Loans and Allowance for Loan Losses - Summary of Impaired Loans (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Sep. 30, 2015	Jun. 30, 2015
Financing Receivable, Impaired [Line Items]
Specific Allowance	$ 111	$ 91
Recorded Balance	4,935	4,907
Unpaid Principal Balance	4,935	4,907
Specific Allowance	111	91
Average Investment in Impaired Loans	4,964	5,026
Interest Income Recognized	32	94
Interest on Cash Basis	32	135
One-to Four-Family [Member]
Financing Receivable, Impaired [Line Items]
Recorded Balance, Loans without a specific allowance	2,729	2,801
Unpaid Principal Balance, Loans without a specific allowance	2,729	2,801
Specific Allowance, Loans without a specific allowance	0	0
Average Investment in Impaired Loans, Loans without a specific allowance	2,736	2,851
Interest Income Recognized, Loans without a specific allowance	7	18
Interest on Cash Basis, Loans without a specific allowance	6	31
Recorded Balance, Loans with a specific allowance	585	473
Unpaid Principal Balance, Loans with a specific allowance	585	473
Specific Allowance	83	57
Average Investment in Impaired Loans, Loans with a specific allowance	589	487
Interest Income Recognized, Loans with a specific allowance	2	6
Interest on Cash Basis, Loans with a specific allowance	3	11
Recorded Balance	3,314	3,274
Unpaid Principal Balance	3,314	3,274
Specific Allowance	83	57
Average Investment in Impaired Loans	3,325	3,338
Interest Income Recognized	9	24
Interest on Cash Basis	9	42
Multi-Family [Member]
Financing Receivable, Impaired [Line Items]
Recorded Balance, Loans without a specific allowance	1,512	1,537
Unpaid Principal Balance, Loans without a specific allowance	1,512	1,537
Specific Allowance, Loans without a specific allowance	0	0
Average Investment in Impaired Loans, Loans without a specific allowance	1,524	1,573
Interest Income Recognized, Loans without a specific allowance	23	69
Interest on Cash Basis, Loans without a specific allowance	23	92
Recorded Balance	1,512	1,537
Unpaid Principal Balance	1,512	1,537
Average Investment in Impaired Loans	1,524	1,573
Interest Income Recognized	23	69
Interest on Cash Basis	23	92
Home Equity Lines of Credit [Member]
Financing Receivable, Impaired [Line Items]
Recorded Balance, Loans without a specific allowance	8	8
Unpaid Principal Balance, Loans without a specific allowance	8	8
Specific Allowance, Loans without a specific allowance	0	0
Average Investment in Impaired Loans, Loans without a specific allowance	8	9
Recorded Balance	8	8
Unpaid Principal Balance	8	8
Average Investment in Impaired Loans	8	9
Construction [Member]
Financing Receivable, Impaired [Line Items]
Specific Allowance, Loans without a specific allowance	0	0
Commercial [Member]
Financing Receivable, Impaired [Line Items]
Recorded Balance, Loans without a specific allowance	31
Unpaid Principal Balance, Loans without a specific allowance	31
Specific Allowance, Loans without a specific allowance	0	0
Average Investment in Impaired Loans, Loans without a specific allowance	31
Recorded Balance, Loans with a specific allowance	42	46
Unpaid Principal Balance, Loans with a specific allowance	42	46
Specific Allowance	22	25
Average Investment in Impaired Loans, Loans with a specific allowance	44	50
Recorded Balance	73	46
Unpaid Principal Balance	73	46
Specific Allowance	22	25
Average Investment in Impaired Loans	75	50
Commercial [Member]
Financing Receivable, Impaired [Line Items]
Recorded Balance, Loans without a specific allowance	17	21
Unpaid Principal Balance, Loans without a specific allowance	17	21
Specific Allowance, Loans without a specific allowance	0	0
Average Investment in Impaired Loans, Loans without a specific allowance	19	25
Recorded Balance	17	21
Unpaid Principal Balance	17	21
Average Investment in Impaired Loans	19	25
Consumer [Member]
Financing Receivable, Impaired [Line Items]
Recorded Balance, Loans without a specific allowance	5	6
Unpaid Principal Balance, Loans without a specific allowance	5	6
Specific Allowance, Loans without a specific allowance	0	0
Average Investment in Impaired Loans, Loans without a specific allowance	6	9
Recorded Balance, Loans with a specific allowance	6	15
Unpaid Principal Balance, Loans with a specific allowance	6	15
Specific Allowance	6	9
Average Investment in Impaired Loans, Loans with a specific allowance	7	22
Interest Income Recognized, Loans with a specific allowance		1
Interest on Cash Basis, Loans with a specific allowance		1
Recorded Balance	11	21
Unpaid Principal Balance	11	21
Specific Allowance	6	9
Average Investment in Impaired Loans	$ 13	31
Interest Income Recognized		1
Interest on Cash Basis		$ 1

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