Annual report pursuant to Section 13 and 15(d)

COMMITMENTS AND CONTINGENCIES (Details)

v2.4.1.9
COMMITMENTS AND CONTINGENCIES (Details) (USD $)
12 Months Ended
Dec. 31, 2014
helicopter
Dec. 31, 2013
Dec. 31, 2012
Operating Leased Assets [Line Items]      
Unrecorded Unconditional Purchase Obligation $ 232,300,000us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceSheetAmount    
Unrecorded Unconditional Purchase Obligation, Due in Next Twelve Months 114,900,000us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFirstAnniversary    
Deposits Paid on Options Not Yet Exercised 1,900,000era_DepositsPaidonOptionsNotYetExercised    
Unrecorded Unconditional Purchase Obligation Balance Sheet Amount Potential Amount To Reduce Liability 131,300,000era_UnrecordedUnconditionalPurchaseObligationBalanceSheetAmountPotentialAmountToReduceLiability    
Unrecorded Unconditional Purchase Obligation Balance Sheet Amount Related To Liquidated Damage 8,700,000era_UnrecordedUnconditionalPurchaseObligationBalanceSheetAmountRelatedToLiquidatedDamage    
Aircraft maintenance credits period 4 years    
Aircraft maintenance utilized credits 4,400,000era_AircraftMaintenanceCreditsAmountUtilizedforthePeriod    
Number of helicopters leased 4era_LesseeLeasingArrangementsNumberofHelicoptersLeased    
Rental expense 4,400,000us-gaap_LeaseAndRentalExpense 6,000,000us-gaap_LeaseAndRentalExpense 4,000,000us-gaap_LeaseAndRentalExpense
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity      
2015 2,078,000us-gaap_OperatingLeasesFutureMinimumPaymentsDueCurrent    
2016 1,848,000us-gaap_OperatingLeasesFutureMinimumPaymentsDueInTwoYears    
2017 1,613,000us-gaap_OperatingLeasesFutureMinimumPaymentsDueInThreeYears    
2018 942,000us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFourYears    
2019 455,000us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFiveYears    
Years subsequent to 2019 $ 7,985,000us-gaap_OperatingLeasesFutureMinimumPaymentsDueThereafter    
Minimum [Member]      
Operating Leased Assets [Line Items]      
Expected duration of aircraft maintenance credits 1 year    
Lease term range 1 year    
Maximum [Member]      
Operating Leased Assets [Line Items]      
Expected duration of aircraft maintenance credits 2 years    
Lease term range 10 years