Variable Interest Entities - Schedule of Payments Made to Entity Related to Guarantee Obligations (Parenthetical) (Detail) (2009 RSA [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2014	Sep. 30, 2014
2009 RSA [Member]
Variable Interest Entity [Line Items]
Recoveries from charged-off loans owed related to regular payments obligation	$ 156	$ 156

The amount of recoveries from charged-off loans that were owed to the reporting entity by the variable interest entity that were offset against amounts the reporting entity owed to the variable interest entity.

No definition available.

Name:	esi_RecoveriesOwedToReportingEntityOffsetAgainstAmountsOwedToVariableInterestEntity
Namespace Prefix:	esi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration