Note 7 - Segment Information (Details) - Results of Operations (USD $) In Thousands, 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
Segment Reporting Information [Line Items]
Revenues from clients	$ 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]
Segment operating profit	79,386	73,037	75,054	74,740	70,534	71,637	56,164	71,085	302,219		269,419		272,990
Total assets	663,212				690,197				663,212		690,197		694,143
Depreciation and Amortization									34,435		35,779		33,779
Stock-based Compensation									22,891		39,951		21,982
Capital expenditures									17,743		18,517		22,520
UNITED STATES
Segment Reporting Information [Line Items]
Revenues from clients									624,642	[1]	586,865	[1]	550,474	[1]
Segment operating profit									165,004		138,706		149,968
Total assets	362,255				444,406				362,255		444,406		377,320
Depreciation and Amortization									25,574		27,757		25,061
Stock-based Compensation									20,288		37,307		20,180
Capital expenditures									16,047		13,649		20,408
Europe [Member]
Segment Reporting Information [Line Items]
Revenues from clients									227,395		208,827		197,404
Segment operating profit									100,937		100,187		95,417
Total assets	239,654				193,202				239,654		193,202		266,967
Depreciation and Amortization									5,656		4,027		4,922
Stock-based Compensation									2,231		2,264		1,680
Capital expenditures									647		1,276		488
Asia Pacific [Member]
Segment Reporting Information [Line Items]
Revenues from clients									68,298	[1]	62,420	[1]	57,915	[1]
Segment operating profit									36,278		30,526		27,605
Total assets	61,303				52,589				61,303		52,589		49,856
Depreciation and Amortization									3,205		3,995		3,796
Stock-based Compensation									372		380		122
Capital expenditures									$ 1,049		$ 3,592		$ 1,624

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