Segment Reporting (Schedule Of Revenues From Countries That Are 10% Or More Of Revenues) (Details) (USD $) In Thousands	3 Months Ended								12 Months Ended
	Aug. 31, 2011	May 31, 2011	Feb. 28, 2011	Nov. 30, 2010	Aug. 31, 2010	May 31, 2010	Feb. 28, 2010	Nov. 30, 2009	Aug. 31, 2011		Aug. 31, 2010		Aug. 31, 2009
Segment Reporting Information [Line Items]
Total revenues	$ 191,939	$ 183,647	$ 177,635	$ 173,289	$ 168,234	$ 160,301	$ 157,281	$ 155,243	$ 726,510	[1]	$ 641,059	[1]	$ 622,023	[1]
U.S. [Member]
Segment Reporting Information [Line Items]
Total revenues									497,564	[1]	435,351	[1]	423,926	[1]
United Kingdom [Member]
Segment Reporting Information [Line Items]
Total revenues									104,698	[1]	94,749	[1]	91,811	[1]
All Other European Countries [Member]
Segment Reporting Information [Line Items]
Total revenues									73,995	[1]	66,900	[1]	64,799	[1]
Asia Pacific [Member]
Segment Reporting Information [Line Items]
Total revenues									$ 50,253	[1]	$ 44,059	[1]	$ 41,487	[1]

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