Securities - Association's Investments Gross Unrealized Investment Losses and Fair Value of Association's Investments with Unrealized Losses (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Jun. 30, 2020
Less than 12 Months, Fair Value	$ 24,760	$ 22,223
Less than 12 Months, Unrealized Losses	(117)	(117)
12 Months or More, Fair Value	2,435	2,351
12 Months or More, Unrealized Losses	(13)	(106)
Total Fair Value	27,195	24,574
Total, Unrealized Losses	(130)	(223)
Mortgage-backed Securities - GSE Residential [Member]
Less than 12 Months, Fair Value	24,699	22,162
Less than 12 Months, Unrealized Losses	(116)	(116)
12 Months or More, Fair Value	2,435	2,351
12 Months or More, Unrealized Losses	(13)	(106)
Total Fair Value	27,134	24,513
Total, Unrealized Losses	(129)	(222)
State and Political Subdivisions [Member]
Less than 12 Months, Fair Value	61	61
Less than 12 Months, Unrealized Losses	(1)	(1)
12 Months or More, Fair Value	0	0
12 Months or More, Unrealized Losses	0	0
Total Fair Value	61	61
Total, Unrealized Losses	$ (1)	$ (1)