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	Mar. 31, 2017	Jun. 30, 2016
Assets and liabilities measured at fair value on a recurring basis
Derivative financial instruments	$ 15.1	$ 11.8
Total assets	19.3	15.9
Derivative financial instruments, liabilities	14.7	43.9
Municipal auction rate securities
Assets and liabilities measured at fair value on a recurring basis
Marketable securities:	$ 4.2	$ 4.1