FAIR VALUE MEASUREMENTS - Quantitative Information (Details) - USD ($) $ in Thousands	6 Months Ended
Mar. 31, 2018	Sep. 30, 2017
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Foreclosed Assets, net	$ 30,050	$ 292
Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Range of estimated selling cost	4.00%
Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Range of estimated selling cost	10.00%
Level 1 [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	$ 0	0
Level 2 [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	0	0
Level 3 [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	1,530,891	1,318,402
Impaired Loans [Member] \| Level 3 [Member] \| Market Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	110	0
1-4 Family Real Estate [Member] \| Level 1 [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	0	0
1-4 Family Real Estate [Member] \| Level 2 [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	0	0
1-4 Family Real Estate [Member] \| Level 3 [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	205,553	196,970
Commercial Operating [Member] \| Level 1 [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	0	0
Commercial Operating [Member] \| Level 2 [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	0	0
Commercial Operating [Member] \| Level 3 [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	46,987	35,723
Foreclosed Assets [Member] \| Level 3 [Member] \| Market Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	30,050	292
Nonrecurring [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	30,160	292
Nonrecurring [Member] \| Level 1 [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	0	0
Nonrecurring [Member] \| Level 2 [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	0	0
Nonrecurring [Member] \| Level 3 [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	30,160	292
Nonrecurring [Member] \| Impaired Loans [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	110
Nonrecurring [Member] \| Impaired Loans [Member] \| Level 1 [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	0
Nonrecurring [Member] \| Impaired Loans [Member] \| Level 2 [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	0
Nonrecurring [Member] \| Impaired Loans [Member] \| Level 3 [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	110
Nonrecurring [Member] \| 1-4 Family Real Estate [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	110
Nonrecurring [Member] \| 1-4 Family Real Estate [Member] \| Level 1 [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	0
Nonrecurring [Member] \| 1-4 Family Real Estate [Member] \| Level 2 [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	0
Nonrecurring [Member] \| 1-4 Family Real Estate [Member] \| Level 3 [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	110
Nonrecurring [Member] \| Foreclosed Assets [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Foreclosed Assets, net	30,050	292
Nonrecurring [Member] \| Foreclosed Assets [Member] \| Level 1 [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Foreclosed Assets, net	0
Nonrecurring [Member] \| Foreclosed Assets [Member] \| Level 2 [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Foreclosed Assets, net	0
Nonrecurring [Member] \| Foreclosed Assets [Member] \| Level 3 [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Foreclosed Assets, net	$ 30,050	$ 292

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No definition available.

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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.

+ Details

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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://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Glossary Loan
-URI http://asc.fasb.org/extlink&oid=6517073

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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/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 10
-Section S99
-Paragraph 6
-Subparagraph (SX 210.5-04(c)(Schedule III))
-URI http://asc.fasb.org/extlink&oid=27047687&loc=d3e5864-122674

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=66008989&loc=d3e5162-111524

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=65884687&loc=d3e4437-111522

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 970
-SubTopic 360
-Section S99
-Paragraph 1
-Subparagraph (SX 210.12-28)
-URI http://asc.fasb.org/extlink&oid=6590653&loc=d3e638233-123024

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