UNAUDITED CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Statement Of Financial Position [Abstract]
Student receivables, allowance for doubtful accounts, current	$ 19,752	$ 21,070
Student receivables, allowance for doubtful accounts, non-current	$ 6,011	$ 6,883
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	82,001,778	81,889,907
Common stock, shares outstanding	67,196,127	67,170,522
Treasury, Shares in treasury	14,805,651	14,719,385