FAIR VALUE OF FINANCIAL INSTRUMENTS - Quantitative Information (Details) - USD ($) $ in Thousands	9 Months Ended
Jun. 30, 2023	Sep. 30, 2022
Minimum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Range of estimated selling cost (percentage)	3.00%
Maximum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Range of estimated selling cost (percentage)	18.00%
Level 1
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	$ 0	$ 0
Level 2
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	0	0
Level 3
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	4,006,176	3,525,803
Total loans and leases, net individually evaluated for credit loss \| Level 3 \| Valuation, Market Approach
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	$ 4,113	1,575
Total loans and leases, net individually evaluated for credit loss \| Level 3 \| Valuation, Market Approach \| Minimum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Range of estimated selling cost (percentage)	3.00%
Total loans and leases, net individually evaluated for credit loss \| Level 3 \| Valuation, Market Approach \| Maximum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Range of estimated selling cost (percentage)	18.00%
Nonrecurring
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	$ 4,113	1,576
Nonrecurring \| Level 1
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	0	0
Nonrecurring \| Level 2
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	0	0
Nonrecurring \| Level 3
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	4,113	1,576
Nonrecurring \| Commercial finance
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	4,113	1,575
Nonrecurring \| Commercial finance \| Level 1
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	0	0
Nonrecurring \| Commercial finance \| Level 2
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	0	0
Nonrecurring \| Commercial finance \| Level 3
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	4,113	1,575
Nonrecurring \| Total loans and leases, net individually evaluated for credit loss
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	4,113	1,575
Nonrecurring \| Total loans and leases, net individually evaluated for credit loss \| Level 1
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	0	0
Nonrecurring \| Total loans and leases, net individually evaluated for credit loss \| Level 2
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	0	0
Nonrecurring \| Total loans and leases, net individually evaluated for credit loss \| Level 3
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	$ 4,113	1,575
Nonrecurring \| Foreclosed assets, net
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Foreclosed assets, net		1
Nonrecurring \| Foreclosed assets, net \| Level 1
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Foreclosed assets, net		0
Nonrecurring \| Foreclosed assets, net \| Level 2
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Foreclosed assets, net		0
Nonrecurring \| Foreclosed assets, net \| Level 3
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Foreclosed assets, net		$ 1

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- Definition

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.

+ References

No definition available.

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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.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Publisher FASB
-URI https://asc.fasb.org//310-10/tableOfContent

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- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481990/310-10-45-3

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 11
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481962/310-10-50-11

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