Commitments (Other Commitments) (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Other Commitments [Line Items]
Commitments	$ 290,371	$ 277,172
Liability Related To Investments In Low Income Housing Tax Credits	2,100	2,200
Signature Bridge Bank N.A Capital Commitment
Other Commitments [Line Items]
Commitments	16,000
Commitments to extend credit
Other Commitments [Line Items]
Commitments	275,372	261,728
Commitments to extend credit | Commercial
Other Commitments [Line Items]
Commitments	209,397	198,542
Commitments to extend credit | Home equity
Other Commitments [Line Items]
Commitments	24,037	22,783
Commitments to extend credit | Credit card
Other Commitments [Line Items]
Commitments	34,197	33,066
Commitments to extend credit | Other
Other Commitments [Line Items]
Commitments	7,741	7,337
Standby letters of credit
Other Commitments [Line Items]
Commitments	10,326	10,575
Standby letters of credit | Remarketing Programs
Other Commitments [Line Items]
Commitments	3,600	3,600
Standby bond purchase agreements
Other Commitments [Line Items]
Commitments	1,088	1,208
Other commitments
Other Commitments [Line Items]
Commitments	$ 3,585	$ 3,661