Goodwill and Other Intangible Assets - Identifiable Intangible Assets (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 4,510	$ 4,282
Accumulated Amortization	(1,494)	(1,140)
Net Carrying Amount	3,016	3,142
CDI
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	2,599	2,474
Accumulated Amortization	(608)	(365)
Net Carrying Amount	1,991	2,109
Other, primarily client relationship intangibles
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	1,911	1,808
Accumulated Amortization	(886)	(775)
Net Carrying Amount	$ 1,025	$ 1,033