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Fair Value Measurements - Fair Value of Assets and Liabilities Measured on Recurring Basis (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	$ 1,142	$ 829
Securities available for sale	37,185	39,117
Loans, net of unearned income	112,606	119,394
Derivative assets	999	1,781
Netting adjustments	(818)	(757)
Total derivative assets	181	1,024
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	1,777	2,750
Netting adjustments	(473)	(1,262)
U.S. Treasury, agencies and corporations
ASSETS MEASURED ON A RECURRING BASIS
Securities available for sale	9,026	9,415
Other securities
ASSETS MEASURED ON A RECURRING BASIS
Securities available for sale	0	0
Agency residential mortgage-backed securities
ASSETS MEASURED ON A RECURRING BASIS
Securities available for sale	3,589	3,920
Agency commercial mortgage-backed securities
ASSETS MEASURED ON A RECURRING BASIS
Securities available for sale	9,092	9,349
Fair Value, Recurring
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	1,139	815
Commercial loans	3	14
Total trading account assets	1,142	829
Securities available for sale	37,185	39,117
Total other investments	63	77
Loans, net of unearned income	9	9
Loans held for sale (residential)	51	24
Derivative assets	999	1,781
Netting adjustments	(818)	(757)
Total derivative assets	181	1,024
Total assets on a recurring basis at fair value	38,631	41,080
LIABILITIES MEASURED ON A RECURRING BASIS
Total liabilities on a recurring basis at fair value	2,108	2,123
Fair Value, Recurring | Agency residential collateralized mortgage obligations
ASSETS MEASURED ON A RECURRING BASIS
Securities available for sale	15,478	16,433
Fair Value, Recurring | U.S. Treasury, agencies and corporations
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	685	698
Securities available for sale	9,026	9,415
Fair Value, Recurring | States and political subdivisions
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	93	33
Securities available for sale	0	0
Fair Value, Recurring | Other securities
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	21	0
Securities available for sale	0	0
Fair Value, Recurring | Agency commercial mortgage-backed securities
ASSETS MEASURED ON A RECURRING BASIS
Securities available for sale	9,092	9,349
Fair Value, Recurring | Principal investments: Direct
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	0	1
Fair Value, Recurring | Principal Investments
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	17	35
Fair Value, Recurring | Equity Investments, Direct
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	2	6
Fair Value, Recurring | Equity Investments
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	46	42
Fair Value, Recurring | Mortgage-backed securities
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	340	84
Fair Value, Recurring | Mortgage-backed securities | Agency residential mortgage-backed securities
ASSETS MEASURED ON A RECURRING BASIS
Securities available for sale	3,589	3,920
Fair Value, Recurring | Short positions
LIABILITIES MEASURED ON A RECURRING BASIS
Short positions	804	635
Fair Value, Recurring | Long positions
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	1,777	2,750
Netting adjustments	(473)	(1,262)
Total derivative liabilities	1,304	1,488
Fair Value, Recurring | Interest rate
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	173	303
Fair Value, Recurring | Interest rate | Long positions
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	985	1,307
Fair Value, Recurring | Foreign exchange
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	89	136
Fair Value, Recurring | Foreign exchange | Long positions
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	73	131
Fair Value, Recurring | Commodity
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	721	1,328
Fair Value, Recurring | Commodity | Long positions
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	698	1,304
Fair Value, Recurring | Credit
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	0	1
Fair Value, Recurring | Credit | Long positions
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	1	3
Fair Value, Recurring | Other
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	16	13
Fair Value, Recurring | Other | Long positions
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	20	5
Level 1 | Fair Value, Recurring
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	0	0
Commercial loans	0	0
Total trading account assets	0	0
Securities available for sale	0	0
Total other investments	0	4
Loans, net of unearned income	0	0
Loans held for sale (residential)	0	0
Derivative assets	74	112
Netting adjustments	0	0
Total derivative assets	74	112
Total assets on a recurring basis at fair value	74	116
LIABILITIES MEASURED ON A RECURRING BASIS
Total liabilities on a recurring basis at fair value	88	233
Level 1 | Fair Value, Recurring | Agency residential collateralized mortgage obligations
ASSETS MEASURED ON A RECURRING BASIS
Securities available for sale	0	0
Level 1 | Fair Value, Recurring | U.S. Treasury, agencies and corporations
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	0	0
Securities available for sale	0	0
Level 1 | Fair Value, Recurring | States and political subdivisions
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	0	0
Securities available for sale	0	0
Level 1 | Fair Value, Recurring | Other securities
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	0	0
Securities available for sale	0	0
Level 1 | Fair Value, Recurring | Agency commercial mortgage-backed securities
ASSETS MEASURED ON A RECURRING BASIS
Securities available for sale	0	0
Level 1 | Fair Value, Recurring | Principal investments: Direct
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	0	0
Level 1 | Fair Value, Recurring | Principal Investments
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	0	0
Level 1 | Fair Value, Recurring | Equity Investments, Direct
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	0	4
Level 1 | Fair Value, Recurring | Equity Investments
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	0	4
Level 1 | Fair Value, Recurring | Mortgage-backed securities
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	0	0
Level 1 | Fair Value, Recurring | Mortgage-backed securities | Agency residential mortgage-backed securities
ASSETS MEASURED ON A RECURRING BASIS
Securities available for sale	0	0
Level 1 | Fair Value, Recurring | Short positions
LIABILITIES MEASURED ON A RECURRING BASIS
Short positions	30	126
Level 1 | Fair Value, Recurring | Long positions
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	58	107
Netting adjustments	0	0
Total derivative liabilities	58	107
Level 1 | Fair Value, Recurring | Interest rate
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	0	0
Level 1 | Fair Value, Recurring | Interest rate | Long positions
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	0	0
Level 1 | Fair Value, Recurring | Foreign exchange
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	74	112
Level 1 | Fair Value, Recurring | Foreign exchange | Long positions
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	58	107
Level 1 | Fair Value, Recurring | Commodity
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	0	0
Level 1 | Fair Value, Recurring | Commodity | Long positions
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	0	0
Level 1 | Fair Value, Recurring | Credit
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	0	0
Level 1 | Fair Value, Recurring | Credit | Long positions
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	0	0
Level 1 | Fair Value, Recurring | Other
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	0	0
Level 1 | Fair Value, Recurring | Other | Long positions
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	0	0
Level 2 | Fair Value, Recurring
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	1,139	815
Commercial loans	3	14
Total trading account assets	1,142	829
Securities available for sale	37,185	39,117
Total other investments	0	0
Loans, net of unearned income	0	0
Loans held for sale (residential)	51	24
Derivative assets	925	1,666
Netting adjustments	0	0
Total derivative assets	925	1,666
Total assets on a recurring basis at fair value	39,303	41,636
LIABILITIES MEASURED ON A RECURRING BASIS
Total liabilities on a recurring basis at fair value	2,493	3,149
Level 2 | Fair Value, Recurring | Agency residential collateralized mortgage obligations
ASSETS MEASURED ON A RECURRING BASIS
Securities available for sale	15,478	16,433
Level 2 | Fair Value, Recurring | U.S. Treasury, agencies and corporations
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	685	698
Securities available for sale	9,026	9,415
Level 2 | Fair Value, Recurring | States and political subdivisions
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	93	33
Securities available for sale	0	0
Level 2 | Fair Value, Recurring | Other securities
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	21	0
Securities available for sale	0	0
Level 2 | Fair Value, Recurring | Agency commercial mortgage-backed securities
ASSETS MEASURED ON A RECURRING BASIS
Securities available for sale	9,092	9,349
Level 2 | Fair Value, Recurring | Principal investments: Direct
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	0	0
Level 2 | Fair Value, Recurring | Principal Investments
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	0	0
Level 2 | Fair Value, Recurring | Equity Investments, Direct
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	0	0
Level 2 | Fair Value, Recurring | Equity Investments
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	0	0
Level 2 | Fair Value, Recurring | Mortgage-backed securities
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	340	84
Level 2 | Fair Value, Recurring | Mortgage-backed securities | Agency residential mortgage-backed securities
ASSETS MEASURED ON A RECURRING BASIS
Securities available for sale	3,589	3,920
Level 2 | Fair Value, Recurring | Short positions
LIABILITIES MEASURED ON A RECURRING BASIS
Short positions	774	509
Level 2 | Fair Value, Recurring | Long positions
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	1,719	2,640
Netting adjustments	0	0
Total derivative liabilities	1,719	2,640
Level 2 | Fair Value, Recurring | Interest rate
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	175	301
Level 2 | Fair Value, Recurring | Interest rate | Long positions
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	985	1,307
Level 2 | Fair Value, Recurring | Foreign exchange
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	15	24
Level 2 | Fair Value, Recurring | Foreign exchange | Long positions
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	15	24
Level 2 | Fair Value, Recurring | Commodity
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	721	1,328
Level 2 | Fair Value, Recurring | Commodity | Long positions
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	698	1,304
Level 2 | Fair Value, Recurring | Credit
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	0	0
Level 2 | Fair Value, Recurring | Credit | Long positions
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	1	0
Level 2 | Fair Value, Recurring | Other
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	14	13
Level 2 | Fair Value, Recurring | Other | Long positions
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	20	5
Level 3 | Fair Value, Recurring
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	0	0
Commercial loans	0	0
Total trading account assets	0	0
Securities available for sale	0	0
Total other investments	2	3
Loans, net of unearned income	9	9
Loans held for sale (residential)	0	0
Derivative assets	0	3
Netting adjustments	0	0
Total derivative assets	0	3
Total assets on a recurring basis at fair value	11	15
LIABILITIES MEASURED ON A RECURRING BASIS
Total liabilities on a recurring basis at fair value	0	3
Level 3 | Fair Value, Recurring | Agency residential collateralized mortgage obligations
ASSETS MEASURED ON A RECURRING BASIS
Securities available for sale	0	0
Level 3 | Fair Value, Recurring | U.S. Treasury, agencies and corporations
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	0	0
Securities available for sale	0	0
Level 3 | Fair Value, Recurring | States and political subdivisions
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	0	0
Securities available for sale	0	0
Level 3 | Fair Value, Recurring | Other securities
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	0	0
Securities available for sale	0	0
Level 3 | Fair Value, Recurring | Agency commercial mortgage-backed securities
ASSETS MEASURED ON A RECURRING BASIS
Securities available for sale	0	0
Level 3 | Fair Value, Recurring | Principal investments: Direct
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	0	1
Level 3 | Fair Value, Recurring | Principal Investments
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	0	1
Level 3 | Fair Value, Recurring | Equity Investments, Direct
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	2	2
Level 3 | Fair Value, Recurring | Equity Investments
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	2	2
Level 3 | Fair Value, Recurring | Mortgage-backed securities
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	0	0
Level 3 | Fair Value, Recurring | Mortgage-backed securities | Agency residential mortgage-backed securities
ASSETS MEASURED ON A RECURRING BASIS
Securities available for sale	0	0
Level 3 | Fair Value, Recurring | Short positions
LIABILITIES MEASURED ON A RECURRING BASIS
Short positions	0	0
Level 3 | Fair Value, Recurring | Long positions
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	0	3
Netting adjustments	0	0
Total derivative liabilities	0	3
Level 3 | Fair Value, Recurring | Interest rate
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	(2)	2
Level 3 | Fair Value, Recurring | Interest rate | Long positions
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	0	0
Level 3 | Fair Value, Recurring | Foreign exchange
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	0	0
Level 3 | Fair Value, Recurring | Foreign exchange | Long positions
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	0	0
Level 3 | Fair Value, Recurring | Commodity
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	0	0
Level 3 | Fair Value, Recurring | Commodity | Long positions
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	0	0
Level 3 | Fair Value, Recurring | Credit
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	0	1
Level 3 | Fair Value, Recurring | Credit | Long positions
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	0	3
Level 3 | Fair Value, Recurring | Other
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	2	0
Level 3 | Fair Value, Recurring | Other | Long positions
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	0	0
Measured at NAV | Fair Value, Recurring | Principal investments: Indirect | Variable Interest Entity, Not Primary Beneficiary
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	17	34
Measured at NAV | Fair Value, Recurring | Equity Investments, Direct, NAV
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	40	32
Measured at NAV | Fair Value, Recurring | Equity Investments, Indirect, NAV
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	$ 4	$ 4

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Fair value of investment other than investment in equity security, investment in debt security and equity method investment. Includes, but is not limited to, investment in certain entities that calculate net asset value per share. Example includes, but is not limited to, investment in hedge fund, venture capital fund, private equity fund, and real estate partnership or fund.

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Amount excluding accrued interest, of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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