Variable Interest Entities - Schedule of Carrying Value of Assets and Liabilities of PEAKS Trust (Detail) - USD ($) $ in Thousands	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2013	Feb. 28, 2013
Variable Interest Entity [Line Items]
Restricted cash	$ 4,293	$ 5,636	$ 6,693
PEAKS Trust student loans, less allowance for loan losses of $0	7,713	7,730	7,282
PEAKS Trust student loans, excluding current portion, less allowance for loan losses of $0	75,619	76,479	105,007
Total assets	780,332	806,851	783,286	$ 6,614
Current portion of PEAKS Trust senior debt	130,692	157,883	103,356
Other current liabilities	52,268	42,136	52,185	3,060
PEAKS Trust senior debt, excluding current portion	63,693	71,341	123,660
Total	664,089	$ 691,205	674,601	46,114
PEAKS Trust [Member]
Variable Interest Entity [Line Items]
Restricted cash	1,640		2,600	1,703
PEAKS Trust student loans, less allowance for loan losses of $0	7,713		7,282	7,282
PEAKS Trust student loans, excluding current portion, less allowance for loan losses of $0	75,619		105,007	104,834
Total assets	84,972		114,889	113,819
Current portion of PEAKS Trust senior debt	130,692		103,356	103,356
Other current liabilities	449		519	471
PEAKS Trust senior debt, excluding current portion	63,693		123,660	122,740
Total	$ 194,834		$ 227,535	$ 226,567