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		9 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2018	Mar. 31, 2017	Jun. 30, 2017
Allowance for loan losses:
Balance, beginning of period	$ 7,122	$ 5,387	$ 6,835	$ 5,351	$ 5,351
Provision charged to expense	110	192	468	225	1,721
Losses charged off	(1,530)	(214)	(1,607)	(242)	(275)
Recoveries	1	1	7	32	38
Balance, end of period	5,703	5,366	5,703	5,366	6,835
Ending balance: individually evaluated for impairment	72	7	72	7	1,533
Ending balance: collectively evaluated for impairment	5,631	5,359	5,631	5,359	5,302
Loans:
Ending balance	463,847	443,143	463,847	443,143	446,954
Ending balance: individually evaluated for impairment	9,669	3,833	9,669	3,833	11,595
Ending balance: collectively evaluated for impairment	454,178	439,310	454,178	439,310	435,359
One- to Four-Family [Member]
Allowance for loan losses:
Balance, beginning of period	2,517	1,205	2,519	1,198	1,198
Provision charged to expense	36	158	78	138	1,521
Losses charged off	(1,528)	(203)	(1,572)	(203)	(232)
Recoveries				27	32
Balance, end of period	1,025	1,160	1,025	1,160	2,519
Ending balance: individually evaluated for impairment	36		36		1,527
Ending balance: collectively evaluated for impairment	989	1,160	989	1,160	992
Loans:
Ending balance	135,888	144,718	135,888	144,718	140,647
Ending balance: individually evaluated for impairment	8,156	2,298	8,156	2,298	10,034
Ending balance: collectively evaluated for impairment	127,732	142,420	127,732	142,420	130,613
Multi-Family [Member]
Allowance for loan losses:
Balance, beginning of period	1,460	1,284	1,336	1,202	1,202
Provision charged to expense	(20)	(87)	104	(5)	134
Balance, end of period	1,440	1,197	1,440	1,197	1,336
Ending balance: collectively evaluated for impairment	1,440	1,197	1,440	1,197	1,336
Loans:
Ending balance	93,890	78,288	93,890	78,288	87,228
Ending balance: individually evaluated for impairment	1,346	1,406	1,346	1,406	1,390
Ending balance: collectively evaluated for impairment	92,544	76,882	92,544	76,882	85,838
Home Equity Lines of Credit [Member]
Allowance for loan losses:
Balance, beginning of period	78	91	76	94	94
Provision charged to expense	(5)		22	(3)	(18)
Losses charged off			(25)
Balance, end of period	73	91	73	91	76
Ending balance: collectively evaluated for impairment	73	91	73	91	76
Loans:
Ending balance	7,363	7,452	7,363	7,452	7,520
Ending balance: individually evaluated for impairment	30	9	30	9	57
Ending balance: collectively evaluated for impairment	7,333	7,443	7,333	7,443	7,463
Construction [Member]
Allowance for loan losses:
Balance, beginning of period	124	284	75	227	227
Provision charged to expense	45	20	94	77	(152)
Balance, end of period	169	304	169	304	75
Ending balance: collectively evaluated for impairment	169	304	169	304	75
Loans:
Ending balance	14,930	25,647	14,930	25,647	7,421
Ending balance: collectively evaluated for impairment	14,930	25,647	14,930	25,647	7,421
Commercial [Member]
Allowance for loan losses:
Balance, beginning of period	1,535	1,386	1,520	1,399	1,399
Provision charged to expense	30	24	45	19	129
Losses charged off				(8)	(8)
Balance, end of period	1,565	1,410	1,565	1,410	1,520
Ending balance: individually evaluated for impairment	4	7	4	7	6
Ending balance: collectively evaluated for impairment	1,561	1,403	1,561	1,403	1,514
Loans:
Ending balance	137,979	121,227	137,979	121,227	133,841
Ending balance: individually evaluated for impairment	71	27	71	27	25
Ending balance: collectively evaluated for impairment	137,908	121,200	137,908	121,200	133,816
Commercial [Member]
Allowance for loan losses:
Balance, beginning of period	1,341	1,060	1,242	1,140	1,140
Provision charged to expense	23	78	122	(2)	102
Balance, end of period	1,364	1,138	1,364	1,138	1,242
Ending balance: individually evaluated for impairment	31		31
Ending balance: collectively evaluated for impairment	1,333	1,138	1,333	1,138	1,242
Loans:
Ending balance	66,003	57,801	66,003	57,801	62,392
Ending balance: individually evaluated for impairment	61	93	61	93	89
Ending balance: collectively evaluated for impairment	65,942	57,708	65,942	57,708	62,303
Consumer [Member]
Allowance for loan losses:
Balance, beginning of period	67	77	67	91	91
Provision charged to expense	1	(1)	3	1	5
Losses charged off	(2)	(11)	(10)	(31)	(35)
Recoveries	1	1	7	5	6
Balance, end of period	67	66	67	66	67
Ending balance: individually evaluated for impairment	1		1
Ending balance: collectively evaluated for impairment	66	66	66	66	67
Loans:
Ending balance	7,794	8,010	7,794	8,010	7,905
Ending balance: individually evaluated for impairment	5		5
Ending balance: collectively evaluated for impairment	$ 7,789	$ 8,010	$ 7,789	$ 8,010	$ 7,905