Income Taxes (Details Textual) - USD ($) $ in Millions	4 Months Ended	8 Months Ended	12 Months Ended
	Apr. 30, 2018	Dec. 31, 2017	Apr. 30, 2021	Apr. 30, 2020	Apr. 30, 2019
Tax Credit Carryforward [Line Items]
Income tax expense (benefit)			$ 295.6	$ 247.2	$ 187.2
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%	35.00%	21.00%	21.00%	21.00%
Tax Cuts and Jobs Act, Income Tax Expense (Benefit)					$ (765.8)
Foreign Earnings Repatriated			$ 100.0
Undistributed earnings of foreign subsidiaries on which deferred income taxes not provided			23.9
Company's unrecognized tax benefits	$ 32.3		10.2	$ 13.1	15.0
Unrecognized tax benefits that would affect the effective tax rate			8.1	10.5	12.0
Tax-related net interest and penalties			1.7	1.9	3.3
Interest Charged (Credited) To Earnings			$ (0.2)	$ (0.1)	$ (0.8)
Time period over which it is reasonably possible that the Company could decrease its unrecognized tax benefits			12 months
Amount unrecognized tax benefit could decrease in next 12 months			$ 3.3
Foreign Tax Authority
Tax Credit Carryforward [Line Items]
Foreign Earning Repatriated, Withholding Taxes			$ 5.0