Income Taxes - Effective Income Tax Rate Reconciliation (Details) - USD ($) $ in Millions	12 Months Ended
Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2018
Income tax reconciliation
Provision for income taxes at U.S. statutory rate	$ 121.7	$ 127.5	$ 157.4
Increase (decrease) in Provision for income taxes from:
State taxes, net of federal tax	11.3	12.0	9.4
Foreign tax differential	3.2	3.8	(2.4)
Valuation allowances	2.4	0.4	(5.0)
Stock-based compensation - excess tax benefits (“ETB”)	(15.6)	(19.3)	(40.9)
Tax Act Items	0.0	(0.5)	15.4
Other	(5.9)	1.3	(0.8)
Total Provision for income taxes	$ 117.0	$ 125.2	$ 133.1
Tax rate reconciliation (percent)
Provision for income taxes at U.S. statutory rate	21.00%	21.00%	28.10%
Increase (decrease) in Provision for income taxes from:
State taxes, net of federal tax	1.90%	2.00%	1.70%
Foreign tax differential	0.60%	0.60%	(0.40%)
Valuation allowances	0.40%	0.10%	(0.90%)
Stock-based compensation - excess tax benefits (“ETB”)	(2.70%)	(3.20%)	(7.30%)
Tax Act Items	0	(0.001)	0.027
Other	(1.00%)	0.20%	(0.10%)
Total Provision for income taxes	20.20%	20.60%	23.70%

Effective Income Tax Rate Reconciliation, Increase (Decrease) In Provision For Income Taxes [Abstract]

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Effective Income Tax Reconciliation, Increase (Decrease) In Provision For Income Taxes [Abstract]

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Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

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