Goodwill and Other Intangible Assets - Identifiable Intangible Assets (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 1,936	$ 1,934
Accumulated Amortization	(1,224)	(1,176)
Net Carrying Amount	712	758
CDI
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	605	605
Accumulated Amortization	(482)	(460)
Net Carrying Amount	123	145
Other, primarily customer relationship intangibles
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	1,331	1,329
Accumulated Amortization	(742)	(716)
Net Carrying Amount	$ 589	$ 613