Goodwill and Other Intangible Assets - Identifiable Intangible Assets (Details) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 2,385	$ 2,067
Accumulated Amortization	(1,493)	(1,381)
Net Carrying Amount	892	686
CDI
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	970	903
Accumulated Amortization	(692)	(634)
Net Carrying Amount	278	269
Other, primarily customer relationship intangibles
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	1,415	1,164
Accumulated Amortization	(801)	(747)
Net Carrying Amount	$ 614	$ 417