Quarterly report pursuant to Section 13 or 15(d)

INCOME TAXES (Details)

v2.4.1.9
INCOME TAXES (Details) (USD $)
3 Months Ended 12 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Income tax provision [Abstract]            
Current Income Taxes $ 0us-gaap_CurrentIncomeTaxExpenseBenefit $ 0us-gaap_CurrentIncomeTaxExpenseBenefit        
Deferred Income Taxes [Abstract]            
Federal (123,429,000)us-gaap_DeferredFederalIncomeTaxExpenseBenefit 3,741,000us-gaap_DeferredFederalIncomeTaxExpenseBenefit        
State (12,051,000)us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit 359,000us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit        
Total Provision (135,480,000)us-gaap_IncomeTaxExpenseBenefit 4,100,000us-gaap_IncomeTaxExpenseBenefit        
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        
Unrecognized tax benefits, interest and penalties accrued $ 0us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued   $ 0us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued      
Open tax years     2014 2013 2012 2011