| **Derivative Instruments and Hedging Activities (Details) (USD $)**                             | 3 Months Ended | 6 Months Ended           |     |
|-------------------------------------------------------------------------------------------------|----------------|--------------------------|-----|
||
| **Derivative Instruments and Hedging Activities [Abstract]**                                    |           |                     |     |   |
| Amount of Gain (Loss) on Derivative Instruments Recognized in Other Comprehensive (Income) Loss | $ 23,000,000   |                     |     |   |
| Net liability position of settled interest rate swap                                            |           |                     |     | 40,000,000 |
| AOCL amount, net of tax, to be reclassified to interest expense over the life of the debt       |           | 26,000,000               |     |   |
| Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months                             |           | 2,000,000                |     |   |
| Crude Oil Commodity Contract | Swaps 1                                                          |           |                     |     |   |
| **Derivative [Line Items]**                                                                     |           |                     |     |   |
| Period                                                                                          |           | 2012                     |     |   |
| Index                                                                                           |           | NYMEX WTI  (1) | [1] |   |
| Volume Per Day                                                                                  |           | 5,000                    |     |   |
| Weighted Average Fixed Price                                                                    |           | 91.84                    |     |   |
| Weighted Average Short Put Price                                                                |           |                |     |   |
| Weighted Average Floor Price                                                                    |           |                |     |   |
| Weighted Average Ceiling Price                                                                  |           |                |     |   |
| Crude Oil Commodity Contract | Swaps 2                                                          |           |                     |     |   |
| **Derivative [Line Items]**                                                                     |           |                     |     |   |
| Period                                                                                          |           | 2012                     |     |   |
| Index                                                                                           |           | Dated Brent              |     |   |
| Volume Per Day                                                                                  |           | 8,000                    |     |   |
| Weighted Average Fixed Price                                                                    |           | 89.06                    |     |   |
| Weighted Average Short Put Price                                                                |           |                |     |   |
| Weighted Average Floor Price                                                                    |           |                |     |   |
| Weighted Average Ceiling Price                                                                  |           |                |     |   |
| Crude Oil Commodity Contract | Three Way Collars 1                                              |           |                     |     |   |
| **Derivative [Line Items]**                                                                     |           |                     |     |   |
| Period                                                                                          |           | 2012                     |     |   |
| Index                                                                                           |           | NYMEX WTI                | [1] |   |
| Volume Per Day                                                                                  |           | 23,000                   |     |   |
| Weighted Average Fixed Price                                                                    |           |                |     |   |
| Weighted Average Short Put Price                                                                |           | 61.09                    |     |   |
| Weighted Average Floor Price                                                                    |           | 83.04                    |     |   |
| Weighted Average Ceiling Price                                                                  |           | 101.66                   |     |   |
| Crude Oil Commodity Contract | Three Way Collars 2                                              |           |                     |     |   |
| **Derivative [Line Items]**                                                                     |           |                     |     |   |
| Period                                                                                          |           | 2012                     |     |   |
| Index                                                                                           |           | Dated Brent              |     |   |
| Volume Per Day                                                                                  |           | 3,000                    |     |   |
| Weighted Average Fixed Price                                                                    |           |                |     |   |
| Weighted Average Short Put Price                                                                |           | 70.00                    |     |   |
| Weighted Average Floor Price                                                                    |           | 95.83                    |     |   |
| Weighted Average Ceiling Price                                                                  |           | 105.00                   |     |   |
| Crude Oil Commodity Contract | Swaps 3                                                          |           |                     |     |   |
| **Derivative [Line Items]**                                                                     |           |                     |     |   |
| Period                                                                                          |           | 2013                     |     |   |
| Index                                                                                           |           | NYMEX WTI                | [1] |   |
| Volume Per Day                                                                                  |           | 3,000                    |     |   |
| Weighted Average Fixed Price                                                                    |           | 87.00                    |     |   |
| Weighted Average Short Put Price                                                                |           |                |     |   |
| Weighted Average Floor Price                                                                    |           |                |     |   |
| Weighted Average Ceiling Price                                                                  |           |                |     |   |
| Crude Oil Commodity Contract | Swaps 4                                                          |           |                     |     |   |
| **Derivative [Line Items]**                                                                     |           |                     |     |   |
| Period                                                                                          |           | 2013                     |     |   |
| Index                                                                                           |           | Dated Brent              |     |   |
| Volume Per Day                                                                                  |           | 3,000                    |     |   |
| Weighted Average Fixed Price                                                                    |           | 98.03                    |     |   |
| Weighted Average Short Put Price                                                                |           |                |     |   |
| Weighted Average Floor Price                                                                    |           |                |     |   |
| Weighted Average Ceiling Price                                                                  |           |                |     |   |
| Crude Oil Commodity Contract | Two Way Collar 1                                                 |           |                     |     |   |
| **Derivative [Line Items]**                                                                     |           |                     |     |   |
| Period                                                                                          |           | 2013                     |     |   |
| Index                                                                                           |           | NYMEX WTI                | [1] |   |
| Volume Per Day                                                                                  |           | 5,000                    |     |   |
| Weighted Average Fixed Price                                                                    |           |                |     |   |
| Weighted Average Short Put Price                                                                |           |                |     |   |
| Weighted Average Floor Price                                                                    |           | 95.00                    |     |   |
| Weighted Average Ceiling Price                                                                  |           | 115.00                   |     |   |
| Crude Oil Commodity Contract | Three Way Collars 3                                              |           |                     |     |   |
| **Derivative [Line Items]**                                                                     |           |                     |     |   |
| Period                                                                                          |           | 2013                     |     |   |
| Index                                                                                           |           | NYMEX WTI                | [1] |   |
| Volume Per Day                                                                                  |           | 7,000                    |     |   |
| Weighted Average Fixed Price                                                                    |           |                |     |   |
| Weighted Average Short Put Price                                                                |           | 63.57                    |     |   |
| Weighted Average Floor Price                                                                    |           | 83.57                    |     |   |
| Weighted Average Ceiling Price                                                                  |           | 109.04                   |     |   |
| Crude Oil Commodity Contract | Three Way Collars 4                                              |           |                     |     |   |
| **Derivative [Line Items]**                                                                     |           |                     |     |   |
| Period                                                                                          |           | 2013                     |     |   |
| Index                                                                                           |           | Dated Brent              |     |   |
| Volume Per Day                                                                                  |           | 26,000                   |     |   |
| Weighted Average Fixed Price                                                                    |           |                |     |   |
| Weighted Average Short Put Price                                                                |           | 82.88                    |     |   |
| Weighted Average Floor Price                                                                    |           | 100.86                   |     |   |
| Weighted Average Ceiling Price                                                                  |           | 127.32                   |     |   |
| Crude Oil Commodity Contract | Swaps 5                                                          |           |                     |     |   |
| **Derivative [Line Items]**                                                                     |           |                     |     |   |
| Period                                                                                          |           | 2014                     |     |   |
| Index                                                                                           |           | NYMEX WTI                | [1] |   |
| Volume Per Day                                                                                  |           | 5,000                    |     |   |
| Weighted Average Fixed Price                                                                    |           | 86.50                    |     |   |
| Weighted Average Short Put Price                                                                |           |                |     |   |
| Weighted Average Floor Price                                                                    |           |                |     |   |
| Weighted Average Ceiling Price                                                                  |           |                |     |   |
| Crude Oil Commodity Contract | Swaps 6                                                          |           |                     |     |   |
| **Derivative [Line Items]**                                                                     |           |                     |     |   |
| Period                                                                                          |           | 2014                     |     |   |
| Index                                                                                           |           | Dated Brent              |     |   |
| Volume Per Day                                                                                  |           | 8,000                    |     |   |
| Weighted Average Fixed Price                                                                    |           | 105.94                   |     |   |
| Weighted Average Short Put Price                                                                |           |                |     |   |
| Weighted Average Floor Price                                                                    |           |                |     |   |
| Weighted Average Ceiling Price                                                                  |           |                |     |   |
| Crude Oil Commodity Contract | Three Way Collars 5                                              |           |                     |     |   |
| **Derivative [Line Items]**                                                                     |           |                     |     |   |
| Period                                                                                          |           | 2014                     |     |   |
| Index                                                                                           |           | Dated Brent              |     |   |
| Volume Per Day                                                                                  |           | 10,000                   |     |   |
| Weighted Average Fixed Price                                                                    |           |                |     |   |
| Weighted Average Short Put Price                                                                |           | 85.00                    |     |   |
| Weighted Average Floor Price                                                                    |           | 98.50                    |     |   |
| Weighted Average Ceiling Price                                                                  |           | 129.24                   |     |   |
| Natural Gas Commodity Contract | Swaps 1                                                        |           |                     |     |   |
| **Derivative [Line Items]**                                                                     |           |                     |     |   |
| Period                                                                                          |           | 2012                     |     |   |
| Index                                                                                           |           | NYMEX HH (1)             | [2] |   |
| Volume Per Day                                                                                  |           | 30,000                   |     |   |
| Weighted Average Fixed Price                                                                    |           | 5.10                     |     |   |
| Weighted Average Short Put Price                                                                |           |                |     |   |
| Weighted Average Floor Price                                                                    |           |                |     |   |
| Weighted Average Ceiling Price                                                                  |           |                |     |   |
| Natural Gas Commodity Contract | Swaps 2                                                        |           |                     |     |   |
| **Derivative [Line Items]**                                                                     |           |                     |     |   |
| Period                                                                                          |           | 2013                     |     |   |
| Index                                                                                           |           | NYMEX HH                 | [2] |   |
| Volume Per Day                                                                                  |           | 30,000                   |     |   |
| Weighted Average Fixed Price                                                                    |           | 5.25                     |     |   |
| Weighted Average Short Put Price                                                                |           |                |     |   |
| Weighted Average Floor Price                                                                    |           |                |     |   |
| Weighted Average Ceiling Price                                                                  |           |                |     |   |
| Natural Gas Commodity Contract | Three Way Collars 1                                            |           |                     |     |   |
| **Derivative [Line Items]**                                                                     |           |                     |     |   |
| Period                                                                                          |           | 2012                     |     |   |
| Index                                                                                           |           | NYMEX HH                 | [2] |   |
| Volume Per Day                                                                                  |           | 110,000                  |     |   |
| Weighted Average Fixed Price                                                                    |           |                |     |   |
| Weighted Average Short Put Price                                                                |           | 4.44                     |     |   |
| Weighted Average Floor Price                                                                    |           | 5.25                     |     |   |
| Weighted Average Ceiling Price                                                                  |           | 6.66                     |     |   |
| Natural Gas Commodity Contract | Three Way Collars 2                                            |           |                     |     |   |
| **Derivative [Line Items]**                                                                     |           |                     |     |   |
| Period                                                                                          |           | 2013                     |     |   |
| Index                                                                                           |           | NYMEX HH                 | [2] |   |
| Volume Per Day                                                                                  |           | 100,000                  |     |   |
| Weighted Average Fixed Price                                                                    |           |                |     |   |
| Weighted Average Short Put Price                                                                |           | 3.88                     |     |   |
| Weighted Average Floor Price                                                                    |           | 4.75                     |     |   |
| Weighted Average Ceiling Price                                                                  |           | 5.63                     |     |   |
| Natural Gas Commodity Contract | Two Way Collar 1                                               |           |                     |     |   |
| **Derivative [Line Items]**                                                                     |           |                     |     |   |
| Period                                                                                          |           | 2012                     |     |   |
| Index                                                                                           |           | NYMEX HH                 | [2] |   |
| Volume Per Day                                                                                  |           | 40,000                   |     |   |
| Weighted Average Fixed Price                                                                    |           |                |     |   |
| Weighted Average Short Put Price                                                                |           |                |     |   |
| Weighted Average Floor Price                                                                    |           | 3.25                     |     |   |
| Weighted Average Ceiling Price                                                                  |           | 5.14                     |     |   |
| Natural Gas Commodity Contract | Two Way Collar 2                                               |           |                     |     |   |
| **Derivative [Line Items]**                                                                     |           |                     |     |   |
| Period                                                                                          |           | 2013                     |     |   |
| Index                                                                                           |           | NYMEX HH                 | [2] |   |
| Volume Per Day                                                                                  |           | 40,000                   |     |   |
| Weighted Average Fixed Price                                                                    |           |                |     |   |
| Weighted Average Short Put Price                                                                |           |                |     |   |
| Weighted Average Floor Price                                                                    |           | 3.25                     |     |   |
| Weighted Average Ceiling Price                                                                  |           | 5.14                     |     |   |
| Natural Gas Commodity Contract | Basis Swaps 1                                                  |           |                     |     |   |
| **Derivative [Line Items]**                                                                     |           |                     |     |   |
| Period                                                                                          |           | 2012                     |     |   |
| Index                                                                                           |           | IFERC CIG (1)            | [3] |   |
| Volume Per Day                                                                                  |           | 150,000                  |     |   |
| Index Less Differential                                                                         |           | NYMEX HH                 |     |   |
| Weighted Average Differential                                                                   |           | $ (0.52)                 |     |   |
|                                                                                                 |
| [1]West Texas Intermediate[2]Henry Hub[3]Colorado Interstate Gas – Northern System       |

| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Aggregate notional amount of derivative expressed in nonmonetary units. For example, the number of barrels specified in a fuel oil forward purchase contract.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Article 12 -Section 13 -Sentence Column B
+ Details**Name:**invest_DerivativeNonmonetaryNotionalAmount**Namespace Prefix:**invest_**Data Type:**xbrli:decimalItemType**Balance Type:**na**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The amount of gain (loss), net of tax, on derivative instruments recognized in other comprehensive (income) loss prior to settlement of interest rate swap.
+ References
No definition available.
+ Details**Name:**nbl_AmountOfGainLossOnDerivativeInstrumentsRecognizedInOtherComprehensiveIncomeLoss**Namespace Prefix:**nbl_**Data Type:**xbrli:monetaryItemType**Balance Type:**credit**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                                                    |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Net of tax amount remaining in Accumulated Other Comprehensive Loss that will be reclassified into interest expense over the life of the debt.
+ References
No definition available.
+ Details**Name:**nbl_AoclAmountNetOfTaxToBeReclassifiedToInterestExpenseOverLifeOfDebt**Namespace Prefix:**nbl_**Data Type:**xbrli:monetaryItemType**Balance Type:**credit**Period Type:**instant |
| X                                                                                                                                                                             |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**nbl_DerivativeInstrumentsAndHedgingActivitiesAbstract**Namespace Prefix:**nbl_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                             |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Contract period of time relating to a derivative instrument.
+ References
No definition available.
+ Details**Name:**nbl_DerivativeProductionPeriod**Namespace Prefix:**nbl_**Data Type:**us-types:dateStringItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                    |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Weighted average price differential related to the Index Less Differential.
+ References
No definition available.
+ Details**Name:**nbl_DerivativeWeightedAverageDifferential**Namespace Prefix:**nbl_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Reference to the index or unit of measurement for the underlying which establishes the pricing terms of the derivative instrument. For example, the basis on the underlying for a natural gas futures contract might be the NYMEX price per million British thermal units (MMBtu).
+ References
No definition available.
+ Details**Name:**nbl_IndexLessDifferential**Namespace Prefix:**nbl_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                           |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The position of the settled interest rate swap as of the settlement date.
+ References
No definition available.
+ Details**Name:**nbl_NetLiabilityPositionOfSettledInterestRateSwap**Namespace Prefix:**nbl_**Data Type:**xbrli:monetaryItemType**Balance Type:**credit**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The estimated net amount of existing gains or losses on cash flow hedges at the reporting date expected to be reclassified to earnings within the next 12 months.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 30 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=7668309&loc=d3e80748-113994Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 133 -Paragraph 45 -Subparagraph b(2) -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.  This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.
+ Details**Name:**us-gaap_CashFlowHedgeGainLossToBeReclassifiedWithinTwelveMonths**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**credit**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The average cap rate on a group of price risk derivatives such as caps or collars. A payment or receipt is triggered if the market rate exceeds the cap rate on the contract.
+ References
No definition available.
+ Details**Name:**us-gaap_DerivativeAverageCapPrice**Namespace Prefix:**us-gaap_**Data Type:**us-types:perUnitItemType**Balance Type:**na**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                                                                                                             |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The average floor rate on a group of price risk derivatives such as floors or collars. A payment or receipt is triggered if the market rate falls below the floor rate on the contract.
+ References
No definition available.
+ Details**Name:**us-gaap_DerivativeAverageFloorPrice**Namespace Prefix:**us-gaap_**Data Type:**us-types:perUnitItemType**Balance Type:**na**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                                               |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The average strike price on the group of price risk option contracts such as put options or call options.
+ References
No definition available.
+ Details**Name:**us-gaap_DerivativeAveragePriceRiskOptionStrikePrice**Namespace Prefix:**us-gaap_**Data Type:**us-types:perUnitItemType**Balance Type:**na**Period Type:**instant |
| X                                                                                                                                                       |
|---------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_DerivativeLineItems**Namespace Prefix:**us-gaap_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                      |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Average fixed price related to the group of price risk swap derivatives.
+ References
No definition available.
+ Details**Name:**us-gaap_DerivativeSwapTypeAverageFixedPrice**Namespace Prefix:**us-gaap_**Data Type:**us-types:perUnitItemType**Balance Type:**na**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Reference to the index or unit of measurement for the underlying which establishes the pricing terms of the derivative instrument. For example, the basis on the underlying for a natural gas futures contract might be the NYMEX price per million British thermal units (MMBtu).
+ References
No definition available.
+ Details**Name:**us-gaap_DerivativeUnderlyingBasis**Namespace Prefix:**us-gaap_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |