OTHER BORROWINGS, Schedule of Other Borrowings (Details) - USD ($) $ in Millions	Sep. 30, 2025	Sep. 30, 2024
Other Borrowings [Line Items]
Total FHLB advances	$ 700	$ 950
Total other borrowings	$ 700	$ 1,049
FHLB Advance Maturing December 2025 -December 2026
Other Borrowings [Line Items]
Weighted average interest rate	4.44%
Total FHLB advances	$ 500
FHLB Advance Maturing December 2028
Other Borrowings [Line Items]
Weighted average interest rate	4.10%
Total FHLB advances	$ 200
FHLB Advance Maturing March 2025 - December 2025
Other Borrowings [Line Items]
Weighted average interest rate		5.14%
Total FHLB advances		$ 650
FHLB Advance Maturing December 2024 - December 2028
Other Borrowings [Line Items]
Weighted average interest rate		4.47%
Total FHLB advances		$ 300
Subordinated Notes due 2030
Other Borrowings [Line Items]
Subordinated notes - fixed-to-floating	0	$ 99
Subordinated Notes | Subordinated Notes due 2030
Other Borrowings [Line Items]
Weighted average interest rate		5.75%
Unaccreted premium	$ 0	$ 1