Debt instrument interest coverage ratio.

No definition available.

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

- Definition

The amount represents debt service and reserve accounts for the period.

+ References

No definition available.

+ Details

Name:	egas_DebtServiceReserveAccount
Namespace Prefix:	egas_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Description about interest coverage ratio.

+ References

No definition available.

+ Details

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

- Definition

Maximum capitalized leases and purchase money obligations.

+ References

No definition available.

+ Details

Name:	egas_MaximumCapitalizedLeasesAndPurchaseMoneyObligations
Namespace Prefix:	egas_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Maximum borrowing capital lease obligation under the credit facility for the period.

+ References

No definition available.

+ Details

Name:	egas_MaximumCapitalLeaseBorrowingObligation
Namespace Prefix:	egas_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

A measurement of a company's financial leverage, calculated as the company's maximum debt divided by its total capital.

+ References

No definition available.

+ Details

Name:	egas_MaximumDebtToCapitalRatio
Namespace Prefix:	egas_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum limit for sale or transfer of assets as a percent of total assets for any twelve month period.

+ References

No definition available.

+ Details

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

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

No definition available.

+ Details

Name:	egas_MaximumOtherBorrowingObligation
Namespace Prefix:	egas_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Maximum percentage of dividend distribution redemptions of net income.

+ References

No definition available.

+ Details

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

- Definition

Maximum percent of assets disposal restriction in fiscal year.

+ References

No definition available.

+ Details

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

- Definition

A measurement of a company's financial leverage, calculated as the company's minimum debt divided by its total capital.

+ References

No definition available.

+ Details

Name:	egas_MinimumDebtToCapitalRatio
Namespace Prefix:	egas_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage net income available for dividend distribution.

+ References

No definition available.

+ Details

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

- Definition

Maximum limit of acquisitions as a percent of total assets in a twelve month period.

+ References

No definition available.

+ Details

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

- Definition

Percent of net income consider for distribution and redemption restriction.

+ References

No definition available.

+ Details

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

- Definition

Period consider for distribution and redemption restriction.

+ References

No definition available.

+ Details

Name:	egas_PeriodConsiderForDistributionAndRedemptionRestriction
Namespace Prefix:	egas_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Total current liabilities of the broker-dealer, less certain exceptions as defined.

+ References

No definition available.

+ Details

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

- Details

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

- Details

Name:	us-gaap_LineOfCreditFacilityAxis=egas_AllstateOrCunaMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LineOfCreditFacilityAxis=egas_BankOfAmericaMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LineOfCreditFacilityAxis=egas_SunLifeAssuranceCompanyOfCanadaMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Credit Facilities and Long-Term Debt - Debt Covenants - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Mar. 31, 2011
Sun Life Assurance Company of Canada [Member]
Summary of outstanding long-term debt balances
Interest coverage ratio	at least 2.0 to 1.0
Maximum other borrowing obligation			$ 500,000
Debt to capitalization rate	60.00%
Debt service reserve account	900,000	1,100,000
Maximum percentage of dividend distribution redemptions of net income	70.00%
Maximum limit for sale or transfer of assets	1.00%
Percentage of maximum limit of making acquisition	10.00%
Bank of America [Member]
Summary of outstanding long-term debt balances
Minimum Debt To Capital Ratio	0.55
Maximum debt to capital ratio	1.00
Maximum capital lease borrowing obligation	1,000,000
Period consider for distribution and redemption restriction	60 years
Percent of net income consider for distribution and redemption restriction	80.00%
Maximum percent of assets disposal restriction in fiscal year	5.00%
Maximum capitalized leases and purchase money obligations	$ 500,000
Allstate/CUNA [Member]
Summary of outstanding long-term debt balances
Aggregate consolidated net income	100.00%
Debt to capitalization rate	65.00%
Debt Instrument Interest Coverage Ratio	150.00%