Fair Value Measurements - Fair Value of Assets and Liabilities Measured on Recurring Basis (Details) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	$ 848	$ 701
Securities available for sale	43,681	45,364
Derivative assets, netting adjustments	(330)	(284)
Total derivative assets	2,739	1,962
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities, netting adjustments	(2,689)	(1,526)
U.S. Treasury, agencies and corporations
ASSETS MEASURED ON A RECURRING BASIS
Securities available for sale	9,638	9,472
Other securities
ASSETS MEASURED ON A RECURRING BASIS
Securities available for sale	1	0
Agency residential mortgage-backed securities
ASSETS MEASURED ON A RECURRING BASIS
Securities available for sale	4,744	5,122
Mortgage-backed securities | Agency commercial mortgage-backed securities
ASSETS MEASURED ON A RECURRING BASIS
Securities available for sale	8,659	9,651
Other
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets, gross	1
Recurring
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	844	683
Commercial loans	4	18
Total trading account assets	848	701
Securities available for sale	43,681	45,364
Total other investments	90	105
Loans, net of unearned income (residential)	11	11
Loans held for sale (residential)	114	281
Derivative assets, gross	3,069	2,246
Derivative assets, netting adjustments	(330)	(284)
Total derivative assets	2,739	1,962
Total assets at fair value	47,483	48,424
LIABILITIES MEASURED ON A RECURRING BASIS
Total liabilities on a recurring basis at fair value	1,320	749
Recurring | U.S. Treasury, agencies and corporations
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	627	530
Securities available for sale	9,638	9,472
Recurring | States and political subdivisions
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	76	96
Securities available for sale	0	0
Recurring | Other securities
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	14	13
Securities available for sale	1	0
Recurring | Agency commercial mortgage-backed securities
ASSETS MEASURED ON A RECURRING BASIS
Securities available for sale	8,659	9,651
Recurring | Principal investments, Direct
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	1	1
Recurring | Principal Investments
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	45	46
Recurring | Equity Investments, Direct
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	13	33
Recurring | Equity Investments
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	45	59
Recurring | Mortgage-backed securities
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	127	44
Recurring | Mortgage-backed securities | Agency residential mortgage-backed securities
ASSETS MEASURED ON A RECURRING BASIS
Securities available for sale	4,744	5,122
Recurring | Short positions
LIABILITIES MEASURED ON A RECURRING BASIS
Short positions	722	588
Recurring | Long positions
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities, gross	3,287	1,687
Derivative liabilities, netting adjustments	(2,689)	(1,526)
Total derivative liabilities	598	161
Recurring | Interest rate
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets, gross	331	807
Recurring | Interest rate | Long positions
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities, gross	562	253
Recurring | Foreign exchange
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets, gross	102	81
Recurring | Foreign exchange | Long positions
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities, gross	96	76
Recurring | Commodity
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets, gross	2,613	1,330
Recurring | Commodity | Long positions
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities, gross	2,613	1,335
Recurring | Credit
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets, gross	1	1
Recurring | Credit | Long positions
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities, gross	6	12
Recurring | Other
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets, gross	22	27
Recurring | Other | Long positions
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities, gross	10	11
Level 1 | 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	6	24
Loans, net of unearned income (residential)	0	0
Loans held for sale (residential)	0	0
Derivative assets, gross	92	71
Derivative assets, netting adjustments	0	0
Total derivative assets	92	71
Total assets at fair value	98	95
LIABILITIES MEASURED ON A RECURRING BASIS
Total liabilities on a recurring basis at fair value	154	141
Level 1 | 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 | 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 | Recurring | Other securities
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	0	0
Securities available for sale	0	0
Level 1 | Recurring | Agency commercial mortgage-backed securities
ASSETS MEASURED ON A RECURRING BASIS
Securities available for sale	0	0
Level 1 | Recurring | Principal investments, Direct
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	0	0
Level 1 | Recurring | Principal Investments
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	0	0
Level 1 | Recurring | Equity Investments, Direct
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	6	24
Level 1 | Recurring | Equity Investments
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	6	24
Level 1 | Recurring | Mortgage-backed securities
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	0	0
Level 1 | Recurring | Mortgage-backed securities | Agency residential mortgage-backed securities
ASSETS MEASURED ON A RECURRING BASIS
Securities available for sale	0	0
Level 1 | Recurring | Short positions
LIABILITIES MEASURED ON A RECURRING BASIS
Short positions	69	75
Level 1 | Recurring | Long positions
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities, gross	85	66
Derivative liabilities, netting adjustments	0	0
Total derivative liabilities	85	66
Level 1 | Recurring | Interest rate
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets, gross	0	0
Level 1 | Recurring | Interest rate | Long positions
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities, gross	0	0
Level 1 | Recurring | Foreign exchange
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets, gross	92	71
Level 1 | Recurring | Foreign exchange | Long positions
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities, gross	85	66
Level 1 | Recurring | Commodity
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets, gross	0	0
Level 1 | Recurring | Commodity | Long positions
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities, gross	0	0
Level 1 | Recurring | Credit
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets, gross	0	0
Level 1 | Recurring | Credit | Long positions
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities, gross	0	0
Level 1 | Recurring | Other
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets, gross	0	0
Level 1 | Recurring | Other | Long positions
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities, gross	0	0
Level 2 | Recurring
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	844	683
Commercial loans	4	18
Total trading account assets	848	701
Securities available for sale	43,681	45,364
Total other investments	0	0
Loans, net of unearned income (residential)	0	0
Loans held for sale (residential)	114	281
Derivative assets, gross	2,932	2,136
Derivative assets, netting adjustments	0	0
Total derivative assets	2,932	2,136
Total assets at fair value	47,575	48,482
LIABILITIES MEASURED ON A RECURRING BASIS
Total liabilities on a recurring basis at fair value	3,846	2,127
Level 2 | Recurring | U.S. Treasury, agencies and corporations
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	627	530
Securities available for sale	9,638	9,472
Level 2 | Recurring | States and political subdivisions
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	76	96
Securities available for sale	0	0
Level 2 | Recurring | Other securities
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	14	13
Securities available for sale	1	0
Level 2 | Recurring | Agency commercial mortgage-backed securities
ASSETS MEASURED ON A RECURRING BASIS
Securities available for sale	8,659	9,651
Level 2 | Recurring | Principal investments, Direct
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	0	0
Level 2 | Recurring | Principal Investments
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	0	0
Level 2 | Recurring | Equity Investments, Direct
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	0	0
Level 2 | Recurring | Equity Investments
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	0	0
Level 2 | Recurring | Mortgage-backed securities
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	127	44
Level 2 | Recurring | Mortgage-backed securities | Agency residential mortgage-backed securities
ASSETS MEASURED ON A RECURRING BASIS
Securities available for sale	4,744	5,122
Level 2 | Recurring | Short positions
LIABILITIES MEASURED ON A RECURRING BASIS
Short positions	653	513
Level 2 | Recurring | Long positions
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities, gross	3,193	1,614
Derivative liabilities, netting adjustments	0	0
Total derivative liabilities	3,193	1,614
Level 2 | Recurring | Interest rate
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets, gross	288	774
Level 2 | Recurring | Interest rate | Long positions
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities, gross	562	253
Level 2 | Recurring | Foreign exchange
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets, gross	10	10
Level 2 | Recurring | Foreign exchange | Long positions
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities, gross	11	10
Level 2 | Recurring | Commodity
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets, gross	2,613	1,330
Level 2 | Recurring | Commodity | Long positions
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities, gross	2,613	1,335
Level 2 | Recurring | Credit
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets, gross	0	0
Level 2 | Recurring | Credit | Long positions
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities, gross	0	5
Level 2 | Recurring | Other
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets, gross	21	22
Level 2 | Recurring | Other | Long positions
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities, gross	7	11
Level 3 | 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	8	10
Loans, net of unearned income (residential)	11	11
Loans held for sale (residential)	0	0
Derivative assets, gross	45	39
Derivative assets, netting adjustments	0	0
Total derivative assets	45	39
Total assets at fair value	64	60
LIABILITIES MEASURED ON A RECURRING BASIS
Total liabilities on a recurring basis at fair value	9	7
Level 3 | 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 | 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 | Recurring | Other securities
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	0	0
Securities available for sale	0	0
Level 3 | Recurring | Agency commercial mortgage-backed securities
ASSETS MEASURED ON A RECURRING BASIS
Securities available for sale	0	0
Level 3 | Recurring | Principal investments, Direct
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	1	1
Level 3 | Recurring | Principal Investments
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	1	1
Level 3 | Recurring | Equity Investments, Direct
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	7	9
Level 3 | Recurring | Equity Investments
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	7	9
Level 3 | Recurring | Mortgage-backed securities
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	0	0
Level 3 | Recurring | Mortgage-backed securities | Agency residential mortgage-backed securities
ASSETS MEASURED ON A RECURRING BASIS
Securities available for sale	0	0
Level 3 | Recurring | Short positions
LIABILITIES MEASURED ON A RECURRING BASIS
Short positions	0	0
Level 3 | Recurring | Long positions
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities, gross	9	7
Derivative liabilities, netting adjustments	0	0
Total derivative liabilities	9	7
Level 3 | Recurring | Interest rate
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets, gross	43	33
Level 3 | Recurring | Interest rate | Long positions
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities, gross	0	0
Level 3 | Recurring | Foreign exchange
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets, gross	0	0
Level 3 | Recurring | Foreign exchange | Long positions
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities, gross	0	0
Level 3 | Recurring | Commodity
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets, gross	0	0
Level 3 | Recurring | Commodity | Long positions
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities, gross	0	0
Level 3 | Recurring | Credit
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets, gross	1	1
Level 3 | Recurring | Credit | Long positions
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities, gross	6	7
Level 3 | Recurring | Other
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets, gross		5
Level 3 | Recurring | Other | Long positions
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities, gross	3	0
Measured at NAV | Recurring | Equity Investments Direct, NAV
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	28	21
Measured at NAV | Recurring | Equity Investments Indirect, NAV
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	4	5
Agency residential collateralized mortgage obligations | Recurring
ASSETS MEASURED ON A RECURRING BASIS
Securities available for sale	20,639	21,119
Agency residential collateralized mortgage obligations | Level 1 | Recurring
ASSETS MEASURED ON A RECURRING BASIS
Securities available for sale	0	0
Agency residential collateralized mortgage obligations | Level 2 | Recurring
ASSETS MEASURED ON A RECURRING BASIS
Securities available for sale	20,639	21,119
Agency residential collateralized mortgage obligations | Level 3 | Recurring
ASSETS MEASURED ON A RECURRING BASIS
Securities available for sale	0	0
Variable Interest Entity, Not Primary Beneficiary | Measured at NAV | Recurring | Principal Investments, Indirect
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	$ 44	$ 45