OTHER BORROWINGS, Schedule of Other Borrowings (Details) - USD ($) $ in Millions	Sep. 30, 2023	Sep. 30, 2022
Other Borrowings [Abstract]
Total FHLB advances	$ 1,000	$ 1,190
Subordinated notes - fixed-to-floating	100	100
Other	0	1
Total other borrowings	$ 1,100	$ 1,291
FHLB Advance Maturing December 2023 to March 2025
Other Borrowings [Abstract]
Weighted average interest rate	5.62%
Total FHLB advances	$ 850
FHLB Advance Maturing December 2023
Other Borrowings [Abstract]
Weighted average interest rate	5.70%	3.32%
Total FHLB advances	$ 150	$ 850
Maturity Overnight
Other Borrowings [Abstract]
Weighted average interest rate		3.11%
Total FHLB advances		$ 140
FHLB Advance Maturing December 2022
Other Borrowings [Abstract]
Weighted average interest rate		3.45%
Total FHLB advances		$ 200
Subordinated Debt
Other Borrowings [Abstract]
Weighted average interest rate	5.75%	5.75%
Premium	$ 2	$ 2