FAIR VALUE MEASUREMENTS - Schedule of Fair Value Measurements (Details) - USD ($) $ in Millions		Mar. 31, 2024	Dec. 31, 2023
Assets
Fair Value	[1]	$ 31,187	$ 29,777
Loans held for sale, at fair value		505	676
Mortgage servicing rights		1,564	1,552
Derivative assets		1,591	1,593
Equity securities, at fair value		118	115
Short-term investments		21
Total assets		34,986	33,713
Liabilities
Total derivative liabilities		2,276	2,183
Short-term borrowed funds		9
Total liabilities		2,285	2,183
Equity securities excluded from investments		178	173
Interest rate contracts
Assets
Derivative assets		481	464
Liabilities
Total derivative liabilities		1,316	1,149
Foreign exchange contracts
Assets
Derivative assets		389	434
Liabilities
Total derivative liabilities		290	378
Commodities contracts
Assets
Derivative assets		711	685
Liabilities
Total derivative liabilities		665	640
TBA contracts
Assets
Derivative assets		2	3
Liabilities
Total derivative liabilities		5	16
Other contracts
Assets
Derivative assets		8	7
Liabilities
Total derivative liabilities		0	0
Level 1
Assets
Fair Value		4,770	4,380
Loans held for sale, at fair value		0	0
Derivative assets		0	0
Equity securities, at fair value		118	115
Short-term investments		10
Total assets		4,898	4,495
Liabilities
Total derivative liabilities		0	0
Short-term borrowed funds		0
Total liabilities		0	0
Level 1 | Interest rate contracts
Assets
Derivative assets		0	0
Liabilities
Total derivative liabilities		0	0
Level 1 | Foreign exchange contracts
Assets
Derivative assets		0	0
Liabilities
Total derivative liabilities		0	0
Level 1 | Commodities contracts
Assets
Derivative assets		0	0
Liabilities
Total derivative liabilities		0	0
Level 1 | TBA contracts
Assets
Derivative assets		0	0
Liabilities
Total derivative liabilities		0	0
Level 1 | Other contracts
Assets
Derivative assets		0	0
Liabilities
Total derivative liabilities		0	0
Level 2
Assets
Fair Value		26,417	25,397
Loans held for sale, at fair value		505	676
Derivative assets		1,583	1,586
Equity securities, at fair value		0	0
Short-term investments		11
Total assets		28,516	27,659
Liabilities
Total derivative liabilities		2,276	2,183
Short-term borrowed funds		9
Total liabilities		2,285	2,183
Level 2 | Interest rate contracts
Assets
Derivative assets		481	464
Liabilities
Total derivative liabilities		1,316	1,149
Level 2 | Foreign exchange contracts
Assets
Derivative assets		389	434
Liabilities
Total derivative liabilities		290	378
Level 2 | Commodities contracts
Assets
Derivative assets		711	685
Liabilities
Total derivative liabilities		665	640
Level 2 | TBA contracts
Assets
Derivative assets		2	3
Liabilities
Total derivative liabilities		5	16
Level 2 | Other contracts
Assets
Derivative assets		0	0
Liabilities
Total derivative liabilities		0	0
Level 3
Assets
Fair Value		0	0
Loans held for sale, at fair value		0	0
Derivative assets		8	7
Equity securities, at fair value		0	0
Short-term investments		0
Total assets		1,572	1,559
Liabilities
Total derivative liabilities		0	0
Short-term borrowed funds		0
Total liabilities		0	0
Level 3 | Interest rate contracts
Assets
Derivative assets		0	0
Liabilities
Total derivative liabilities		0	0
Level 3 | Foreign exchange contracts
Assets
Derivative assets		0	0
Liabilities
Total derivative liabilities		0	0
Level 3 | Commodities contracts
Assets
Derivative assets		0	0
Liabilities
Total derivative liabilities		0	0
Level 3 | TBA contracts
Assets
Derivative assets		0	0
Liabilities
Total derivative liabilities		0	0
Level 3 | Other contracts
Assets
Derivative assets		8	7
Liabilities
Total derivative liabilities		0	0
Fair Value Measured at Net Asset Value Per Share
Liabilities
Equity securities excluded from investments		60	58
Unfunded capital commitments		25	28
Mortgage-backed securities
Assets
Fair Value		26,122	24,732
Mortgage-backed securities | Level 1
Assets
Fair Value		0	0
Mortgage-backed securities | Level 2
Assets
Fair Value		26,122	24,732
Mortgage-backed securities | Level 3
Assets
Fair Value		0	0
Collateralized loan obligations
Assets
Fair Value		294	664
Collateralized loan obligations | Level 1
Assets
Fair Value		0	0
Collateralized loan obligations | Level 2
Assets
Fair Value		294	664
Collateralized loan obligations | Level 3
Assets
Fair Value		0	0
State and political subdivisions
Assets
Fair Value		1	1
State and political subdivisions | Level 1
Assets
Fair Value		0	0
State and political subdivisions | Level 2
Assets
Fair Value		1	1
State and political subdivisions | Level 3
Assets
Fair Value		0	0
U.S. Treasury and other
Assets
Fair Value		4,770	4,380
U.S. Treasury and other | Level 1
Assets
Fair Value		4,770	4,380
U.S. Treasury and other | Level 2
Assets
Fair Value		0	0
U.S. Treasury and other | Level 3
Assets
Fair Value		0	0
Residential loans held for sale
Assets
Loans held for sale, at fair value		437	614
Residential loans held for sale | Level 1
Assets
Loans held for sale, at fair value		0	0
Residential loans held for sale | Level 2
Assets
Loans held for sale, at fair value		437	614
Residential loans held for sale | Level 3
Assets
Loans held for sale, at fair value		0	0
Commercial loans held for sale
Assets
Loans held for sale, at fair value		68	62
Commercial loans held for sale | Level 1
Assets
Loans held for sale, at fair value		0	0
Commercial loans held for sale | Level 2
Assets
Loans held for sale, at fair value		68	62
Commercial loans held for sale | Level 3
Assets
Loans held for sale, at fair value		0	0
Mortgage servicing rights
Assets
Mortgage servicing rights		1,564	1,552
Mortgage servicing rights | Level 1
Assets
Mortgage servicing rights		0	0
Mortgage servicing rights | Level 2
Assets
Mortgage servicing rights		0	0
Mortgage servicing rights | Level 3
Assets
Mortgage servicing rights		$ 1,564	$ 1,552

[1] Includes only collateral pledged by the Company where counterparties have the right to sell or pledge the collateral.