DERIVATIVE ASSETS AND DERIVATIVE LIABILITIES, Narrative (Details) - USD ($)	3 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Sep. 30, 2023
Derivative [Line Items]
Gain (loss) excluded from assessment of hedge effectiveness	$ 0	$ 0
Amount of interest expense expected to reclassify from AOCI	27,000,000
Derivative liabilities	310,000,000		$ 490,000,000
Credit Risk Contract
Derivative [Line Items]
Derivative liabilities	$ 6,000,000		$ 3,000,000
Bank
Derivative [Line Items]
Maximum length of time hedged in cash flow hedge (in years)	4 years