Debt Textuals.

No definition available.

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- Definition

Largest individual loan commitment percent of total loan commitments by any one lender for our revolving credit facility.

+ References

No definition available.

+ Details

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- Definition

Percentage added to the prime rate based upon a grid of our debt rating to determine the interest rate on borrowings under our credit facility (one of two options).

+ References

No definition available.

+ Details

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- Definition

Percentage added to LIBOR based upon a grid of our debt rating to determine the interest rate on borrowings under our credit facility (one of two options).

+ References

No definition available.

+ Details

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- Definition

Percentage based on a grid of our debt rating on which letters of credit fees are subject.

+ References

No definition available.

+ Details

Name:	nfx_PercentageOnWhichAnnualFeesOnGridOfDebtRatingAreSubject
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Period Type:	duration

- Definition

Percentage on which issuance fees on Letter of credit are subject

+ References

No definition available.

+ Details

Name:	nfx_PercentageOnWhichIssuanceFeesOnLetterOfCreditAreSubject
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Balance Type:	na
Period Type:	duration

- Definition

Increase in percentage added to credit facility margins based upon a grid of our debt rating to determine the interest rate on borrowings under our credit facility (two options).

+ References

No definition available.

+ Details

Name:	nfx_PercentageaddedtoCreditFacilityMargins
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- Definition

Ratio of earnings before gain or loss on the disposition of assets, interest expense, income taxes and noncash items (such as depreciation, depletion and amortization expense, unrealized gains and losses on commodity derivatives, ceiling test writedowns and goodwill impairments) to interest expense.

+ References

No definition available.

+ Details

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- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

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Balance Type:	na
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- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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- Definition

Amount of debt issuance costs (for example, but not limited to, legal, accounting, broker, and regulatory fees).

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

No definition available.

+ Details

Name:	us-gaap_LettersOfCreditOutstandingAmount
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.16)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.16)
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 19, 20, 22
-Article 5

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of the fee for available but unused credit capacity under the credit facility.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The fee, expressed as a percentage of the line of credit facility, for available but unused credit capacity under the credit facility.

+ References

No definition available.

+ Details

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- Definition

Carrying amount of long-term debt, net of unamortized discount or premium, excluding amounts to be repaid within one year or the normal operating cycle, if longer (current maturities). Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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- Definition

The cash outflow for incremental, external costs directly pertaining to an early extinguishment of debt, including legal costs and prepayment penalties, and excluding interest and repayment of debt principal.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The cash outflow paid to third parties in connection with debt origination, which will be amortized over the remaining maturity period of the associated long-term debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3291-108585

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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- Definition

The cash outflow for loan and debt issuance costs.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3291-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Financing Activities
-URI http://asc.fasb.org/extlink&oid=6513228

+ Details

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Data Type:	xbrli:monetaryItemType
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- Definition

Indebtedness divided by net capital.

+ References

No definition available.

+ Details

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- Definition

Write-off of amounts previously capitalized as debt issuance cost in an extinguishment of debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.8)
-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

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- Details

Name:	us-gaap_DebtInstrumentAxis=nfx_MoneyMarketLinesOfCreditMember
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- Details

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- Details

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- Details

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Debt (Details)	3 Months Ended			6 Months Ended		12 Months Ended
Debt (Details)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2016 USD ($)	Jun. 30, 2015 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Debt Instrument [Line Items]
Line of Credit Facility, Amount Outstanding	$ 0			$ 0		$ 39,000,000
Long-term debt	(2,430,000,000)			(2,430,000,000)		(2,467,000,000)
Debt Issuance Cost				(20,000,000)		$ (22,000,000)
Payments of Debt Issuance Costs				0	$ 8,000,000
Debt (Textuals)
Line of Credit Facility, Maximum Borrowing Capacity	$ 1,800,000,000			$ 1,800,000,000
Largest individual loan commitment by any lender of total commitments	12.00%			12.00%
Commitment fees incurred	$ 2,000,000		$ 1,000,000	$ 4,000,000	$ 2,000,000
Ratio of Indebtedness to Net Capital 1	0.6			0.6
Ratio of total debt to earnings before gain or loss on disposition of assets, interest expense, income taxes and noncash items	2.5	2.5		2.5		3.0
Line of Credit Facility, Current Borrowing Capacity	$ 135,000,000	$ 160,000,000		$ 135,000,000		$ 195,000,000
Percentage of basis points to be added for calculation of interest rate				0.50%
Percent added to prime rate based on grid of our debt rating				1.25%
Percentage added to LIBOR based on grid of our debt rating				2.25%
Commitment fee percentage on unused capacity of line of credit				0.425%
Issuance fees percentage on letter of credit				0.20%
Percentage based on a grid of our debt rating on which letters of credit fees are based.				2.25%
Letters of Credit Outstanding, Amount	0			$ 0
Payments Of Debt Extinguishment Costs						24,000,000
Write off of Deferred Debt Issuance Cost						8,000,000
Percentage added to Credit Facility Margins				0.50%
Revolving credit facility — LIBOR based loans (matures in June 2020)
Debt Instrument [Line Items]
Payments of Financing Costs		$ 3,000,000
Line of Credit Facility, Amount Outstanding	0			$ 0		0
Money market lines of credit(1)
Debt Instrument [Line Items]
Line of Credit Facility, Amount Outstanding	0			0		39,000,000
5¾% Senior Notes due 2022
Debt Instrument [Line Items]
Long-term debt	$ (750,000,000)			$ (750,000,000)		$ (750,000,000)
Debt Instrument, Interest Rate, Stated Percentage	5.75%			5.75%		5.75%
5⅝% Senior Notes due 2024
Debt Instrument [Line Items]
Long-term debt	$ (1,000,000,000)			$ (1,000,000,000)		$ (1,000,000,000)
Debt Instrument, Interest Rate, Stated Percentage	5.625%			5.625%		5.625%
5⅜% Senior Notes due 2026
Debt Instrument [Line Items]
Long-term debt	$ (700,000,000)			$ (700,000,000)		$ (700,000,000)
Debt Instrument, Interest Rate, Stated Percentage	5.375%			5.375%		5.375%
Total senior unsecured debt
Debt Instrument [Line Items]
Long-term debt	$ (2,450,000,000)			$ (2,450,000,000)		$ (2,489,000,000)
6.875% Senior Subordinated Notes due 2020 [Member]
Debt Instrument [Line Items]
Long-term debt							$ (700,000,000)