Income Taxes - Components of Income Tax Expense (Benefit) of Continuing Operations (Detail) - USD ($) $ in Millions	12 Months Ended
	Aug. 31, 2023	Aug. 31, 2022	Aug. 31, 2021
Current
Federal	$ 7.4	$ (6.7)	$ (95.9)
State	2.7	0.9	1.9
Foreign	9.7	19.2	4.3
Current Income Tax Expense (Benefit), Total	19.8	13.4	(89.7)
Deferred
Federal	7.9	2.2	54.1
State	0.6	1.4	(2.3)
Foreign	(3.4)	1.6	(3.4)
Total Deferred Income Tax Expense (Benefit)	5.1	5.2	48.4
Change in valuation allowance	(0.3)	(0.5)	1.1
Income tax expense (benefit)	$ 24.6	$ 18.1	$ (40.2)