INCOME TAXES (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Federal:
Current	$ 12,153	$ 4,410	$ 4,217
Deferred	(5,040)	(440)	(3,896)
Federal income tax expense	7,113	3,970	321
State:
Current	4,366	1,422	1,048
Deferred	(1,246)	210	(1)
State tax expense	3,120	1,632	1,047
Income tax expense	10,233	5,602	1,368
Income tax expense (benefit) to statutory federal income tax rate reconciliation [Abstract]
Income tax expense at federal tax rate	19,303	13,588	6,798
Increase (decrease) resulting from:
State income taxes net of federal benefit	2,014	933	692
Nontaxable buildup in cash surrender value	(776)	(580)	(711)
Stock based compensation	(593)	(66)	(37)
Tax exempt income	(9,991)	(8,257)	(5,230)
Nondeductible expenses	316	196	188
Other, net	(40)	(212)	(332)
Income tax expense	10,233	5,602	1,368
Deferred tax assets:
Bad debts	2,832	2,044
Deferred compensation	1,548	1,345
Stock based compensation	3,436	265
Operational reserve	645	540
AMT Credit	1,869	5,563
Intangibles	5,235	393
Indirect tax benefits of unrecognized tax positions	266	216
Other assets	1,933	1,362
Gross deferred tax assets	17,764	11,728
Deferred tax liabilities:
FHLB stock dividend	(425)	(411)
Premises and equipment	(1,789)	(1,913)
Patents	(842)	(988)
Prepaid expenses	(673)	(668)
Net unrealized gains on securities available for sale	(4,934)	(12,348)
Gross deferred tax liabilities	(8,663)	(16,328)
Net deferred tax assets	9,101
Net deferred tax liabilities		(4,600)
Gross deferred tax on state net operating loss carryforwards	1,300	900
Additional bad debt deductions provided by federal income tax laws	6,700
Deferred tax liability, bad debt deductions	2,300	2,300
Reconciliation for liabilities [Abstract]
Balance at beginning of year	525	974
Additions for tax positions related to the current year	192	63
Additions for tax positions related to the prior years	31	0
Reductions for tax positions due to settlement with taxing authorities	0	(372)
Reductions for tax positions related to prior years	(103)	(140)
Balance at end of year	645	$ 525	$ 974
Unrecognized tax benefits that, if recognized, would impact the effective rate	460
Accrued interest related to unrecognized tax benefits	114
Deferred Tax Expense, Event of Liquidation	$ 2,300