Basis of Presentation - Additional Information (Details) $ in Millions	12 Months Ended
	Jun. 30, 2020 USD ($) segment	Jun. 30, 2020 USD ($) Segment	Jun. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Number of reportable segments	2	2
Cumulative effect of changes in accounting principle	$ 1,346.5	$ 1,346.5	$ 1,127.5	$ 1,094.3	$ 1,003.8
Cumulative Effect, Period of Adoption, Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of changes in accounting principle			0.2	101.3
Accounting Standards Update 2018-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Increase to retained earnings as a result of the Tax Act of 2017				1.5
AOCI Attributable to Parent
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of changes in accounting principle	(100.4)	(100.4)	(71.2)	(51.9)	(55.8)
AOCI Attributable to Parent | Cumulative Effect, Period of Adoption, Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of changes in accounting principle				(1.5)
AOCI Attributable to Parent | Accounting Standards Update 2016-01 | Cumulative Effect, Period of Adoption, Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of changes in accounting principle				(0.1)
Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of changes in accounting principle	$ 2,302.6	$ 2,302.6	2,087.7	1,727.0	$ 1,469.4
Retained Earnings | Cumulative Effect, Period of Adoption, Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of changes in accounting principle			$ 0.2	102.8
Retained Earnings | Accounting Standards Update 2016-01 | Cumulative Effect, Period of Adoption, Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of changes in accounting principle				$ 0.1