Fair Value Measures - Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Millions		Aug. 31, 2023	Aug. 31, 2022
Assets:
Nonqualified savings plan investments		$ 47.7	$ 40.3
Fair Value, Measurements, Recurring
Assets:
Derivative financial instruments		37.9	21.4
Nonqualified savings plan investments		47.7	40.3
Cash equivalents		51.2	119.4
Assets, Fair Value Disclosure, Total		136.8	181.1
Liabilities:
Derivative financial instruments		0.2	3.0
Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring
Assets:
Nonqualified savings plan investments		47.7	40.3
Cash equivalents		51.2	119.4
Assets, Fair Value Disclosure, Total		98.9	159.7
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring
Assets:
Derivative financial instruments	[1]	37.9	21.4
Assets, Fair Value Disclosure, Total	[1]	37.9	21.4
Liabilities:
Derivative financial instruments	[1]	$ 0.2	$ 3.0

[1] Level 2 assets include derivative financial instruments which are valued based on significant observable inputs. See Note 14 - Derivative Instruments for further discussion.