XML 60 R38.htm IDEA: XBRL DOCUMENT v2.4.1.9
Financial Instruments Balance Sheet Location (Details) (USD $)
In Thousands, unless otherwise specified
Mar. 31, 2015
Sep. 30, 2014
Derivatives Fair Value [Line Items]    
Derivative, Collateral, Right to Reclaim Cash $ 16,600us-gaap_DerivativeCollateralRightToReclaimCash $ 22,700us-gaap_DerivativeCollateralRightToReclaimCash
Derivative Asset 16,947us-gaap_DerivativeAssets 58,865us-gaap_DerivativeAssets
Derivative Liability, Collateral, Right to Reclaim Cash, Offset 36,100us-gaap_DerivativeLiabilityCollateralRightToReclaimCashOffset 3,100us-gaap_DerivativeLiabilityCollateralRightToReclaimCashOffset
Derivative Liability (138,074)us-gaap_DerivativeLiabilities (21,856)us-gaap_DerivativeLiabilities
Regulated Distribution Segment [Member]    
Derivatives Fair Value [Line Items]    
Derivative Asset, Fair Value, Gross Asset 364us-gaap_DerivativeFairValueOfDerivativeAsset
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36,140us-gaap_DerivativeFairValueOfDerivativeAsset
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Derivative Asset, Contract Netting 0ato_DerivativeAssetContractNetting
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0ato_DerivativeAssetContractNetting
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Derivative Asset, Net of Contract Netting 364ato_DerivativeAssetNetofContractNetting
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36,140ato_DerivativeAssetNetofContractNetting
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Derivative, Collateral, Right to Reclaim Cash 0us-gaap_DerivativeCollateralRightToReclaimCash
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0us-gaap_DerivativeCollateralRightToReclaimCash
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Derivative Asset 364us-gaap_DerivativeAssets
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36,140us-gaap_DerivativeAssets
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Derivative Liability, Fair Value, Gross Liability (138,074)us-gaap_DerivativeFairValueOfDerivativeLiability
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= ato_RegulatedDistributionSegmentMember
(21,856)us-gaap_DerivativeFairValueOfDerivativeLiability
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Derivative Liability, Contract Netting 0ato_DerivativeLiabilityContractNetting
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= ato_RegulatedDistributionSegmentMember
0ato_DerivativeLiabilityContractNetting
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Derivative Liability, Net of Contract Netting (138,074)ato_DerivativeLiabilityNetofContractNetting
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= ato_RegulatedDistributionSegmentMember
(21,856)ato_DerivativeLiabilityNetofContractNetting
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Derivative Liability, Collateral, Right to Reclaim Cash, Offset 0us-gaap_DerivativeLiabilityCollateralRightToReclaimCashOffset
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0us-gaap_DerivativeLiabilityCollateralRightToReclaimCashOffset
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Derivative Liability (138,074)us-gaap_DerivativeLiabilities
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= ato_RegulatedDistributionSegmentMember
(21,856)us-gaap_DerivativeLiabilities
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= ato_RegulatedDistributionSegmentMember
Nonregulated Segment [Member]    
Derivatives Fair Value [Line Items]    
Derivative Asset, Fair Value, Gross Asset 158,188us-gaap_DerivativeFairValueOfDerivativeAsset
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= ato_NonregulatedSegmentMember
69,023us-gaap_DerivativeFairValueOfDerivativeAsset
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= ato_NonregulatedSegmentMember
Derivative Asset, Contract Netting (158,188)ato_DerivativeAssetContractNetting
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= ato_NonregulatedSegmentMember
(69,023)ato_DerivativeAssetContractNetting
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= ato_NonregulatedSegmentMember
Derivative Asset, Net of Contract Netting 0ato_DerivativeAssetNetofContractNetting
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= ato_NonregulatedSegmentMember
0ato_DerivativeAssetNetofContractNetting
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Derivative, Collateral, Right to Reclaim Cash 16,583us-gaap_DerivativeCollateralRightToReclaimCash
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= ato_NonregulatedSegmentMember
22,725us-gaap_DerivativeCollateralRightToReclaimCash
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Derivative Asset 16,583us-gaap_DerivativeAssets
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22,725us-gaap_DerivativeAssets
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Derivative Liability, Fair Value, Gross Liability (194,328)us-gaap_DerivativeFairValueOfDerivativeLiability
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(72,056)us-gaap_DerivativeFairValueOfDerivativeLiability
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= ato_NonregulatedSegmentMember
Derivative Liability, Contract Netting 158,188ato_DerivativeLiabilityContractNetting
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= ato_NonregulatedSegmentMember
69,023ato_DerivativeLiabilityContractNetting
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= ato_NonregulatedSegmentMember
Derivative Liability, Net of Contract Netting (36,140)ato_DerivativeLiabilityNetofContractNetting
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= ato_NonregulatedSegmentMember
(3,033)ato_DerivativeLiabilityNetofContractNetting
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Derivative Liability, Collateral, Right to Reclaim Cash, Offset 36,140us-gaap_DerivativeLiabilityCollateralRightToReclaimCashOffset
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3,033us-gaap_DerivativeLiabilityCollateralRightToReclaimCashOffset
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Derivative Liability 0us-gaap_DerivativeLiabilities
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0us-gaap_DerivativeLiabilities
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Designated As Hedging Instrument [Member] | Regulated Distribution Segment [Member]    
Derivatives Fair Value [Line Items]    
Derivative Asset, Fair Value, Gross Asset 0us-gaap_DerivativeFairValueOfDerivativeAsset
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34,477us-gaap_DerivativeFairValueOfDerivativeAsset
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(19,835)us-gaap_DerivativeFairValueOfDerivativeLiability
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Designated As Hedging Instrument [Member] | Regulated Distribution Segment [Member] | Other Current Assets [Member] | Interest Rate Contract [Member]    
Derivatives Fair Value [Line Items]    
Derivative Asset, Fair Value, Gross Asset   21,869us-gaap_DerivativeFairValueOfDerivativeAsset
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Designated As Hedging Instrument [Member] | Regulated Distribution Segment [Member] | Other Current Assets [Member] | Commodity Contract [Member]    
Derivatives Fair Value [Line Items]    
Derivative Asset, Fair Value, Gross Asset 0us-gaap_DerivativeFairValueOfDerivativeAsset
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Designated As Hedging Instrument [Member] | Regulated Distribution Segment [Member] | Deferred Charges And Other Assets [Member] | Interest Rate Contract [Member]    
Derivatives Fair Value [Line Items]    
Derivative Asset, Fair Value, Gross Asset 0us-gaap_DerivativeFairValueOfDerivativeAsset
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Designated As Hedging Instrument [Member] | Regulated Distribution Segment [Member] | Deferred Charges And Other Assets [Member] | Commodity Contract [Member]    
Derivatives Fair Value [Line Items]    
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Derivatives Fair Value [Line Items]    
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Derivatives Fair Value [Line Items]    
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Derivatives Fair Value [Line Items]    
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Derivatives Fair Value [Line Items]    
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Derivatives Fair Value [Line Items]    
Derivative Asset, Fair Value, Gross Asset 15,658us-gaap_DerivativeFairValueOfDerivativeAsset
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Derivatives Fair Value [Line Items]    
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Derivatives Fair Value [Line Items]    
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Derivatives Fair Value [Line Items]    
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Derivatives Fair Value [Line Items]    
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Derivatives Fair Value [Line Items]    
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Derivatives Fair Value [Line Items]    
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Derivatives Fair Value [Line Items]    
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Derivatives Fair Value [Line Items]    
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Derivatives Fair Value [Line Items]    
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Nondesignated [Member] | Regulated Distribution Segment [Member] | Other Current Assets [Member] | Commodity Contract [Member]    
Derivatives Fair Value [Line Items]    
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Nondesignated [Member] | Regulated Distribution Segment [Member] | Deferred Charges And Other Assets [Member] | Commodity Contract [Member]    
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Nondesignated [Member] | Regulated Distribution Segment [Member] | Other Current Liabilities [Member] | Commodity Contract [Member]    
Derivatives Fair Value [Line Items]    
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Nondesignated [Member] | Regulated Distribution Segment [Member] | Deferred Credits And Other Liabilities [Member] | Commodity Contract [Member]    
Derivatives Fair Value [Line Items]    
Derivative Liability, Fair Value, Gross Liability 0us-gaap_DerivativeFairValueOfDerivativeLiability
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/ us-gaap_StatementBusinessSegmentsAxis
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Nondesignated [Member] | Nonregulated Segment [Member]    
Derivatives Fair Value [Line Items]    
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Nondesignated [Member] | Nonregulated Segment [Member] | Other Current Assets [Member] | Commodity Contract [Member]    
Derivatives Fair Value [Line Items]    
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Nondesignated [Member] | Nonregulated Segment [Member] | Deferred Charges And Other Assets [Member] | Commodity Contract [Member]    
Derivatives Fair Value [Line Items]    
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Nondesignated [Member] | Nonregulated Segment [Member] | Other Current Liabilities [Member] | Commodity Contract [Member]    
Derivatives Fair Value [Line Items]    
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Derivatives Fair Value [Line Items]    
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$ (14,786)us-gaap_DerivativeFairValueOfDerivativeLiability
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