FAIR VALUE MEASUREMENTS - Schedule of Financial Instruments not Recorded at Fair Value (Details) - USD ($) $ in Millions		Mar. 31, 2026	Dec. 31, 2025
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt securities held to maturity, carrying value	[1]	$ 7,800	$ 7,933
Debt securities held to maturity, fair value		6,998	7,150
Loans held for sale, carrying value		620	133
Loans held for sale, fair value		620	133
Net loans and leases	[2]	141,709	140,749
Net loans and leases, fair value		142,607	140,131
Other assets, carrying value		836	807
Other assets, fair value		836	807
Deposits, carrying value		184,035	183,313
Deposits, fair value		183,980	183,277
Short-term borrowed funds		0	6
Short-term borrowed funds, fair value		0	6
Long-term borrowed funds	[2]	12,260	11,224
Long-term borrowed funds, fair value		12,083	11,472
Cash-related financial instruments not recorded at fair value in the consolidated balance sheet		13,100	13,600
Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt securities held to maturity, carrying value		0	0
Debt securities held to maturity, fair value		0	0
Loans held for sale, carrying value		0	0
Loans held for sale, fair value		0	0
Net loans and leases		0	0
Net loans and leases, fair value		0	0
Other assets, carrying value		0	0
Other assets, fair value		0	0
Deposits, carrying value		0	0
Deposits, fair value		0	0
Short-term borrowed funds		0	0
Short-term borrowed funds, fair value		0	0
Long-term borrowed funds		0	0
Long-term borrowed funds, fair value		0	0
Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt securities held to maturity, carrying value		7,484	7,595
Debt securities held to maturity, fair value		6,684	6,812
Loans held for sale, carrying value		0	0
Loans held for sale, fair value		0	0
Net loans and leases		458	437
Net loans and leases, fair value		458	437
Other assets, carrying value		788	768
Other assets, fair value		788	768
Deposits, carrying value		184,035	183,313
Deposits, fair value		183,980	183,277
Short-term borrowed funds		0	6
Short-term borrowed funds, fair value		0	6
Long-term borrowed funds		12,260	11,224
Long-term borrowed funds, fair value		12,083	11,472
Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt securities held to maturity, carrying value		316	338
Debt securities held to maturity, fair value		314	338
Loans held for sale, carrying value		620	133
Loans held for sale, fair value		620	133
Net loans and leases		141,251	140,312
Net loans and leases, fair value		142,149	139,694
Other assets, carrying value		48	39
Other assets, fair value		48	39
Deposits, carrying value		0	0
Deposits, fair value		0	0
Short-term borrowed funds		0	0
Short-term borrowed funds, fair value		0	0
Long-term borrowed funds		0	0
Long-term borrowed funds, fair value		$ 0	$ 0

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

[2] Includes amounts in consolidated VIEs. See Note 6 for additional information.