Intangibles and Other Assets, Net - Identifiable Intangible and Other Assets (Detail) - USD ($) $ in Millions	May 31, 2022	Aug. 31, 2021
Intangibles and Other Assets by Major Class [Line Items]
Finite-Lived Intangible Assets, Net, Total	$ 48.8	$ 53.0
Intangible assets not subject to amortization	2.4	2.4
Prepaid and other assets	33.4	26.7
Operating lease ROU assets	39.4	39.8
Nonqualified savings plan investments	44.2	47.7
Debt issuance costs, net	7.8	8.6
Assets held for sale	1.8	5.4
Total Intangible and other assets, net	177.8	183.6
Customer Relationships
Intangibles and Other Assets by Major Class [Line Items]
Finite lived intangible assets gross	87.5	89.8
Accumulated amortization	(65.3)	(64.1)
Other Intangible Assets
Intangibles and Other Assets by Major Class [Line Items]
Finite lived intangible assets gross	42.4	40.3
Accumulated amortization	$ (15.8)	$ (13.0)