Goodwill and Other Intangible Assets - Gross Carrying Amount and Accumulated Amortization of Intangible Assets (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Goodwill [Line Items]
Gross Carrying Amount	$ 622	$ 663
Accumulated Amortization	369	347
Core Deposit Intangibles [Member]
Goodwill [Line Items]
Gross Carrying Amount	355	396
Accumulated Amortization	193	184
Purchased Credit Card Relationship Intangible [Member]
Goodwill [Line Items]
Gross Carrying Amount	152	152
Accumulated Amortization	145	138
Other Intangible Assets [Member]
Goodwill [Line Items]
Gross Carrying Amount	115	115
Accumulated Amortization	$ 31	$ 25