Fair Value (Details) - USD ($) $ in Millions	Sep. 30, 2015	Jun. 30, 2015
Level 1 Inputs
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Cash equivalents	$ 100.9	$ 130.2
Level 2 Inputs | U.S. corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Marketable Securities	$ 51.8	$ 62.2