Annual report pursuant to Section 13 and 15(d)

VARIABLE INTEREST ENTITIES AND EQUITY INVESTMENTS AND ADVANCES Era do Brazil Narrative (Details)

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VARIABLE INTEREST ENTITIES AND EQUITY INVESTMENTS AND ADVANCES Era do Brazil Narrative (Details) (USD $)
12 Months Ended 0 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Jul. 01, 2011
Schedule of Equity Method Investments [Line Items]        
Cash paid $ 125,000us-gaap_PaymentsToAcquireEquityMethodInvestments $ 0us-gaap_PaymentsToAcquireEquityMethodInvestments $ 10,627,000us-gaap_PaymentsToAcquireEquityMethodInvestments  
Equity Method Investee [Member] | Era do Brazil [Member]        
Schedule of Equity Method Investments [Line Items]        
Notes receivable to related party     9,200,000us-gaap_NotesReceivableRelatedParties
/ dei_LegalEntityAxis
= era_EradoBrazilMember
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= us-gaap_EquityMethodInvesteeMember
 
Number of notes receivable to related parties     2era_NotesReceivableRelatedPartiesNumberofNotes
/ dei_LegalEntityAxis
= era_EradoBrazilMember
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= us-gaap_EquityMethodInvesteeMember
 
Era do Brazil [Member]        
Schedule of Equity Method Investments [Line Items]        
Cash paid       4,800,000us-gaap_PaymentsToAcquireEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= era_EradoBrazilMember
Ownership 50.00%us-gaap_EquityMethodInvestmentOwnershipPercentage
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= era_EradoBrazilMember
[1]     50.00%us-gaap_EquityMethodInvestmentOwnershipPercentage
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= era_EradoBrazilMember
Consideration received       11,500,000us-gaap_SignificantAcquisitionsAndDisposalsAcquisitionCostsOrSaleProceeds
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= era_EradoBrazilMember
Cash from sale of leased equipment       9,500,000us-gaap_ProceedsFromSaleOfOtherPropertyPlantAndEquipment
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= era_EradoBrazilMember
Proceeds from related party debt     1,600,000us-gaap_ProceedsFromRelatedPartyDebt
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= era_EradoBrazilMember
 
Era do Brazil [Member] | Co-venturer [Member]        
Schedule of Equity Method Investments [Line Items]        
Cash paid       4,800,000us-gaap_PaymentsToAcquireEquityMethodInvestments
/ dei_LegalEntityAxis
= us-gaap_CoVenturerMember
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= era_EradoBrazilMember
Era do Brazil [Member] | Equity Method Investee [Member]        
Schedule of Equity Method Investments [Line Items]        
Notes receivable to related party     $ 10,800,000us-gaap_NotesReceivableRelatedParties
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= us-gaap_EquityMethodInvesteeMember
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= era_EradoBrazilMember
$ 2,000,000us-gaap_NotesReceivableRelatedParties
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= us-gaap_EquityMethodInvesteeMember
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= era_EradoBrazilMember
Number of notes receivable to related parties     2era_NotesReceivableRelatedPartiesNumberofNotes
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= us-gaap_EquityMethodInvesteeMember
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= era_EradoBrazilMember
 
[1] Consolidated entity as of September 30, 2012 as this is a VIE in which the Company is the primary beneficiary.