Loans and Allowance for Loan Losses - Summary of Impaired Loans (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended	12 Months Ended
Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019	Jun. 30, 2019
Financing Receivable, Impaired [Line Items]
Specific Allowance	$ 0	$ 23	$ 0	$ 23	$ 23
Recorded Balance	1,659	2,054	1,659	2,054	1,851
Unpaid Principal Balance	1,659	2,054	1,659	2,054	1,851
Specific Allowance	0	23	0	23	23
Average Investment in Impaired Loans	1,687	2,080	1,731	2,130	1,922
Interest Income Recognized	13	12	47	60	74
Interest on Cash Basis	15	22	48	70	83
Commercial [Member]
Financing Receivable, Impaired [Line Items]
Recorded Balance, Loans without a specific allowance	4	24	4	24	18
Unpaid Principal Balance, Loans without a specific allowance	4	24	4	24	18
Specific Allowance, Loans without a specific allowance	0		0
Average Investment in Impaired Loans, Loans without a specific allowance	5	30	11	36	34
Interest Income Recognized, Loans without a specific allowance	0		0
Interest on Cash Basis, Loans without a specific allowance	0		0
Recorded Balance, Loans with a specific allowance	0	1	0	1
Unpaid Principal Balance, Loans with a specific allowance	0	1	0	1
Specific Allowance	0	1	0	1
Average Investment in Impaired Loans, Loans with a specific allowance	0	1	0	2
Interest Income Recognized, Loans with a specific allowance	0		0
Interest on Cash Basis, Loans with a specific allowance	0		0
Recorded Balance	4	25	4	25	18
Unpaid Principal Balance	4	25	4	25	18
Specific Allowance	0	1	0	1
Average Investment in Impaired Loans	5	31	11	38	34
Interest Income Recognized	0		0
Interest on Cash Basis	0		0
Commercial [Member]
Financing Receivable, Impaired [Line Items]
Recorded Balance, Loans without a specific allowance	41	167	41	167	60
Unpaid Principal Balance, Loans without a specific allowance	41	167	41	167	60
Specific Allowance, Loans without a specific allowance	0		0
Average Investment in Impaired Loans, Loans without a specific allowance	44	176	51	194	63
Interest Income Recognized, Loans without a specific allowance	0		0	5	6
Interest on Cash Basis, Loans without a specific allowance	0		0	7	6
Recorded Balance, Loans with a specific allowance	0	5	0	5
Unpaid Principal Balance, Loans with a specific allowance	0	5	0	5
Specific Allowance	0	5	0	5
Average Investment in Impaired Loans, Loans with a specific allowance	0	5	0	7
Interest Income Recognized, Loans with a specific allowance	0		0
Interest on Cash Basis, Loans with a specific allowance	0		0
Recorded Balance	41	172	41	172	60
Unpaid Principal Balance	41	172	41	172	60
Specific Allowance	0	5	0	5
Average Investment in Impaired Loans	44	181	51	201	63
Interest Income Recognized	0		0	5	6
Interest on Cash Basis	0		0	7	6
Consumer [Member]
Financing Receivable, Impaired [Line Items]
Recorded Balance, Loans without a specific allowance	7	3	7	3	19
Unpaid Principal Balance, Loans without a specific allowance	7	3	7	3	19
Specific Allowance, Loans without a specific allowance	0		0
Average Investment in Impaired Loans, Loans without a specific allowance	8	3	9	3	24
Interest Income Recognized, Loans without a specific allowance	0		0		2
Interest on Cash Basis, Loans without a specific allowance	0		0		2
Recorded Balance, Loans with a specific allowance	0		0		10
Unpaid Principal Balance, Loans with a specific allowance	0		0		10
Specific Allowance	0		0		10
Average Investment in Impaired Loans, Loans with a specific allowance	0		0		11
Interest Income Recognized, Loans with a specific allowance	0		0		1
Interest on Cash Basis, Loans with a specific allowance	0		0		1
Recorded Balance	7	3	7	3	29
Unpaid Principal Balance	7	3	7	3	29
Specific Allowance	0		0		10
Average Investment in Impaired Loans	8	3	9	3	35
Interest Income Recognized	0		0		3
Interest on Cash Basis	0		0		3
One- to four-family [Member]
Financing Receivable, Impaired [Line Items]
Recorded Balance, Loans without a specific allowance	1,591	1,741	1,591	1,741	1,676
Unpaid Principal Balance, Loans without a specific allowance	1,591	1,741	1,591	1,741	1,676
Specific Allowance, Loans without a specific allowance	0		0
Average Investment in Impaired Loans, Loans without a specific allowance	1,613	1,752	1,641	1,773	1,718
Interest Income Recognized, Loans without a specific allowance	13	11	47	50	63
Interest on Cash Basis, Loans without a specific allowance	15	20	48	57	71
Recorded Balance, Loans with a specific allowance	0	90	0	90	46
Unpaid Principal Balance, Loans with a specific allowance	0	90	0	90	46
Specific Allowance	0	17	0	17	13
Average Investment in Impaired Loans, Loans with a specific allowance	0	90	0	90	47
Interest Income Recognized, Loans with a specific allowance	0	1	0	4	1
Interest on Cash Basis, Loans with a specific allowance	0	1	0	4	1
Recorded Balance	1,591	1,831	1,591	1,831	1,722
Unpaid Principal Balance	1,591	1,831	1,591	1,831	1,722
Specific Allowance	0	17	0	17	13
Average Investment in Impaired Loans	1,613	1,842	1,641	1,863	1,765
Interest Income Recognized	13	12	47	54	64
Interest on Cash Basis	15	21	48	61	72
Multi-family [Member]
Financing Receivable, Impaired [Line Items]
Recorded Balance, Loans without a specific allowance	0		0
Unpaid Principal Balance, Loans without a specific allowance	0		0
Specific Allowance, Loans without a specific allowance	0		0
Average Investment in Impaired Loans, Loans without a specific allowance	0		0	1	1
Interest Income Recognized, Loans without a specific allowance	0		0
Interest on Cash Basis, Loans without a specific allowance	0		0
Recorded Balance, Loans with a specific allowance	0		0
Unpaid Principal Balance, Loans with a specific allowance	0		0
Specific Allowance	0		0
Average Investment in Impaired Loans, Loans with a specific allowance	0		0
Interest Income Recognized, Loans with a specific allowance	0		0
Interest on Cash Basis, Loans with a specific allowance	0		0
Recorded Balance	0		0
Unpaid Principal Balance	0		0
Specific Allowance	0		0
Average Investment in Impaired Loans	0		0	1	1
Interest Income Recognized	0		0
Interest on Cash Basis	0		0
Home equity lines of credit [Member]
Financing Receivable, Impaired [Line Items]
Recorded Balance, Loans without a specific allowance	16	23	16	23	22
Unpaid Principal Balance, Loans without a specific allowance	16	23	16	23	22
Specific Allowance, Loans without a specific allowance	0		0
Average Investment in Impaired Loans, Loans without a specific allowance	17	23	19	24	24
Interest Income Recognized, Loans without a specific allowance	0		0	1	1
Interest on Cash Basis, Loans without a specific allowance	0	1	0	2	2
Recorded Balance, Loans with a specific allowance	0		0
Unpaid Principal Balance, Loans with a specific allowance	0		0
Specific Allowance	0		0
Average Investment in Impaired Loans, Loans with a specific allowance	0		0
Interest Income Recognized, Loans with a specific allowance	0		0
Interest on Cash Basis, Loans with a specific allowance	0		0
Recorded Balance	16	23	16	23	22
Unpaid Principal Balance	16	23	16	23	22
Specific Allowance	0		0
Average Investment in Impaired Loans	17	23	19	24	24
Interest Income Recognized	0		0	1	1
Interest on Cash Basis	0	$ 1	0	$ 2	$ 2
Construction [Member]
Financing Receivable, Impaired [Line Items]
Recorded Balance, Loans without a specific allowance	0		0
Unpaid Principal Balance, Loans without a specific allowance	0		0
Specific Allowance, Loans without a specific allowance	0		0
Average Investment in Impaired Loans, Loans without a specific allowance	0		0
Interest Income Recognized, Loans without a specific allowance	0		0
Interest on Cash Basis, Loans without a specific allowance	0		0
Recorded Balance, Loans with a specific allowance	0		0
Unpaid Principal Balance, Loans with a specific allowance	0		0
Specific Allowance	0		0
Average Investment in Impaired Loans, Loans with a specific allowance	0		0
Interest Income Recognized, Loans with a specific allowance	0		0
Interest on Cash Basis, Loans with a specific allowance	0		0
Recorded Balance	0		0
Unpaid Principal Balance	0		0
Specific Allowance	0		0
Average Investment in Impaired Loans	0		0
Interest Income Recognized	0		0
Interest on Cash Basis	$ 0		$ 0

Impaired financing receivable interest income loss accrual method.

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Impaired financing receivable with no related allowance interest income loss accrual method.

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Impaired financing receivable with related allowance interest income loss accrual method.

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Specific Allowance On Impaired Financing Receivable With No Related Allowance

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Average amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

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Amount of interest income recognized on a cash-basis method of accounting that the financing receivables (with related allowance for credit losses and without a related allowance for credit losses) were impaired.

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Amount of allowance for credit losses related to recorded investment.

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Amount of unpaid principal balance of impaired financing receivables with related allowance for credit losses and without related allowance for credit losses.

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