2021		25
2022		23
2023		21
Later years		130
Sublease income	$ 0	0
Minimum lease commitments		276
Leases, Capital [Abstract]
2019		42
2020		42
2021		40
2022		32
2023		23
Later years		88
Sublease income		0
Minimum lease commitments		267
Less amounts representing interest		(100)
Present value of net minimum lease obligations		$ 167