FAIR VALUE MEASUREMENTS - Schedule of Fair Value Measurements (Details) - USD ($) $ in Millions		Sep. 30, 2025	Dec. 31, 2024
Assets
Debt securities available for sale	[1]	$ 35,419	$ 32,765
Loans held for sale at fair value		768	825
Mortgage servicing rights		1,430	1,491
Derivative assets		1,523	1,476
Equity securities, at fair value		224	162
Short-term investments		73	53
Total assets		39,437	36,772
Liabilities
Total derivative liabilities		1,286	1,710
Short-term borrowed funds		213	0
Other liabilities		162	101
Total liabilities		1,661	1,811
Equity securities excluded from investments		286	220
Interest rate contracts
Assets
Derivative assets		492	562
Liabilities
Total derivative liabilities		489	910
Foreign exchange contracts
Assets
Derivative assets		563	472
Liabilities
Total derivative liabilities		399	411
Commodities contracts
Assets
Derivative assets		438	429
Liabilities
Total derivative liabilities		381	379
TBA contracts
Assets
Derivative assets		7	10
Liabilities
Total derivative liabilities		13	8
Other contracts
Assets
Derivative assets		23	3
Liabilities
Total derivative liabilities		4	2
Level 1
Assets
Debt securities available for sale		4,514	3,525
Loans held for sale at fair value		0	0
Derivative assets		0	0
Equity securities, at fair value		224	162
Short-term investments		30	40
Total assets		4,768	3,727
Liabilities
Total derivative liabilities		0	0
Short-term borrowed funds		203	0
Other liabilities		0	0
Total liabilities		203	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
Debt securities available for sale		30,905	29,240
Loans held for sale at fair value		768	825
Derivative assets		1,515	1,473
Equity securities, at fair value		0	0
Short-term investments		43	13
Total assets		33,231	31,551
Liabilities
Total derivative liabilities		1,282	1,708
Short-term borrowed funds		10	0
Other liabilities		162	101
Total liabilities		1,454	1,809
Level 2 | Interest rate contracts
Assets
Derivative assets		492	562
Liabilities
Total derivative liabilities		489	910
Level 2 | Foreign exchange contracts
Assets
Derivative assets		563	472
Liabilities
Total derivative liabilities		399	411
Level 2 | Commodities contracts
Assets
Derivative assets		438	429
Liabilities
Total derivative liabilities		381	379
Level 2 | TBA contracts
Assets
Derivative assets		7	10
Liabilities
Total derivative liabilities		13	8
Level 2 | Other contracts
Assets
Derivative assets		15	0
Liabilities
Total derivative liabilities		0	0
Level 3
Assets
Debt securities available for sale		0	0
Loans held for sale at fair value		0	0
Derivative assets		8	3
Equity securities, at fair value		0	0
Short-term investments		0	0
Total assets		1,438	1,494
Liabilities
Total derivative liabilities		4	2
Short-term borrowed funds		0	0
Other liabilities		0	0
Total liabilities		4	2
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	3
Liabilities
Total derivative liabilities		4	2
Fair Value Measured at Net Asset Value Per Share
Liabilities
Equity securities excluded from investments		62	58
Unfunded capital commitments		17	24
Mortgage-backed securities
Assets
Debt securities available for sale		30,814	29,055
Mortgage-backed securities | Level 1
Assets
Debt securities available for sale		0	0
Mortgage-backed securities | Level 2
Assets
Debt securities available for sale		30,814	29,055
Mortgage-backed securities | Level 3
Assets
Debt securities available for sale		0	0
Collateralized loan obligations
Assets
Debt securities available for sale		90	184
Collateralized loan obligations | Level 1
Assets
Debt securities available for sale		0	0
Collateralized loan obligations | Level 2
Assets
Debt securities available for sale		90	184
Collateralized loan obligations | Level 3
Assets
Debt securities available for sale		0	0
State and political subdivisions
Assets
Debt securities available for sale		1	1
State and political subdivisions | Level 1
Assets
Debt securities available for sale		0	0
State and political subdivisions | Level 2
Assets
Debt securities available for sale		1	1
State and political subdivisions | Level 3
Assets
Debt securities available for sale		0	0
U.S. Treasury and other
Assets
Debt securities available for sale		4,514	3,525
U.S. Treasury and other | Level 1
Assets
Debt securities available for sale		4,514	3,525
U.S. Treasury and other | Level 2
Assets
Debt securities available for sale		0	0
U.S. Treasury and other | Level 3
Assets
Debt securities available for sale		0	0
Residential loans held for sale
Assets
Loans held for sale at fair value		592	633
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		592	633
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		176	192
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		176	192
Commercial loans held for sale | Level 3
Assets
Loans held for sale at fair value		0	0
Mortgage servicing rights
Assets
Mortgage servicing rights		1,430	1,491
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		$ 1,430	$ 1,491

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