Variable Interest Entities - Schedule of Carrying Value of Assets and Liabilities of PEAKS Trust (Parenthetical) (Detail) - USD ($) $ in Thousands	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2013	Feb. 28, 2013
Variable Interest Entity [Line Items]
Allowance for loan losses	$ 0	$ 0	$ 0	$ 0
Allowance for loan losses	38,420	$ 29,349	4,319
PEAKS Trust [Member]
Variable Interest Entity [Line Items]
Allowance for loan losses	0		0	0
Allowance for loan losses	$ 38,420		$ 4,319	$ 0

A valuation allowance relating to a written agreement to receive money (at a specified future date(s) within one year from the reporting date (or the normal operating cycle, whichever is longer), consisting of principal as well as any accrued interest) for the portion that is expected to be uncollectible.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.4)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=49124121&loc=d3e5074-111524

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Balance Type:	credit
Period Type:	instant

- Definition

A valuation allowance relating to a written agreement to receive money (at a specified future date(s) more than one year from the reporting date, consisting of principal as well as any accrued interest) for the portion that is expected to be uncollectible.

+ References

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	dei_LegalEntityAxis=esi_PeaksTrustMember
Namespace Prefix:
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Period Type: