FAIR VALUE MEASUREMENTS - Schedule of Fair Value Measurements (Details) - USD ($) $ in Millions		Jun. 30, 2025	Dec. 31, 2024
Assets
Debt securities available for sale	[1]	$ 34,658	$ 32,765
Loans held for sale at fair value		935	825
Mortgage servicing rights		1,426	1,491
Derivative assets		1,572	1,476
Equity securities, at fair value		198	162
Short-term investments		49	53
Total assets		38,838	36,772
Liabilities
Total derivative liabilities		1,566	1,710
Short-term borrowed funds		249	0
Other liabilities		137	101
Total liabilities		1,952	1,811
Equity securities excluded from investments		257	220
Interest rate contracts
Assets
Derivative assets		407	562
Liabilities
Total derivative liabilities		563	910
Foreign exchange contracts
Assets
Derivative assets		635	472
Liabilities
Total derivative liabilities		543	411
Commodities contracts
Assets
Derivative assets		499	429
Liabilities
Total derivative liabilities		441	379
TBA contracts
Assets
Derivative assets		5	10
Liabilities
Total derivative liabilities		19	8
Other contracts
Assets
Derivative assets		26	3
Liabilities
Total derivative liabilities		0	2
Level 1
Assets
Debt securities available for sale		4,401	3,525
Loans held for sale at fair value		0	0
Derivative assets		0	0
Equity securities, at fair value		198	162
Short-term investments		10	40
Total assets		4,609	3,727
Liabilities
Total derivative liabilities		0	0
Short-term borrowed funds		242	0
Other liabilities		0	0
Total liabilities		242	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		30,257	29,240
Loans held for sale at fair value		935	825
Derivative assets		1,557	1,473
Equity securities, at fair value		0	0
Short-term investments		39	13
Total assets		32,788	31,551
Liabilities
Total derivative liabilities		1,566	1,708
Short-term borrowed funds		7	0
Other liabilities		137	101
Total liabilities		1,710	1,809
Level 2 | Interest rate contracts
Assets
Derivative assets		407	562
Liabilities
Total derivative liabilities		563	910
Level 2 | Foreign exchange contracts
Assets
Derivative assets		635	472
Liabilities
Total derivative liabilities		543	411
Level 2 | Commodities contracts
Assets
Derivative assets		499	429
Liabilities
Total derivative liabilities		441	379
Level 2 | TBA contracts
Assets
Derivative assets		5	10
Liabilities
Total derivative liabilities		19	8
Level 2 | Other contracts
Assets
Derivative assets		11	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		15	3
Equity securities, at fair value		0	0
Short-term investments		0	0
Total assets		1,441	1,494
Liabilities
Total derivative liabilities		0	2
Short-term borrowed funds		0	0
Other liabilities		0	0
Total liabilities		0	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		15	3
Liabilities
Total derivative liabilities		0	2
Fair Value Measured at Net Asset Value Per Share
Liabilities
Equity securities excluded from investments		59	58
Unfunded capital commitments		21	24
Mortgage-backed securities
Assets
Debt securities available for sale		30,132	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		30,132	29,055
Mortgage-backed securities | Level 3
Assets
Debt securities available for sale		0	0
Collateralized loan obligations
Assets
Debt securities available for sale		124	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		124	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		4,401	3,525
U.S. Treasury and other | Level 1
Assets
Debt securities available for sale		4,401	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		766	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		766	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		169	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		169	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		1,426	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		$ 1,426	$ 1,491

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