Total advances made in accordance with a note arrangement.

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Namespace Prefix:	esi
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The imputed interest rate on a non-interest bearing note receivable.

+ Details

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Namespace Prefix:	esi
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Date of maturity of note receivable.

+ Details

Name:	esi_NotesAndLoansReceivableMaturityDate
Namespace Prefix:	esi
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The term of a note receivable.

+ Details

Name:	esi_NotesAndLoansReceivableTerm
Namespace Prefix:	esi
Data Type:	xbrli:positiveIntegerItemType
Balance Type:	na
Period Type:	duration

- Definition

The amount of Senior Debt issued by a variable interest entity in which the Reporting Entity holds a variable interest.

+ Details

Name:	esi_SeniorDebtIssuedByVariableInterestEntity
Namespace Prefix:	esi
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

n/a

+ Details

Name:	esi_VariableInterestsAbstract
Namespace Prefix:	esi
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

An amount representing an agreement for an unconditional promise by the maker to pay the Entity (holder) a definite sum of money at a future date(s) more than one year from the balance sheet date. 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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 17
-Article 5

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.17)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

An amount representing an agreement for an unconditional promise by the maker to pay the Entity (holder) a definite sum of money at a future date more than one year from the balance sheet date, 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.

+ References

+ Details

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Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Variable Interests (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Jan. 20, 2010
Variable Interests
Senior debt in the aggregate principal amount					$ 300,000
Face value of subordinated note	85,000		85,000
Imputed interest rate			9.00%
Subordinate note maturity term, years			15
Advances to 2009 entity	200	150	200	2,719
Revolving note maturity date			2026
Carrying value	$ 17,896		$ 17,896