Loans and Allowance for Loan Losses - Allowance for Loan Losses and Recorded Investment in Loans Based on Portfolio Segment and Impairment Method (Detail) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Jun. 30, 2015
Allowance for loan losses:
Balance, beginning of period	$ 4,211	$ 3,958	$ 3,958
Provision charged to expense	480	104	460
Losses charged off	(24)	(34)	(278)
Recoveries		9	71
Balance, end of period	4,667	4,037	4,211
Ending balance: individually evaluated for impairment	111	237	91
Ending balance: collectively evaluated for impairment	4,556	3,800	4,120
Loans:
Ending balance	394,715	337,246	361,253
Ending balance: individually evaluated for impairment	4,935	5,290	4,907
Ending balance: collectively evaluated for impairment	389,780	331,956	356,346
One-to Four-Family [Member]
Allowance for loan losses:
Balance, beginning of period	1,216	1,391	1,391
Provision charged to expense	54	19	27
Losses charged off	(23)	(2)	(231)
Recoveries			29
Balance, end of period	1,247	1,408	1,216
Ending balance: individually evaluated for impairment	83	192	57
Ending balance: collectively evaluated for impairment	1,164	1,216	1,159
Loans:
Ending balance	146,081	3,590	145,064
Ending balance: individually evaluated for impairment	3,314	145,095	3,274
Ending balance: collectively evaluated for impairment	142,767		141,790
Multi-Family [Member]
Allowance for loan losses:
Balance, beginning of period	827	842	842
Provision charged to expense	237	(55)	(15)
Balance, end of period	1,064	787	827
Ending balance: collectively evaluated for impairment	1,064	787	827
Loans:
Ending balance	74,721	1,596	58,399
Ending balance: individually evaluated for impairment	1,512	55,392	1,537
Ending balance: collectively evaluated for impairment	73,209		56,862
Home Equity Lines of Credit [Member]
Allowance for loan losses:
Balance, beginning of period	85	111	111
Provision charged to expense		8	(4)
Losses charged off		(28)	(35)
Recoveries			13
Balance, end of period	85	91	85
Ending balance: collectively evaluated for impairment	85	91	85
Loans:
Ending balance	7,741		7,713
Ending balance: individually evaluated for impairment	8	7,905	8
Ending balance: collectively evaluated for impairment	7,733		7,705
Construction [Member]
Allowance for loan losses:
Balance, beginning of period	6	10	10
Provision charged to expense	31	(4)	(4)
Balance, end of period	37	6	6
Ending balance: collectively evaluated for impairment	37	6	6
Loans:
Ending balance	3,858	922	987
Ending balance: collectively evaluated for impairment	3,858	922	987
Commercial [Member]
Allowance for loan losses:
Balance, beginning of period	1,246	968	968
Provision charged to expense	106	(6)	278
Balance, end of period	1,352	962	1,246
Ending balance: individually evaluated for impairment	22	32	25
Ending balance: collectively evaluated for impairment	1,330	930	1,221
Loans:
Ending balance	113,126	52	103,614
Ending balance: individually evaluated for impairment	73	82,976	46
Ending balance: collectively evaluated for impairment	113,053		103,568
Commercial [Member]
Allowance for loan losses:
Balance, beginning of period	744	543	543
Provision charged to expense	54	150	201
Balance, end of period	798	693	744
Ending balance: collectively evaluated for impairment	798	693	744
Loans:
Ending balance	40,718	31,255	37,151
Ending balance: individually evaluated for impairment	17	27	21
Ending balance: collectively evaluated for impairment	40,701	31,228	37,130
Consumer [Member]
Allowance for loan losses:
Balance, beginning of period	87	93	93
Provision charged to expense	(2)	(8)	(23)
Losses charged off	(1)	(4)	(12)
Recoveries		9	29
Balance, end of period	84	90	87
Ending balance: individually evaluated for impairment	6	13	9
Ending balance: collectively evaluated for impairment	78	77	78
Loans:
Ending balance	8,470	8,463	8,325
Ending balance: individually evaluated for impairment	11	25	21
Ending balance: collectively evaluated for impairment	$ 8,459	$ 8,438	$ 8,304