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, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Salaries and Employee Benefits [Member]
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	$ 14	$ 12	$ 28	$ 24
Miscellaneous Non Interest Expense [Member]
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Interest cost	94	93	188	186
Amortization of unrecognized loss	11	11	22	22
Expected return on assets	(28)	(30)	(56)	(60)
Net periodic benefit cost	$ 91	$ 86	$ 182	$ 172