FAIR VALUE OF FINANCIAL INSTRUMENTS - Assets Measured at Fair Value on Recurring and Non-recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Sep. 30, 2019
Available-for-sale debt securities [Abstract]
Mortgage-backed securities	$ 362,120	$ 382,546
Debt securities available for sale	1,214,723	1,272,493
Debt Securities, Held-to-maturity, Fair Value to Amortized Cost [Abstract]
Total held to maturity securities	121,899	133,470
Level 1
Fair Value, Assets Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value	0	0
Available-for-sale debt securities [Abstract]
Debt securities available for sale	0	0
Common equities and mutual funds	2,947	2,606
Debt Securities, Held-to-maturity, Fair Value to Amortized Cost [Abstract]
Total held to maturity securities	0	0
Level 2
Fair Value, Assets Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value	0	0
Available-for-sale debt securities [Abstract]
Debt securities available for sale	1,214,723	1,272,493
Common equities and mutual funds	0	0
Debt Securities, Held-to-maturity, Fair Value to Amortized Cost [Abstract]
Total held to maturity securities	121,899	133,470
Level 3
Fair Value, Assets Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value	3,557,579	3,622,597
Available-for-sale debt securities [Abstract]
Debt securities available for sale	0	0
Common equities and mutual funds	0	0
Debt Securities, Held-to-maturity, Fair Value to Amortized Cost [Abstract]
Total held to maturity securities	0	0
Nonrecurring
Fair Value, Assets Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value	14,345	38,201
Nonrecurring \| Level 1
Fair Value, Assets Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value	0	0
Nonrecurring \| Level 2
Fair Value, Assets Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value	0	0
Nonrecurring \| Level 3
Fair Value, Assets Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value	14,345	38,201
Recurring
Available-for-sale debt securities [Abstract]
Small business administration securities	180,920	185,982
Obligations of states and political subdivisions	874	874
Non-bank qualified obligations of states and political subdivisions	373,989	400,557
Asset-baked securities	296,820	302,534
Mortgage-backed securities	362,120	382,546
Debt securities available for sale	1,214,723	1,272,493
Common equities and mutual funds	2,947	2,606
Non-marketable equity securities	2,640	1,669
Recurring \| Level 1
Available-for-sale debt securities [Abstract]
Small business administration securities	0	0
Obligations of states and political subdivisions	0	0
Non-bank qualified obligations of states and political subdivisions	0	0
Asset-baked securities	0	0
Mortgage-backed securities	0	0
Debt securities available for sale	0	0
Common equities and mutual funds	2,947	2,606
Non-marketable equity securities	0	0
Recurring \| Level 2
Available-for-sale debt securities [Abstract]
Small business administration securities	180,920	185,982
Obligations of states and political subdivisions	874	874
Non-bank qualified obligations of states and political subdivisions	373,989	400,557
Asset-baked securities	296,820	302,534
Mortgage-backed securities	362,120	382,546
Debt securities available for sale	1,214,723	1,272,493
Common equities and mutual funds	0	0
Non-marketable equity securities	0	0
Recurring \| Level 3
Available-for-sale debt securities [Abstract]
Small business administration securities	0	0
Obligations of states and political subdivisions	0	0
Non-bank qualified obligations of states and political subdivisions	0	0
Asset-baked securities	0	0
Mortgage-backed securities	0	0
Debt securities available for sale	0	0
Common equities and mutual funds	0	0
Non-marketable equity securities	0	0
Commercial Portfolio Segment \| Nonrecurring
Fair Value, Assets Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value	13,017	8,707
Commercial Portfolio Segment \| Nonrecurring \| Level 1
Fair Value, Assets Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value	0	0
Commercial Portfolio Segment \| Nonrecurring \| Level 2
Fair Value, Assets Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value	0	0
Commercial Portfolio Segment \| Nonrecurring \| Level 3
Fair Value, Assets Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value	$ 13,017	$ 8,707

Fair value of asset backed securities investments classified as available for sale.

No definition available.

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- Definition

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents common equities and mutual funds as of the balance sheet date which have been categorized as available-for-sale.

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

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-Publisher FASB
-Name Accounting Standards Codification
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Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Fair value of investment in debt security measured at amortized cost (held-to-maturity).

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Fair value portion of loan receivable, including, but not limited to, mortgage loans held for investment, finance receivables held for investment, policy loans on insurance contracts.

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Fair value of securitized, pay-through debt securities collateralized by real estate mortgage loans classified as available-for-sale.

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No definition available.

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