Derivative Instruments (Narrative) (Details) (USD $)
|
3 Months Ended | |||
---|---|---|---|---|
Mar. 31, 2015
|
Mar. 31, 2014
|
Dec. 31, 2014
|
Dec. 31, 2011
interest_rate_derivative_held
|
|
Derivative [Line Items] | ||||
Derivative Liability | $ 200,000us-gaap_DerivativeLiabilities | $ 300,000us-gaap_DerivativeLiabilities | ||
Recognized gain | 100,000us-gaap_DerivativeGainOnDerivative | 100,000us-gaap_DerivativeGainOnDerivative | ||
Derivative Loss | 300,000us-gaap_DerivativeLossOnDerivative | |||
Interest Rate Swap [Member] | ||||
Derivative [Line Items] | ||||
Number of interest rate swaps held |
2us-gaap_NumberOfInterestRateDerivativesHeld / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember |
|||
Notional amount of interest rate derivatives |
$ 27,100,000us-gaap_DerivativeAssetNotionalAmount / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember |
|||
Interest Rate Swap Agreement 1 [Member] | Interest Rate Swap [Member] | ||||
Derivative [Line Items] | ||||
Fixed interest rate |
1.29%us-gaap_DerivativeFixedInterestRate / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember / era_InterestRateSwapAgreementAxis = era_InterestRateSwapAgreement1Member |
|||
Interest Rate Swap Agreement 2 [Member] | Interest Rate Swap [Member] | ||||
Derivative [Line Items] | ||||
Fixed interest rate |
1.76%us-gaap_DerivativeFixedInterestRate / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember / era_InterestRateSwapAgreementAxis = era_InterestRateSwapAgreement2Member |
X | ||||||||||
- Definition
Nominal or face amount used to calculate payments on the derivative asset. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
X | ||||||||||
- Definition
Fixed interest rate related to the interest rate derivative. No definition available.
|
X | ||||||||||
- Definition
Amount of increase in the fair value of derivatives recognized in the income statement. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
X | ||||||||||
- Definition
Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities not subject to a master netting arrangement and not elected to be offset. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
X | ||||||||||
- Details
|
X | ||||||||||
- Definition
Amount of decrease in the fair value of derivatives recognized in the income statement. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
X | ||||||||||
- Definition
Number of interest rate derivative instruments held by the entity at the reporting date. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
X | ||||||||||
- Details
|
X | ||||||||||
- Details
|
X | ||||||||||
- Details
|