Note 19. Unaudited Quarterly Financial Data (Detail) - Schedule of Quarterly Financial Data (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Aug. 31, 2012		Aug. 31, 2011		Aug. 31, 2010
Revenues	$ 805,793	[1]	$ 726,510	[1]	$ 641,059	[1]
Cost of services	275,537		244,623		206,550
Selling, general and administrative	257,266		243,552		212,875
Operating income	272,990		238,335		221,634
Net income	188,809		171,046		150,211
Diluted earnings per common share (in Dollars per share)	$ 4.12		$ 3.61		$ 3.13
Weighted average common shares (diluted) (in Shares)	45,810		47,355		48,004
First Quarter [Member]
Revenues	196,448		173,289
Cost of services	66,833		56,785
Selling, general and administrative	62,862		57,075
Operating income	66,753		59,429
Net income	45,544		41,601
Diluted earnings per common share (in Dollars per share)	$ 0.99		$ 0.88
Weighted average common shares (diluted) (in Shares)	46,103		47,487
Second Quarter [Member]
Revenues	199,371		177,635
Cost of services	67,531		60,137
Selling, general and administrative	64,723		59,405
Operating income	67,117		58,093
Net income	46,746		45,254
Diluted earnings per common share (in Dollars per share)	$ 1.02		$ 0.95
Weighted average common shares (diluted) (in Shares)	45,707		47,427
Third Quarter [Member]
Revenues	202,311		183,647
Cost of services	68,878		62,224
Selling, general and administrative	64,939		59,600
Operating income	68,494		61,823
Net income	47,980		43,311
Diluted earnings per common share (in Dollars per share)	$ 1.05		$ 0.92
Weighted average common shares (diluted) (in Shares)	45,736		47,154
Fourth Quarter [Member]
Revenues	207,663		191,939
Cost of services	72,295		65,477
Selling, general and administrative	64,741		67,472
Operating income	70,627		58,990
Net income	$ 48,539		$ 40,880
Diluted earnings per common share (in Dollars per share)	$ 1.08		$ 0.88
Weighted average common shares (diluted) (in Shares)	45,152		46,595

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