Goodwill and Other Intangible Assets - Summary of Intangible Assets and Accumulated Amortization Included in the Consolidated Statements of Condition (Details) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Intangible Assets [Line Items]
Gross Carrying Amount	$ 444	$ 449
Accumulated Amortization	(159)	(151)
Net Carrying Value	285	298
Core deposit intangibles
Intangible Assets [Line Items]
Gross Carrying Amount	371	371
Accumulated Amortization	(139)	(128)
Net Carrying Value	232	243
Client relationships
Intangible Assets [Line Items]
Gross Carrying Amount	37	37
Accumulated Amortization	(12)	(11)
Net Carrying Value	25	26
Other
Intangible Assets [Line Items]
Gross Carrying Amount	36	41
Accumulated Amortization	(8)	(12)
Net Carrying Value	$ 28	$ 29