LOANS RECEIVABLE, NET - Allowance for Loan Losses and Recorded Investment in Loans (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2017	Sep. 30, 2016
Allowance for Credit Losses [Roll Forward]
Beginning balance	$ 5,635	$ 6,255	$ 5,397
Provision (recovery) for loan losses	(10,589)	(4,605)	(1,465)
Recoveries	307	147	123
Charge offs	(8,997)	(5,372)	(730)
Ending balance	7,534	5,635	6,255
Ending balance: individually evaluated for impairment				$ 0	$ 10
Ending balance: collectively evaluated for impairment				7,534	5,625
Total	5,635	6,255	5,397	7,534	5,635
Loans:
Ending balance: individually evaluated for impairment				1,181	595
Ending balance: collectively evaluated for impairment				1,325,651	925,299
Total loans receivable				1,326,832	925,894
1-4 Family Real Estate [Member]
Allowance for Credit Losses [Roll Forward]
Beginning balance	654	278
Provision (recovery) for loan losses	(149)	(408)
Recoveries	0	0
Charge offs	0	(32)
Ending balance	803	654	278
Ending balance: individually evaluated for impairment				0	10
Ending balance: collectively evaluated for impairment				803	644
Total	654	278	278	803	654
Loans:
Ending balance: individually evaluated for impairment				72	162
Ending balance: collectively evaluated for impairment				196,634	162,136
Total loans receivable				196,706	162,298
Commercial and Multi-Family Real Estate [Member]
Allowance for Credit Losses [Roll Forward]
Beginning balance	2,198	1,187
Provision (recovery) for loan losses	(610)	(1,369)
Recoveries	0	27
Charge offs	(138)	(385)
Ending balance	2,670	2,198	1,187
Ending balance: individually evaluated for impairment				0	0
Ending balance: collectively evaluated for impairment				2,670	2,198
Total	2,198	1,187	1,187	2,670	2,198
Loans:
Ending balance: individually evaluated for impairment				1,109	433
Ending balance: collectively evaluated for impairment				584,401	422,499
Total loans receivable				585,510	422,932
Agricultural Real Estate [Member]
Allowance for Credit Losses [Roll Forward]
Beginning balance	142	163
Provision (recovery) for loan losses	(1,248)	21
Recoveries	0	0
Charge offs	0	0
Ending balance	1,390	142	163
Ending balance: individually evaluated for impairment				0	0
Ending balance: collectively evaluated for impairment				1,390	142
Total	142	163	163	1,390	142
Loans:
Ending balance: individually evaluated for impairment				0	0
Ending balance: collectively evaluated for impairment				61,800	63,612
Total loans receivable				61,800	63,612
Consumer [Member]
Allowance for Credit Losses [Roll Forward]
Beginning balance	51	20
Provision (recovery) for loan losses	(6,830)	(748)
Recoveries	209	11
Charge offs	(7,084)	(728)
Ending balance	6	51	20
Ending balance: individually evaluated for impairment				0	0
Ending balance: collectively evaluated for impairment				6	51
Total	51	20	20	6	51
Loans:
Ending balance: individually evaluated for impairment				0	0
Ending balance: collectively evaluated for impairment				163,004	37,094
Total loans receivable				163,004	37,094
Commercial Operating [Member]
Allowance for Credit Losses [Roll Forward]
Beginning balance	117	28
Provision (recovery) for loan losses	(1,165)	(338)
Recoveries	25	0
Charge offs	(1,149)	(249)
Ending balance	158	117	28
Ending balance: individually evaluated for impairment				0	0
Ending balance: collectively evaluated for impairment				158	117
Total	117	28	28	158	117
Loans:
Ending balance: individually evaluated for impairment				0	0
Ending balance: collectively evaluated for impairment				35,759	31,271
Total loans receivable				35,759	31,271
Agricultural Operating [Member]
Allowance for Credit Losses [Roll Forward]
Beginning balance	1,332	3,537
Provision (recovery) for loan losses	160	(1,045)
Recoveries	12	2
Charge offs	0	(3,252)
Ending balance	1,184	1,332	3,537
Ending balance: individually evaluated for impairment				0	0
Ending balance: collectively evaluated for impairment				1,184	1,332
Total	1,332	3,537	3,537	1,184	1,332
Loans:
Ending balance: individually evaluated for impairment				0	0
Ending balance: collectively evaluated for impairment				33,594	37,083
Total loans receivable				33,594	37,083
Premium Finance [Member]
Allowance for Credit Losses [Roll Forward]
Beginning balance	588	293
Provision (recovery) for loan losses	(773)	(914)
Recoveries	61	107
Charge offs	(626)	(726)
Ending balance	796	588	293
Ending balance: individually evaluated for impairment				0	0
Ending balance: collectively evaluated for impairment				796	588
Total	588	293	293	796	588
Loans:
Ending balance: individually evaluated for impairment				0	0
Ending balance: collectively evaluated for impairment				250,459	171,604
Total loans receivable				250,459	171,604
Unallocated [Member]
Allowance for Credit Losses [Roll Forward]
Beginning balance	553	749
Provision (recovery) for loan losses	26	196
Recoveries	0	0
Charge offs	0	0
Ending balance	527	553	749
Ending balance: individually evaluated for impairment				0	0
Ending balance: collectively evaluated for impairment				527	553
Total	$ 553	$ 749	$ 749	527	553
Loans:
Ending balance: individually evaluated for impairment				0	0
Ending balance: collectively evaluated for impairment				0	0
Total loans receivable				$ 0	$ 0