Note 14 - Stock-based Compensation (Tables)

9 Months Ended

May 31, 2019

Notes Tables

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

Three Months Ended May 31,	2019					2018*
Term structure of risk-free interest rate		2.48%	-	3.14	%	—
Expected life (years)				7.1		—
Term structure of volatility		18%	-	25	%	—
Dividend yield				1.15	%	—
Weighted average estimated fair value	$			68.33		—
Weighted average exercise price	$			267.02		—
Fair value as a percentage of exercise price				25.6	%	—

Nine Months Ended May 31,	2019					2018
Term structure of risk-free interest rate		1.28%	-	3.14	%		1.28%	-	2.41	%
Expected life (years)				7.1					7.4
Term structure of volatility		18%	-	29	%		19%	-	29	%
Dividend yield				1.15	%				1.32	%
Weighted average estimated fair value	$			56.78		$			48.29
Weighted average exercise price	$			221.97		$			190.04
Fair value as a percentage of exercise price				25.6	%				25.4	%

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 May 31,	2019			2018
Risk-free interest rate		2.43	%		1.81	%
Expected life (months)		3			3
Expected volatility		10.58	%		10.07	%
Dividend yield		1.21	%		1.26	%
Weighted average estimated fair value	$	40.11		$	34.39

Nine Months Ended May 31,	2019			2018
Risk-free interest rate		2.38	%		1.43	%
Expected life (months)		3			3
Expected volatility		10.65	%		10.38	%
Dividend yield		1.13	%		1.28	%
Weighted average estimated fair value	$	39.73		$	31.25

Non Employee Directors Stock Option Plan [Member]

Notes Tables

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

Risk-free interest rate	2.51	%
Expected life (years)	5.4
Expected volatility	20.5	%
Dividend yield	1.17	%

Risk-free interest rate	2.34	%
Expected life (years)	5.4
Expected volatility	19.7	%
Dividend yield	1.16	%