Shareholders' Equity (Details) $ / shares in Units, $ in Millions	12 Months Ended			116 Months Ended
	Jun. 30, 2020 USD ($) votes $ / shares shares	Jun. 30, 2019 USD ($) $ / shares shares	Jun. 30, 2018 USD ($) $ / shares shares	Jun. 30, 2020 USD ($) votes $ / shares shares
Common Shares
Common shares, authorized (in shares) | shares	100,000,000	100,000,000		100,000,000
Common shares, par value (in dollars per share)	$ 0.002	$ 0.002		$ 0.002
Number of votes per each common share | votes	1			1
Common stock, dividends declared per share	$ 0
Treasury Shares
Share repurchase program, authorized amount | $	$ 30.0			$ 30.0
Share repurchase program, remaining authorized amount | $	$ 13.4			$ 13.4
Treasury stock acquired, shares repurchased (in shares) | shares	0	111,509	950,046	6,784,648
Treasury stock acquired less handling fees | $		$ 1.5	$ 15.1	$ 67.3
Treasury stock acquired, average price per share (in dollars per share)		$ 13.43	$ 15.86	$ 9.92
Treasury stock retired (in shares) | shares	0
Treasury Stock Reissued [Member]
Treasury Shares
Treasury stock acquired, average price per share (in dollars per share)				$ 10.32
Treasury stock reissued (in shares) | shares				145,428
Treasury stock reissued average price per share				$ 5.30