Accumulated Other Comprehensive Loss - Amounts Reclassified out of Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	May 31, 2022	May 31, 2021	May 31, 2022	May 31, 2021
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Interest and foreign exchange	$ 14.9	$ 10.2	$ 39.3	$ 30.9
Total before tax	(4.7)	(10.7)	(17.3)	37.8
Income tax expense	1.1	(6.9)	2.9	(36.0)
Unrealized Gain (Loss) on Derivative Financial Instruments | Reclassification out of Accumulated Other Comprehensive loss
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Total before tax	2.2	1.8	5.2	5.1
Income tax expense	(0.7)	(0.4)	(1.4)	(1.2)
Net of tax	1.5	1.4	3.8	3.9
Unrealized Gain (Loss) on Derivative Financial Instruments | Reclassification out of Accumulated Other Comprehensive loss | Foreign Exchange Contracts
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Revenue and Cost of revenue	0.5	0.5	0.9	1.2
Unrealized Gain (Loss) on Derivative Financial Instruments | Reclassification out of Accumulated Other Comprehensive loss | Interest rate swap contracts
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Interest and foreign exchange	$ 1.7	$ 1.3	$ 4.3	$ 3.9