Note 3 - Unrealized Gain (Loss) on Investments (Details) - USD ($) $ in Millions	Sep. 30, 2015	Jun. 30, 2015
Money Market Funds [Member]
At Cost	$ 6.1	$ 6.3
Unrealized Gains
Unrealized (Losses)
Cash equivalents	$ 6.1	$ 6.3
US Government Agencies Debt Securities [Member]
At Cost	$ 6.5	$ 6.5
Unrealized Gains
Unrealized (Losses)
Cash equivalents	$ 6.5	$ 6.5
US Treasury Securities [Member]
At Cost	$ 9.5	$ 9.6
Unrealized Gains
Unrealized (Losses)		$ (0.1)
Cash equivalents	$ 9.5	9.5
Corporate Note Securities [Member]
At Cost	$ 1.9	$ 2.9
Unrealized Gains
Unrealized (Losses)
Cash equivalents	$ 1.9	$ 2.9
Certificates of Deposit [Member]
At Cost	$ 3.1	$ 1.9
Unrealized Gains
Unrealized (Losses)
Cash equivalents	$ 3.1	$ 1.9
At Cost	$ 27.1	$ 27.2
Unrealized Gains
Unrealized (Losses)		$ (0.1)
Cash equivalents	$ 27.1	$ 27.1