Fair Value Measures - Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Millions		May 31, 2022	Aug. 31, 2021
Assets:
Nonqualified savings plan investments		$ 44.2	$ 47.7
Fair Value, Measurements, Recurring
Assets:
Derivative financial instruments		13.6	0.1
Nonqualified savings plan investments		44.2	47.7
Cash equivalents		109.1	228.9
Assets, Fair Value Disclosure, Total		166.9	276.7
Liabilities:
Derivative financial instruments		2.9	10.5
Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring
Assets:
Nonqualified savings plan investments		44.2	47.7
Cash equivalents		109.1	228.9
Assets, Fair Value Disclosure, Total		153.3	276.6
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring
Assets:
Derivative financial instruments	[1]	13.6	0.1
Assets, Fair Value Disclosure, Total	[1]	13.6	0.1
Liabilities:
Derivative financial instruments	[1]	$ 2.9	$ 10.5

[1] Level 2 assets and liabilities include derivative financial instruments that are valued based on observable inputs. See Note 12 - Derivative Instruments for further discussion.