Fair Value Measures - Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Millions		Feb. 29, 2024	Aug. 31, 2023
Assets:
Nonqualified savings plan investments		$ 56.4	$ 47.7
Fair Value, Measurements, Recurring
Assets:
Derivative financial instruments		37.4	37.9
Nonqualified savings plan investments		56.4	47.7
Cash equivalents		52.0	51.2
Assets, Fair Value Disclosure, Total		145.8	136.8
Liabilities:
Derivative financial instruments		0.2	0.2
Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring
Assets:
Nonqualified savings plan investments		56.4	47.7
Cash equivalents		52.0	51.2
Assets, Fair Value Disclosure, Total		108.4	98.9
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring
Assets:
Derivative financial instruments	[1]	37.4	37.9
Assets, Fair Value Disclosure, Total	[1]	37.4	37.9
Liabilities:
Derivative financial instruments	[1]	$ 0.2	$ 0.2

[1] Level 2 assets and liabilities include derivative financial instruments that are valued based on observable inputs. See Note 11 - Derivative Instruments for further discussion.