FAIR VALUES OF FINANCIAL INSTRUMENTS - Assets Measured at Fair Value on Recurring and Non-recurring Basis (Details) - USD ($)	Sep. 30, 2022	Sep. 30, 2021
Fair Value, Assets Measured on Recurring and Nonrecurring Basis [Line Items]
Transfers between levels of fair value hierarchy	$ 0	$ 0
Level 1
Available For Sale
Total debt securities AFS	0	0
Common equities and mutual funds	2,874,000	12,668,000
Fair value of assets measured on non-recurring basis [Abstract]
Loans and leases	0	0
Level 2
Available For Sale
Total debt securities AFS	1,882,869,000	1,864,899,000
Common equities and mutual funds	0	0
Fair value of assets measured on non-recurring basis [Abstract]
Loans and leases	0	0
Level 3
Available For Sale
Total debt securities AFS	0	0
Common equities and mutual funds	0	0
Fair value of assets measured on non-recurring basis [Abstract]
Loans and leases	3,525,803,000	3,616,646,000
Recurring
Available For Sale
Corporate securities	97,768,000	25,000,000
SBA securities	2,344,000	157,209,000
Obligations of states and political subdivisions	263,783,000	2,507,000
Non-bank qualified obligations of states and political subdivisions	147,790,000	268,295,000
Asset-backed securities	1,348,997,000	394,859,000
Mortgage-Backed Securities Available-for-Sale, Fair Value Disclosure	22,187,000	1,017,029,000
Total debt securities AFS	1,882,869,000	1,864,899,000
Common equities and mutual funds	2,874,000	12,668,000
Investment securities available for sale, at fair value	7,212,000	4,560,000
Recurring \| Level 1
Available For Sale
Corporate securities	0	0
SBA securities	0	0
Obligations of states and political subdivisions	0	0
Non-bank qualified obligations of states and political subdivisions	0	0
Asset-backed securities	0	0
Mortgage-Backed Securities Available-for-Sale, Fair Value Disclosure	0	0
Total debt securities AFS	0	0
Common equities and mutual funds	2,874,000	12,668,000
Investment securities available for sale, at fair value	0	0
Recurring \| Level 2
Available For Sale
Corporate securities	97,768,000	25,000,000
SBA securities	2,344,000	157,209,000
Obligations of states and political subdivisions	263,783,000	2,507,000
Non-bank qualified obligations of states and political subdivisions	147,790,000	268,295,000
Asset-backed securities	1,348,997,000	394,859,000
Mortgage-Backed Securities Available-for-Sale, Fair Value Disclosure	22,187,000	1,017,029,000
Total debt securities AFS	1,882,869,000	1,864,899,000
Common equities and mutual funds	0	0
Investment securities available for sale, at fair value	0	0
Recurring \| Level 3
Available For Sale
Corporate securities	0	0
SBA securities	0	0
Obligations of states and political subdivisions	0	0
Non-bank qualified obligations of states and political subdivisions	0	0
Asset-backed securities	0	0
Mortgage-Backed Securities Available-for-Sale, Fair Value Disclosure	0	0
Total debt securities AFS	0	0
Common equities and mutual funds	0	0
Investment securities available for sale, at fair value	0	0
Nonrecurring
Fair value of assets measured on non-recurring basis [Abstract]
Loans and leases	1,576,000	14,852,000
Nonrecurring \| National Lending
Fair value of assets measured on non-recurring basis [Abstract]
Loans and leases	1,575,000	3,404,000
Nonrecurring \| Community Banking
Fair value of assets measured on non-recurring basis [Abstract]
Loans and leases		9,371,000
Nonrecurring \| Impaired Loans
Fair value of assets measured on non-recurring basis [Abstract]
Loans and leases	1,575,000	12,775,000
Nonrecurring \| Foreclosed Assets
Fair value of assets measured on non-recurring basis [Abstract]
Foreclosed assets, net	1,000	2,077,000
Nonrecurring \| Level 1
Fair value of assets measured on non-recurring basis [Abstract]
Loans and leases	0	0
Nonrecurring \| Level 1 \| National Lending
Fair value of assets measured on non-recurring basis [Abstract]
Loans and leases	0	0
Nonrecurring \| Level 1 \| Community Banking
Fair value of assets measured on non-recurring basis [Abstract]
Loans and leases		0
Nonrecurring \| Level 1 \| Impaired Loans
Fair value of assets measured on non-recurring basis [Abstract]
Loans and leases	0	0
Nonrecurring \| Level 1 \| Foreclosed Assets
Fair value of assets measured on non-recurring basis [Abstract]
Foreclosed assets, net	0	0
Nonrecurring \| Level 2
Fair value of assets measured on non-recurring basis [Abstract]
Loans and leases	0	0
Nonrecurring \| Level 2 \| National Lending
Fair value of assets measured on non-recurring basis [Abstract]
Loans and leases	0	0
Nonrecurring \| Level 2 \| Community Banking
Fair value of assets measured on non-recurring basis [Abstract]
Loans and leases		0
Nonrecurring \| Level 2 \| Impaired Loans
Fair value of assets measured on non-recurring basis [Abstract]
Loans and leases	0	0
Nonrecurring \| Level 2 \| Foreclosed Assets
Fair value of assets measured on non-recurring basis [Abstract]
Foreclosed assets, net	0	0
Nonrecurring \| Level 3
Fair value of assets measured on non-recurring basis [Abstract]
Loans and leases	1,576,000	14,852,000
Nonrecurring \| Level 3 \| National Lending
Fair value of assets measured on non-recurring basis [Abstract]
Loans and leases	1,575,000	3,404,000
Nonrecurring \| Level 3 \| Community Banking
Fair value of assets measured on non-recurring basis [Abstract]
Loans and leases		9,371,000
Nonrecurring \| Level 3 \| Impaired Loans
Fair value of assets measured on non-recurring basis [Abstract]
Loans and leases	1,575,000	12,775,000
Nonrecurring \| Level 3 \| Foreclosed Assets
Fair value of assets measured on non-recurring basis [Abstract]
Foreclosed assets, net	$ 1,000	$ 2,077,000

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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- Definition

Corporate Securities Available For Sale

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Fair Value, Assets, total transfer amount between any of the levels 1, 2 or 3.

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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 non-bank qualified obligations of states and political subdivision as of the balance sheet date which have been categorized as available-for-sale.

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- Definition

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

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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), classified as current.

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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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- Definition

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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Carrying amount as of the balance sheet date of land and buildings obtained through foreclosure proceedings or defeasance in full or partial satisfaction of a debt arrangement.

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