Annual distribution of natural gas.

No definition available.

Name:	egas_AnnualDistributionOfNaturalGas
Namespace Prefix:	egas_
Data Type:	num:volumeItemType
Balance Type:	na
Period Type:	duration

- Definition

Cost of natural gas purchased and associated transportation and storage costs during the period.

+ References

No definition available.

+ Details

Name:	egas_AnnualMarketOfNaturalGas
Namespace Prefix:	egas_
Data Type:	num:volumeItemType
Balance Type:	na
Period Type:	duration

- Definition

The percentage of average net revenue interest.

+ References

No definition available.

+ Details

Name:	egas_AverageNetRevenueInterestPercentage
Namespace Prefix:	egas_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The gross percentage of working capital.

+ References

No definition available.

+ Details

Name:	egas_GrossPercentageOfWorkingInterest
Namespace Prefix:	egas_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of customers related to residential, commercial, and industrial.

+ References

No definition available.

+ Details

Name:	egas_NumberOfCustomers
Namespace Prefix:	egas_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of natural gas producing wells and gas gathering assets.

+ References

No definition available.

+ Details

Name:	egas_NumberOfNaturalGasProducingWellsAndGasGatheringAssets
Namespace Prefix:	egas_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

It represents percentage of revenue of revenue on natural gas operations during the reporting period.

+ References

No definition available.

+ Details

Name:	egas_PercentageOfRevenueOnNaturalGasOperations
Namespace Prefix:	egas_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	egas_SummaryOfBusinessAndAccountingPoliciesLineItems
Namespace Prefix:	egas_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

+ References

No definition available.

+ Details

Name:	us-gaap_NumberOfReportableSegments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=egas_EwrSubsidiaryMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

Summary of Business - Additional Information (Detail)	12 Months Ended
Summary of Business - Additional Information (Detail)	Dec. 31, 2014 bbl	Dec. 31, 2013	Dec. 31, 2012
Summary of Business and Accounting Policies [Line Items]
Number of reporting segments	3us-gaap_NumberOfReportableSegments
Natural Gas Operations [Member]
Summary of Business and Accounting Policies [Line Items]
Annual distribution of natural gas	26,000,000,000
Natural gas customers	68,000
Percentage Of Revenue On Natural Gas Operations	93.00%	89.00%	91.00%
Marketing & Production Operations [Member]
Summary of Business and Accounting Policies [Line Items]
Annually market of natural gas	1,300,000,000
EWR Subsidiary [Member]
Summary of Business and Accounting Policies [Line Items]
Number of natural gas producing wells and gas gathering assets	160
Gross Percentage Of Working Interest	55.00%
Average Net Revenue Interest, Percentage	46.00%