XML 16 R54.htm IDEA: XBRL DOCUMENT
v2.4.0.6

Commitments and Contingencies (Details 2) (USD $) In Millions, unless otherwise specified | 3 Months Ended | 15 Months Ended
--- | --- | ---
Mar. 31, 2013 | Mar. 31, 2013
Ad valorem tax |  |
Ad valorem tax benefit | $ 2.0 | $ 8.8
Ad valorem tax benefit agreed to by a number of Appraisal Review Boards | 1.5 | 1.5
Maximum |  |
Business acquisition, contingent consideration |  |
Contingent payments | $ 46 | $ 46

X
- Definition The amount of ad valorem tax benefit included as a component of cost of goods sold (excluding depreciation and amortization). + References No definition available. + Details
Name: | exh_AdValoremTaxExpenseBenefit
Namespace Prefix: | exh_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The amount of ad valorem tax benefit agreed to by one or more appraisal review boards. + References No definition available. + Details
Name: | exh_AdValoremTaxExpenseBenefitAgreedToByAppraisalReviewBoards
Namespace Prefix: | exh_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | exh_OtherTaxAbstract
Namespace Prefix: | exh_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_BusinessAcquisitionContingentConsiderationLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of potential cash payments that could result from the contingent consideration arrangement. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 141 -Paragraph 51 -Subparagraph f -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. + Details
Name: | us-gaap_BusinessAcquisitionContingentConsiderationPotentialCashPayment
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant