Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Student receivables, allowance for doubtful accounts, current	$ 37,612	$ 43,891
Student receivables, allowance for doubtful accounts, Non-current	$ 16,075	$ 21,062
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	81,718,240	81,966,793
Common stock, shares outstanding	67,175,342	73,621,548
Treasury, Shares in treasury	14,542,898	8,345,245