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, 2016	Jun. 30, 2016
Assets and liabilities measured at fair value on a recurring basis
Derivative financial instruments	$ 5.5	$ 11.8
Total assets	9.7	15.9
Derivative financial instruments, liabilities	18.9	43.9
Municipal auction rate securities
Assets and liabilities measured at fair value on a recurring basis
Marketable securities:	$ 4.2	$ 4.1