Income Taxes (Components of Deferred Income Tax Assets and Liabilities) (Details) - USD ($) $ in Millions	Jun. 30, 2018	Jun. 30, 2017
Income Tax Disclosure [Abstract]
Accrued expenses not currently deductible	$ 178.3	$ 294.5
Stock-based compensation expense	49.6	75.5
Foreign Tax Credits	40.0	49.5
Net operating losses	44.6	49.5
Deferred Tax Assets, Unrealized Losses on Trading Securities	83.6	0.0
Other	20.4	18.7
Deferred Tax Assets, Gross	416.5	487.7
Valuation Allowance	(46.0)	(9.4)
Deferred Tax Assets, Net of Valuation Allowance	370.5	478.3
Prepaid retirement benefits	19.3	125.1
Deferred Revenue	16.5	35.5
Fixed and intangible assets	242.4	226.3
Prepaid expenses	71.8	122.5
Unrealized investment gains, net	0.0	33.4
Tax on unrepatriated earnings	28.3	0.0
Other	9.4	5.2
Deferred Tax Liabilities	387.7	548.0
Deferred Tax Liabilities, Net	$ 17.2	$ 69.7