Note 14 - Stock-based Compensation (Tables)

6 Months Ended

Feb. 28, 2015

Note 14 - Stock-based Compensation (Tables) [Line Items]

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

	Three Months Ended February 28,		Six Months Ended February 28,
	2015	2014	2015	2014
Term structure of risk-free interest rate	0.06% - 2.34%	0.01% - 2.48%	0.06% - 2.34%	0.01% - 2.61%
Expected life (in years)	8.3	7.6	8.2	7.6
Term structure of volatility	21% - 31%	23% - 32%	21% - 31%	23% - 33%
Dividend yield	1.29%	1.35%	1.35%	1.35%
Weighted average estimated fair value	$43.05	$29.14	$39.07	$29.64
Weighted average exercise price	$147.05	$106.03	$135.40	$106.69
Fair value as a percentage of exercise price	29.3%	27.5%	28.9%	27.8%

Non-Employee Directors' Stock Option Plan [Member]

Note 14 - Stock-based Compensation (Tables) [Line Items]

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

Risk-free interest rate	1.45	%
Expected life (in years)	5.4
Expected volatility	23.5	%
Dividend yield	1.30	%

Risk-free interest rate	1.66	%
Expected life (in years)	5.4
Expected volatility	28.9	%
Dividend yield	1.35	%

2008 Employee Stock Purchase Plan [Member]

Note 14 - Stock-based Compensation (Tables) [Line Items]

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

	Three Months Ended February 28,
	2015			2014
Risk-free interest rate		0.03	%		0.05	%
Expected life (in months)		3			3
Expected volatility		8.1	%		10.3	%
Dividend yield		1.13	%		1.23	%

	Six Months Ended February 28,
	2015			2014
Risk-free interest rate		0.02	%		0.05	%
Expected life (in months)		3			3
Expected volatility		8.3	%		9.6	%
Dividend yield		1.17	%		1.29	%