Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data	Sep. 30, 2011	Dec. 31, 2010
Consolidated Balance Sheets [Abstract]
Student receivables, allowance for doubtful accounts, current	$ 44,277	$ 50,104
Student receivables, allowance for doubtful accounts, non-current	$ 25,808	$ 40,840
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	1,000,000	1,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	300,000,000	300,000,000
Common stock, shares issued	82,425,459	81,220,265
Common stock, shares outstanding	75,916,618	81,209,410
Treasury, shares in treasury	6,508,841	10,855