SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) $ / shares in Units, $ in Thousands	3 Months Ended												12 Months Ended
	Sep. 30, 2017 USD ($) $ / shares	Jun. 30, 2017 $ / shares	Mar. 31, 2017 $ / shares	Dec. 31, 2016 $ / shares	Sep. 30, 2016 USD ($) $ / shares	Jun. 30, 2016 $ / shares	Mar. 31, 2016 $ / shares	Dec. 31, 2015 $ / shares	Sep. 30, 2015 $ / shares	Jun. 30, 2015 $ / shares	Mar. 31, 2015 $ / shares	Dec. 31, 2014 $ / shares	Sep. 30, 2017 USD ($) segment $ / shares		Sep. 30, 2016 USD ($) $ / shares		Sep. 30, 2015 USD ($) $ / shares
PRINCIPLES OF CONSOLIDATION [Abstract]
Percentage of interest in subsidiary	100.00%												100.00%
NATURE OF BUSINESS AND INDUSTRY SEGMENT INFORMATION [Abstract]
Number of reporting segments | segment													3
CASH AND CASH EQUIVALENTS AND FEDERAL FUNDS SOLD [Abstract]
Terms of FHLB advances													90 days
Reserve balances in cash or on deposit with FRB (Federal Reserve Bank)	$ 1,500				$ 0								$ 1,500		$ 0
SECURITIES [Abstract]
Recorded balance	0				78								0		78
Other than temporary impairment													$ 0		0		$ 0
LOANS RECEIVABLE [Abstract]
Period when loan becomes delinquent													90 days
MORTGAGE SERVICING AND TRANSFERS OF FINANCIAL ASSETS [Abstract]
Aggregate unpaid balance of loans serviced for others	$ 21,800				$ 19,400								$ 21,800		$ 19,400
ALLOWANCE FOR LOAN LOSSES [Abstract]
Look back period													7 years
Property, Plant and Equipment [Line Items]
Basic (in dollars per share) | $ / shares	$ 0.19	$ 1.05	$ 3.44	$ 0.14	$ 0.70	$ 1.04	$ 1.68	$ 0.49	$ 0.64	$ 0.67	$ 0.79	$ 0.58	$ 4.86	[1]	$ 3.93	[1]	$ 2.68	[1]
Diluted (in dollars per share) | $ / shares	$ 0.19	$ 1.04	$ 3.42	$ 0.14	$ 0.70	$ 1.04	$ 1.67	$ 0.49	$ 0.63	$ 0.66	$ 0.78	$ 0.58	$ 4.83	[1]	$ 3.91	[1]	$ 2.66	[1]
Decrease in Loans Sold													$ 4,720		$ 89		$ 5,462
Net change in loans receivable													$ 274,840		217,985		146,111
Buildings [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Premises, furniture and equipment, estimated useful lives													10 years
Buildings [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Premises, furniture and equipment, estimated useful lives													40 years
Leasehold Improvements [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Premises, furniture and equipment, estimated useful lives													2 years
Leasehold Improvements [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Premises, furniture and equipment, estimated useful lives													15 years
Scenario, Previously Reported [Member]
Property, Plant and Equipment [Line Items]
Net change in loans receivable															$ 217,807		$ 135,187
FRB [Member]
Investment Holdings [Line Items]
Interest bearing deposits	$ 1,230,000												$ 1,230,000
FHLB [Member]
Investment Holdings [Line Items]
Interest bearing deposits	$ 0												$ 0
Accounting Standards Update 2015-06 [Member]
Property, Plant and Equipment [Line Items]
Basic (in dollars per share) | $ / shares															$ 3.93
Diluted (in dollars per share) | $ / shares															3.91
Accounting Standards Update 2015-06 [Member] | Scenario, Previously Reported [Member]
Property, Plant and Equipment [Line Items]
Basic (in dollars per share) | $ / shares															3.95
Diluted (in dollars per share) | $ / shares															$ 3.92

[1] See Reclassification and Revision of Prior Period Balances under Note 1 Summary of Significant Accounting Policies for additional information describing adjustments made to the Company's EPS calculation. Basic EPS for the fiscal year ended September 30, 2016 of $3.95 was corrected to $3.93 and diluted EPS of $3.92 was corrected to $3.91.