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Subsequent Event (Details) $ in Millions	Mar. 31, 2017 USD ($)
Subsequent Events [Abstract]
Project Costs	$ 67.8

Project costs included within Property, Plant and Equipment and Deferred Charges on the Consolidated Balance Sheet.

No definition available.

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

No definition available.

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