CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Cash flows from operating activities:
Net income (loss)	$ 29,253us-gaap_NetIncomeLoss	$ (27,024)us-gaap_NetIncomeLoss	$ 138,970us-gaap_NetIncomeLoss
Adjustments to reconcile net income (loss) to net cash flows from operating activities:
Depreciation and amortization	26,456	27,252	29,350
Provision for doubtful accounts	63,928us-gaap_ProvisionForDoubtfulAccounts	67,640us-gaap_ProvisionForDoubtfulAccounts	56,818us-gaap_ProvisionForDoubtfulAccounts
Deferred income taxes	41,969us-gaap_DeferredIncomeTaxExpenseBenefit	(54,102)us-gaap_DeferredIncomeTaxExpenseBenefit	(59,571)us-gaap_DeferredIncomeTaxExpenseBenefit
Excess tax benefit from stock option exercises	0	0	(1,382)
Stock-based compensation expense	10,336us-gaap_ShareBasedCompensation	11,638us-gaap_ShareBasedCompensation	16,658us-gaap_ShareBasedCompensation
Settlement cost	0esi_PaymentsChargesForSettlements	(46,000)esi_PaymentsChargesForSettlements	21,750esi_PaymentsChargesForSettlements
Goodwill and asset impairment	2,454us-gaap_AssetImpairmentCharges	0us-gaap_AssetImpairmentCharges	15,166us-gaap_AssetImpairmentCharges
Accretion of discount on private education loans	(12,170)	(12,996)	0
Accretion of discount on long-term debt	118esi_AccretionOfDiscountOnLongTermDebt	0esi_AccretionOfDiscountOnLongTermDebt	0esi_AccretionOfDiscountOnLongTermDebt
Accretion of discount on PEAKS Trust senior debt	6,712esi_AccretionOfDiscountOnSeniorDebt	4,926esi_AccretionOfDiscountOnSeniorDebt	0esi_AccretionOfDiscountOnSeniorDebt
Accretion of discount on CUSO secured borrowing obligation	231	0	0
Provision for private education loan losses	14,150us-gaap_ProvisionForLoanAndLeaseLosses	29,349us-gaap_ProvisionForLoanAndLeaseLosses	0us-gaap_ProvisionForLoanAndLeaseLosses
(Gain) loss on consolidation of variable interest entities	(16,631)	73,248	0
Other	(613)	315	6,992
Changes in operating assets and liabilities, net of acquisition:
Restricted cash	2,334	(455)	3,794
Accounts receivable	(10,010)	(87,225)	(87,138)
Private education loans	18,552	11,554	0
Accounts payable	9,591	(5,574)	(15,572)
Other operating assets and liabilities	(48,727)	73,880	72,429
Deferred revenue	(1,156)	11,299	(90,643)
Net cash flows from operating activities	136,777	77,725	107,621
Cash flows from investing activities:
Capital expenditures, net	(6,092)	(5,147)	(18,250)
Acquisition of company, net of cash acquired	(5,220)	(7,150)	0
Collateralization of letters of credit	(89,304)esi_CollateralizationOfLettersOfCredit	0esi_CollateralizationOfLettersOfCredit	0esi_CollateralizationOfLettersOfCredit
Proceeds from sales and maturities of investments and repayment of notes	293	461	217,301
Note advances and purchases of investments	(2)us-gaap_PaymentsToAcquireInvestments	(1,242)us-gaap_PaymentsToAcquireInvestments	(75,887)us-gaap_PaymentsToAcquireInvestments
Net cash flows from investing activities	(100,325)	(13,078)	123,164
Cash flows from financing activities:
Excess tax benefit from stock option exercises	0	0	1,382
Proceeds from exercise of stock options	0	0	8,345
Debt issue costs	(4,938)us-gaap_PaymentsOfDebtIssuanceCosts	0us-gaap_PaymentsOfDebtIssuanceCosts	(1,525)us-gaap_PaymentsOfDebtIssuanceCosts
Proceeds from term and revolving borrowings	100,000	0	175,000
Repayment of revolving borrowings	(50,000)	(90,000)	(185,000)
Repayment of PEAKS Trust senior debt	(158,668)us-gaap_RepaymentsOfLongTermDebt	(1,946)us-gaap_RepaymentsOfLongTermDebt	0us-gaap_RepaymentsOfLongTermDebt
Repayment of CUSO secured borrowing obligation	(1,766)us-gaap_RepaymentsOfSecuredDebt	0us-gaap_RepaymentsOfSecuredDebt	0us-gaap_RepaymentsOfSecuredDebt
Repurchase of common stock and shares tendered for taxes	(914)	(395)	(209,371)
Net cash flows from financing activities	(116,286)	(92,341)	(211,169)
Net change in cash and cash equivalents	(79,834)	(27,694)	19,616
Cash and cash equivalents at beginning of period	215,771	243,465	223,849
Cash and cash equivalents at end of period	135,937	215,771	243,465
Cash paid during the period for:
Income taxes (net of refunds)	14,466us-gaap_IncomeTaxesPaidNet	61,131us-gaap_IncomeTaxesPaidNet	139,919us-gaap_IncomeTaxesPaidNet
Interest	20,897us-gaap_InterestPaid	3,310us-gaap_InterestPaid	3,047us-gaap_InterestPaid
Non-cash operating activities:
Consolidation of variable interest entities assets	30,136	113,819	0
Consolidation of variable interest entities liabilities	2,564	471	0
Non-cash operating and investing activities:
Accrued capital expenditures	236	0	0
Non-cash financing activities:
Issuance of treasury stock for Directors' compensation	38us-gaap_StockIssued1	0us-gaap_StockIssued1	37us-gaap_StockIssued1
PEAKS Trust [Member]
Adjustments to reconcile net income (loss) to net cash flows from operating activities:
Goodwill and asset impairment			10,300
Provision for private education loan losses	12,111	29,349
Non-cash financing activities:
Consolidation of debt	0	226,096	0
CUSO [Member]
Adjustments to reconcile net income (loss) to net cash flows from operating activities:
Provision for private education loan losses	2,039
(Gain) loss on consolidation of variable interest entities	(16,631)
Non-cash financing activities:
Consolidation of debt	$ 122,542	$ 0	$ 0

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