Quarterly report pursuant to Section 13 or 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
3 Months Ended
Mar. 31, 2015
Dec. 31, 2014
Mar. 31, 2014
Apr. 30, 2015
Line of Credit Facility [Line Items]        
Rate of senior unsecured notes (in hundredths) 8.00%us-gaap_DebtInstrumentInterestRateStatedPercentage 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 338us-gaap_LineOfCredit
/ us-gaap_LineOfCreditFacilityAxis
= us-gaap_RevolvingCreditFacilityMember
     
Remaining borrowing capacity of Credit Facility 212us-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 March 31, 2015, the commitment fee was 0.5% and the interest rate margin was 2.0% on LIBOR loans and 1.0% on base rate loans. At March 31, 2015, the Company had $338.0 million of LIBOR loans issued under the Revolving Credit Facility at a weighted average interest rate of 2.17%. The Company was in compliance with the financial covenants of the Revolving Credit Facility at March 31, 2015.      
Commitment fee, description A commitment fee is paid on the undrawn balance based on an annual rate of either 0.375% or 0.50%.      
Loans issued under revolving credit facility 338.0us-gaap_LoansPayable
/ us-gaap_LineOfCreditFacilityAxis
= us-gaap_RevolvingCreditFacilityMember
     
Weighted average interest rate (in hundredths) 2.17%us-gaap_DebtWeightedAverageInterestRate
/ us-gaap_LineOfCreditFacilityAxis
= us-gaap_RevolvingCreditFacilityMember
     
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, a ratio of secured debt to EBITDAX (as defined) of no greater than 2.5 to 1.0 and a ratio of EBITDAX (as defined) to interest expense (as defined) of no less than 2.5 to 1.0.      
Line of credit facility covenant terms current ratio 1.0nog_LineOfCreditFacilityCovenantTermsCurrentRatio
/ us-gaap_LineOfCreditFacilityAxis
= us-gaap_RevolvingCreditFacilityMember
     
Revolving Credit Facility [Member] | Subsequent Event [Member]        
Line of Credit Facility [Line Items]        
Borrowing base       550nog_LineOfCreditFacilityBorrowingBase
/ us-gaap_LineOfCreditFacilityAxis
= us-gaap_RevolvingCreditFacilityMember
/ us-gaap_SubsequentEventTypeAxis
= us-gaap_SubsequentEventMember
Line of credit facility covenant terms current ratio       1.0nog_LineOfCreditFacilityCovenantTermsCurrentRatio
/ us-gaap_LineOfCreditFacilityAxis
= us-gaap_RevolvingCreditFacilityMember
/ us-gaap_SubsequentEventTypeAxis
= us-gaap_SubsequentEventMember
Line of credit facility ratio of debt to EBITDAX       2.5nog_LineOfCreditFacilityRatioOfDebtToEBITDAX
/ us-gaap_LineOfCreditFacilityAxis
= us-gaap_RevolvingCreditFacilityMember
/ us-gaap_SubsequentEventTypeAxis
= us-gaap_SubsequentEventMember
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% 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]        
Commitment fee percentage (in hundredths) 0.50%us-gaap_LineOfCreditFacilityCommitmentFeePercentage
/ us-gaap_LineOfCreditFacilityAxis
= us-gaap_RevolvingCreditFacilityMember
/ us-gaap_LongtermDebtTypeAxis
= nog_LondonInterbankOfferedRateLoansMember
     
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
     
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