Benefit Plans - Schedule of Net Periodic Benefit Expense (Detail) - Benefit Equalization Plan, Postretirement Welfare Plan, Directors Consultation and Retirement Plan and Atlas Bank Retirement Income Plan [Member] - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2020	Dec. 31, 2019
Salaries and Employee Benefits [Member]
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	$ 27	$ 19	$ 53	$ 39
Miscellaneous Non Interest Expense [Member]
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Interest cost	65	82	131	163
Amortization of unrecognized loss	21	5	42	10
Expected return on assets	(29)	(28)	(57)	(56)
Net periodic benefit cost	$ 84	$ 78	$ 169	$ 156