Note 11. Common Stock and Earnings Per Share (Detail) - Weighted Average Shares Outstanding (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Nov. 30, 2012	Nov. 30, 2011
Net Income (Numerator) (in Dollars)	$ 49,769	$ 45,544
Weighted Average Common Shares (Denominator)	44,316	45,107
Per Share Amount (in Dollars per share)	$ 1.12	$ 1.01
Weighted Average Common Shares (Denominator)	668	996
Net Income (Numerator) (in Dollars)	$ 49,769	$ 45,544
Weighted Average Common Shares (Denominator)	44,984	46,103
Per Share Amount (in Dollars per share)	$ 1.11	$ 0.99