Income Taxes (Components of Deferred Income Tax Assets and Liabilities) (Details) - USD ($) $ in Millions	Jun. 30, 2019	Jun. 30, 2018
Income Tax Disclosure [Abstract]
Accrued expenses not currently deductible	$ 228.9	$ 178.3
Stock-based compensation expense	45.3	49.6
Foreign Tax Credits	25.1	40.0
Net operating losses	54.0	44.6
Deferred Tax Assets, Unrealized Losses on Trading Securities	0.0	83.6
Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Postretirement Benefits	5.6	0.0
Other	20.2	20.4
Deferred Tax Assets, Gross	379.1	416.5
Valuation Allowance	(31.6)	(46.0)
Deferred Tax Assets, Net of Valuation Allowance	347.5	370.5
Prepaid retirement benefits	0.0	19.3
Deferred Revenue	475.9	452.4
Fixed and intangible assets	279.5	242.4
Prepaid expenses	86.2	71.8
Unrealized investment gains, net	63.0	0.0
Tax on unrepatriated earnings	31.6	28.3
Other	7.2	9.4
Deferred Tax Liabilities	943.4	823.6
Deferred Tax Liabilities, Net	$ 595.9	$ 453.1