Condensed Consolidated Statements Of Income (USD $) In Thousands, except Per Share data	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Condensed Consolidated Statements Of Income [Abstract]
Revenue	$ 360,638	$ 400,597	$ 1,131,686	$ 1,186,403
Costs and expenses:
Cost of educational services	141,262	134,478	421,460	402,623
Student services and administrative expenses	109,512	114,706	329,721	332,620
Total costs and expenses	250,774	249,184	751,181	735,243
Operating income	109,864	151,413	380,505	451,160
Interest income	716	634	2,341	1,876
Interest (expense)	(378)	(490)	(1,442)	(1,424)
Income before provision for income taxes	110,202	151,557	381,404	451,612
Provision for income taxes	42,884	58,380	149,700	174,944
Net income	$ 67,318	$ 93,177	$ 231,704	$ 276,668
Earnings per share:
Basic	$ 2.51	$ 2.84	$ 8.34	$ 8.15
Diluted	$ 2.48	$ 2.82	$ 8.27	$ 8.06
Weighted average shares outstanding:
Basic	26,839	32,777	27,791	33,954
Diluted	27,098	33,011	28,035	34,336