Variable Interest Entities - Schedule of Carrying Value of Assets and Liabilities of PEAKS Trust (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Variable Interest Entity [Line Items]
Restricted cash	$ 5,538	$ 6,015	$ 6,328
Current portion of PEAKS Trust student loans	9,787	8,480	9,541
PEAKS Trust student loans, excluding current portion, less allowance for loan losses of $17,122, $21,816 and $39,596	54,912	62,161	76,528
Total assets	622,391	663,654	739,247
Current portion of PEAKS Trust senior debt	15,634	20,105	26,533
Other current liabilities	29,631	31,973	28,602
PEAKS Trust senior debt, excluding current portion	28,916	30,701	45,127
Total liabilities	460,335	502,518	591,324
PEAKS Trust [Member]
Variable Interest Entity [Line Items]
Restricted cash	1,820	1,462	1,727
Current portion of PEAKS Trust student loans	5,536	5,746	6,475
PEAKS Trust student loans, excluding current portion, less allowance for loan losses of $17,122, $21,816 and $39,596	42,196	45,987	57,596
Total assets	49,552	53,195	65,798
Current portion of PEAKS Trust senior debt	15,634	20,105	26,533
Other current liabilities	0	191	175
PEAKS Trust senior debt, excluding current portion	28,916	30,701	45,127
Total liabilities	$ 44,550	$ 50,997	$ 71,835