Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended
	Nov. 30, 2018	Nov. 30, 2017
Income Tax Disclosure [Abstract]
Tax Cuts and Jobs Act, provisional income tax expense (benefit)	$ (13.3)	$ 142.3
Tax Cuts and Jobs Act, net provisional income tax expense	65.9
Tax Cuts and Jobs Act, re-measurement of U.S. deferred tax	(10.5)
Tax Cuts and Jobs Act, foreign tax impact of change in indefinite reinvestment assertion	85.0
Tax Cuts and Jobs Act, income tax expense, net	$ 129.0
U.S. federal statutory rate	21.00%	35.00%