Variable Interest Entities - Schedule of Carrying Value of Assets and Liabilities of PEAKS Trust (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Feb. 28, 2013
Variable Interest Entity [Line Items]
Restricted cash	$ 6,040	$ 5,636
Current portion of PEAKS Trust student loans	10,584	7,730
PEAKS Trust student loans, excluding current portion	80,292	76,479
Total assets	749,160us-gaap_Assets	806,851us-gaap_Assets
Current portion of PEAKS Trust senior debt	37,545us-gaap_LongTermDebtCurrent	157,883us-gaap_LongTermDebtCurrent
Other current liabilities	27,050us-gaap_OtherLiabilitiesCurrent	42,136us-gaap_OtherLiabilitiesCurrent
PEAKS Trust senior debt, excluding current portion	38,658us-gaap_LongTermDebtNoncurrent	71,341us-gaap_LongTermDebtNoncurrent
Total liabilities	601,155us-gaap_Liabilities	691,205us-gaap_Liabilities
PEAKS Trust [Member]
Variable Interest Entity [Line Items]
Restricted cash	1,556	2,593	1,703
Current portion of PEAKS Trust student loans	7,169	7,730	7,282
PEAKS Trust student loans, excluding current portion	59,902	76,479	104,834
Total assets	68,627	86,802	113,819
Current portion of PEAKS Trust senior debt	37,545	157,883	103,356
Other current liabilities	199	697	471
PEAKS Trust senior debt, excluding current portion	38,658	71,341	122,740
Total liabilities	$ 76,402	$ 229,921	$ 226,567

Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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Sum of the carrying amounts as of the balance sheet date of all liabilities that are recognized. Liabilities are probable future sacrifices of economic benefits arising from present obligations of an entity to transfer assets or provide services to other entities in the future.

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