LOANS RECEIVABLE, NET AND RELATED ALLOWANCE FOR LOAN LOSSES (Schedule of Activity in the Allowance for Loan Losses by Loan Category) (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2020	Mar. 31, 2019
Activity in the allowance for loan losses by loan category:
Balance at beginning of period	$ 5,100	$ 4,888	$ 4,402	$ 4,200	$ 4,888	$ 4,200
Charge-offs
Recoveries	5	2	92	1
Provision (credit)	420	210	106	201	631	307
Balance at the end of period	5,525	5,100	4,600	4,402	5,525	4,600
One-to four-family residential [Member]
Activity in the allowance for loan losses by loan category:
Balance at beginning of period	707	731	698	687	731	687
Charge-offs
Recoveries	5	2	92
Provision (credit)	227	(26)	(80)	11
Balance at the end of period	939	707	710	698	939	710
Commercial real estate [Member]
Activity in the allowance for loan losses by loan category:
Balance at beginning of period	1,919	2,066	1,590	1,540	2,066	1,540
Charge-offs
Recoveries
Provision (credit)	457	(147)	95	50
Balance at the end of period	2,376	1,919	1,685	1,590	2,376	1,685
Construction [Member]
Activity in the allowance for loan losses by loan category:
Balance at beginning of period	574	511	674	493	511	493
Charge-offs
Recoveries
Provision (credit)	70	63	142	181
Balance at the end of period	644	574	816	674	644	816
Home equity lines of credit [Member]
Activity in the allowance for loan losses by loan category:
Balance at beginning of period	140	138	121	109	138	109
Charge-offs
Recoveries				1
Provision (credit)	42	2	17	11
Balance at the end of period	182	140	138	121	182	138
Commercial business [Member]
Activity in the allowance for loan losses by loan category:
Balance at beginning of period	1,495	1,184	1,182	1,151	1,184	1,151
Charge-offs
Recoveries
Provision (credit)	(287)	311	(78)	31
Balance at the end of period	1,208	1,495	1,104	1,182	1,208	1,104
Other [Member]
Activity in the allowance for loan losses by loan category:
Balance at beginning of period	2	8	4	25	8	25
Charge-offs
Recoveries
Provision (credit)	(2)	(6)	(1)	(21)
Balance at the end of period		2	3	4		3
Unallocated [Member]
Activity in the allowance for loan losses by loan category:
Balance at beginning of period	263	250	133	195	250	195
Charge-offs
Recoveries
Provision (credit)	(87)	13	11	(62)
Balance at the end of period	$ 176	$ 263	$ 144	$ 133	$ 176	$ 144

Amount of allowance for credit loss on financing receivable. Excludes allowance for financing receivable covered under loss sharing agreement.

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