Common Stock (Details) shares in Millions	12 Months Ended
	Jun. 30, 2021 USD ($) vote class shares	Jun. 30, 2020 USD ($) shares	Jun. 30, 2019 USD ($) shares	May 31, 2014 USD ($)
Class of Stock [Line Items]
Number of classes of common stock outstanding | class	2
Votes per share | vote	10
Authorized dollar amount of shares to be repurchased				$ 100,000,000
Remaining authorized repurchase amount	$ 45,400,000
Number of shares (in shares) | shares	0.1	0.1	0.2
Cost at market value	$ 2,900,000	$ 4,700,000	$ 10,000,000.0
Cost of shares tendered for the exercise price of options	$ 1,800,000	$ 1,000,000	$ 4,100,000
Shares tendered for the exercise of price of options (in shares) | shares			0.1