Goodwill and Other Intangible Assets Intangible Assets Schedule of Future Amortization (Details) - USD ($) $ in Millions		Dec. 31, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Indefinite-Lived Intangible Assets (Excluding Goodwill)		$ 12	$ 10
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months		13
Finite-Lived Intangible Assets, Amortization Expense, Year Two		10
Finite-Lived Intangible Assets, Amortization Expense, Year Three		9
Finite-Lived Intangible Assets, Amortization Expense, Year Four		8
Finite-Lived Intangible Assets, Amortization Expense, Year Five		6
Finite-Lived Intangible Assets, Amortization Expense, after Year Five		23
Finite-Lived Intangible Assets, Net	[1]	69
Other Intangible Assets [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Net	[2]	$ 4	$ 13

[1] Does not include indefinite-lived intangible assets of $12 million.

[2] Excludes fully amortized other intangible assets.