Goodwill and Other Intangible Assets Intangible Assets Schedule of Future Amortization (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Indefinite-lived Intangible Assets (Excluding Goodwill)	$ 12	$ 12
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	10
Finite-Lived Intangible Assets, Amortization Expense, Year Two	8
Finite-Lived Intangible Assets, Amortization Expense, Year Three	7
Finite-Lived Intangible Assets, Amortization Expense, Year Four	6
Finite-Lived Intangible Assets, Amortization Expense, Year Five	5
Finite-Lived Intangible Assets, Amortization Expense, after Year Five	31
Finite-Lived Intangible Assets, Net	$ 67