Annual report pursuant to Section 13 and 15(d)

REVOLVING CREDIT FACILITY AND LONG TERM DEBT (Details)

v2.4.1.9
REVOLVING CREDIT FACILITY AND LONG TERM DEBT (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Line of Credit Facility [Line Items]    
Rate of Senior unsecured notes (in hundredths) 8.00%us-gaap_DebtInstrumentInterestRateStatedPercentage 8.00%us-gaap_DebtInstrumentInterestRateStatedPercentage
Revolving Credit Facility [Member]    
Line of Credit Facility [Line Items]    
Revolving credit facility, maximum borrowing $ 750us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
/ us-gaap_LineOfCreditFacilityAxis
= us-gaap_RevolvingCreditFacilityMember
 
Borrowing base 550nog_LineOfCreditFacilityBorrowingBase
/ us-gaap_LineOfCreditFacilityAxis
= us-gaap_RevolvingCreditFacilityMember
 
Borrowings under Credit Facility 298us-gaap_LineOfCredit
/ us-gaap_LineOfCreditFacilityAxis
= us-gaap_RevolvingCreditFacilityMember
 
Remaining borrowing capacity of Credit Facility 252us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity
/ us-gaap_LineOfCreditFacilityAxis
= us-gaap_RevolvingCreditFacilityMember
 
Percent of total additional permitted borrowing (in hundredths) 25.00%nog_PercentOfTotalAdditionalPermittedBorrowing
/ us-gaap_LineOfCreditFacilityAxis
= us-gaap_RevolvingCreditFacilityMember
 
Permitted additional indebtedness 500nog_LineOfCreditFacilityPermittedAdditionalIndebtedness
/ us-gaap_LineOfCreditFacilityAxis
= us-gaap_RevolvingCreditFacilityMember
 
Revolving credit facility, maturity date Sep. 30, 2018  
Credit Facility interest rate description Borrowings under the Revolving Credit Facility can either be at the Alternate Base Rate (as defined) plus a spread ranging from 0.5% to 1.5% or LIBOR borrowings at the Adjusted LIBOR Rate (as defined) plus a spread ranging from 1.5% to 2.5%. The applicable spread at any time is dependent upon the amount of borrowings relative to the borrowing base at such time. The Company may elect, from time to time, to convert all or any part of its LIBOR loans to base rate loans or to convert all or any of the base rate loans to LIBOR loans. A commitment fee is paid on the undrawn balance based on an annual rate of either 0.375% or 0.50%. At December 31, 2014, the commitment fee was 0.5% and the interest rate margin was 2.0% on LIBOR loans and 1.0% on base rate loans.  
Commitment fee, description A commitment fee is paid on the undrawn balance based on an annual rate of either 0.375% or 0.50%.  
Credit facility covenants The Revolving Credit Facility contains negative covenants that limit the Company’s ability, among other things, to pay any cash dividends, incur additional indebtedness, sell assets, enter into certain hedging contracts, change the nature of its business or operations, merge, consolidate, or make investments. In addition, the Company is required to maintain a current ratio (as defined in the credit agreement) of no less than 1.0 to 1.0 and a ratio of debt (as defined) to EBITDAX (as defined) of no greater than 4.0 to 1.0.  
Line Of Credit Facility Covenant Terms Current Ratio 1.0nog_LineOfCreditFacilityCovenantTermsCurrentRatio
/ us-gaap_LineOfCreditFacilityAxis
= us-gaap_RevolvingCreditFacilityMember
 
Line Of Credit Facility ratio of debt to EBITDAX 4.0nog_LineOfCreditFacilityRatioOfDebtToEBITDAX
/ us-gaap_LineOfCreditFacilityAxis
= us-gaap_RevolvingCreditFacilityMember
 
Minimum [Member] | Revolving Credit Facility [Member]    
Line of Credit Facility [Line Items]    
Commitment fee percentage (in hundredths) 0.375%us-gaap_LineOfCreditFacilityCommitmentFeePercentage
/ us-gaap_LineOfCreditFacilityAxis
= us-gaap_RevolvingCreditFacilityMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
 
Maximum [Member] | Revolving Credit Facility [Member]    
Line of Credit Facility [Line Items]    
Commitment fee percentage (in hundredths) 0.50%us-gaap_LineOfCreditFacilityCommitmentFeePercentage
/ us-gaap_LineOfCreditFacilityAxis
= us-gaap_RevolvingCreditFacilityMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
 
8.000% Senior Notes Due 2020 [Member]    
Line of Credit Facility [Line Items]    
Principal amount of Senior unsecured notes 300us-gaap_DebtInstrumentFaceAmount
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_UnsecuredDebtMember
 
Rate of Senior unsecured notes (in hundredths) 8.00%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_UnsecuredDebtMember
 
Maturity date Jun. 01, 2020  
Price of Senior unsecured notes (in hundredths) 105.25%nog_PriceOfSeniorUnsecuredNotes
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_UnsecuredDebtMember
 
Additional amount of Senior unsecured notes 200nog_AdditionalAmountOfSeniorUnsecuredNotes
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_UnsecuredDebtMember
 
Net proceeds from issuance of Senior unsecured notes 291.2nog_NetProceedsFromIssuanceOfSeniorUnsecuredNotes
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_UnsecuredDebtMember
 
Additional net proceeds from issuance of Senior unsecured notes 200.1nog_AdditionalNetProceedsFromIssuanceOfSeniorUnsecuredNotes
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_UnsecuredDebtMember
 
Percentage of notes that can be redeemed (in hundredths) 35.00%nog_PercentageOfNotesThatCanBeRedeemed
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_UnsecuredDebtMember
 
Rate of redemption price of notes (in hundredths) 108.00%nog_RateOfRedemptionPriceOfNotes
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_UnsecuredDebtMember
 
Limitation (in number of days) to redeemed the notes 180 days  
Limitation (in percentage of aggregate principal amount of Notes) to redeemed the notes 65.00%nog_LimitationInPercentageOfAggregatePrincipalAmountOfNotesToRedeemedNotes
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_UnsecuredDebtMember
 
Percentage of notes at redemption prices for prior to June 1, 2016 (in hundredths) 100.00%nog_PercentageOfNotesAtRedemptionPricesForPriorToJune12016
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_UnsecuredDebtMember
 
Percentage of notes at redemption prices for the twelve-month period beginning on June 1, 2016 (in hundredths) 104.00%nog_PercentageOfNotesAtRedemptionPricesForTwelveMonthPeriodBeginningOnJune12016
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_UnsecuredDebtMember
 
Percentage of notes at redemption prices for the twelve-month period beginning on June 1, 2017 (in hundredths) 102.00%nog_PercentageOfNotesAtRedemptionPricesForTwelveMonthPeriodBeginningOnJune12017
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_UnsecuredDebtMember
 
Percentage of notes at redemption prices for beginning on June 1, 2018 (in hundredths) 100.00%nog_PercentageOfNotesAtRedemptionPricesForBeginningOnJune12018
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_UnsecuredDebtMember
 
Number of days in default payment of interest 30 days  
Payment of certain final judgments $ 25nog_PaymentOfCertainFinalJudgments
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_UnsecuredDebtMember
 
Number of days related to payment certain final judgments 60 days  
LIBOR Loans [Member] | Revolving Credit Facility [Member]    
Line of Credit Facility [Line Items]    
Interest rate margin in effect during period (in hundredths) 2.00%us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
/ us-gaap_LineOfCreditFacilityAxis
= us-gaap_RevolvingCreditFacilityMember
/ us-gaap_LongtermDebtTypeAxis
= nog_LondonInterbankOfferedRateLoansMember
 
Commitment fee percentage (in hundredths) 0.50%us-gaap_LineOfCreditFacilityCommitmentFeePercentage
/ us-gaap_LineOfCreditFacilityAxis
= us-gaap_RevolvingCreditFacilityMember
/ us-gaap_LongtermDebtTypeAxis
= nog_LondonInterbankOfferedRateLoansMember
 
LIBOR Loans [Member] | Minimum [Member] | Revolving Credit Facility [Member]    
Line of Credit Facility [Line Items]    
Interest rate margin in effect during period (in hundredths) 1.50%us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
/ us-gaap_LineOfCreditFacilityAxis
= us-gaap_RevolvingCreditFacilityMember
/ us-gaap_LongtermDebtTypeAxis
= nog_LondonInterbankOfferedRateLoansMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
 
LIBOR Loans [Member] | Maximum [Member] | Revolving Credit Facility [Member]    
Line of Credit Facility [Line Items]    
Interest rate margin in effect during period (in hundredths) 2.50%us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
/ us-gaap_LineOfCreditFacilityAxis
= us-gaap_RevolvingCreditFacilityMember
/ us-gaap_LongtermDebtTypeAxis
= nog_LondonInterbankOfferedRateLoansMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
 
Alternate Base Rate Loans [Member] | Revolving Credit Facility [Member]    
Line of Credit Facility [Line Items]    
Interest rate margin in effect during period (in hundredths) 1.00%us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
/ us-gaap_LineOfCreditFacilityAxis
= us-gaap_RevolvingCreditFacilityMember
/ us-gaap_LongtermDebtTypeAxis
= nog_AlternateBaseRateLoansMember
 
Alternate Base Rate Loans [Member] | Minimum [Member] | Revolving Credit Facility [Member]    
Line of Credit Facility [Line Items]    
Interest rate margin in effect during period (in hundredths) 0.50%us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
/ us-gaap_LineOfCreditFacilityAxis
= us-gaap_RevolvingCreditFacilityMember
/ us-gaap_LongtermDebtTypeAxis
= nog_AlternateBaseRateLoansMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
 
Alternate Base Rate Loans [Member] | Maximum [Member] | Revolving Credit Facility [Member]    
Line of Credit Facility [Line Items]    
Interest rate margin in effect during period (in hundredths) 1.50%us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
/ us-gaap_LineOfCreditFacilityAxis
= us-gaap_RevolvingCreditFacilityMember
/ us-gaap_LongtermDebtTypeAxis
= nog_AlternateBaseRateLoansMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember