Full Cost Ceiling Exceeds Book Value Of Oil And Gas Properties

No definition available.

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

- Definition

The discount factor used in the computation of the SEC full cost ceiling test that determines the limit of property acquisition, exploration and development costs that can be capitalized each period.

+ References

No definition available.

+ Details

Name:	nfg_FullCostCeilingTestDiscountFactor
Namespace Prefix:	nfg_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Greenhouse Gas Emissions Reductions, Performance Cycle

+ References

No definition available.

+ Details

Name:	nfg_GreenhouseGasEmissionsReductionsPerformanceCycle
Namespace Prefix:	nfg_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

The expense recorded to reduce the value of exploration and production properties accounted for under the full cost method of accounting to the cost center ceiling.

+ References

No definition available.

+ Details

Name:	nfg_ImpairmentOfExplorationAndProductionProperties
Namespace Prefix:	nfg_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Relative Shareholder Return, Performance Cycle

+ References

No definition available.

+ Details

Name:	nfg_RelativeShareholderReturnPerformanceCycle
Namespace Prefix:	nfg_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Return On Capital, Performance Cycle

+ References

No definition available.

+ Details

Name:	nfg_ReturnOnCapitalPerformanceCycle
Namespace Prefix:	nfg_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Summary Of Significant Accounting Policies [Line Items]

+ References

No definition available.

+ Details

Name:	nfg_SummaryOfSignificantAccountingPoliciesLineItems
Namespace Prefix:	nfg_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 260
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482662/260-10-50-1

+ Details

Name:	us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of capitalized acquisition, exploration, and development costs and capitalized interest incurred during period and excluded from amortization for oil- and gas-producing activities accounted for under full cost method.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 932
-SubTopic 360
-Name Accounting Standards Codification
-Section S50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477385/932-360-S50-1

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 932
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-10(c)(7)(ii))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479664/932-10-S99-1

+ Details

Name:	us-gaap_CapitalizedCostsOfUnprovedPropertiesExcludedFromAmortization
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount, after accumulated depreciation, depletion, amortization, and valuation allowance, of capitalized cost in oil- and gas-producing activities.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 932
-SubTopic 235
-Name Accounting Standards Codification
-Section 55
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477916/932-235-55-3

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 932
-SubTopic 235
-Name Accounting Standards Codification
-Section 50
-Paragraph 12
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477215/932-235-50-12

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 932
-SubTopic 235
-Name Accounting Standards Codification
-Section 50
-Paragraph 15
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477215/932-235-50-15

Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 932
-SubTopic 235
-Name Accounting Standards Codification
-Section 50
-Paragraph 15
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477215/932-235-50-15

Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 932
-SubTopic 235
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477215/932-235-50-13

+ Details

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

- Definition

Amount of deferred income tax expense (benefit) pertaining to income (loss) from continuing operations.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 45
-Paragraph 28
-Subparagraph (b)
-SubTopic 10
-Topic 230
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482740/230-10-45-28

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480738/235-10-S50-1

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(h)(1)(Note 1))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480678/235-10-S99-1

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Name Accounting Standards Codification
-Section 50
-Paragraph 9
-Subparagraph (b)
-SubTopic 10
-Topic 740
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482685/740-10-50-9

+ Details

Name:	us-gaap_DeferredIncomeTaxExpenseBenefit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The quantified amount of the future effect on cash flows.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 420
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SAB Topic 5.P.4)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479823/420-10-S99-2

+ Details

Name:	us-gaap_EffectOnFutureCashFlowsAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Carrying amount as of the balance sheet date of natural gas stored underground in depleted gas reservoirs, aquifers, or salt caverns to meet seasonal and peak load demands, and also as insurance against unforeseen supply disruptions, and deemed to be a current asset because it is expected to be used within twelve months or in the normal operating cycle.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(6)(a))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1

+ Details

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

- Definition

The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(iii)(01)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ References

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_ImpairedLongLivedAssetsHeldAndUsedByTypeAxis=nfg_ImpairmentOfExplorationAndProductionPropertiesMemberMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=nfg_ReserveForGasReplacementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementScenarioAxis=srt_ScenarioForecastMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=nfg_NonPerformanceBasedRestrictedStockUnitsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=us-gaap_PerformanceSharesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Summary Of Significant Accounting Policies (Narrative) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended			9 Months Ended		12 Months Ended
	Jun. 30, 2025	Dec. 31, 2024	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024	Sep. 30, 2024	Sep. 30, 2025
Summary Of Significant Accounting Policies [Line Items]
Gas Stored Underground	$ 12,810			$ 12,810		$ 35,055
Capitalized Costs Exploration and Production Activities Net	$ 2,320,000			2,320,000		2,280,000
Capitalized costs of unproved properties excluded from amortization				$ 132,600		$ 201,000
Full cost ceiling test discount factor (as a percent)	10.00%			10.00%
Amount full cost ceiling exceeds book value of oil and gas properties	$ 798,800			$ 798,800
Impairment of exploration and production properties		$ 108,300
Increase estimated future net cash flows	$ 338,600
Antidilutive securities (in shares)	1,126		567,681	1,097	335
Impairment of Exploration and Production Properties
Summary Of Significant Accounting Policies [Line Items]
Deferred income tax benefit		$ 29,200
Reserve For Gas Replacement
Summary Of Significant Accounting Policies [Line Items]
Gas Stored Underground	$ 12,700			$ 12,700
Reserve For Gas Replacement \| Forecast
Summary Of Significant Accounting Policies [Line Items]
Gas Stored Underground							$ 0
Restricted Stock Units
Summary Of Significant Accounting Policies [Line Items]
Share based compensation other than options grants in period (in shares)				132,352
Granted in fiscal year, weighted average grant date fair value (in USD per share)				$ 58.64
Performance Shares
Summary Of Significant Accounting Policies [Line Items]
Share based compensation other than options grants in period (in shares)				239,042
Granted in fiscal year, weighted average grant date fair value (in USD per share)				$ 55.43
Return on capital, performance cycle (in years)				3 years
Greenhouse gas emissions reductions, performance cycle				3 years
Relative shareholder return, performance cycle				3 years