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Note 14. Stock-Based Compensation (Detail) - Summary of Stock Option Weighted Average Assumptions (Employee Stock Purchase Plan [Member])	3 Months Ended
	Nov. 30, 2012	Nov. 30, 2011
Employee Stock Purchase Plan [Member]
Risk-free interest rate	0.10%	0.02%
Expected life (in months)	3 months	3 months
Expected volatility	10.00%	18.00%
Dividend yield	1.32%	1.25%

The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

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