Share Repurchase Program - Additional Information (Detail) (USD $)	12 Months Ended
	Aug. 31, 2012	Aug. 31, 2011	Aug. 31, 2010
Equity, Class of Treasury Stock [Line Items]
Common shares repurchased, shares	47,070,000
Remaining shares authorized to repurchase	1,000,000
Common shares repurchased, amount	$ 2,003,000	$ 442,000	$ 886,000
Common shares repurchased, average price	$ 47.07
October 2008 Program Member]
Equity, Class of Treasury Stock [Line Items]
Common shares repurchased, shares	3,000,000
Common shares repurchased, amount	$ 187,200
June 2012 Program [Member]
Equity, Class of Treasury Stock [Line Items]
Common shares repurchased, shares	2,000,000