XML 16 R39.htm IDEA: XBRL DOCUMENT v2.4.1.9
Property And Equipment (Narrative) (Details) (USD $)
3 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Dec. 31, 2014
Business Acquisition [Line Items]      
Directly related employee costs capitalized $ 2,400,000us-gaap_ExplorationCosts $ 3,100,000us-gaap_ExplorationCosts  
Impairment of oil and gas properties 90,087,000us-gaap_ImpairmentOfOilAndGasProperties    
Average price per barrel, oil 78.58end_AveragePriceUsedInCalculatingStandardizedMeasureOfDiscountedFutureNetCashFlowsProvedOilReserves 98.43end_AveragePriceUsedInCalculatingStandardizedMeasureOfDiscountedFutureNetCashFlowsProvedOilReserves  
Average price per barrel, gas 3.73end_AveragePriceUsedInCalculatingStandardizedMeasureOfDiscountedFutureNetCashFlowsProvedGasReserves 3.99end_AveragePriceUsedInCalculatingStandardizedMeasureOfDiscountedFutureNetCashFlowsProvedGasReserves  
U.K. Activities [Member]      
Business Acquisition [Line Items]      
Properties not subject to amortization 0end_PropertiesNotSubjectToAmortization
/ us-gaap_CapitalizedCostsOfUnprovedPropertiesExcludedFromAmortizationByPropertyOrProjectAxis
= end_UKActivitiesMember
   
Exploration and development related capitalized costs 0us-gaap_InterestCostsCapitalized
/ us-gaap_CapitalizedCostsOfUnprovedPropertiesExcludedFromAmortizationByPropertyOrProjectAxis
= end_UKActivitiesMember
2,600,000us-gaap_InterestCostsCapitalized
/ us-gaap_CapitalizedCostsOfUnprovedPropertiesExcludedFromAmortizationByPropertyOrProjectAxis
= end_UKActivitiesMember
 
Average price per barrel, oil 83.49end_AveragePriceUsedInCalculatingStandardizedMeasureOfDiscountedFutureNetCashFlowsProvedOilReserves
/ us-gaap_CapitalizedCostsOfUnprovedPropertiesExcludedFromAmortizationByPropertyOrProjectAxis
= end_UKActivitiesMember
107.06end_AveragePriceUsedInCalculatingStandardizedMeasureOfDiscountedFutureNetCashFlowsProvedOilReserves
/ us-gaap_CapitalizedCostsOfUnprovedPropertiesExcludedFromAmortizationByPropertyOrProjectAxis
= end_UKActivitiesMember
 
Average price per barrel, gas 7.60end_AveragePriceUsedInCalculatingStandardizedMeasureOfDiscountedFutureNetCashFlowsProvedGasReserves
/ us-gaap_CapitalizedCostsOfUnprovedPropertiesExcludedFromAmortizationByPropertyOrProjectAxis
= end_UKActivitiesMember
10.57end_AveragePriceUsedInCalculatingStandardizedMeasureOfDiscountedFutureNetCashFlowsProvedGasReserves
/ us-gaap_CapitalizedCostsOfUnprovedPropertiesExcludedFromAmortizationByPropertyOrProjectAxis
= end_UKActivitiesMember
 
Marcellus Acreage [Member]      
Business Acquisition [Line Items]      
Properties not subject to amortization 11,500,000end_PropertiesNotSubjectToAmortization
/ us-gaap_BusinessAcquisitionAxis
= end_MarcellusAcreageMember
10,800,000end_PropertiesNotSubjectToAmortization
/ us-gaap_BusinessAcquisitionAxis
= end_MarcellusAcreageMember
 
Alba Field [Member] | Loss Of Production Income [Member]      
Business Acquisition [Line Items]      
Proceeds from insurance claim 8,400,000us-gaap_UnusualOrInfrequentItemInsuranceProceeds
/ us-gaap_BusinessAcquisitionAxis
= end_AlbaFieldMember
/ us-gaap_UnusualOrInfrequentItemAxis
= end_LossOfProductionIncomeMember
  13,000,000us-gaap_UnusualOrInfrequentItemInsuranceProceeds
/ us-gaap_BusinessAcquisitionAxis
= end_AlbaFieldMember
/ us-gaap_UnusualOrInfrequentItemAxis
= end_LossOfProductionIncomeMember
Alba Field [Member] | Loss Of Production Income [Member] | Forecast [Member] | Minimum [Member]      
Business Acquisition [Line Items]      
Proceeds from insurance claim 5,000,000us-gaap_UnusualOrInfrequentItemInsuranceProceeds
/ us-gaap_BusinessAcquisitionAxis
= end_AlbaFieldMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
/ us-gaap_StatementScenarioAxis
= us-gaap_ScenarioForecastMember
/ us-gaap_UnusualOrInfrequentItemAxis
= end_LossOfProductionIncomeMember
   
Alba Field [Member] | Loss Of Production Income [Member] | Forecast [Member] | Maximum [Member]      
Business Acquisition [Line Items]      
Proceeds from insurance claim $ 7,000,000us-gaap_UnusualOrInfrequentItemInsuranceProceeds
/ us-gaap_BusinessAcquisitionAxis
= end_AlbaFieldMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
/ us-gaap_StatementScenarioAxis
= us-gaap_ScenarioForecastMember
/ us-gaap_UnusualOrInfrequentItemAxis
= end_LossOfProductionIncomeMember