Fair Value of Financial Instruments - Additional Information (Detail)	3 Months Ended		9 Months Ended
	Mar. 31, 2020 USD ($)	Mar. 31, 2019 USD ($)	Mar. 31, 2020 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2019 USD ($)	Jun. 30, 2019 USD ($)	Dec. 31, 2018 USD ($)	Jun. 30, 2018 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value transfers between levels	$ 0	$ 0	$ 0	$ 0
Carrying amount of loans	1,220,682,000		1,220,682,000			$ 1,093,121,000
Remaining valuation allowance	8,346,000	4,945,000	8,346,000	4,945,000	$ 6,216,000	5,664,000	$ 4,943,000	$ 4,904,000
Net charge-offs	9,000	11,000	223,000	141,000
Provision for loan losses	2,008,000	$ 7,000	2,755,000	71,000
Impaired Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying amount of loans	547,000		547,000			937,000
Remaining valuation allowance	$ 123,000		123,000			$ 173,000
Net charge-offs			0	0
Provision for loan losses			$ 6,000	$ 9,000
Minimum [Member] | Measurement Input, Discount Rates [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rates	0.10		0.10
Maximum [Member] | Measurement Input, Discount Rates [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rates	0.20		0.20