Name:	gas_RegulatoryLiabilitiesAbstract
Namespace Prefix:	gas_
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The amount for the individual regulatory asset as itemized in a table of regulatory assets as of the end of the period.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 980
-SubTopic 340
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6499975&loc=d3e44250-110382

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Period Type:	instant

Carrying amount as of the balance sheet date of capitalized costs of regulated entities that are expected to be recovered through revenue sources within one year or the normal operating cycle, if longer. Such costs are capitalized if they meet both of the following criteria: a. It is probable that future revenue in an amount at least equal to the capitalized cost will result from inclusion of that cost in allowable costs for rate-making purposes. b. Based on available evidence, the future revenue will be provided to permit recovery of the previously incurred cost rather than to provide for expected levels of similar future costs. If the revenue will be provided through an automatic rate-adjustment clause, this criterion requires that the regulator's intent clearly be to permit recovery of the previously incurred cost.

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Carrying amount as of the balance sheet date of capitalized costs of regulated entities that are not expected to be recovered through revenue sources within one year or the normal operating cycle if longer.

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

The amount for the individual regulatory liability as itemized in a table of regulatory liabilities as of the end of the period.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 980
-SubTopic 405
-Section 25
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6500807&loc=d3e48068-110394

Name:	us-gaap_RegulatoryLiabilities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
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Period Type:	instant

The amount for the individual regulatory current liability as itemized in a table of regulatory current liabilities as of the end of the period.

Name:	us-gaap_RegulatoryLiabilityCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
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The amount for the individual regulatory noncurrent liability as itemized in a table of regulatory noncurrent liabilities as of the end of the period.

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 210.5-02.24)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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Name:	us-gaap_RegulatoryAssetAxis=gas_RecoverablePensionAndOtherRetirementBenefitCostsMember
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Name:	us-gaap_RegulatoryAssetAxis=gas_RecoverableRegulatoryInfrastructureProgramCostsMember
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Name:	us-gaap_RegulatoryAssetAxis=gas_DeferredNaturalGasCostsMember
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Name:	us-gaap_RegulatoryAssetAxis=gas_LongTermDebtFairValueAdjustmentMember
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Name:	us-gaap_RegulatoryAssetAxis=gas_OtherRegulatoryAssetsMember
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Name:	us-gaap_RegulatoryLiabilityAxis=gas_BadDebtRiderMember
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Name:	us-gaap_RegulatoryLiabilityAxis=gas_AccruedNaturalGasCostsMember
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Name:	us-gaap_RegulatoryLiabilityAxis=gas_OtherRegulatoryLiabilitiesMember
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Name:	us-gaap_RegulatoryLiabilityAxis=gas_RegulatoryIncomeTaxLiabilityMember
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