Summary of Restricted Stock Share and Restricted Stock Unit Grant Transactions for Shares, both Vested and Unvested (Detail) - shares		12 Months Ended
		Aug. 31, 2017	Aug. 31, 2016	Aug. 31, 2015
Reconciliation of Restricted Stock Activity [Line Items]
Beginning Balance	[1]	3,848,230	3,419,861	3,180,857
Granted		269,705	447,895	402,196
Forfeited		(26,206)	(19,526)	(163,192)
Ending Balance	[1]	4,091,729	3,848,230	3,419,861

[1] Balance represents cumulative grants net of forfeitures.