Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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 210.5-02.18)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 03
-Paragraph 12
-Article 7

+ Details

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

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Net Income
-URI http://asc.fasb.org/extlink&oid=51831255

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3602-108585

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04.19)
-URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.18)
-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04.22)
-URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Other Comprehensive Income
-URI http://asc.fasb.org/extlink&oid=51831270

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 03
-Paragraph 19
-Article 5

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 04
-Paragraph 20
-Article 9

+ Details

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

- Definition

Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

+ 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 210.5-03.1)
-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

+ Details

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

- 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

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

- Details

Name:	us-gaap_ConsolidationItemsAxis=nfg_RevenueFromExternalCustomersMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ConsolidationItemsAxis=nfg_IntersegmentRevenuesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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

Business Segment Information (Financial Segment Information By Segment) (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Sep. 30, 2015
Segment Reporting Information [Line Items]
Segment Profit: Net Income (Loss)	$ (189,109)	$ 84,740
Segment Assets	6,190,332		$ 6,564,939
Revenue From External Customers [Member]
Segment Reporting Information [Line Items]
Revenue	375,195	523,909
Intersegment Revenues [Member]
Segment Reporting Information [Line Items]
Revenue	0	0
Exploration And Production [Member]
Segment Reporting Information [Line Items]
Segment Profit: Net Income (Loss)	(237,086)	26,720
Segment Assets	2,103,633		2,439,801
Exploration And Production [Member] \| Revenue From External Customers [Member]
Segment Reporting Information [Line Items]
Revenue	151,965	204,665
Exploration And Production [Member] \| Intersegment Revenues [Member]
Segment Reporting Information [Line Items]
Revenue	0	0
Pipeline And Storage [Member]
Segment Reporting Information [Line Items]
Segment Profit: Net Income (Loss)	21,276	20,778
Segment Assets	1,597,432		1,590,525
Pipeline And Storage [Member] \| Revenue From External Customers [Member]
Segment Reporting Information [Line Items]
Revenue	53,354	51,745
Pipeline And Storage [Member] \| Intersegment Revenues [Member]
Segment Reporting Information [Line Items]
Revenue	22,183	21,461
Gathering [Member]
Segment Reporting Information [Line Items]
Segment Profit: Net Income (Loss)	4,921	11,623
Segment Assets	467,220		444,358
Gathering [Member] \| Revenue From External Customers [Member]
Segment Reporting Information [Line Items]
Revenue	125	146
Gathering [Member] \| Intersegment Revenues [Member]
Segment Reporting Information [Line Items]
Revenue	18,640	24,428
Utility [Member]
Segment Reporting Information [Line Items]
Segment Profit: Net Income (Loss)	18,606	22,594
Segment Assets	1,930,977		1,934,730
Utility [Member] \| Revenue From External Customers [Member]
Segment Reporting Information [Line Items]
Revenue	143,848	210,073
Utility [Member] \| Intersegment Revenues [Member]
Segment Reporting Information [Line Items]
Revenue	3,664	4,534
Energy Marketing [Member]
Segment Reporting Information [Line Items]
Segment Profit: Net Income (Loss)	1,223	2,826
Segment Assets	87,870		90,676
Energy Marketing [Member] \| Revenue From External Customers [Member]
Segment Reporting Information [Line Items]
Revenue	24,984	56,166
Energy Marketing [Member] \| Intersegment Revenues [Member]
Segment Reporting Information [Line Items]
Revenue	311	206
Total Reportable Segments [Member]
Segment Reporting Information [Line Items]
Segment Profit: Net Income (Loss)	(191,060)	84,541
Segment Assets	6,187,132		6,500,090
Total Reportable Segments [Member] \| Revenue From External Customers [Member]
Segment Reporting Information [Line Items]
Revenue	374,276	522,795
Total Reportable Segments [Member] \| Intersegment Revenues [Member]
Segment Reporting Information [Line Items]
Revenue	44,798	50,629
All Other [Member]
Segment Reporting Information [Line Items]
Segment Profit: Net Income (Loss)	189	(6)
Segment Assets	78,293		77,350
All Other [Member] \| Revenue From External Customers [Member]
Segment Reporting Information [Line Items]
Revenue	706	884
All Other [Member] \| Intersegment Revenues [Member]
Segment Reporting Information [Line Items]
Revenue	0	0
Corporate And Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Segment Profit: Net Income (Loss)	1,762	205
Segment Assets	(75,093)		$ (12,501)
Corporate And Intersegment Eliminations [Member] \| Revenue From External Customers [Member]
Segment Reporting Information [Line Items]
Revenue	213	230
Corporate And Intersegment Eliminations [Member] \| Intersegment Revenues [Member]
Segment Reporting Information [Line Items]
Revenue	$ (44,798)	$ (50,629)