Stock-Based Compensation - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Net of Forfeitures	0
Stock-Based Compensation (Textual) [Abstract]
Tax benefits resulting from stock-based compensation deductions in excess of amounts reported for financial reporting purposes	$ 1.4
Stock-Based Compensation (Additional Textual) [Abstract]
Maximum period of achievement of performance goals to earn performance units	3 years
Minimum performance period of individual required to earn performance units	3 years
Stock Option [Member]
Stock-Based Compensation (Textual) [Abstract]
Compensation expense related to stock option	$ 0.7	$ 1.5	$ 3.3
Unrecognized compensation cost	$ 0.1
Unrecognized compensation costs, weighted average period	3 months
Weighted average fair value of options granted			$ 6.45
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested in Period, Fair Value	$ 1.9	3.3	$ 2.3
Tax benefits resulting from stock-based compensation deductions in excess of amounts reported for financial reporting purposes		0.0	(1.9)
Cash received from the exercise of capital stock option	22.2	21.3	1.0
Employee Service Share-based Compensation, Tax Benefit from Exercise of Stock Options	1.4	0.0
Total Intrinsic value of options exercised	6.6	3.1
Restricted Stock Units - Time Vesting Performance Vesting [Member]
Stock-Based Compensation (Textual) [Abstract]
Compensation expense related to stock option	19.4	$ 19.3	$ 14.6
Unrecognized compensation cost	$ 13.9
Unrecognized compensation costs, weighted average period	1 year 10 months 15 days

Maximum period of achievement of performance goals to earn performance units.

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Stock-based compensation.

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Stock based compensation.

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Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 14.F)
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Unrecognized cost of unvested share-based compensation awards.

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Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Amount of tax benefit from exercise of stock options granted under share-based compensation arrangement.

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Amount of cash inflow from realized tax benefit related to deductible compensation cost reported on the entity's tax return for equity instruments in excess of the compensation cost for those instruments recognized for financial reporting purposes.

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Amount of cash inflow from exercise of stock options granted under share-based compensation arrangement.

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-Publisher FASB
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Estimated period over which an employee is required to provide service in exchange for the equity-based payment award, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

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- Definition

Net number of share options (or share units) granted during the period.

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The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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Fair value of options vested. Excludes equity instruments other than options, for example, but not limited to, share units, stock appreciation rights, restricted stock.

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