Note 14 - Stock-based Compensation (Tables)

3 Months Ended

Nov. 30, 2015

The 2008 Employee Stock Purchase Plan [Member]

Notes Tables

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

Three months ended November 30,	2015			2014
Risk-free interest rate		0.05	%		0.02	%
Expected life (months)		3			3
Expected volatility		9.9	%		8.5	%
Dividend yield		1.15	%		1.22	%

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

Three months ended November 30,		2015				2014
Term structure of risk-free interest rate		0.07%	-	2.12%		0.06%	-	2.34%
Expected life (years)			7.8				8.2
Term structure of volatility		21%	-	30%		21%	-	31%
Dividend yield			1.07%				1.37%
Weighted average estimated fair value	$		46.62		$		37.67
Weighted average exercise price	$		170.21		$		131.31
Fair value as a percentage of exercise price			27.4%				28.7%