Name:	ato_AccumulatedOtherComprehensiveIncomeLossDerivativesQualifyingasHedgesInterestRateAgreementsRealizedGainLossNetofTax
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Anticipated debt issuance amount of future debt issuance.

No definition available.

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Aggregate net gain (loss) on all derivative instruments not designated as hedges recognized in gross profit during the period, before tax effects.

No definition available.

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Gain or loss recognized in earnings during the reporting period representing the amount of the hedges' ineffectiveness for fair value and cash flow hedges.

No definition available.

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Anticipated percentage of heating season gas purchases using financial instruments.

No definition available.

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Anticipated volume of heating season gas purchases using financial instruments.

No definition available.

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Maximum anticipated percentage of heating season gas purchases hedged using financial instruments.

No definition available.

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Minimum anticipated percentage of heating season gas purchases hedged using financial instruments.

No definition available.

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Minimum length of time over which the entity is hedging its exposure to the variability in future cash flows for forecasted transactions, excluding those forecasted transactions related to the payment of variable interest on existing financial instruments, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

No definition available.

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The domestic federal statutory tax rate applicable under enacted tax laws to the Nonregulated operations pretax income from continuing operations for the period. The "statutory" tax rate shall be the regular tax rate if there are alternative tax systems.

No definition available.

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The domestic federal statutory tax rate applicable under enacted tax laws to the Regulated operations pretax income from continuing operations for the period. The "statutory" tax rate shall be the regular tax rate if there are alternative tax systems.

No definition available.

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Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Article 12

-Section 13

-Sentence Column B

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Average stated rate on a group of interest rate forward or futures contracts.

No definition available.

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Data Type:	num:percentItemType
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Maximum length of time over which the entity is hedging its exposure to the variability in future cash flows for forecasted transactions, excluding those forecasted transactions related to the payment of variable interest on existing financial instruments, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 30

-Section 50

-Paragraph 1

-Subparagraph (d)

-URI http://asc.fasb.org/extlink&oid=35736893&loc=d3e80748-113994

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