Fair Value Measurements - Schedule of Fair Value of Assets and Liabilities Measured on Recurring Basis (Details) - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	$ 1,219	$ 1,142
Total securities available for sale	37,460	37,185
Loans, net of unearned income (residential)	107,078	112,606
Netting adjustments	(532)	(818)
Total derivative assets	230	181
LIABILITIES MEASURED ON A RECURRING BASIS
Netting adjustments	(466)	(473)
U.S. Treasury, agencies and corporations
ASSETS MEASURED ON A RECURRING BASIS
Total securities available for sale	8,995	9,026
Agency residential mortgage-backed securities
ASSETS MEASURED ON A RECURRING BASIS
Total securities available for sale	4,243	3,589
Agency commercial mortgage-backed securities
ASSETS MEASURED ON A RECURRING BASIS
Total securities available for sale	8,946	9,092
Level 3 | Other
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	1
Recurring
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	1,210	1,139
Commercial loans	9	3
Total trading account assets	1,219	1,142
Total securities available for sale	37,460	37,185
Total other investments	70	63
Loans, net of unearned income (residential)	11	9
Loans held for sale (residential)	91	51
Derivative assets	762	999
Netting adjustments	(532)	(818)
Total derivative assets	230	181
Total assets on a recurring basis at fair value	39,081	38,631
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	1,676	1,777
Netting adjustments	(466)	(473)
Total derivative liabilities	1,210	1,304
Total liabilities on a recurring basis at fair value	2,002	2,108
Recurring | Short positions
LIABILITIES MEASURED ON A RECURRING BASIS
Short positions	792	804
Recurring | Interest rate
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	132	173
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	1,086	985
Recurring | Foreign exchange
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	94	89
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	74	73
Recurring | Commodity
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	531	721
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	510	698
Recurring | Credit
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	0	0
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	1	1
Recurring | Other
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	5	16
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	5	20
Recurring | Agency residential collateralized mortgage obligations
ASSETS MEASURED ON A RECURRING BASIS
Total securities available for sale	15,276	15,478
Recurring | Mortgage-backed securities
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	278	340
Recurring | U.S. Treasury, agencies and corporations
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	747	685
Total securities available for sale	8,995	9,026
Recurring | States and political subdivisions
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	118	93
Recurring | Agency residential mortgage-backed securities | Mortgage-backed securities
ASSETS MEASURED ON A RECURRING BASIS
Total securities available for sale	4,243	3,589
Recurring | Agency commercial mortgage-backed securities
ASSETS MEASURED ON A RECURRING BASIS
Total securities available for sale	8,946	9,092
Recurring | Other securities
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	67	21
Total securities available for sale	0	0
Recurring | Direct
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	0	0
Recurring | Principal Investments
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	16	17
Recurring | Equity Investments, Direct
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	8	2
Recurring | Equity Investments
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	54	46
Recurring | Level 1
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	52	0
Commercial loans	0	0
Total trading account assets	52	0
Total securities available for sale	0	0
Total other investments	0	0
Loans, net of unearned income (residential)	0	0
Loans held for sale (residential)	0	0
Derivative assets	74	74
Netting adjustments	0	0
Total derivative assets	74	74
Total assets on a recurring basis at fair value	126	74
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	54	58
Netting adjustments	0	0
Total derivative liabilities	54	58
Total liabilities on a recurring basis at fair value	82	88
Recurring | Level 1 | Short positions
LIABILITIES MEASURED ON A RECURRING BASIS
Short positions	28	30
Recurring | Level 1 | Interest rate
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	0	0
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	0	0
Recurring | Level 1 | Foreign exchange
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	74	74
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	54	58
Recurring | Level 1 | Commodity
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	0	0
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	0	0
Recurring | Level 1 | Credit
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	0	0
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	0	0
Recurring | Level 1 | Other
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	0	0
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	0	0
Recurring | Level 1 | Agency residential collateralized mortgage obligations
ASSETS MEASURED ON A RECURRING BASIS
Total securities available for sale	0	0
Recurring | Level 1 | Mortgage-backed securities
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	0	0
Recurring | Level 1 | U.S. Treasury, agencies and corporations
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	0	0
Total securities available for sale	0	0
Recurring | Level 1 | States and political subdivisions
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	0	0
Recurring | Level 1 | Agency residential mortgage-backed securities | Mortgage-backed securities
ASSETS MEASURED ON A RECURRING BASIS
Total securities available for sale	0	0
Recurring | Level 1 | Agency commercial mortgage-backed securities
ASSETS MEASURED ON A RECURRING BASIS
Total securities available for sale	0	0
Recurring | Level 1 | Other securities
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	52	0
Total securities available for sale	0	0
Recurring | Level 1 | Direct
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	0	0
Recurring | Level 1 | Principal Investments
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	0	0
Recurring | Level 1 | Equity Investments, Direct
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	0	0
Recurring | Level 1 | Equity Investments
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	0	0
Recurring | Level 2
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	1,158	1,139
Commercial loans	9	3
Total trading account assets	1,167	1,142
Total securities available for sale	37,460	37,185
Total other investments	6	0
Loans, net of unearned income (residential)	0	0
Loans held for sale (residential)	91	51
Derivative assets	689	925
Netting adjustments	0	0
Total derivative assets	689	925
Total assets on a recurring basis at fair value	39,413	39,303
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	1,622	1,719
Netting adjustments	0	0
Total derivative liabilities	1,622	1,719
Total liabilities on a recurring basis at fair value	2,386	2,493
Recurring | Level 2 | Short positions
LIABILITIES MEASURED ON A RECURRING BASIS
Short positions	764	774
Recurring | Level 2 | Interest rate
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	134	175
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	1,086	985
Recurring | Level 2 | Foreign exchange
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	20	15
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	20	15
Recurring | Level 2 | Commodity
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	531	721
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	510	698
Recurring | Level 2 | Credit
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	0	0
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	1	1
Recurring | Level 2 | Other
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	4	14
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	5	20
Recurring | Level 2 | Agency residential collateralized mortgage obligations
ASSETS MEASURED ON A RECURRING BASIS
Total securities available for sale	15,276	15,478
Recurring | Level 2 | Mortgage-backed securities
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	278	340
Recurring | Level 2 | U.S. Treasury, agencies and corporations
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	747	685
Total securities available for sale	8,995	9,026
Recurring | Level 2 | States and political subdivisions
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	118	93
Recurring | Level 2 | Agency residential mortgage-backed securities | Mortgage-backed securities
ASSETS MEASURED ON A RECURRING BASIS
Total securities available for sale	4,243	3,589
Recurring | Level 2 | Agency commercial mortgage-backed securities
ASSETS MEASURED ON A RECURRING BASIS
Total securities available for sale	8,946	9,092
Recurring | Level 2 | Other securities
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	15	21
Total securities available for sale	0	0
Recurring | Level 2 | Direct
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	0	0
Recurring | Level 2 | Principal Investments
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	0	0
Recurring | Level 2 | Equity Investments, Direct
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	6	0
Recurring | Level 2 | Equity Investments
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	6	0
Recurring | Level 3
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	0	0
Commercial loans	0	0
Total trading account assets	0	0
Total securities available for sale	0	0
Total other investments	2	2
Loans, net of unearned income (residential)	11	9
Loans held for sale (residential)	0	0
Derivative assets	(1)	0
Netting adjustments	0	0
Total derivative assets	(1)	0
Total assets on a recurring basis at fair value	12	11
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	0	0
Netting adjustments	0	0
Total derivative liabilities	0	0
Total liabilities on a recurring basis at fair value	0	0
Recurring | Level 3 | Short positions
LIABILITIES MEASURED ON A RECURRING BASIS
Short positions	0	0
Recurring | Level 3 | Interest rate
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	(2)	(2)
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	0	0
Recurring | Level 3 | Foreign exchange
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	0	0
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	0	0
Recurring | Level 3 | Commodity
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	0	0
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	0	0
Recurring | Level 3 | Credit
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	0	0
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	0	0
Recurring | Level 3 | Other
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets		2
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	0	0
Recurring | Level 3 | Agency residential collateralized mortgage obligations
ASSETS MEASURED ON A RECURRING BASIS
Total securities available for sale	0	0
Recurring | Level 3 | Mortgage-backed securities
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	0	0
Recurring | Level 3 | U.S. Treasury, agencies and corporations
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	0	0
Total securities available for sale	0	0
Recurring | Level 3 | States and political subdivisions
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	0	0
Recurring | Level 3 | Agency residential mortgage-backed securities | Mortgage-backed securities
ASSETS MEASURED ON A RECURRING BASIS
Total securities available for sale	0	0
Recurring | Level 3 | Agency commercial mortgage-backed securities
ASSETS MEASURED ON A RECURRING BASIS
Total securities available for sale	0	0
Recurring | Level 3 | Other securities
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	0	0
Total securities available for sale	0	0
Recurring | Level 3 | Direct
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	0	0
Recurring | Level 3 | Principal Investments
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	0	0
Recurring | Level 3 | Equity Investments, Direct
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	2	2
Recurring | Level 3 | Equity Investments
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	2	2
Recurring | Measured at NAV | Indirect investments | Variable Interest Entity, Not Primary Beneficiary
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	16	17
Recurring | Measured at NAV | Equity Investments Direct, NAV
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	42	40
Recurring | Measured at NAV | Equity Investments Indirect, NAV
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	$ 4	$ 4