Variable Interest Entities - Schedule of Carrying Value of Assets and Liabilities of PEAKS Trust (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Feb. 28, 2013	Dec. 31, 2012	Jun. 30, 2012
Variable Interest Entity [Line Items]
Restricted cash	$ 5,819		$ 3,478	$ 6,787
PEAKS Trust student loans, less allowance for loan losses of $0	7,307		0	0
PEAKS Trust student loans, excluding current portion, less allowance for loan losses of $0	101,375		0	0
Total assets	767,578	6,614	675,204	558,651
Current portion of PEAKS Trust senior debt	102,695		0	0
Other current liabilities	43,177	3,060	106,796	33,091
PEAKS Trust senior debt, excluding current portion	124,983		0	0
Total liabilities	637,892	46,114	549,439	474,621
PEAKS Trust Student Loans [Member]
Variable Interest Entity [Line Items]
Restricted cash	2,203	1,703
PEAKS Trust student loans, less allowance for loan losses of $0	7,307	7,282
PEAKS Trust student loans, excluding current portion, less allowance for loan losses of $0	101,375	104,834
Total assets	110,885	113,819
Current portion of PEAKS Trust senior debt	102,695	103,356
Other current liabilities	559	471
PEAKS Trust senior debt, excluding current portion	124,983	122,740
Total liabilities	$ 228,237	$ 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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Amount of long-term debt, after unamortized discount or premium, scheduled to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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An amount representing an agreement for an unconditional promise by the maker to pay the Company (holder) a definite sum of money within one year from the balance sheet date (or the normal operating cycle, whichever is longer), net of any write-downs taken for collection uncertainty on the part of the holder. Such amount may include accrued interest receivable in accordance with the terms of the debt. The debt also may contain provisions and related items including a discount or premium, payable on demand, secured, or unsecured, interest bearing or noninterest bearing, among a myriad of other features and characteristics. This amount does not include amounts related to receivables held-for-sale.

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Aggregate carrying amount of current liabilities (due within one year or within the normal operating cycle if longer) not separately disclosed in the balance sheet. Includes costs that are statutory in nature, are incurred on contractual obligations, or accumulate over time and for which invoices have not yet been received or will not be rendered and of liabilities not separately disclosed.

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The carrying amounts of cash and cash equivalent items which are restricted as to withdrawal or usage. Restrictions may include legally restricted deposits held as compensating balances against short-term borrowing arrangements, contracts entered into with others, or entity statements of intention with regard to particular deposits; however, time deposits and short-term certificates of deposit are not generally included in legally restricted deposits. Excludes compensating balance arrangements that are not agreements which legally restrict the use of cash amounts shown on the balance sheet. For a classified balance sheet represents the current portion only (the noncurrent portion has a separate concept); there is a separate and distinct element for unclassified presentations.

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