Name:	nfg_CashFlowHedgeGainLossToBeReclassifiedWithinTwelveMonthsAfterTax
Namespace Prefix:	nfg_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

The credit risk exposure per counterparty.

No definition available.

Name:	nfg_CreditRiskExposurePerCounterparty
Namespace Prefix:	nfg_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Maximum Credit Risk Exposure Per Counterparty.

No definition available.

Name:	nfg_MaximumCreditRiskExposurePerCounterparty
Namespace Prefix:	nfg_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Amount, before tax, of accumulated gain (loss) on derivative instrument designated and qualifying as cash flow hedge included in assessment of hedge effectiveness.

No definition available.

Name:	nfg_NetHedgingGainsLossesinAccumulatedOtherComprehensiveIncomeLoss
Namespace Prefix:	nfg_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Nonmonetary notional amount of price risk cash flow hedge derivatives, crude oil.

No definition available.

Name:	nfg_NonmonetaryNotionalAmountOfPriceRiskCashFlowHedgeDerivativesCrudeOil
Namespace Prefix:	nfg_
Data Type:	num:volumeItemType
Balance Type:	na
Period Type:	instant

Nonmonetary notional amount of price risk cash flow hedge derivatives, natural gas.

No definition available.

Name:	nfg_NonmonetaryNotionalAmountOfPriceRiskCashFlowHedgeDerivativesNaturalGas
Namespace Prefix:	nfg_
Data Type:	num:volumeItemType
Balance Type:	na
Period Type:	instant

Nonmonetary notional amount of price risk fair value hedge derivatives, natural gas.

No definition available.

Name:	nfg_NonmonetaryNotionalAmountOfPriceRiskFairValueHedgeDerivativesNaturalGas
Namespace Prefix:	nfg_
Data Type:	num:volumeItemType
Balance Type:	na
Period Type:	instant

Number Of Counterparties In Net Gain Position

No definition available.

Name:	nfg_NumberOfCounterpartiesInNetGainPosition
Namespace Prefix:	nfg_
Data Type:	xbrli:positiveIntegerItemType
Balance Type:	na
Period Type:	instant

The number of counterparties in which the company holds over-the-counter swap positions.

No definition available.

Name:	nfg_NumberOfCounterpartiesInWhichCompanyHoldsOverCounterSwapPositions
Namespace Prefix:	nfg_
Data Type:	xbrli:positiveIntegerItemType
Balance Type:	na
Period Type:	instant

The number of counterparties with a common credit-risk related contingency.

No definition available.

Name:	nfg_NumberOfCounterpartiesWithCommonCreditRiskRelatedContingency
Namespace Prefix:	nfg_
Data Type:	xbrli:positiveIntegerItemType
Balance Type:	na
Period Type:	instant

Amount, after tax, of accumulated gain (loss) on derivative instrument designated and qualifying as cash flow hedge included in assessment of hedge effectiveness.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=121641772&loc=d3e637-108580

Name:	us-gaap_AociLossCashFlowHedgeCumulativeGainLossAfterTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

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.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=121549185&loc=d3e80748-113994

Name:	us-gaap_CashFlowHedgeGainLossToBeReclassifiedWithinTwelveMonths
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Fair value of credit risk derivative asset.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4K
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5708775-113959

Name:	us-gaap_CreditRiskDerivativeAssetsAtFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Fair value of credit risk derivative liability.

Name:	us-gaap_CreditRiskDerivativeLiabilitiesAtFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Amount of obligation to return cash collateral under master netting arrangements that have not been offset against derivative assets.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
-Paragraph 13
-URI http://asc.fasb.org/extlink&oid=99393222&loc=SL20226016-175313

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 8
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121590274&loc=d3e41678-113959

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (d)(2)
-URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312

Name:	us-gaap_DerivativeCollateralObligationToReturnCash
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

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.

No definition available.

Name:	us-gaap_DerivativeInstrumentsGainLossLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

The portion of gains and losses (net) on derivative instruments designated and qualifying as hedging instruments representing (a) the amount of the hedge ineffectiveness and (b) the amount, if any, excluded from the assessment of hedge effectiveness.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5624171-113959

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 25
-Section 50
-Paragraph 1
-Subparagraph (a)(1),(2)
-URI http://asc.fasb.org/extlink&oid=121577467&loc=d3e76258-113986

Name:	us-gaap_DerivativeInstrumentsGainLossRecognizedInIncomeIneffectivePortionAndAmountExcludedFromEffectivenessTestingNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Nominal or face amount used to calculate payment on derivative.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1B
-URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5580258-113959

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5579245-113959

Name:	us-gaap_DerivativeNotionalAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant

Period the derivative contract is outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

No definition available.

Name:	us-gaap_DerivativeTermOfContract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

The amount of cash or securities placed with a broker or counterparty as security for a trading or derivatives securities position which was partially obtained with funds provided by the broker dealer.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.8,17)
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Name:	us-gaap_MarginDepositAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Maximum amount of time remaining before foreign currency exchange rate derivatives mature or expire, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

No definition available.

Name:	us-gaap_MaximumRemainingMaturityOfForeignCurrencyDerivatives1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_CommodityContractMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_DerivativeInstrumentRiskAxis=nfg_FixedPriceSalesCommitmentsMmcfMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_DerivativeInstrumentRiskAxis=nfg_OvertheCounterSwapsNoCostCollarsandForeignCurrencyForwardContractsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_DerivativeInstrumentRiskAxis=nfg_NaturalGasMmcfMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis=nfg_CashFlowHedgesShortPositionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis=nfg_CashFlowHedgesLongPositionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_DerivativeInstrumentRiskAxis=nfg_CrudeOilBblsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_DerivativeInstrumentRiskAxis=nfg_ExchangeTradedFuturesContractsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_InvestmentTypeAxis=us-gaap_ForeignExchangeContractMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: