Goodwill and Intangible Assets Goodwill and Intangible Assets (Summary of Changes in Carrying Value of Goodwill) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Goodwill [Line Items]
Balance	$ 635	$ 635
Business Bank
Goodwill [Line Items]
Balance	380	380
Retail Bank
Goodwill [Line Items]
Balance	194	194
Wealth Management
Goodwill [Line Items]
Balance	$ 61	$ 61