Securities - Available-for-sale securities, continuous unrealized loss position, Fair value (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Jun. 30, 2020
State and political subdivisions
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 7,175
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses	105
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	7,175
Available-for-sale Securities, Continuous Unrealized Loss Position, Unrealized Losses	105
Other securities
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	10,723	$ 995
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses	157	5
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or more, Fair Value	735	643
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or more, Unrealized Losses	241	338
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	11,458	1,638
Available-for-sale Securities, Continuous Unrealized Loss Position, Unrealized Losses	398	343
Mortgage-backed securities
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	45,723	9,037
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses	1,135	39
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	45,723	9,037
Available-for-sale Securities, Continuous Unrealized Loss Position, Unrealized Losses	1,135	39
Total investments and mortgage-backed securities
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	63,621	10,032
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses	1,397	44
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or more, Fair Value	735	643
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or more, Unrealized Losses	241	338
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	64,356	10,675
Available-for-sale Securities, Continuous Unrealized Loss Position, Unrealized Losses	$ 1,638	$ 382