Goodwill and Other Intangible Assets - Identifiable Intangible Assets (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 4,066	$ 4,071
Accumulated Amortization	(2,250)	(2,162)
Net Carrying Amount	1,816	1,909
CDI
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	2,473	2,473
Accumulated Amortization	(1,703)	(1,650)
Net Carrying Amount	770	823
Other, primarily client relationship intangibles
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	1,593	1,598
Accumulated Amortization	(547)	(512)
Net Carrying Amount	$ 1,046	$ 1,086