Note 14. Stock-Based Compensation (Tables)

6 Months Ended

3 Months Ended

6 Months Ended

Feb. 28, 2013

Nov. 30, 2012

Non-Employee Stock Option Plan [Member]

Feb. 28, 2013

Employee Stock Purchase Plan [Member]

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]

	Three Months Ended				Six Months Ended
	Feb 28, 2013			Feb 29, 2012	Feb 28, 2013			Feb 29, 2012
Term structure of risk-free interest rate	0.16%	-	1.91%	n/a	0.16%	-	1.91%	0.13%	-	2.41%
Expected life (in years)			7.6	n/a	7.6	–	7.8	7.6	–	7.8
Term structure of volatility	24%	-	33%	n/a	24%	-	33%	30%	-	36%
Dividend yield			1.30%	n/a			1.30%			1.11%
Weighted average estimated fair value			$26.69	n/a			$26.87			$32.08
Weighted average exercise price			$92.55	n/a			$92.22			$94.84
Fair value as a percentage of exercise price			28.8%	n/a			29.1%			33.8%

Risk-free interest rate	0.89	%
Expected life (in years)	5.4
Expected volatility	32	%
Dividend yield	1.30	%

Risk-free interest rate	0.94	%
Expected life (in years)	5.4
Expected volatility	34	%
Dividend yield	1.11	%

	Three Months Ended
	February 28, 2013			February 29, 2012
Risk-free interest rate		0.08	%		0.05	%
Expected life (in months)		3			3
Expected volatility		9.2	%		12.4	%
Dividend yield		1.34	%		1.21	%

	Six Months Ended
	February 28, 2013			February 29, 2012
Risk-free interest rate		0.09	%		0.03	%
Expected life (in months)		3			3
Expected volatility		9.7	%		15.1	%
Dividend yield		1.33	%		1.21	%