Annual report pursuant to Section 13 and 15(d)

INCOME TAXES (Details)

v2.4.1.9
INCOME TAXES (Details) (USD $)
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2010
INCOME TAXES [Abstract]        
Decrease in deferred state income tax expense   $ 500,000nog_IncreaseDecreaseInDeferredStateIncomeTaxExpense    
Income tax provision [Abstract]        
Current Income Taxes 3,259,445us-gaap_CurrentIncomeTaxExpenseBenefit (8,386)us-gaap_CurrentIncomeTaxExpenseBenefit 17,772us-gaap_CurrentIncomeTaxExpenseBenefit  
Deferred Income Taxes [Abstract]        
Federal 87,625,430us-gaap_DeferredFederalIncomeTaxExpenseBenefit 29,826,000us-gaap_DeferredFederalIncomeTaxExpenseBenefit 39,850,000us-gaap_DeferredFederalIncomeTaxExpenseBenefit  
State 8,482,125us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit 1,950,000us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit 3,134,000us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit  
Total Expense 99,367,000us-gaap_IncomeTaxExpenseBenefit 31,767,614us-gaap_IncomeTaxExpenseBenefit 43,001,772us-gaap_IncomeTaxExpenseBenefit  
Reconciliation of reported amount of income tax expense (benefit) [Abstract]        
Income Before Taxes and NOL 263,112,945us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest 84,834,650us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest 115,286,396us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest  
Federal Statutory Rate (in hundredths) 35.00%us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate 35.00%us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate 35.00%us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate  
Taxes Computed at Federal Statutory Rates 92,090,000us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate 29,692,000us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate 40,350,000us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate  
State Taxes, Net of Federal Taxes 5,404,300us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes 909,614us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes 2,086,772us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes  
Non-Deductible Compensation 1,872,700us-gaap_IncomeTaxReconciliationNondeductibleExpenseOther 1,166,000us-gaap_IncomeTaxReconciliationNondeductibleExpenseOther 565,000us-gaap_IncomeTaxReconciliationNondeductibleExpenseOther  
Total Expense 99,367,000us-gaap_IncomeTaxExpenseBenefit 31,767,614us-gaap_IncomeTaxExpenseBenefit 43,001,772us-gaap_IncomeTaxExpenseBenefit  
Deferred Tax Assets [Abstract]        
Total Deferred Tax Asset 198,369,445us-gaap_DeferredTaxAssetsGross 326,895,000us-gaap_DeferredTaxAssetsGross    
Deferred Tax Liabilities [Abstract]        
Total Current 43,938,000us-gaap_DeferredTaxLiabilitiesCurrent 0us-gaap_DeferredTaxLiabilitiesCurrent    
Total Non-Current 158,412,555us-gaap_DeferredTaxLiabilitiesNoncurrent 116,674,000us-gaap_DeferredTaxLiabilitiesNoncurrent    
Total Deferred Tax Liability (400,720,000)us-gaap_DeferredTaxLiabilities (433,138,000)us-gaap_DeferredTaxLiabilities    
Total Net Deferred Tax Liability (202,350,555)us-gaap_DeferredTaxAssetsLiabilitiesNet (106,243,000)us-gaap_DeferredTaxAssetsLiabilitiesNet    
Minimum Amount Tax Benefits Likely Realized Upon Settlement Percentage (in hundredths) 50.00%nog_MinimumAmountTaxBenefitsLikelyRealizedUponSettlementPercentage      
Unrecognized tax benefits 0us-gaap_UnrecognizedTaxBenefits      
Unrecognized tax benefits, income tax penalties and interest expense 0us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestExpense 0us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestExpense 0us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestExpense  
Unrecognized tax benefits, interest and penalties accrued 0us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued 0us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued    
Open tax years 2014 2013 2012 2011
Current [Member]        
Deferred Tax Assets [Abstract]        
Share Based Compensation 1,141,000us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost
/ nog_IncomeTaxesDeferredTaxAssetsAndLiabilitiesBalanceSheetClassificationAxis
= nog_CurrentMember
1,834,000us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost
/ nog_IncomeTaxesDeferredTaxAssetsAndLiabilitiesBalanceSheetClassificationAxis
= nog_CurrentMember
   
Accrued Interest 1,238,000us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAccruedLiabilities
/ nog_IncomeTaxesDeferredTaxAssetsAndLiabilitiesBalanceSheetClassificationAxis
= nog_CurrentMember
1,241,000us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAccruedLiabilities
/ nog_IncomeTaxesDeferredTaxAssetsAndLiabilitiesBalanceSheetClassificationAxis
= nog_CurrentMember
   
Derivative Instruments 0us-gaap_DeferredTaxAssetsDerivativeInstruments
/ nog_IncomeTaxesDeferredTaxAssetsAndLiabilitiesBalanceSheetClassificationAxis
= nog_CurrentMember
7,094,000us-gaap_DeferredTaxAssetsDerivativeInstruments
/ nog_IncomeTaxesDeferredTaxAssetsAndLiabilitiesBalanceSheetClassificationAxis
= nog_CurrentMember
   
Accrued expenses 986,000nog_DeferredTaxAssetsTaxAccruedExpenses
/ nog_IncomeTaxesDeferredTaxAssetsAndLiabilitiesBalanceSheetClassificationAxis
= nog_CurrentMember
0nog_DeferredTaxAssetsTaxAccruedExpenses
/ nog_IncomeTaxesDeferredTaxAssetsAndLiabilitiesBalanceSheetClassificationAxis
= nog_CurrentMember
   
Other 683,000us-gaap_DeferredTaxAssetsOther
/ nog_IncomeTaxesDeferredTaxAssetsAndLiabilitiesBalanceSheetClassificationAxis
= nog_CurrentMember
391,000us-gaap_DeferredTaxAssetsOther
/ nog_IncomeTaxesDeferredTaxAssetsAndLiabilitiesBalanceSheetClassificationAxis
= nog_CurrentMember
   
Total Current 4,048,000us-gaap_DeferredTaxAssetsGrossCurrent
/ nog_IncomeTaxesDeferredTaxAssetsAndLiabilitiesBalanceSheetClassificationAxis
= nog_CurrentMember
10,560,000us-gaap_DeferredTaxAssetsGrossCurrent
/ nog_IncomeTaxesDeferredTaxAssetsAndLiabilitiesBalanceSheetClassificationAxis
= nog_CurrentMember
   
Deferred Tax Liabilities [Abstract]        
Derivative Instruments (47,877,000)us-gaap_DeferredTaxLiabilitiesDerivatives
/ nog_IncomeTaxesDeferredTaxAssetsAndLiabilitiesBalanceSheetClassificationAxis
= nog_CurrentMember
0us-gaap_DeferredTaxLiabilitiesDerivatives
/ nog_IncomeTaxesDeferredTaxAssetsAndLiabilitiesBalanceSheetClassificationAxis
= nog_CurrentMember
   
Other (110,000)us-gaap_DeferredTaxLiabilitiesOther
/ nog_IncomeTaxesDeferredTaxAssetsAndLiabilitiesBalanceSheetClassificationAxis
= nog_CurrentMember
(129,000)us-gaap_DeferredTaxLiabilitiesOther
/ nog_IncomeTaxesDeferredTaxAssetsAndLiabilitiesBalanceSheetClassificationAxis
= nog_CurrentMember
   
Total Current (47,987,000)us-gaap_DeferredTaxLiabilitiesCurrent
/ nog_IncomeTaxesDeferredTaxAssetsAndLiabilitiesBalanceSheetClassificationAxis
= nog_CurrentMember
(129,000)us-gaap_DeferredTaxLiabilitiesCurrent
/ nog_IncomeTaxesDeferredTaxAssetsAndLiabilitiesBalanceSheetClassificationAxis
= nog_CurrentMember
   
Non-Current [Member]        
Deferred Tax Assets [Abstract]        
Other 94,000us-gaap_DeferredTaxAssetsOther
/ nog_IncomeTaxesDeferredTaxAssetsAndLiabilitiesBalanceSheetClassificationAxis
= nog_NonCurrentMember
69,000us-gaap_DeferredTaxAssetsOther
/ nog_IncomeTaxesDeferredTaxAssetsAndLiabilitiesBalanceSheetClassificationAxis
= nog_NonCurrentMember
   
Net Operating Loss (NOLs) and Tax Credit Carryforwards 194,227,445us-gaap_DeferredTaxAssetsOperatingLossCarryforwards
/ nog_IncomeTaxesDeferredTaxAssetsAndLiabilitiesBalanceSheetClassificationAxis
= nog_NonCurrentMember
316,266,000us-gaap_DeferredTaxAssetsOperatingLossCarryforwards
/ nog_IncomeTaxesDeferredTaxAssetsAndLiabilitiesBalanceSheetClassificationAxis
= nog_NonCurrentMember
   
Total Non-Current 194,321,445us-gaap_DeferredTaxAssetsGrossNoncurrent
/ nog_IncomeTaxesDeferredTaxAssetsAndLiabilitiesBalanceSheetClassificationAxis
= nog_NonCurrentMember
316,335,000us-gaap_DeferredTaxAssetsGrossNoncurrent
/ nog_IncomeTaxesDeferredTaxAssetsAndLiabilitiesBalanceSheetClassificationAxis
= nog_NonCurrentMember
   
Deferred Tax Liabilities [Abstract]        
Derivative Instruments (9,076,000)us-gaap_DeferredTaxLiabilitiesDerivatives
/ nog_IncomeTaxesDeferredTaxAssetsAndLiabilitiesBalanceSheetClassificationAxis
= nog_NonCurrentMember
(413,000)us-gaap_DeferredTaxLiabilitiesDerivatives
/ nog_IncomeTaxesDeferredTaxAssetsAndLiabilitiesBalanceSheetClassificationAxis
= nog_NonCurrentMember
   
Crude Oil and Natural Gas Properties and Other Property (343,657,000)us-gaap_DeferredTaxLiabilitiesPropertyPlantAndEquipment
/ nog_IncomeTaxesDeferredTaxAssetsAndLiabilitiesBalanceSheetClassificationAxis
= nog_NonCurrentMember
(432,596,000)us-gaap_DeferredTaxLiabilitiesPropertyPlantAndEquipment
/ nog_IncomeTaxesDeferredTaxAssetsAndLiabilitiesBalanceSheetClassificationAxis
= nog_NonCurrentMember
   
Total Non-Current (352,733,000)us-gaap_DeferredTaxLiabilitiesNoncurrent
/ nog_IncomeTaxesDeferredTaxAssetsAndLiabilitiesBalanceSheetClassificationAxis
= nog_NonCurrentMember
(433,009,000)us-gaap_DeferredTaxLiabilitiesNoncurrent
/ nog_IncomeTaxesDeferredTaxAssetsAndLiabilitiesBalanceSheetClassificationAxis
= nog_NonCurrentMember
   
Federal [Member]        
Operating Loss Carryforwards [Line Items]        
Net operating loss carryforward 516,500,000us-gaap_OperatingLossCarryforwards
/ us-gaap_IncomeTaxAuthorityAxis
= us-gaap_InternalRevenueServiceIRSMember
     
Alternative minimum tax credit $ 3,300,000us-gaap_DeferredTaxAssetsTaxCreditCarryforwardsAlternativeMinimumTax
/ us-gaap_IncomeTaxAuthorityAxis
= us-gaap_InternalRevenueServiceIRSMember
     
Federal [Member] | Minimum [Member]        
Operating Loss Carryforwards [Line Items]        
Net operating loss carryforward, expiration date Dec. 31, 2027      
Federal [Member] | Maximum [Member]        
Operating Loss Carryforwards [Line Items]        
Net operating loss carryforward, expiration date Dec. 31, 2034