Note 6 - Segment Information (Details) - Results of Operations (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Aug. 31, 2013	May 31, 2013	Feb. 28, 2013	Nov. 30, 2012	Aug. 31, 2012	May 31, 2012	Feb. 29, 2012	Nov. 30, 2011	Aug. 31, 2013		Aug. 31, 2012		Aug. 31, 2011
Segment Reporting Information [Line Items]
Revenues from clients	$ 219,332	$ 214,613	$ 213,083	$ 211,085	$ 207,663	$ 202,311	$ 199,371	$ 196,448	$ 858,112	[1]	$ 805,793	[1]	$ 726,510	[1]
Segment operating profit	70,534	71,637	56,164	71,085	70,627	68,494	67,117	66,753	269,419		272,990		238,335
Total assets	690,197				694,143				690,197		694,143		657,440
Depreciation and amortization									35,779		33,779		36,847
Stock-based compensation	2,600								39,951		21,982		25,773
Capital expenditures									18,517		22,520		29,343
United States [Member]
Segment Reporting Information [Line Items]
Revenues from clients									586,865	[1]	550,474	[1]	497,564	[1]
Segment operating profit									138,706		149,968		135,327
Total assets	444,406				377,320				444,406		377,320		353,205
Depreciation and amortization									27,757		25,061		27,463
Stock-based compensation									37,307		20,180		23,091
Capital expenditures									13,649		20,408		20,588
Europe [Member]
Segment Reporting Information [Line Items]
Revenues from clients									208,827		197,404		178,693
Segment operating profit									100,187		95,417		79,637
Total assets	193,202				266,967				193,202		266,967		274,139
Depreciation and amortization									4,027		4,922		6,092
Stock-based compensation									2,264		1,680		2,364
Capital expenditures									1,276		488		2,770
Asia Pacific [Member]
Segment Reporting Information [Line Items]
Revenues from clients									62,420	[1]	57,915	[1]	50,253	[1]
Segment operating profit									30,526		27,605		23,371
Total assets	52,589				49,856				52,589		49,856		30,096
Depreciation and amortization									3,995		3,796		3,292
Stock-based compensation									380		122		318
Capital expenditures									$ 3,592		$ 1,624		$ 5,985

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