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BORROWINGS - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024
Federal Home Loan Bank, Advance, Branch of FHLBank [Line Items]
Borrowings	$ 1,765,604	$ 3,267,589
Weighted average effective maturity of FHLB advances	2 years 2 months 8 days
FRB Bank Term Funding Program
Federal Home Loan Bank, Advance, Branch of FHLBank [Line Items]
Borrowings		$ 1,074,714
Federal Home Loan Bank of Des Moines
Federal Home Loan Bank, Advance, Branch of FHLBank [Line Items]
Federal home loan bank, percent of assets	45.00%

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- Definition

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+ References

No definition available.

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- Definition

Amount of long-term debt classified as other.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-SubTopic 10
-Topic 210
-Publisher FASB
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-Topic 942
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-Name Accounting Standards Codification
-Section S99
-Paragraph 1
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-Publisher FASB
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-Topic 944
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
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-Publisher FASB
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Federal Home Loan Bank, Advances, Weighted Average Effective Maturity

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