Goodwill and Other Intangible Assets - Gross Carrying Amount, Accumulated Amortization And Net Carrying Amount Of Other Intangible Assets (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 3,894	$ 4,280
Accumulated Amortization	(2,067)	(2,250)
Net Carrying Amount	1,827	2,030	$ 2,369
Client relationships
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	2,704	3,104
Accumulated Amortization	(1,450)	(1,718)
Net Carrying Amount	1,254	1,386
Technology
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	393	403
Accumulated Amortization	(113)	(87)
Net Carrying Amount	280	316
Core deposits
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	690	673
Accumulated Amortization	(425)	(381)
Net Carrying Amount	265	292
Other
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	107	100
Accumulated Amortization	(79)	(64)
Net Carrying Amount	$ 28	$ 36