Borrowings - Schedule of Outstanding Borrowings (Details) - USD ($) $ in Millions	Dec. 31, 2018	Jun. 30, 2018
Debt Instrument [Line Items]
Principal amount outstanding at December 31, 2018	$ 1,200.0
Long-term debt	1,194.1	$ 1,053.4
Unused Available Capacity	700.0
Fair Value at December 31, 2018	1,175.2
Fiscal 2017 Revolving Credit Facility \| Revolving Credit Facility \| Long-term debt
Debt Instrument [Line Items]
Principal amount outstanding at December 31, 2018	300.0
Long-term debt	300.0	160.0
Unused Available Capacity	700.0
Fair Value at December 31, 2018	300.0
Fiscal 2014 Senior Notes \| Senior Notes \| Long-term debt
Debt Instrument [Line Items]
Principal amount outstanding at December 31, 2018	400.0
Long-term debt	398.9	398.5
Fair Value at December 31, 2018	402.9
Fiscal 2016 Senior Notes \| Senior Notes \| Long-term debt
Debt Instrument [Line Items]
Principal amount outstanding at December 31, 2018	500.0
Long-term debt	495.2	$ 494.8
Fair Value at December 31, 2018	$ 472.3

Face (par) amount of debt instrument at time of issuance.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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