FAIR VALUE - Schedule of Carrying Values and Estimated Fair Values for Financial Instruments (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Financial Assets
Investment in marketable equity securities	$ 82	$ 84
Investment securities available for sale	28,190	19,936
Investment securities held to maturity	10,391	9,979
Fair value of derivative financial instruments	553	640
Financial Liabilities
Fair value of derivative financial instruments	507	636
Carrying Value
Financial Assets
Cash and due from banks	862	908
Interest-earning deposits at banks	25,640	33,609
Securities purchased under agreements to resell	455	473
Investment in marketable equity securities	82	84
Investment securities available for sale	28,190	19,936
Investment securities held to maturity	10,391	9,979
Loans held for sale	65	73
Net loans	135,036	129,545
Accrued interest receivable	904	832
Federal Home Loan Bank stock	19	20
Mortgage servicing rights	27	25
Financial Liabilities
Deposits with no stated maturity	137,445	129,427
Time deposits	14,129	16,427
Credit balances of factoring clients	1,250	1,089
Securities sold under customer repurchase agreements	391	485
Long-term borrowings	36,762	37,160
Accrued interest payable	149	137
Carrying Value | Qualifying Hedges
Financial Assets
Fair value of derivative financial instruments	0	0
Financial Liabilities
Fair value of derivative financial instruments	0	0
Carrying Value | Non-qualifying Hedges
Financial Assets
Fair value of derivative financial instruments	553	640
Financial Liabilities
Fair value of derivative financial instruments	507	636
Estimated Fair Value
Financial Assets
Cash and due from banks	862	908
Interest-earning deposits at banks	25,640	33,609
Securities purchased under agreements to resell	455	473
Investment in marketable equity securities	82	84
Investment securities available for sale	28,190	19,936
Investment securities held to maturity	9,168	8,503
Loans held for sale	65	73
Net loans	134,914	126,696
Accrued interest receivable	904	832
Federal Home Loan Bank stock	19	20
Mortgage servicing rights	42	42
Financial Liabilities
Deposits with no stated maturity	137,445	129,427
Time deposits	14,128	16,416
Credit balances of factoring clients	1,250	1,089
Securities sold under customer repurchase agreements	391	485
Long-term borrowings	36,765	36,816
Accrued interest payable	149	137
Estimated Fair Value | Level 1
Financial Assets
Cash and due from banks	862	908
Interest-earning deposits at banks	25,640	33,609
Securities purchased under agreements to resell	0	0
Investment in marketable equity securities	31	36
Investment securities available for sale	0	0
Investment securities held to maturity	0	0
Loans held for sale	0	0
Net loans	0	0
Accrued interest receivable	0	0
Federal Home Loan Bank stock	0	0
Mortgage servicing rights	0	0
Financial Liabilities
Deposits with no stated maturity	0	0
Time deposits	0	0
Credit balances of factoring clients	0	0
Securities sold under customer repurchase agreements	0	0
Long-term borrowings	0	0
Accrued interest payable	0	0
Estimated Fair Value | Level 2
Financial Assets
Cash and due from banks	0	0
Interest-earning deposits at banks	0	0
Securities purchased under agreements to resell	455	473
Investment in marketable equity securities	51	48
Investment securities available for sale	28,026	19,779
Investment securities held to maturity	9,168	8,503
Loans held for sale	41	38
Net loans	1,450	1,479
Accrued interest receivable	904	832
Federal Home Loan Bank stock	19	20
Mortgage servicing rights	0	0
Financial Liabilities
Deposits with no stated maturity	137,445	129,427
Time deposits	14,128	16,416
Credit balances of factoring clients	0	0
Securities sold under customer repurchase agreements	391	485
Long-term borrowings	36,765	36,816
Accrued interest payable	149	137
Estimated Fair Value | Level 3
Financial Assets
Cash and due from banks	0	0
Interest-earning deposits at banks	0	0
Securities purchased under agreements to resell	0	0
Investment in marketable equity securities	0	0
Investment securities available for sale	164	157
Investment securities held to maturity	0	0
Loans held for sale	24	35
Net loans	133,464	125,217
Accrued interest receivable	0	0
Federal Home Loan Bank stock	0	0
Mortgage servicing rights	42	42
Financial Liabilities
Deposits with no stated maturity	0	0
Time deposits	0	0
Credit balances of factoring clients	1,250	1,089
Securities sold under customer repurchase agreements	0	0
Long-term borrowings	0	0
Accrued interest payable	0	0
Estimated Fair Value | Qualifying Hedges
Financial Assets
Fair value of derivative financial instruments	0	0
Financial Liabilities
Fair value of derivative financial instruments	0	0
Estimated Fair Value | Qualifying Hedges | Level 1
Financial Assets
Fair value of derivative financial instruments	0	0
Financial Liabilities
Fair value of derivative financial instruments	0	0
Estimated Fair Value | Qualifying Hedges | Level 2
Financial Assets
Fair value of derivative financial instruments	0	0
Financial Liabilities
Fair value of derivative financial instruments	0	0
Estimated Fair Value | Qualifying Hedges | Level 3
Financial Assets
Fair value of derivative financial instruments	0	0
Financial Liabilities
Fair value of derivative financial instruments	0	0
Estimated Fair Value | Non-qualifying Hedges
Financial Assets
Fair value of derivative financial instruments	553	640
Financial Liabilities
Fair value of derivative financial instruments	507	636
Estimated Fair Value | Non-qualifying Hedges | Level 1
Financial Assets
Fair value of derivative financial instruments	0	0
Financial Liabilities
Fair value of derivative financial instruments	0	0
Estimated Fair Value | Non-qualifying Hedges | Level 2
Financial Assets
Fair value of derivative financial instruments	538	633
Financial Liabilities
Fair value of derivative financial instruments	506	635
Estimated Fair Value | Non-qualifying Hedges | Level 3
Financial Assets
Fair value of derivative financial instruments	15	7
Financial Liabilities
Fair value of derivative financial instruments	$ 1	$ 1