Income Taxes (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Jul. 31, 2019	Jul. 31, 2018	Jul. 31, 2017	Jul. 31, 2016
Income Tax Contingency [Line Items]
Statutory U.S. federal rate (percentage)		26.90%	35.00%	35.00%
Discrete tax charge on repatriated earnings		$ 111.7
Tax benefit related to dividends		17.2
Transition tax not due within 12 months		85.1
Net tax benefit		2.1
Re-measurement of tax benefits		2.8
TCJA tax benefit		8.2
TCJA tax benefit related to dividends		3.4
Total dividends received deduction benefit		20.6
Additional tax expense to be recognized		20.6
Interest expense recognized		0.4
Gross accrued interest and penalties		$ 1.7	$ 2.3
Statute of limitations (in years)		5 years
Unrecognized tax benefits		$ 1.8
Scenario, Forecast
Income Tax Contingency [Line Items]
Statutory U.S. federal rate (percentage)	21.00%