Fair Value Measurements - Schedule of fair value of assets and liabilities measured on a recurring basis (Details) - Level 2 - USD ($) $ in Millions	Dec. 31, 2018	Jun. 30, 2018
Assets:
Derivative financial instruments	$ 2.8	$ 35.2
Total assets		38.1
Liabilities:
Derivative financial instruments, liabilities	$ 22.4	3.4
Municipal auction rate securities
Assets:
Municipal auction rate securities		$ 2.9

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

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