Fair Value Measurements - Schedule of Fair Value of Assets and Liabilities Measured on Recurring Basis (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	$ 1,404	$ 1,142
Total securities available for sale	34,169	37,185
Loans, net of unearned income (residential)	105,346	112,606
Netting adjustments	(499)	(818)
Total derivative assets	191	181
LIABILITIES MEASURED ON A RECURRING BASIS
Netting adjustments	(343)	(473)
U.S. Treasury, agencies and corporations
ASSETS MEASURED ON A RECURRING BASIS
Total securities available for sale	9,223	9,026
Agency residential mortgage-backed securities
ASSETS MEASURED ON A RECURRING BASIS
Total securities available for sale	7,321	3,589
Agency commercial mortgage-backed securities
ASSETS MEASURED ON A RECURRING BASIS
Total securities available for sale	4,634	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	1,399	1,139
Commercial loans	5	3
Total trading account assets	1,404	1,142
Total securities available for sale	34,169	37,185
Total other investments	73	63
Loans, net of unearned income (residential)	9	9
Loans held for sale (residential)	61	51
Derivative assets	690	999
Netting adjustments	(499)	(818)
Total derivative assets	191	181
Total assets on a recurring basis at fair value	35,907	38,631
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	1,183	1,777
Netting adjustments	(343)	(473)
Total derivative liabilities	840	1,304
Total liabilities on a recurring basis at fair value	1,699	2,108
Recurring | Short positions
LIABILITIES MEASURED ON A RECURRING BASIS
Short positions	859	804
Recurring | Interest rate
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	186	173
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	695	985
Recurring | Foreign exchange
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	70	89
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	63	73
Recurring | Commodity
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	423	721
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	401	698
Recurring | Credit
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	0	0
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	17	1
Recurring | Other
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	11	16
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	7	20
Recurring | Agency residential collateralized mortgage obligations
ASSETS MEASURED ON A RECURRING BASIS
Total securities available for sale	12,991	15,478
Recurring | Other mortgage-backed securities
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	355	340
Recurring | U.S. Treasury, agencies and corporations
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	928	685
Total securities available for sale	9,223	9,026
Recurring | States and political subdivisions
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	102	93
Recurring | Agency residential mortgage-backed securities | Other mortgage-backed securities
ASSETS MEASURED ON A RECURRING BASIS
Total securities available for sale	7,321	3,589
Recurring | Agency commercial mortgage-backed securities
ASSETS MEASURED ON A RECURRING BASIS
Total securities available for sale	4,634	9,092
Recurring | Other securities
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	14	21
Total securities available for sale	0	0
Recurring | Principal Investments
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	16	17
Recurring | Direct
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	0	0
Recurring | Equity Investments
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	57	46
Recurring | Equity Investments, Direct
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	9	2
Recurring | Level 1
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	0	0
Loans, net of unearned income (residential)	0	0
Loans held for sale (residential)	0	0
Derivative assets	48	74
Netting adjustments	0	0
Total derivative assets	48	74
Total assets on a recurring basis at fair value	48	74
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	41	58
Netting adjustments	0	0
Total derivative liabilities	41	58
Total liabilities on a recurring basis at fair value	120	88
Recurring | Level 1 | Short positions
LIABILITIES MEASURED ON A RECURRING BASIS
Short positions	79	30
Recurring | Level 1 | Interest rate
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	0	0
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	1	0
Recurring | Level 1 | Foreign exchange
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	48	74
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	40	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 | Other 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 | Other 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	0	0
Total securities available for sale	0	0
Recurring | Level 1 | Principal Investments
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	0	0
Recurring | Level 1 | 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 1 | Equity Investments, Direct
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	0	0
Recurring | Level 2
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	1,399	1,139
Commercial loans	5	3
Total trading account assets	1,404	1,142
Total securities available for sale	34,169	37,185
Total other investments	6	0
Loans, net of unearned income (residential)	0	0
Loans held for sale (residential)	61	51
Derivative assets	634	925
Netting adjustments	0	0
Total derivative assets	634	925
Total assets on a recurring basis at fair value	36,274	39,303
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	1,142	1,719
Netting adjustments	0	0
Total derivative liabilities	1,142	1,719
Total liabilities on a recurring basis at fair value	1,922	2,493
Recurring | Level 2 | Short positions
LIABILITIES MEASURED ON A RECURRING BASIS
Short positions	780	774
Recurring | Level 2 | Interest rate
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	179	175
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	694	985
Recurring | Level 2 | Foreign exchange
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	22	15
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	23	15
Recurring | Level 2 | Commodity
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	423	721
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	401	698
Recurring | Level 2 | Credit
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	0	0
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	17	1
Recurring | Level 2 | Other
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	10	14
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	7	20
Recurring | Level 2 | Agency residential collateralized mortgage obligations
ASSETS MEASURED ON A RECURRING BASIS
Total securities available for sale	12,991	15,478
Recurring | Level 2 | Other mortgage-backed securities
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	355	340
Recurring | Level 2 | U.S. Treasury, agencies and corporations
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	928	685
Total securities available for sale	9,223	9,026
Recurring | Level 2 | States and political subdivisions
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	102	93
Recurring | Level 2 | Agency residential mortgage-backed securities | Other mortgage-backed securities
ASSETS MEASURED ON A RECURRING BASIS
Total securities available for sale	7,321	3,589
Recurring | Level 2 | Agency commercial mortgage-backed securities
ASSETS MEASURED ON A RECURRING BASIS
Total securities available for sale	4,634	9,092
Recurring | Level 2 | Other securities
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	14	21
Total securities available for sale	0	0
Recurring | Level 2 | Principal Investments
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	0	0
Recurring | Level 2 | Direct
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	0	0
Recurring | Level 2 | Equity Investments
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	6	0
Recurring | Level 2 | Equity Investments, Direct
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	3	2
Loans, net of unearned income (residential)	9	9
Loans held for sale (residential)	0	0
Derivative assets	8	0
Netting adjustments	0	0
Total derivative assets	8	0
Total assets on a recurring basis at fair value	20	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	7	(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 | Other 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 | Other 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 | Principal Investments
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	0	0
Recurring | Level 3 | Direct
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	0	0
Recurring | Level 3 | Equity Investments
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	3	2
Recurring | Level 3 | Equity Investments, Direct
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	3	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	45	40
Recurring | Measured at NAV | Equity Investments Indirect, NAV
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	$ 3	$ 4