Note 10. Common Stock and Earnings Per Share (Detail) - Weighted Average Shares Outstanding (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Feb. 29, 2012	Feb. 28, 2011	Feb. 29, 2012	Feb. 28, 2011
Basic EPS
Income available to common stockholders (in Dollars)	$ 46,746	$ 45,254	$ 92,290	$ 86,855
Income available to common stockholders	44,880	46,226	44,993	46,244
Income available to common stockholders (in Dollars per share)	$ 1.04	$ 0.98	$ 2.05	$ 1.88
Diluted EPS
Dilutive effect of stock options and restricted stock	827	1,201	979	1,251
Income available to common stockholders plus assumed conversions (in Dollars)	$ 46,746	$ 45,254	$ 92,290	$ 86,855
Income available to common stockholders plus assumed conversions	45,707	47,427	45,972	47,495
Income available to common stockholders plus assumed conversions (in Dollars per share)	$ 1.02	$ 0.95	$ 2.01	$ 1.83