SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES, Other Narrative (Details) $ in Millions		12 Months Ended
	Jun. 01, 2022 USD ($)	Sep. 30, 2022 USD ($) tax_credit_fund subsidiary institution portfolio_segment investor
Bank loans and allowances for losses [Abstract]
Loan discounts, fair value adjustments | $	$ 145
Loan discounts, fair value adjustments, amortization period	4 years
Number of loan portfolio segments | portfolio_segment		6
Minimum past due for loans placed on nonaccrual status (or more)		90 days
Period of satisfactory performance for loans to be returned to accrual status		6 months
Minimum amount of Shared National Credit (SNC) loan syndications | $		$ 100
Minimum number of regulated institutions with which SNCs are shared (or more) | institution		3
Minimum past due for residential loans to be reviewed		60 days
Minimum past due for charge-offs to be considered on residential mortgage loans		90 days
Maximum past due for charge-offs taken on residential mortgage loans		120 days
Minimum period for which updated valuation is obtained for loans in pre-foreclosure status		9 months
Brokerage client receivables and loans to financial advisors [Abstract]
Repayment period of loans to financial advisors and certain key revenue producers, minimum		5 years
Repayment period of loans to financial advisors and certain key revenue producers, maximum		10 years
LIHTC Funds [Abstract]
Minimum number of investor members or limited partners of LIHTC Funds (or more) | investor		1
Number of general types of non-guaranteed tax credit funds | tax_credit_fund		2
Number of single investor members or limited partners in funds | subsidiary		1
Number of party with power | subsidiary		1