Goodwill and Other Intangible Assets - Schedule of Intangible Assets and Accumulated Amortization Included in the Consolidated Statements of Condition (Details) - USD ($) $ in Millions	Mar. 31, 2025	Dec. 31, 2024
Intangible Assets [Line Items]
Gross Carrying Amount	$ 415	$ 415
Accumulated Amortization	(282)	(272)
Net Carrying Value	133	143
Core deposit intangibles
Intangible Assets [Line Items]
Gross Carrying Amount	356	356
Accumulated Amortization	(241)	(233)
Net Carrying Value	115	123
Client relationships
Intangible Assets [Line Items]
Gross Carrying Amount	32	32
Accumulated Amortization	(19)	(18)
Net Carrying Value	13	14
Other
Intangible Assets [Line Items]
Gross Carrying Amount	27	27
Accumulated Amortization	(22)	(21)
Net Carrying Value	$ 5	$ 6