Fair Value Measurements - Schedule of fair value of assets and liabilities measured on a recurring basis (Details) - Measured on a recurring basis - Level 2 - USD ($) $ in Millions	Dec. 31, 2015	Jun. 30, 2015
Assets and liabilities measured at fair value on a recurring basis
Derivative financial instruments	$ 6.8	$ 4.4
Total assets	11.8	9.4
Derivative financial instruments, liabilities	73.3	53.5
Municipal auction rate securities
Assets and liabilities measured at fair value on a recurring basis
Marketable securities	$ 5.0	$ 5.0