Debt Securities - Narrative (Details)	12 Months Ended
	Jun. 30, 2020 USD ($) security	Jun. 30, 2019 USD ($) security	Jun. 30, 2018 USD ($)
Debt Securities, Available-for-sale [Line Items]
Gross realized losses	$ 0	$ 0	$ 0
Securities available for sale, at fair value	127,537,000	121,786,000
Market value of available-for-sale securities pledged as collateral	$ 84,456,000	$ 94,876,000
Number of securities with unrealized losses | security	24	100
Collateral Pledged
Debt Securities, Available-for-sale [Line Items]
Securities available for sale, at fair value	$ 82,888,000	$ 94,337,000