Note 19 - Unaudited Quarterly Financial Data (Details) - Quarterly Financial Data (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Aug. 31, 2014	May 31, 2014	Feb. 28, 2014	Nov. 30, 2013	Aug. 31, 2013	May 31, 2013	Feb. 28, 2013	Nov. 30, 2012	Aug. 31, 2014		Aug. 31, 2013		Aug. 31, 2012
Quarterly Financial Data [Abstract]
Revenues	$ 238,664	$ 231,761	$ 226,934	$ 222,975	$ 219,332	$ 214,613	$ 213,083	$ 211,085	$ 920,335	[1]	$ 858,112	[1]	$ 805,793	[1]
Cost of services	92,521	90,661	87,254	83,250	80,231	76,721	75,842	73,586	353,686		306,379		275,537
Selling, general and administrative	66,757	68,063	64,626	64,985	68,567	66,255	81,077	66,414	264,430		282,314		257,266
Operating income	79,386	73,037	75,054	74,740	70,534	71,637	56,164	71,085	302,219		269,419		272,990
Net income	$ 55,407	$ 51,532	$ 52,426	$ 52,178	$ 50,964	$ 53,367	$ 44,539	$ 49,769	$ 211,543		$ 198,637		$ 188,809
Diluted earnings per common share* (in Dollars per share)	$ 1.31	$ 1.21	$ 1.22	$ 1.19	$ 1.16	$ 1.20	$ 1.00	$ 1.11	$ 4.92		$ 4.45		$ 4.12
Weighted average common shares (diluted) (in Shares)	42,386	42,615	43,107	43,773	44,043	44,485	44,455	44,984	42,970		44,624		45,810

[1] Revenues are attributed to countries based on the location of the client.