Goodwill and Other Intangible Assets - Additional Information (Detail) - USD ($)				12 Months Ended
	Aug. 31, 2015	Aug. 31, 2014	Aug. 31, 2013	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Schedule Of Other Intangible Assets [Line Items]
Goodwill impairment	$ 0	$ 0	$ 0
Amortization expense for intangible assets				$ 13,500,000	$ 11,500,000	$ 9,200,000
Customer Lists
Schedule Of Other Intangible Assets [Line Items]
Weighted average remaining life of intangible assets				7 years
Trade Names And Other Intangibles
Schedule Of Other Intangible Assets [Line Items]
Weighted average remaining life of intangible assets				17 years