$ATO
Atmos Energy Corp Stock $ato

$ato Overview Financials Valuation SEC Filings Company Website

2011 Q3 Form 10-K Financial Statement

#000119312512466518 Filed on November 13, 2012

Income Statement

Concept	2011 Q3	2011 Q2	2011 Q1
Revenue	$779.7M	$833.2M	$1.556B
YoY Change	0.14%	9.44%	-23.96%
Cost Of Revenue	$547.2M	$576.8M	$1.152B
YoY Change	1.86%	11.56%	-22.44%
Gross Profit	$237.2M	$261.6M	$444.5M
YoY Change	-1.75%	5.63%	-0.22%
Gross Profit Margin	30.42%	31.4%	28.56%
Selling, General & Admin
YoY Change
% of Gross Profit
Research & Development
YoY Change
% of Gross Profit
Depreciation & Amortization	$61.50M	$58.40M	$57.10M
YoY Change	8.27%	9.57%	7.53%
% of Gross Profit	25.93%	22.32%	12.85%
Operating Expenses	$200.7M	$232.7M	$242.5M
YoY Change	-1.04%	8.04%	5.52%
Operating Profit	$39.20M	$31.39M	$204.6M
YoY Change	1.71%	-2.68%	-6.89%
Interest Expense	-$38.20M	$35.85M	$37.88M
YoY Change	-1.8%	-3.82%	-4.31%
% of Operating Profit	-97.46%	114.18%	18.51%
Other Income/Expense, Net	-$2.500M	-$1.430M	$26.20M
YoY Change	-457.14%	79.2%	53373.47%
Pretax Income	$600.0K	-$3.197M	$199.5M
YoY Change	50.0%	-44.94%	7.85%
Income Tax	-$500.0K	-$1.723M	$71.37M
% Of Pretax Income	-83.33%		35.77%
Net Earnings	$1.961M	-$566.0K	$132.2M
YoY Change	27.59%	-82.05%	15.84%
Net Earnings / Revenue	0.25%	-0.07%	8.49%
Basic Earnings Per Share	$0.02	-$0.01	$1.45
Diluted Earnings Per Share	$0.02	-$0.01	$1.45
COMMON SHARES
Basic Shares Outstanding	90.29M shares	90.13M shares	90.25M shares
Diluted Shares Outstanding		90.13M shares	90.53M shares

Balance Sheet

Concept	2011 Q3	2011 Q2	2011 Q1
SHORT-TERM ASSETS
Cash & Short-Term Investments	$184.1M	$117.0M	$153.0M
YoY Change	6.13%	-35.0%	-33.77%
Cash & Equivalents	$131.4M	$117.4M	$153.2M
Short-Term Investments	$52.63M
Other Short-Term Assets	$316.5M	$273.5M	$144.0M
YoY Change	109.59%	110.35%	18.99%
Inventory	$290.0M	$257.0M	$228.0M
Prepaid Expenses	$22.50M
Receivables	$273.3M	$342.1M	$458.8M
Other Receivables	$0.00	$0.00	$0.00
Total Short-Term Assets	$1.011B	$989.7M	$984.1M
YoY Change	15.51%	13.25%	-11.1%
LONG-TERM ASSETS
Property, Plant & Equipment	$5.148B	$4.916B	$4.915B
YoY Change	7.4%	5.29%	7.07%
Goodwill	$740.0M
YoY Change	0.09%
Intangibles
YoY Change
Long-Term Investments
YoY Change
Other Assets	$383.8M	$348.0M	$357.3M
YoY Change	8.0%	14.83%	13.05%
Total Long-Term Assets	$6.272B	$6.004B	$6.012B
YoY Change	6.51%	5.11%	6.48%
TOTAL ASSETS
Total Short-Term Assets	$1.011B	$989.7M	$984.1M
Total Long-Term Assets	$6.272B	$6.004B	$6.012B
Total Assets	$7.283B	$6.993B	$6.996B
YoY Change	7.67%	6.19%	3.6%
SHORT-TERM LIABILITIES
YoY Change
Accounts Payable	$291.0M	$312.0M	$424.0M
YoY Change	9.4%	22.83%	-18.77%
Accrued Expenses
YoY Change
Deferred Revenue
YoY Change
Short-Term Debt	$206.4M	$0.00	$0.00
YoY Change	63.68%
Long-Term Debt Due	$2.434M	$2.434M	$352.4M
YoY Change	-99.32%	-99.32%	3424.34%
Total Short-Term Liabilities	$867.6M	$648.3M	$1.078B
YoY Change	-25.6%	-35.67%	11.71%
LONG-TERM LIABILITIES
Long-Term Debt	$2.206B	$2.206B	$1.807B
YoY Change	21.92%	21.91%	-16.29%
Other Long-Term Liabilities	$564.7M	$439.5M	$427.2M
YoY Change	31.27%	14.38%	-38.62%
Total Long-Term Liabilities	$2.771B	$2.646B	$2.235B
YoY Change	23.71%	20.6%	-21.73%
TOTAL LIABILITIES
Total Short-Term Liabilities	$867.6M	$648.3M	$1.078B
Total Long-Term Liabilities	$2.771B	$2.646B	$2.235B
Total Liabilities	$3.638B	$3.294B	$3.313B
YoY Change	6.83%	2.88%	-24.95%
SHAREHOLDERS EQUITY
Retained Earnings	$570.5M	$599.5M	$631.0M
YoY Change	17.17%	16.24%
Common Stock	$1.733B	$1.731B	$1.729B
YoY Change	1.08%	-4.52%
Preferred Stock
YoY Change
Treasury Stock (at cost)
YoY Change
Treasury Stock Shares
Shareholders Equity	$2.255B	$2.336B	$2.374B
YoY Change
Total Liabilities & Shareholders Equity	$7.283B	$6.993B	$6.996B
YoY Change	7.67%	6.19%	3.6%

Cashflow Statement

Concept	2011 Q3	2011 Q2	2011 Q1
OPERATING ACTIVITIES
Net Income	$1.961M	-$566.0K	$132.2M
YoY Change	27.59%	-82.05%	15.84%
Depreciation, Depletion And Amortization	$61.50M	$58.40M	$57.10M
YoY Change	8.27%	9.57%	7.53%
Cash From Operating Activities	$63.20M	$81.10M	$392.7M
YoY Change	-52.08%	-27.0%	1.13%
INVESTING ACTIVITIES
Capital Expenditures	-$232.7M	-$143.6M	-$123.5M
YoY Change	29.06%	10.72%	5.38%
Acquisitions
YoY Change
Other Investing Activities	-$1.000M	-$1.900M	-$1.100M
YoY Change	-433.33%	-480.0%	-210.0%
Cash From Investing Activities	-$233.7M	-$145.5M	-$124.7M
YoY Change	29.91%	12.62%	7.22%
FINANCING ACTIVITIES
Cash Dividend Paid
YoY Change
Common Stock Issuance & Retirement, Net
YoY Change
Debt Paid & Issued, Net
YoY Change
Cash From Financing Activities	184.4M	28.60M	-244.6M
YoY Change	-46200.0%	-187.46%	13.4%
NET CHANGE
Cash From Operating Activities	63.20M	81.10M	392.7M
Cash From Investing Activities	-233.7M	-145.5M	-124.7M
Cash From Financing Activities	184.4M	28.60M	-244.6M
Net Change In Cash	13.90M	-35.80M	23.40M
YoY Change	-128.72%	-29.53%	-58.44%
FREE CASH FLOW
Cash From Operating Activities	$63.20M	$81.10M	$392.7M
Capital Expenditures	-$232.7M	-$143.6M	-$123.5M
Free Cash Flow	$295.9M	$224.7M	$516.2M
YoY Change	-5.22%	-6.69%	2.12%

Facts In Submission

Frame	Concept Type	Concept / XBRL Key	Value	Unit
CY2012	dei	Document Type DocumentType	10-K
CY2012	dei	Document Period End Date DocumentPeriodEndDate	2012-09-30
CY2012	dei	Amendment Flag AmendmentFlag	false
CY2012	dei	Entity Registrant Name EntityRegistrantName	Atmos Energy Corporation
CY2012	dei	Entity Central Index Key EntityCentralIndexKey	0000731802
CY2012	dei	Entity Current Reporting Status EntityCurrentReportingStatus	Yes
CY2012	dei	Entity Voluntary Filers EntityVoluntaryFilers	No
CY2012	dei	Current Fiscal Year End Date CurrentFiscalYearEndDate	--09-30
CY2012	dei	Entity Filer Category EntityFilerCategory	Large Accelerated Filer
CY2012	dei	Entity Well Known Seasoned Issuer EntityWellKnownSeasonedIssuer	Yes
CY2012	dei	Document Fiscal Year Focus DocumentFiscalYearFocus	2012
CY2012	dei	Document Fiscal Period Focus DocumentFiscalPeriodFocus	FY
CY2012Q1	dei	Entity Public Float EntityPublicFloat	2764486845	USD
CY2012Q4	dei	Entity Common Stock Shares Outstanding EntityCommonStockSharesOutstanding	90240464	shares
CY2012Q3	us-gaap	Construction In Progress Gross ConstructionInProgressGross	274112000	USD
CY2012Q3	us-gaap	Accumulated Depreciation Depletion And Amortization Property Plant And Equipment AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment	1658866000	USD
CY2012Q3	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	5475604000	USD
CY2012Q3	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	64239000	USD
CY2012Q3	us-gaap	Accounts Receivable Net Current AccountsReceivableNetCurrent	234526000	USD
CY2012Q3	us-gaap	Energy Related Inventory Gas Stored Underground EnergyRelatedInventoryGasStoredUnderground	256415000	USD
CY2012	us-gaap	Accelerated Share Repurchases Final Price Paid Per Share AcceleratedShareRepurchasesFinalPricePaidPerShare	29.99
CY2012	ato	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number Beginning Balance ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumberBeginningBalance	1264142	shares
CY2012	ato	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Weighted Average Grant Date Fair Value Beginning Of Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueBeginningOfPeriod	29.56
CY2012	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod	532711	shares
CY2012Q3	us-gaap	Other Assets Current OtherAssetsCurrent	272782000	USD
CY2012Q3	us-gaap	Assets Current AssetsCurrent	827962000	USD
CY2012Q3	ato	Goodwill And Intangible Assets GoodwillAndIntangibleAssets	740847000	USD
CY2012Q3	us-gaap	Other Assets Noncurrent OtherAssetsNoncurrent	451262000	USD
CY2012Q3	us-gaap	Assets Assets	7495675000	USD
CY2011Q3	us-gaap	Accumulated Depreciation Depletion And Amortization Property Plant And Equipment AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment	1668876000	USD
CY2011Q3	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	5147918000	USD
CY2011Q3	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	131419000	USD
CY2011Q3	us-gaap	Accounts Receivable Net Current AccountsReceivableNetCurrent	273303000	USD
CY2011Q3	us-gaap	Energy Related Inventory Gas Stored Underground EnergyRelatedInventoryGasStoredUnderground	289760000	USD
CY2011Q3	us-gaap	Other Assets Current OtherAssetsCurrent	316471000	USD
CY2011Q3	us-gaap	Assets Current AssetsCurrent	1010953000	USD
CY2011Q3	ato	Goodwill And Intangible Assets GoodwillAndIntangibleAssets	740207000	USD
CY2011Q3	us-gaap	Other Assets Noncurrent OtherAssetsNoncurrent	383793000	USD
CY2011Q3	us-gaap	Assets Assets	7282871000	USD
CY2012Q3	us-gaap	Common Stock Value CommonStockValue	451000	USD
CY2012Q3	us-gaap	Additional Paid In Capital Common Stock AdditionalPaidInCapitalCommonStock	1745467000	USD
CY2012Q3	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-47607000	USD
CY2012Q3	us-gaap	Retained Earnings Accumulated Deficit RetainedEarningsAccumulatedDeficit	660932000	USD
CY2012Q3	us-gaap	Stockholders Equity StockholdersEquity	2359243000	USD
CY2012Q3	us-gaap	Long Term Debt Noncurrent LongTermDebtNoncurrent	1956305000	USD
CY2012Q3	us-gaap	Capitalization Longterm Debt And Equity CapitalizationLongtermDebtAndEquity	4315548000	USD
CY2012Q3	us-gaap	Accounts Payable And Accrued Liabilities Current AccountsPayableAndAccruedLiabilitiesCurrent	215229000	USD
CY2012Q3	us-gaap	Other Liabilities Current OtherLiabilitiesCurrent	489665000	USD
CY2012Q3	us-gaap	Short Term Borrowings ShortTermBorrowings	570929000	USD
CY2012Q3	us-gaap	Long Term Debt Current LongTermDebtCurrent	131000	USD
CY2012Q3	us-gaap	Liabilities Current LiabilitiesCurrent	1275954000	USD
CY2012Q3	us-gaap	Deferred Income Tax Liabilities DeferredIncomeTaxLiabilities	1015083000	USD
CY2012Q3	us-gaap	Other Liabilities Noncurrent OtherLiabilitiesNoncurrent	507926000	USD
CY2012Q3	us-gaap	Liabilities And Stockholders Equity LiabilitiesAndStockholdersEquity	7495675000	USD
CY2011Q3	us-gaap	Accounts Payable And Accrued Liabilities Current AccountsPayableAndAccruedLiabilitiesCurrent	291205000	USD
CY2011Q3	us-gaap	Other Liabilities Current OtherLiabilitiesCurrent	367563000	USD
CY2011Q3	us-gaap	Short Term Borrowings ShortTermBorrowings	206396000	USD
CY2011Q3	us-gaap	Long Term Debt Current LongTermDebtCurrent	2434000	USD
CY2011Q3	us-gaap	Liabilities Current LiabilitiesCurrent	867598000	USD
CY2011Q3	us-gaap	Deferred Income Tax Liabilities DeferredIncomeTaxLiabilities	960093000	USD
CY2011Q3	us-gaap	Other Liabilities Noncurrent OtherLiabilitiesNoncurrent	564695000	USD
CY2011Q3	us-gaap	Liabilities And Stockholders Equity LiabilitiesAndStockholdersEquity	7282871000	USD
CY2011Q3	us-gaap	Construction In Progress Gross ConstructionInProgressGross	209242000	USD
CY2011Q3	us-gaap	Common Stock Value CommonStockValue	451000	USD
CY2011Q3	us-gaap	Additional Paid In Capital Common Stock AdditionalPaidInCapitalCommonStock	1732935000	USD
CY2011Q3	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-48460000	USD
CY2011Q3	us-gaap	Retained Earnings Accumulated Deficit RetainedEarningsAccumulatedDeficit	570495000	USD
CY2011Q3	us-gaap	Long Term Debt Noncurrent LongTermDebtNoncurrent	2206117000	USD
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CY2011Q3	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	200000000	shares
CY2012Q3	ato	Common Stock Stated Value Per Share CommonStockStatedValuePerShare	0.005
CY2011Q3	ato	Common Stock Stated Value Per Share CommonStockStatedValuePerShare	0.005
CY2012Q3	us-gaap	Common Stock Par Or Stated Value Per Share CommonStockParOrStatedValuePerShare	0.000
CY2011Q3	us-gaap	Common Stock Par Or Stated Value Per Share CommonStockParOrStatedValuePerShare	0.000
CY2011Q3	us-gaap	Stockholders Equity StockholdersEquity	2255421000	USD
CY2012Q3	us-gaap	Allowance For Doubtful Accounts Receivable Current AllowanceForDoubtfulAccountsReceivableCurrent	9425000	USD
CY2011Q3	us-gaap	Allowance For Doubtful Accounts Receivable Current AllowanceForDoubtfulAccountsReceivableCurrent	7440000	USD
CY2012Q3	ato	Property Plant And Equipment Excluding Cip Gross PropertyPlantAndEquipmentExcludingCipGross	6860358000	USD
CY2011Q3	ato	Property Plant And Equipment Excluding Cip Gross PropertyPlantAndEquipmentExcludingCipGross	6607552000	USD
CY2012Q3	us-gaap	Property Plant And Equipment Gross PropertyPlantAndEquipmentGross	7134470000	USD
CY2011Q3	us-gaap	Property Plant And Equipment Gross PropertyPlantAndEquipmentGross	6816794000	USD
CY2012Q3	ato	Regulatory Cost Of Removal Liability RegulatoryCostOfRemovalLiability	381164000	USD
CY2011Q3	ato	Regulatory Cost Of Removal Liability RegulatoryCostOfRemovalLiability	428947000	USD
CY2012	us-gaap	Regulated And Unregulated Operating Revenue RegulatedAndUnregulatedOperatingRevenue	3438483000	USD
CY2012	ato	Purchased Gas Cost PurchasedGasCost	2114744000	USD
CY2011	ato	Purchased Gas Cost PurchasedGasCost	2985615000	USD
CY2010	ato	Purchased Gas Cost PurchasedGasCost	3346924000	USD
CY2010	us-gaap	Regulated And Unregulated Operating Revenue RegulatedAndUnregulatedOperatingRevenue	4661060000	USD
CY2011	us-gaap	Regulated And Unregulated Operating Revenue RegulatedAndUnregulatedOperatingRevenue	4286435000	USD
CY2012	us-gaap	Gross Profit GrossProfit	1323739000	USD
CY2011	us-gaap	Gross Profit GrossProfit	1300820000	USD
CY2010	us-gaap	Gross Profit GrossProfit	1314136000	USD
CY2012	us-gaap	Other Selling General And Administrative Expense OtherSellingGeneralAndAdministrativeExpense	453613000	USD
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CY2011	us-gaap	Depreciation And Amortization DepreciationAndAmortization	223832000	USD
CY2010	us-gaap	Depreciation And Amortization DepreciationAndAmortization	208539000	USD
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CY2012	us-gaap	Asset Impairment Charges AssetImpairmentCharges	5288000	USD
CY2011	us-gaap	Asset Impairment Charges AssetImpairmentCharges	30270000	USD
CY2010	us-gaap	Asset Impairment Charges AssetImpairmentCharges	0	USD
CY2012	us-gaap	Operating Expenses OperatingExpenses	877499000	USD
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CY2010	us-gaap	Operating Expenses OperatingExpenses	850303000	USD
CY2012	us-gaap	Operating Income Loss OperatingIncomeLoss	446240000	USD
CY2011	us-gaap	Operating Income Loss OperatingIncomeLoss	425986000	USD
CY2010	us-gaap	Operating Income Loss OperatingIncomeLoss	463833000	USD
CY2012	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	-14644000	USD
CY2011	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	21184000	USD
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CY2012	us-gaap	Interest Expense InterestExpense	141174000	USD
CY2011	us-gaap	Interest Expense InterestExpense	150763000	USD
CY2010	us-gaap	Interest Expense InterestExpense	154188000	USD
CY2012	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	290422000	USD
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CY2010	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	309054000	USD
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CY2012	us-gaap	Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest	192196000	USD
CY2011	us-gaap	Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest	189588000	USD
CY2010	us-gaap	Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest	189851000	USD
CY2012	us-gaap	Discontinued Operation Income Loss From Discontinued Operation During Phase Out Period Net Of Tax DiscontinuedOperationIncomeLossFromDiscontinuedOperationDuringPhaseOutPeriodNetOfTax	18172000	USD
CY2011	us-gaap	Discontinued Operation Income Loss From Discontinued Operation During Phase Out Period Net Of Tax DiscontinuedOperationIncomeLossFromDiscontinuedOperationDuringPhaseOutPeriodNetOfTax	18013000	USD
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CY2012	us-gaap	Net Income Loss NetIncomeLoss	216717000	USD
CY2011	us-gaap	Net Income Loss NetIncomeLoss	207601000	USD
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CY2010	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	2.22
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CY2010	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Diluted Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare	0.17
CY2012	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	2.37
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CY2010	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	2.20
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CY2011	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	90201000	shares
CY2010	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	91852000	shares
CY2012	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	91172000	shares
CY2011	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	90652000	shares
CY2010	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	92422000	shares
CY2012	us-gaap	Discontinued Operation Tax Effect Of Income Loss From Discontinued Operation During Phase Out Period DiscontinuedOperationTaxEffectOfIncomeLossFromDiscontinuedOperationDuringPhaseOutPeriod	10066000	USD
CY2011	us-gaap	Discontinued Operation Tax Effect Of Income Loss From Discontinued Operation During Phase Out Period DiscontinuedOperationTaxEffectOfIncomeLossFromDiscontinuedOperationDuringPhaseOutPeriod	12372000	USD
CY2010	us-gaap	Discontinued Operation Tax Effect Of Income Loss From Discontinued Operation During Phase Out Period DiscontinuedOperationTaxEffectOfIncomeLossFromDiscontinuedOperationDuringPhaseOutPeriod	9584000	USD
CY2012	us-gaap	Discontinued Operation Gain Loss On Disposal Of Discontinued Operation Net Of Tax DiscontinuedOperationGainLossOnDisposalOfDiscontinuedOperationNetOfTax	6349000	USD
CY2011	us-gaap	Discontinued Operation Gain Loss On Disposal Of Discontinued Operation Net Of Tax DiscontinuedOperationGainLossOnDisposalOfDiscontinuedOperationNetOfTax	0	USD
CY2010	us-gaap	Discontinued Operation Gain Loss On Disposal Of Discontinued Operation Net Of Tax DiscontinuedOperationGainLossOnDisposalOfDiscontinuedOperationNetOfTax	0	USD
CY2012	us-gaap	Discontinued Operation Tax Effect Of Income Loss From Disposal Of Discontinued Operation DiscontinuedOperationTaxEffectOfIncomeLossFromDisposalOfDiscontinuedOperation	3519000	USD
CY2011	us-gaap	Discontinued Operation Tax Effect Of Income Loss From Disposal Of Discontinued Operation DiscontinuedOperationTaxEffectOfIncomeLossFromDisposalOfDiscontinuedOperation	0	USD
CY2010	us-gaap	Discontinued Operation Tax Effect Of Income Loss From Disposal Of Discontinued Operation DiscontinuedOperationTaxEffectOfIncomeLossFromDisposalOfDiscontinuedOperation	0	USD
CY2011	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	1.36
CY2012	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	1.38
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CY2010	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	1.34
CY2009Q3	us-gaap	Stockholders Equity StockholdersEquity	2176761000	USD
CY2010	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	1745000	USD
CY2010	ato	Treasury Lock Agreements Net TreasuryLockAgreementsNet	2030000	USD
CY2010	ato	Share Repurchases Amount ShareRepurchasesAmount	-100450000	USD
CY2010	ato	Repurchase Of Equity Awards Value RepurchaseOfEquityAwardsValue	-1191000	USD
CY2010	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	124287000	USD
CY2010	ato	Stock Issued During Period Value Direct Stock Purchase Plan StockIssuedDuringPeriodValueDirectStockPurchasePlan	2882000	USD
CY2010	ato	Stock Issued During Period Value Retirement Savings Plan StockIssuedDuringPeriodValueRetirementSavingsPlan	2281000	USD
CY2010	ato	Stock Issued During Period Value Long Term Incentive Plan StockIssuedDuringPeriodValueLongTermIncentivePlan	8710000	USD
CY2010	us-gaap	Stock Issued During Period Value Share Based Compensation StockIssuedDuringPeriodValueShareBasedCompensation	10894000	USD
CY2010	ato	Stock Issued During Period Value Directors Stock For Fee Plan StockIssuedDuringPeriodValueDirectorsStockForFeePlan	97000	USD
CY2010Q3	us-gaap	Stockholders Equity StockholdersEquity	2178348000	USD
CY2011	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	-1647000	USD
CY2011	ato	Treasury Lock Agreements Net TreasuryLockAgreementsNet	-28689000	USD
CY2011	ato	Share Repurchases Amount ShareRepurchasesAmount	0	USD
CY2011	ato	Repurchase Of Equity Awards Value RepurchaseOfEquityAwardsValue	-5299000	USD
CY2011	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	124011000	USD
CY2011	ato	Stock Issued During Period Value Long Term Incentive Plan StockIssuedDuringPeriodValueLongTermIncentivePlan	13889000	USD
CY2011	us-gaap	Stock Issued During Period Value Share Based Compensation StockIssuedDuringPeriodValueShareBasedCompensation	9958000	USD
CY2011	ato	Stock Issued During Period Value Directors Stock For Fee Plan StockIssuedDuringPeriodValueDirectorsStockForFeePlan	77000	USD
CY2012	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	3103000	USD
CY2012	ato	Treasury Lock Agreements Net TreasuryLockAgreementsNet	-10116000	USD
CY2012	ato	Share Repurchases Amount ShareRepurchasesAmount	-12535000	USD
CY2012	ato	Repurchase Of Equity Awards Value RepurchaseOfEquityAwardsValue	-5219000	USD
CY2012	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	125796000	USD
CY2012	ato	Stock Issued During Period Value Direct Stock Purchase Plan StockIssuedDuringPeriodValueDirectStockPurchasePlan	-65000	USD
CY2012	ato	Stock Issued During Period Value Long Term Incentive Plan StockIssuedDuringPeriodValueLongTermIncentivePlan	12037000	USD
CY2012	us-gaap	Stock Issued During Period Value Share Based Compensation StockIssuedDuringPeriodValueShareBasedCompensation	17752000	USD
CY2012	ato	Stock Issued During Period Value Directors Stock For Fee Plan StockIssuedDuringPeriodValueDirectorsStockForFeePlan	78000	USD
CY2010	ato	Cash Flow Hedges Net CashFlowHedgesNet	-6963000	USD
CY2011	ato	Cash Flow Hedges Net CashFlowHedgesNet	5248000	USD
CY2012	ato	Cash Flow Hedges Net CashFlowHedgesNet	7866000	USD
CY2012	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	1881000	USD
CY2011	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	-953000	USD
CY2010	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	1025000	USD
CY2010	ato	Other Comprehensive Income Reclassification Adjustment And Unrealized Gain Loss On Derivatives Included In Net Income And Arising During Period Tax OtherComprehensiveIncomeReclassificationAdjustmentAndUnrealizedGainLossOnDerivativesIncludedInNetIncomeAndArisingDuringPeriodTax	1193000	USD
CY2011	ato	Other Comprehensive Income Reclassification Adjustment And Unrealized Gain Loss On Derivatives Included In Net Income And Arising During Period Tax OtherComprehensiveIncomeReclassificationAdjustmentAndUnrealizedGainLossOnDerivativesIncludedInNetIncomeAndArisingDuringPeriodTax	-16850000	USD
CY2012	ato	Other Comprehensive Income Reclassification Adjustment And Unrealized Gain Loss On Derivatives Included In Net Income And Arising During Period Tax OtherComprehensiveIncomeReclassificationAdjustmentAndUnrealizedGainLossOnDerivativesIncludedInNetIncomeAndArisingDuringPeriodTax	-5388000	USD
CY2012	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodTax	5029000	USD
CY2011	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodTax	3355000	USD
CY2010	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodTax	-4452000	USD
CY2012	us-gaap	Discontinued Operation Gain Loss From Disposal Of Discontinued Operation Before Income Tax DiscontinuedOperationGainLossFromDisposalOfDiscontinuedOperationBeforeIncomeTax	9868000	USD
CY2012	ato	Depreciation And Amortization Cash Flow DepreciationAndAmortizationCashFlow	246093000	USD
CY2012	us-gaap	Other Depreciation And Amortization OtherDepreciationAndAmortization	484000	USD
CY2012	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	104319000	USD
CY2012	us-gaap	Share Based Compensation ShareBasedCompensation	19222000	USD
CY2012	us-gaap	Amortization Of Financing Costs And Discounts AmortizationOfFinancingCostsAndDiscounts	8147000	USD
CY2012	us-gaap	Other Noncash Income Expense OtherNoncashIncomeExpense	493000	USD
CY2012	us-gaap	Increase Decrease In Accounts Receivable IncreaseDecreaseInAccountsReceivable	-32578000	USD
CY2012	ato	Increase Decrease In Other Noncurrent Operating Assets IncreaseDecreaseInOtherNoncurrentOperatingAssets	50055000	USD
CY2012	us-gaap	Increase Decrease In Inventories IncreaseDecreaseInInventories	-28417000	USD
CY2012	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	-20989000	USD
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CY2012	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	7889000	USD
CY2012	ato	Increase Decrease In Other Noncurrent Operating Liabilities IncreaseDecreaseInOtherNoncurrentOperatingLiabilities	21424000	USD
CY2012	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	586917000	USD
CY2011	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	-57495000	USD
CY2011	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	117353000	USD
CY2011	us-gaap	Discontinued Operation Gain Loss From Disposal Of Discontinued Operation Before Income Tax DiscontinuedOperationGainLossFromDisposalOfDiscontinuedOperationBeforeIncomeTax	0	USD
CY2011	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	582844000	USD
CY2011	ato	Depreciation And Amortization Cash Flow DepreciationAndAmortizationCashFlow	233155000	USD
CY2011	us-gaap	Increase Decrease In Accounts Payable And Accrued Liabilities IncreaseDecreaseInAccountsPayableAndAccruedLiabilities	23904000	USD
CY2011	us-gaap	Amortization Of Financing Costs And Discounts AmortizationOfFinancingCostsAndDiscounts	9438000	USD
CY2011	us-gaap	Other Noncash Income Expense OtherNoncashIncomeExpense	961000	USD
CY2011	ato	Increase Decrease In Other Noncurrent Operating Assets IncreaseDecreaseInOtherNoncurrentOperatingAssets	53519000	USD
CY2011	ato	Increase Decrease In Other Noncurrent Operating Liabilities IncreaseDecreaseInOtherNoncurrentOperatingLiabilities	71691000	USD
CY2011	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	38048000	USD
CY2011	us-gaap	Increase Decrease In Inventories IncreaseDecreaseInInventories	-27737000	USD
CY2011	us-gaap	Share Based Compensation ShareBasedCompensation	11586000	USD
CY2011	us-gaap	Increase Decrease In Accounts Receivable IncreaseDecreaseInAccountsReceivable	96000	USD
CY2011	us-gaap	Other Depreciation And Amortization OtherDepreciationAndAmortization	228000	USD
CY2010	us-gaap	Increase Decrease In Inventories IncreaseDecreaseInInventories	-54014000	USD
CY2010	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	726476000	USD
CY2010	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	18387000	USD
CY2010	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	196731000	USD
CY2010	ato	Increase Decrease In Other Noncurrent Operating Liabilities IncreaseDecreaseInOtherNoncurrentOperatingLiabilities	64266000	USD
CY2010	us-gaap	Other Noncash Income Expense OtherNoncashIncomeExpense	1245000	USD
CY2010	ato	Increase Decrease In Other Noncurrent Operating Assets IncreaseDecreaseInOtherNoncurrentOperatingAssets	-14886000	USD
CY2010	us-gaap	Increase Decrease In Accounts Receivable IncreaseDecreaseInAccountsReceivable	40401000	USD
CY2010	us-gaap	Share Based Compensation ShareBasedCompensation	12655000	USD
CY2010	us-gaap	Increase Decrease In Accounts Payable And Accrued Liabilities IncreaseDecreaseInAccountsPayableAndAccruedLiabilities	58069000	USD
CY2010	us-gaap	Discontinued Operation Gain Loss From Disposal Of Discontinued Operation Before Income Tax DiscontinuedOperationGainLossFromDisposalOfDiscontinuedOperationBeforeIncomeTax	0	USD
CY2010	ato	Depreciation And Amortization Cash Flow DepreciationAndAmortizationCashFlow	216960000	USD
CY2010	us-gaap	Amortization Of Financing Costs And Discounts AmortizationOfFinancingCostsAndDiscounts	11908000	USD
CY2010	us-gaap	Other Depreciation And Amortization OtherDepreciationAndAmortization	173000	USD
CY2010	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	-48992000	USD
CY2012	us-gaap	Proceeds From Sale Of Productive Assets ProceedsFromSaleOfProductiveAssets	128223000	USD
CY2012	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	4625000	USD
CY2012	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-609260000	USD
CY2012	us-gaap	Payments To Acquire Productive Assets PaymentsToAcquireProductiveAssets	732858000	USD
CY2012	us-gaap	Proceeds From Repayments Of Short Term Debt ProceedsFromRepaymentsOfShortTermDebt	354141000	USD
CY2012	us-gaap	Proceeds From Issuance Of Long Term Debt ProceedsFromIssuanceOfLongTermDebt	0	USD
CY2012	us-gaap	Payments For Proceeds From Hedge Financing Activities PaymentsForProceedsFromHedgeFinancingActivities	0	USD
CY2012	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	257034000	USD
CY2012	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	125796000	USD
CY2012	ato	Payments To Repurchase Common Stock PaymentsToRepurchaseCommonStock	12535000	USD
CY2012	ato	Repurchase Of Equity Awards RepurchaseOfEquityAwards	5219000	USD
CY2012	us-gaap	Proceeds From Issuance Of Common Stock ProceedsFromIssuanceOfCommonStock	1606000	USD
CY2012	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-44837000	USD
CY2012	us-gaap	Cash And Cash Equivalents Period Increase Decrease CashAndCashEquivalentsPeriodIncreaseDecrease	-67180000	USD
CY2010	us-gaap	Proceeds From Issuance Of Common Stock ProceedsFromIssuanceOfCommonStock	8766000	USD
CY2010	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-542702000	USD
CY2010	us-gaap	Proceeds From Issuance Of Long Term Debt ProceedsFromIssuanceOfLongTermDebt	0	USD
CY2010	us-gaap	Proceeds From Sale Of Productive Assets ProceedsFromSaleOfProductiveAssets	0	USD
CY2010	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	131000	USD
CY2010	us-gaap	Payments To Acquire Productive Assets PaymentsToAcquireProductiveAssets	542636000	USD
CY2010	ato	Payments To Repurchase Common Stock PaymentsToRepurchaseCommonStock	100450000	USD
CY2010	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-163025000	USD
CY2010	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	66000	USD
CY2010	us-gaap	Payments For Proceeds From Hedge Financing Activities PaymentsForProceedsFromHedgeFinancingActivities	0	USD
CY2010	us-gaap	Proceeds From Repayments Of Short Term Debt ProceedsFromRepaymentsOfShortTermDebt	54268000	USD
CY2010	us-gaap	Cash And Cash Equivalents Period Increase Decrease CashAndCashEquivalentsPeriodIncreaseDecrease	20749000	USD
CY2010	ato	Repurchase Of Equity Awards RepurchaseOfEquityAwards	1191000	USD
CY2010	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	124287000	USD
CY2010Q3	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	131952000	USD
CY2011	ato	Repurchase Of Equity Awards RepurchaseOfEquityAwards	5299000	USD
CY2011	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	124011000	USD
CY2011	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-627386000	USD
CY2011	ato	Payments To Repurchase Common Stock PaymentsToRepurchaseCommonStock	0	USD
CY2011	us-gaap	Proceeds From Issuance Of Long Term Debt ProceedsFromIssuanceOfLongTermDebt	394466000	USD
CY2011	us-gaap	Payments To Acquire Productive Assets PaymentsToAcquireProductiveAssets	622965000	USD
CY2011	us-gaap	Proceeds From Issuance Of Common Stock ProceedsFromIssuanceOfCommonStock	7796000	USD
CY2011	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	44009000	USD
CY2011	us-gaap	Proceeds From Sale Of Productive Assets ProceedsFromSaleOfProductiveAssets	0	USD
CY2011	us-gaap	Proceeds From Repayments Of Short Term Debt ProceedsFromRepaymentsOfShortTermDebt	83306000	USD
CY2011	us-gaap	Payments For Proceeds From Hedge Financing Activities PaymentsForProceedsFromHedgeFinancingActivities	-20079000	USD
CY2011	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	360131000	USD
CY2011	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	4421000	USD
CY2011	us-gaap	Cash And Cash Equivalents Period Increase Decrease CashAndCashEquivalentsPeriodIncreaseDecrease	-533000	USD
CY2009Q3	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	111203000	USD
CY2012	us-gaap	Proceeds From Payments For Other Financing Activities ProceedsFromPaymentsForOtherFinancingActivities	0	USD
CY2011	us-gaap	Proceeds From Payments For Other Financing Activities ProceedsFromPaymentsForOtherFinancingActivities	27803000	USD
CY2010	us-gaap	Proceeds From Payments For Other Financing Activities ProceedsFromPaymentsForOtherFinancingActivities	0	USD
CY2012	us-gaap	Nature Of Operations NatureOfOperations	<p style='margin-top:0pt; margin-bottom:0pt'><font style="font-family:Times New Roman;font-size:12pt;font-weight:bold;margin-left:0px;">1.       </font><font style="font-family:Times New Roman;font-size:12pt;font-weight:bold;">Nature of Business</font></p><p style='margin-top:0pt; margin-bottom:0pt'> </p><p style='margin-top:0pt; margin-bottom:0pt'><font style="font-family:Times New Roman;font-size:12pt;margin-left:0px;">Atmos Energy Corporation </font><font style="font-family:Times New Roman;font-size:12pt;">(“Atmos Energy” or the “Company”) </font><font style="font-family:Times New Roman;font-size:12pt;">and our subsidiaries are engaged primarily in the regulated natural gas distribution and transmission and storage businesses as well as certain other nonregulated businesses. Through our natural gas distribution business, we deliver natural gas through sales and transportation arrangements to </font><font style="font-family:Times New Roman;font-size:12pt;">over </font><font style="font-family:Times New Roman;font-size:12pt;">three</font><font style="font-family:Times New Roman;font-size:12pt;"> million residential</font><font style="font-family:Times New Roman;font-size:12pt;">, commercial, public-authority and industrial customers through our six regulated natural gas distribution divisions in the service areas described below:</font></p><p style='margin-top: 0pt; margin-bottom: 0pt;'></p><div><table style="border-collapse:collapse;margin-top:20px;"><tr style="height: 21px"><td style="width: 287px; border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:287px;"><font style="FONT-WEIGHT: bold;FONT-FAMILY: Times New Roman;FONT-SIZE: 12pt;COLOR: #000000;TEXT-ALIGN: center;">Division</font></td><td style="width: 14px; text-align:left;border-color:#000000;min-width:14px;"> </td><td style="width: 278px; border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:278px;"><font style="FONT-WEIGHT: bold;FONT-FAMILY: Times New Roman;FONT-SIZE: 12pt;COLOR: #000000;TEXT-ALIGN: center;">Service Area</font></td></tr><tr style="height: 21px"><td style="width: 287px; border-top-style:solid;border-top-width:1px;text-align:left;border-color:#000000;min-width:287px;"><font style="FONT-FAMILY: Times New Roman;FONT-SIZE: 12pt;COLOR: #000000;">Atmos Energy Colorado-Kansas Division</font></td><td style="width: 14px; text-align:left;border-color:#000000;min-width:14px;"> </td><td style="width: 278px; border-top-style:solid;border-top-width:1px;text-align:left;border-color:#000000;min-width:278px;"><font style="FONT-FAMILY: Times New Roman;FONT-SIZE: 12pt;COLOR: #000000;TEXT-ALIGN: left;">Colorado, Kansas</font></td></tr><tr style="height: 42px"><td style="width: 287px; text-align:left;border-color:#000000;min-width:287px;"><font style="FONT-FAMILY: Times New Roman;FONT-SIZE: 12pt;COLOR: #000000;">Atmos Energy Kentucky/Mid-States Division</font></td><td style="width: 14px; text-align:left;border-color:#000000;min-width:14px;"> </td><td style="width: 278px; text-align:left;border-color:#000000;min-width:278px;"><font style="FONT-FAMILY: Times New Roman;FONT-SIZE: 12pt;COLOR: #000000;TEXT-ALIGN: left;">Georgia(1), Kentucky, Tennessee, Virginia(1)</font></td></tr><tr style="height: 21px"><td style="width: 287px; text-align:left;border-color:#000000;min-width:287px;"><font style="FONT-FAMILY: Times New Roman;FONT-SIZE: 12pt;COLOR: #000000;">Atmos Energy Louisiana Division</font></td><td style="width: 14px; text-align:left;border-color:#000000;min-width:14px;"> </td><td style="width: 278px; text-align:left;border-color:#000000;min-width:278px;"><font style="FONT-FAMILY: Times New Roman;FONT-SIZE: 12pt;COLOR: #000000;TEXT-ALIGN: left;">Louisiana</font></td></tr><tr style="height: 42px"><td style="width: 287px; text-align:left;border-color:#000000;min-width:287px;"><font style="FONT-FAMILY: Times New Roman;FONT-SIZE: 12pt;COLOR: #000000;">Atmos Energy Mid-Tex Division </font></td><td style="width: 14px; text-align:left;border-color:#000000;min-width:14px;"> </td><td style="width: 278px; text-align:left;border-color:#000000;min-width:278px;"><font style="FONT-FAMILY: Times New Roman;FONT-SIZE: 12pt;COLOR: #000000;TEXT-ALIGN: left;">Texas, including the Dallas/Fort Worth metropolitan area</font></td></tr><tr style="height: 21px"><td style="width: 287px; text-align:left;border-color:#000000;min-width:287px;"><font style="FONT-FAMILY: Times New Roman;FONT-SIZE: 12pt;COLOR: #000000;">Atmos Energy Mississippi Division </font></td><td style="width: 14px; text-align:left;border-color:#000000;min-width:14px;"> </td><td style="width: 278px; text-align:left;border-color:#000000;min-width:278px;"><font style="FONT-FAMILY: Times New Roman;FONT-SIZE: 12pt;COLOR: #000000;TEXT-ALIGN: left;">Mississippi</font></td></tr><tr style="height: 21px"><td style="width: 287px; text-align:left;border-color:#000000;min-width:287px;"><font style="FONT-FAMILY: Times New Roman;FONT-SIZE: 12pt;COLOR: #000000;">Atmos Energy West Texas Division</font></td><td style="width: 14px; text-align:left;border-color:#000000;min-width:14px;"> </td><td style="width: 278px; text-align:left;border-color:#000000;min-width:278px;"><font style="FONT-FAMILY: Times New Roman;FONT-SIZE: 12pt;COLOR: #000000;TEXT-ALIGN: left;">West Texas</font></td></tr></table></div><p style='margin-top: 0pt; margin-bottom: 0pt;'></p><p style='margin-top:12pt; margin-bottom:0pt'><font style="font-family:Times New Roman;font-size:12pt;margin-left:0px;">(1)</font><font style="font-family:Times New Roman;font-size:10pt;"> </font><font style="font-family:Times New Roman;font-size:10pt;">Denotes locations where we have more limited service areas.</font></p><p style='margin-top:0pt; margin-bottom:0pt'> </p><p style='margin-top:0pt; margin-bottom:0pt'><font style="font-family:Times New Roman;font-size:12pt;margin-left:0px;">In addition, we transport natural gas for others through our distribution system. Our natural gas distribution business is subject to federal and state regulation and/or regulation by local authorities in each of the states in which our natural gas distribution divisions operate. Our corporate headquarters and shared-services function are located in </font><font style="font-family:Times New Roman;font-size:12pt;">Dallas</font><font style="font-family:Times New Roman;font-size:12pt;">, </font><font style="font-family:Times New Roman;font-size:12pt;">Texas</font><font style="font-family:Times New Roman;font-size:12pt;">, and our customer support centers are located in </font><font style="font-family:Times New Roman;font-size:12pt;">Amarillo</font><font style="font-family:Times New Roman;font-size:12pt;"> and </font><font style="font-family:Times New Roman;font-size:12pt;">Waco</font><font style="font-family:Times New Roman;font-size:12pt;">, </font><font style="font-family:Times New Roman;font-size:12pt;">Texas</font><font style="font-family:Times New Roman;font-size:12pt;">.</font></p><p style='margin-top:0pt; margin-bottom:0pt'> </p><p style='margin-top:0pt; margin-bottom:0pt'><font style="font-family:Times New Roman;font-size:12pt;margin-left:0px;">On August 1, 2012, we completed the divesture of our natural gas distribution</font><font style="font-family:Times New Roman;font-size:12pt;"> </font><font style="font-family:Times New Roman;font-size:12pt;">operations in Missouri, Illinois and Iowa, representing approximately 84,000 customers. </font><font style="font-family:Times New Roman;font-size:12pt;">On August 8, 2012, we entered into a definitive agreement to sell our natural gas distribution operations in Georgia, representing approximately 64,000 customers. </font><font style="font-family:Times New Roman;font-size:12pt;">The results of these operations have been separately reported as discontinued operations</font><font style="font-family:Times New Roman;font-size:12pt;">. </font><font style="font-family:Times New Roman;font-size:12pt;"> </font></p><p style='margin-top:0pt; margin-bottom:0pt'> </p><p style='margin-top:0pt; margin-bottom:0pt'><font style="font-family:Times New Roman;font-size:12pt;margin-left:0px;">Our regulated transmission and storage business consists of </font><font style="font-family:Times New Roman;font-size:12pt;">the regulated operations of our Atmos Pipeline–Texas Division, a division of the Company</font><font style="font-family:Times New Roman;font-size:12pt;">. This division transports natural gas to our Mid-Tex Division, transports natural gas for third parties and manages </font><font style="font-family:Times New Roman;font-size:12pt;">five u</font><font style="font-family:Times New Roman;font-size:12pt;">nderground storage reservoirs in </font><font style="font-family:Times New Roman;font-size:12pt;">Texas</font><font style="font-family:Times New Roman;font-size:12pt;">. We also provide ancillary services customary to the pipeline industry including parking arrangements, lending and sales of inventory on hand. Parking arrangements provide short-term interruptible storage of gas on our pipeline. Lending services provide short-term interruptible loans of natural gas from our pipeline to meet market demands.</font></p><p style='margin-top:0pt; margin-bottom:0pt'> </p><p style='margin-top:0pt; margin-bottom:0pt'><font style="font-family:Times New Roman;font-size:12pt;margin-left:0px;">Our nonregulated businesses operate primarily in the </font><font style="font-family:Times New Roman;font-size:12pt;">Midwest</font><font style="font-family:Times New Roman;font-size:12pt;"> and Southeast through various wholly-owned subsidiaries of Atmos Energy Holdings, Inc</font><font style="font-family:Times New Roman;font-size:12pt;">.</font><font style="font-family:Times New Roman;font-size:12pt;">, (AEH). AEH is wholly owned by the Company and based in </font><font style="font-family:Times New Roman;font-size:12pt;">Houston</font><font style="font-family:Times New Roman;font-size:12pt;">, </font><font style="font-family:Times New Roman;font-size:12pt;">Texas</font><font style="font-family:Times New Roman;font-size:12pt;">. Through AEH, we provide natural gas management and transportation services to municipalities, natural gas distribution companies, including certain divisions of </font><font style="font-family:Times New Roman;font-size:12pt;">Atmos Energy and third parties</font><font style="font-family:Times New Roman;font-size:12pt;">.</font></p>
CY2012	ato	Schedule Of Divisions And Service Areas ScheduleOfDivisionsAndServiceAreas	<div><table style="border-collapse:collapse;margin-top:20px;"><tr style="height: 21px"><td style="width: 287px; border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:287px;"><font style="FONT-WEIGHT: bold;FONT-FAMILY: Times New Roman;FONT-SIZE: 12pt;COLOR: #000000;TEXT-ALIGN: center;">Division</font></td><td style="width: 14px; text-align:left;border-color:#000000;min-width:14px;"> </td><td style="width: 278px; border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:278px;"><font style="FONT-WEIGHT: bold;FONT-FAMILY: Times New Roman;FONT-SIZE: 12pt;COLOR: #000000;TEXT-ALIGN: center;">Service Area</font></td></tr><tr style="height: 21px"><td style="width: 287px; border-top-style:solid;border-top-width:1px;text-align:left;border-color:#000000;min-width:287px;"><font style="FONT-FAMILY: Times New Roman;FONT-SIZE: 12pt;COLOR: #000000;">Atmos Energy Colorado-Kansas Division</font></td><td style="width: 14px; text-align:left;border-color:#000000;min-width:14px;"> </td><td style="width: 278px; border-top-style:solid;border-top-width:1px;text-align:left;border-color:#000000;min-width:278px;"><font style="FONT-FAMILY: Times New Roman;FONT-SIZE: 12pt;COLOR: #000000;TEXT-ALIGN: left;">Colorado, Kansas</font></td></tr><tr style="height: 42px"><td style="width: 287px; text-align:left;border-color:#000000;min-width:287px;"><font style="FONT-FAMILY: Times New Roman;FONT-SIZE: 12pt;COLOR: #000000;">Atmos Energy Kentucky/Mid-States Division</font></td><td style="width: 14px; text-align:left;border-color:#000000;min-width:14px;"> </td><td style="width: 278px; text-align:left;border-color:#000000;min-width:278px;"><font style="FONT-FAMILY: Times New Roman;FONT-SIZE: 12pt;COLOR: #000000;TEXT-ALIGN: left;">Georgia(1), Kentucky, Tennessee, Virginia(1)</font></td></tr><tr style="height: 21px"><td style="width: 287px; text-align:left;border-color:#000000;min-width:287px;"><font style="FONT-FAMILY: Times New Roman;FONT-SIZE: 12pt;COLOR: #000000;">Atmos Energy Louisiana Division</font></td><td style="width: 14px; text-align:left;border-color:#000000;min-width:14px;"> </td><td style="width: 278px; text-align:left;border-color:#000000;min-width:278px;"><font style="FONT-FAMILY: Times New Roman;FONT-SIZE: 12pt;COLOR: #000000;TEXT-ALIGN: left;">Louisiana</font></td></tr><tr style="height: 42px"><td style="width: 287px; text-align:left;border-color:#000000;min-width:287px;"><font style="FONT-FAMILY: Times New Roman;FONT-SIZE: 12pt;COLOR: #000000;">Atmos Energy Mid-Tex Division </font></td><td style="width: 14px; text-align:left;border-color:#000000;min-width:14px;"> </td><td style="width: 278px; text-align:left;border-color:#000000;min-width:278px;"><font style="FONT-FAMILY: Times New Roman;FONT-SIZE: 12pt;COLOR: #000000;TEXT-ALIGN: left;">Texas, including the Dallas/Fort Worth metropolitan area</font></td></tr><tr style="height: 21px"><td style="width: 287px; text-align:left;border-color:#000000;min-width:287px;"><font style="FONT-FAMILY: Times New Roman;FONT-SIZE: 12pt;COLOR: #000000;">Atmos Energy Mississippi Division </font></td><td style="width: 14px; text-align:left;border-color:#000000;min-width:14px;"> </td><td style="width: 278px; text-align:left;border-color:#000000;min-width:278px;"><font style="FONT-FAMILY: Times New Roman;FONT-SIZE: 12pt;COLOR: #000000;TEXT-ALIGN: left;">Mississippi</font></td></tr><tr style="height: 21px"><td style="width: 287px; text-align:left;border-color:#000000;min-width:287px;"><font style="FONT-FAMILY: Times New Roman;FONT-SIZE: 12pt;COLOR: #000000;">Atmos Energy West Texas Division</font></td><td style="width: 14px; text-align:left;border-color:#000000;min-width:14px;"> </td><td style="width: 278px; text-align:left;border-color:#000000;min-width:278px;"><font style="FONT-FAMILY: Times New Roman;FONT-SIZE: 12pt;COLOR: #000000;TEXT-ALIGN: left;">West Texas</font></td></tr></table></div>
CY2012	us-gaap	Use Of Estimates UseOfEstimates	<p style='margin-top:0pt; margin-bottom:0pt'><font style="font-family:Times New Roman;font-size:12pt;font-weight:bold;font-style:italic;margin-left:0px;">Use of estimates</font><font style="font-family:Times New Roman;font-size:12pt;"> — The preparation of financial statements in conformity with accounting principles generally accepted in the </font><font style="font-family:Times New Roman;font-size:12pt;">United States</font><font style="font-family:Times New Roman;font-size:12pt;"> requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses. The most significant estimates include the allowance for doubtful accounts, </font><font style="font-family:Times New Roman;font-size:12pt;">unbilled revenues, </font><font style="font-family:Times New Roman;font-size:12pt;">legal and environmental accruals, insurance accruals, pension and postretirement obligations, deferred income taxes, asset retirement obligations, impairment of long-lived assets, risk management and trading activities, fair value measurements and the valuation of goodwill, indefinite-lived intangible assets and other long-lived assets. Actual results could differ from those estimates.</font></p>
CY2012	us-gaap	Unrealized Gain Loss On Price Risk Fair Value Hedging Instruments UnrealizedGainLossOnPriceRiskFairValueHedgingInstruments	-8000000	USD
CY2012	us-gaap	Derivatives Reporting Of Derivative Activity DerivativesReportingOfDerivativeActivity	<p style='margin-top:0pt; margin-bottom:0pt'><font style="font-family:Times New Roman;font-size:12pt;font-weight:bold;font-style:italic;margin-left:0px;">Financial instruments and hedging activities</font><font style="font-family:Times New Roman;font-size:12pt;"> — We use financial instruments to mitigate commodity price risk</font><font style="font-family:Times New Roman;font-size:12pt;"> in our natural gas distribution and nonregulated segments and interest rate risk</font><font style="font-family:Times New Roman;font-size:12pt;">. The objectives and strategies for using financial in</font><font style="font-family:Times New Roman;font-size:12pt;">struments have been tailored to</font><font style="font-family:Times New Roman;font-size:12pt;"> our regulated and nonregulated businesses</font><font style="font-family:Times New Roman;font-size:12pt;"> and </font><font style="font-family:Times New Roman;font-size:12pt;">are discussed in Note 4.</font></p><p style='margin-top:0pt; margin-bottom:0pt'> </p><p style='margin-top:0pt; margin-bottom:0pt'><font style="font-family:Times New Roman;font-size:12pt;margin-left:0px;">We record all of our financial instruments on the balance sheet at fair value</font><font style="font-family:Times New Roman;font-size:12pt;font-style:italic;">, </font><font style="font-family:Times New Roman;font-size:12pt;">with changes in fair value ultimately recorded in the income statement. These financial instruments are reported as risk management assets and liabilities and are classified as current or noncurrent other assets or liabilities based upon the anticipated settlement date of the underlying financial instrument. </font></p><p style='margin-top:0pt; margin-bottom:0pt'> </p><p style='margin-top:0pt; margin-bottom:0pt'><font style="font-family:Times New Roman;font-size:12pt;margin-left:0px;">The timing of when changes in fair value of our financial instruments are recorded in the income statement depends on whether the financial instrument has been designated and qualifies as a part of a hedging relationship or if regulatory rulings require a different accounting treatment. Changes in fair value for financial instruments that do not meet one of these criteria are recognized in the income statement as they occur.</font></p><p style='margin-top:0pt; margin-bottom:0pt'> </p><p style='margin-top:0pt; margin-bottom:0pt'><font style="font-family:Times New Roman;font-size:12pt;font-style:italic;margin-left:0px;">Financial Instruments Associated with Commodity Price Risk</font></p><p style='margin-top:0pt; margin-bottom:0pt'> </p><p style='margin-top:0pt; margin-bottom:0pt'><font style="font-family:Times New Roman;font-size:12pt;margin-left:0px;">In our natural gas distribution segment, </font><font style="font-family:Times New Roman;font-size:12pt;">the costs associated with and the gains and losses arising from the use of financial instruments to mitigate commodity price risk are included in our purchased gas cost adjustment mechanisms in accordance with regulatory requirements. Therefore, changes in the fair value of these financial instruments are initially recorded as a component of deferred gas costs and recognized in the consolidated statement of income as a component of purchased gas cost when the related costs are recovered through our rates and recognized in revenue in accordance with accounting principles generally accepted in the </font><font style="font-family:Times New Roman;font-size:12pt;">United States</font><font style="font-family:Times New Roman;font-size:12pt;">. Accordingly</font><font style="font-family:Times New Roman;font-size:12pt;">, there is no earnings impact on</font><font style="font-family:Times New Roman;font-size:12pt;"> our natural gas distribution segment as a result of the use of financial instruments. </font></p><p style='margin-top:0pt; margin-bottom:0pt'> </p><p style='margin-top:0pt; margin-bottom:0pt'><font style="font-family:Times New Roman;font-size:12pt;margin-left:0px;">In our </font><font style="font-family:Times New Roman;font-size:12pt;">nonregulated </font><font style="font-family:Times New Roman;font-size:12pt;">segment, w</font><font style="font-family:Times New Roman;font-size:12pt;">e have designated </font><font style="font-family:Times New Roman;font-size:12pt;">most of </font><font style="font-family:Times New Roman;font-size:12pt;">the n</font><font style="font-family:Times New Roman;font-size:12pt;">atural gas inventory held by this operating segment</font><font style="font-family:Times New Roman;font-size:12pt;"> as </font><font style="font-family:Times New Roman;font-size:12pt;">the hedged item in a fair-value hedge. This inventory is marked to market at the end of each month based on the Gas Daily index, with changes in fair value recognized as unrealized gains or losses in revenue in the period of change. The financial instruments associated with this natural gas inventory have been designated as fair-value hedges and are marked to market each month based upon the NYMEX price with changes in fair value recognized as unrealized gains or losses in revenue in the period of change. C</font><font style="font-family:Times New Roman;font-size:12pt;">hanges in the </font><font style="font-family:Times New Roman;font-size:12pt;">spreads between the forward natural gas prices used to value the financial hedges designated against our physical inventory (NYMEX) and the market (spot) prices used to value our physical storage</font><font style="font-family:Times New Roman;font-size:12pt;"> (Gas Daily) result in unrealized margins until the underlying physical gas is withdrawn and the related financial instruments are settled. Once the gas is withdrawn and the financial instruments are settled, the previously unrealized margins associated with these net positions are realized. </font><font style="font-family:Times New Roman;font-size:12pt;">We have elected to exclude this spot/forward differential for purposes of assessing the effectiveness of these fair-value hedges. Over time, we expect gains and losses on the sale of storage gas inventory to be offset by gains and losses on the fair-value hedges, resulting in the realization of the economic gross profit margin we anticipated at the time we structured the original transaction.</font></p><p style='margin-top:0pt; margin-bottom:0pt'> </p><p style='margin-top:0pt; margin-bottom:0pt'><font style="font-family:Times New Roman;font-size:12pt;margin-left:0px;">Additionally, </font><font style="font-family:Times New Roman;font-size:12pt;">w</font><font style="font-family:Times New Roman;font-size:12pt;">e have elected to treat fixed-price forward contracts</font><font style="font-family:Times New Roman;font-size:12pt;"> used in our nonregulated segment</font><font style="font-family:Times New Roman;font-size:12pt;"> to deliver natural gas as normal purchases and normal sales. As such, these deliveries are recorded on an accrual basis in accordance with our revenue recognition policy. Financial instruments used to mitigate the commodity price risk associated with these contracts have been designated as cash flow hedges of anticipated purchases and sales at indexed prices. Accordingly, unrealized gains and losses on these open financial instruments are recorded as a component of accumulated other comprehensive income, and are recognized in earnings as a component of revenue when the hedged volumes are sold. </font></p><p style='margin-top:0pt; margin-bottom:0pt'> </p><p style='margin-top:0pt; margin-bottom:0pt'><font style="font-family:Times New Roman;font-size:12pt;margin-left:0px;">Gains and losses from hedge ineffectiveness are recognized in the income statement. Fair value and cash flow hedge ineffectiveness arising from natural gas market price differences between the locations of the hedged inventory and the delivery location specified in the financial instruments is referred to as basis ineffectiveness. Ineffectiveness arising from changes in the fair value of the fair value hedges due to changes in the difference between the spot price and the futures price, as well as the difference between the timing of the settlement of the futures and the valuation of the underlying physical commodity </font><font style="font-family:Times New Roman;font-size:12pt;">is </font><font style="font-family:Times New Roman;font-size:12pt;">referred to as timing ineffectiveness. </font><font style="font-family:Times New Roman;font-size:12pt;">Hedge ineffectiveness, to the extent incurred, is reported as a component of revenue.</font></p><p style='margin-top:0pt; margin-bottom:0pt'> </p><p style='margin-top:0pt; margin-bottom:0pt'><font style="font-family:Times New Roman;font-size:12pt;margin-left:0px;">O</font><font style="font-family:Times New Roman;font-size:12pt;">ur </font><font style="font-family:Times New Roman;font-size:12pt;">nonregulated </font><font style="font-family:Times New Roman;font-size:12pt;">segment</font><font style="font-family:Times New Roman;font-size:12pt;"> </font><font style="font-family:Times New Roman;font-size:12pt;">also utilize</font><font style="font-family:Times New Roman;font-size:12pt;">s</font><font style="font-family:Times New Roman;font-size:12pt;"> master netting agreements with significant counterparties that allow us to offset gains and losses arising from financial instruments that may be settled in cash with gains and losses arising from financial instruments that may be settled with the physical commodity. Assets and liabilities from risk management activities, as well as accounts receivable and payable, reflect the master netting agreements in place. Additionally, the accounting guidance for master netting arrangements requires us to i</font><font style="font-family:Times New Roman;font-size:12pt;">nclude the fair value of cash collateral or the obligation to return cash in the amounts that have been netted under master netting agreements used to offset gains and losses arising from financial instruments. As of </font><font style="font-family:Times New Roman;font-size:12pt;">September 30, 2012</font><font style="font-family:Times New Roman;font-size:12pt;"> and 2011</font><font style="font-family:Times New Roman;font-size:12pt;">,</font><font style="font-family:Times New Roman;font-size:12pt;"> the Company netted $</font><font style="font-family:Times New Roman;font-size:12pt;">23.7</font><font style="font-family:Times New Roman;font-size:12pt;"> million and $</font><font style="font-family:Times New Roman;font-size:12pt;">28.8</font><font style="font-family:Times New Roman;font-size:12pt;"> million of cash held in margin accounts into its current risk mana</font><font style="font-family:Times New Roman;font-size:12pt;">gement assets and liabilities.</font></p><p style='margin-top:0pt; margin-bottom:0pt'> </p><p style='margin-top:0pt; margin-bottom:0pt'><font style="font-family:Times New Roman;font-size:12pt;font-style:italic;margin-left:0px;">Financial Instruments Associated with Interest Rate Risk</font></p><p style='margin-top:0pt; margin-bottom:0pt'> </p><p style='margin-top:0pt; margin-bottom:0pt'><font style="font-family:Times New Roman;font-size:12pt;margin-left:0px;">We manage interest rate risk, typically when we</font><font style="font-family:Times New Roman;font-size:12pt;"> plan to </font><font style="font-family:Times New Roman;font-size:12pt;">issue new </font><font style="font-family:Times New Roman;font-size:12pt;">long-term debt </font><font style="font-family:Times New Roman;font-size:12pt;">or </font><font style="font-family:Times New Roman;font-size:12pt;">to </font><font style="font-family:Times New Roman;font-size:12pt;">refinance existing long-term debt. </font><font style="font-family:Times New Roman;font-size:12pt;">Prior to fiscal 2012</font><font style="font-family:Times New Roman;font-size:12pt;">, we entered into Treasury lock agreements to fix the Treasury yield component of the interest cost associated with anticipated financings. </font><font style="font-family:Times New Roman;font-size:12pt;">We designated these Treasury lock agreements as cash flow hedge</font><font style="font-family:Times New Roman;font-size:12pt;">s</font><font style="font-family:Times New Roman;font-size:12pt;"> at the time the agreements were executed. Accordingly, unrealized gains and losses associated with the Treasury</font><font style="font-family:Times New Roman;font-size:12pt;"> lo</font><font style="font-family:Times New Roman;font-size:12pt;">ck agreements were </font><font style="font-family:Times New Roman;font-size:12pt;">recorded as a component of accumulated other comprehensive income (loss). When the Treasury locks </font><font style="font-family:Times New Roman;font-size:12pt;">were </font><font style="font-family:Times New Roman;font-size:12pt;">settle</font><font style="font-family:Times New Roman;font-size:12pt;">d</font><font style="font-family:Times New Roman;font-size:12pt;">, the realized gain or loss </font><font style="font-family:Times New Roman;font-size:12pt;">was</font><font style="font-family:Times New Roman;font-size:12pt;"> recorded as a component of accumulated other comprehensive income (loss) and </font><font style="font-family:Times New Roman;font-size:12pt;">is being</font><font style="font-family:Times New Roman;font-size:12pt;"> recognized as a component of interest expense over the life of the related financing arrangement.</font></p><p style='margin-top: 0pt; margin-bottom: 0pt;'></p><p style='margin-top:12pt; margin-bottom:0pt'><font style="font-family:Times New Roman;font-size:12pt;margin-left:0px;">During fiscal 2012, we began using interest rate swaps to mitigate interest rate risk. We entered into an interest rate swap </font><font style="font-family:Times New Roman;font-size:12pt;">a</font><font style="font-family:Times New Roman;font-size:12pt;">ssociated with </font><font style="font-family:Times New Roman;font-size:12pt;">our</font><font style="font-family:Times New Roman;font-size:12pt;"> $260 million short-term </font><font style="font-family:Times New Roman;font-size:12pt;">financing facility</font><font style="font-family:Times New Roman;font-size:12pt;"> through December </font><font style="font-family:Times New Roman;font-size:12pt;">27, </font><font style="font-family:Times New Roman;font-size:12pt;">2012</font><font style="font-family:Times New Roman;font-size:12pt;">.</font><font style="font-family:Times New Roman;font-size:12pt;"> Due to the short-term nature of the swap and</font><font style="font-family:Times New Roman;font-size:12pt;"> the related financing facility</font><font style="font-family:Times New Roman;font-size:12pt;">,</font><font style="font-family:Times New Roman;font-size:12pt;"> we did not designate the interest rate swap as a hedge.</font><font style="font-family:Times New Roman;font-size:12pt;"> </font><font style="font-family:Times New Roman;font-size:12pt;">Gains and losses associated with the swap </font><font style="font-family:Times New Roman;font-size:12pt;">are</font><font style="font-family:Times New Roman;font-size:12pt;"> reported as a component of interest expense.</font><font style="font-family:Times New Roman;font-size:12pt;"> </font></p><p style='margin-top:0pt; margin-bottom:0pt'> </p><p style='margin-top:0pt; margin-bottom:0pt'><font style="font-family:Times New Roman;font-size:12pt;margin-left:0px;">Additionally, in October 2</font><font style="font-family:Times New Roman;font-size:12pt;">012, we entered into </font><font style="font-family:Times New Roman;font-size:12pt;">forward starting interest rate swaps to </font><font style="font-family:Times New Roman;font-size:12pt;">fix the Treasury yield component</font><font style="font-family:Times New Roman;font-size:12pt;"> associated with the anticipated issuance of </font><font style="font-family:Times New Roman;font-size:12pt;">$500 million and $250 million </font><font style="font-family:Times New Roman;font-size:12pt;">unsecured senior notes</font><font style="font-family:Times New Roman;font-size:12pt;"> in fiscal 201</font><font style="font-family:Times New Roman;font-size:12pt;">5</font><font style="font-family:Times New Roman;font-size:12pt;"> and fiscal 2017, which we designated as cash flow hedges at the time the agreements were executed. </font><font style="font-family:Times New Roman;font-size:12pt;">U</font><font style="font-family:Times New Roman;font-size:12pt;">nrealized gains and losses associated with the forward starting interest rate swaps will be recorded as a component of accumulated other comprehensive income (loss). When the forward starting interest rate swaps settle, the realized gain or loss will be recorded as a component of accumulated other comprehensive income (loss) and recognized as a component of interest expense over the life of the related financing arrangement. </font><font style="font-family:Times New Roman;font-size:12pt;">Hedge ineffectiveness to the extent incurred </font><font style="font-family:Times New Roman;font-size:12pt;">will be</font><font style="font-family:Times New Roman;font-size:12pt;"> reported as a component of interest expense.</font></p>
CY2012Q3	us-gaap	Asset Retirement Obligation AssetRetirementObligation	10500000	USD
CY2011Q3	us-gaap	Asset Retirement Obligation AssetRetirementObligation	14000000	USD
CY2012Q3	ato	Asset Retirement Costs In Property Plant And Equipment AssetRetirementCostsInPropertyPlantAndEquipment	4200000	USD
CY2011Q3	ato	Asset Retirement Costs In Property Plant And Equipment AssetRetirementCostsInPropertyPlantAndEquipment	5400000	USD
CY2010	us-gaap	Other Deferred Cost Amortization Expense OtherDeferredCostAmortizationExpense	400000	USD
CY2011	us-gaap	Unrealized Gain Loss On Price Risk Fair Value Hedging Instruments UnrealizedGainLossOnPriceRiskFairValueHedgingInstruments	-10400000	USD
CY2010	us-gaap	Unrealized Gain Loss On Price Risk Fair Value Hedging Instruments UnrealizedGainLossOnPriceRiskFairValueHedgingInstruments	-7800000	USD
CY2012	us-gaap	Interest Costs Capitalized InterestCostsCapitalized	2600000	USD
CY2012	us-gaap	Public Utilities Property Plant And Equipment Disclosure Of Composite Depreciation Rate For Plants In Service PublicUtilitiesPropertyPlantAndEquipmentDisclosureOfCompositeDepreciationRateForPlantsInService	0.036	pure
CY2011	us-gaap	Public Utilities Property Plant And Equipment Disclosure Of Composite Depreciation Rate For Plants In Service PublicUtilitiesPropertyPlantAndEquipmentDisclosureOfCompositeDepreciationRateForPlantsInService	0.036	pure
CY2010	us-gaap	Public Utilities Property Plant And Equipment Disclosure Of Composite Depreciation Rate For Plants In Service PublicUtilitiesPropertyPlantAndEquipmentDisclosureOfCompositeDepreciationRateForPlantsInService	0.035	pure
CY2011	us-gaap	Other Deferred Cost Amortization Expense OtherDeferredCostAmortizationExpense	500000	USD
CY2012	us-gaap	Other Deferred Cost Amortization Expense OtherDeferredCostAmortizationExpense	500000	USD
CY2011	us-gaap	Interest Costs Capitalized InterestCostsCapitalized	1700000	USD
CY2010	us-gaap	Interest Costs Capitalized InterestCostsCapitalized	3900000	USD
CY2012	us-gaap	Description Of Specific Regulatory Assets DescriptionOfSpecificRegulatoryAssets	During the prior fiscal year, the Railroad Commission of Texas’ Division of Public Safety issued a new rule requiring natural gas distribution companies to develop and implement a risk-based program for the renewal or replacement of distribution facilities, including steel service lines. The rule allows for the deferral of all expenses associated with capital expenditures incurred pursuant to this rule, including the recording of interest on the deferred expenses until the next rate proceeding (rate case or annual rate filing) at which time investment and costs would be recovered through base rates. As of September 30, 2012, we had deferred $5.4 million associated with the requirements of this rule. Effective January 1, 2012, the Texas Legislature amended its Gas Utility Regulatory Act (GURA) to permit natural gas utilities to defer into a regulatory asset or liability the difference between a gas utility’s actual pension and postretirement expense and the level of such expense recoverable in its existing rates.  The deferred amount will become eligible for inclusion in the utility’s rates in its next rate proceeding.  We elected to utilize this provision of GURA, effective January 1, 2012, and established a regulatory asset totaling $7.6 million, which is recorded in “Pension and postretirement benefit costs” in the regulatory assets table above. Of this amount, $4.2 million represented a reduction to operation and maintenance expense during fiscal 2012.
CY2012Q3	us-gaap	Accumulated Other Comprehensive Income Loss Available For Sale Securities Adjustment Net Of Tax AccumulatedOtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax	5661000	USD
CY2012Q3	ato	Accumulated Other Comprehensive Income Loss Cumulative Changes In Net Gain Loss From Interest Rate Hedges Effect Net Of Tax AccumulatedOtherComprehensiveIncomeLossCumulativeChangesInNetGainLossFromInterestRateHedgesEffectNetOfTax	-44273000	USD
CY2012Q3	us-gaap	Accumulated Other Comprehensive Income Loss Cumulative Changes In Net Gain Loss From Cash Flow Hedges Effect Net Of Tax AccumulatedOtherComprehensiveIncomeLossCumulativeChangesInNetGainLossFromCashFlowHedgesEffectNetOfTax	-8995000	USD
CY2011Q3	us-gaap	Accumulated Other Comprehensive Income Loss Available For Sale Securities Adjustment Net Of Tax AccumulatedOtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax	2558000	USD
CY2011Q3	ato	Accumulated Other Comprehensive Income Loss Cumulative Changes In Net Gain Loss From Interest Rate Hedges Effect Net Of Tax AccumulatedOtherComprehensiveIncomeLossCumulativeChangesInNetGainLossFromInterestRateHedgesEffectNetOfTax	-34157000	USD
CY2011Q3	us-gaap	Accumulated Other Comprehensive Income Loss Cumulative Changes In Net Gain Loss From Cash Flow Hedges Effect Net Of Tax AccumulatedOtherComprehensiveIncomeLossCumulativeChangesInNetGainLossFromCashFlowHedgesEffectNetOfTax	-16861000	USD
CY2012	us-gaap	Goodwill Other Changes GoodwillOtherChanges	683000	USD
CY2011	ato	Gain Loss On Treasury Lock Agreements Settlements Net Of Tax GainLossOnTreasuryLockAgreementsSettlementsNetOfTax	12600000	USD
CY2012	ato	Minimum Length Of Time Hedged In Cash Flow Hedge MinimumLengthOfTimeHedgedInCashFlowHedge	one
CY2012	us-gaap	Maximum Length Of Time Hedged In Cash Flow Hedge MaximumLengthOfTimeHedgedInCashFlowHedge	63 months
CY2012Q3	ato	Net Open Positions NetOpenPositions	0.4	Bcf
CY2012Q3	ato	Total Financial Instruments TotalFinancialInstruments	-91383000	USD
CY2012Q3	ato	Disposal Group Including Discontinued Operation Derivative Assets Current DisposalGroupIncludingDiscontinuedOperationDerivativeAssetsCurrent	100000	USD
CY2012Q3	ato	Disposal Group Including Discontinued Operation Derivative Liabilities Current DisposalGroupIncludingDiscontinuedOperationDerivativeLiabilitiesCurrent	300000	USD
CY2011Q3	ato	Total Financial Instruments TotalFinancialInstruments	-104327000	USD
CY2012	ato	Gain Loss On Hedge Ineffectiveness GainLossOnHedgeIneffectiveness	23100000	USD
CY2011	ato	Gain Loss On Hedge Ineffectiveness GainLossOnHedgeIneffectiveness	24800000	USD
CY2010	ato	Gain Loss On Hedge Ineffectiveness GainLossOnHedgeIneffectiveness	51800000	USD
CY2011Q3	ato	Disposal Group Including Discontinued Operation Derivative Liabilities Current DisposalGroupIncludingDiscontinuedOperationDerivativeLiabilitiesCurrent	1300000	USD
CY2012	us-gaap	Change In Unrealized Gain Loss On Fair Value Hedging Instruments ChangeInUnrealizedGainLossOnFairValueHedgingInstruments	-30266000	USD
CY2012	us-gaap	Change In Unrealized Gain Loss On Hedged Item In Fair Value Hedge ChangeInUnrealizedGainLossOnHedgedItemInFairValueHedge	5797000	USD
CY2012	us-gaap	Gain Loss On Fair Value Hedges Recognized In Earnings GainLossOnFairValueHedgesRecognizedInEarnings	24469000	USD
CY2012	ato	Fair Value Hedge Basis Ineffectiveness FairValueHedgeBasisIneffectiveness	1170000	USD
CY2012	ato	Fair Value Hedge Timing Ineffectiveness FairValueHedgeTimingIneffectiveness	23299000	USD
CY2011	us-gaap	Change In Unrealized Gain Loss On Fair Value Hedging Instruments ChangeInUnrealizedGainLossOnFairValueHedgingInstruments	-16552000	USD
CY2011	us-gaap	Change In Unrealized Gain Loss On Hedged Item In Fair Value Hedge ChangeInUnrealizedGainLossOnHedgedItemInFairValueHedge	-9824000	USD
CY2011	us-gaap	Gain Loss On Fair Value Hedges Recognized In Earnings GainLossOnFairValueHedgesRecognizedInEarnings	26376000	USD
CY2011	ato	Fair Value Hedge Basis Ineffectiveness FairValueHedgeBasisIneffectiveness	803000	USD
CY2011	ato	Fair Value Hedge Timing Ineffectiveness FairValueHedgeTimingIneffectiveness	25573000	USD
CY2010	us-gaap	Change In Unrealized Gain Loss On Fair Value Hedging Instruments ChangeInUnrealizedGainLossOnFairValueHedgingInstruments	-34650000	USD
CY2010	us-gaap	Change In Unrealized Gain Loss On Hedged Item In Fair Value Hedge ChangeInUnrealizedGainLossOnHedgedItemInFairValueHedge	-19867000	USD
CY2010	us-gaap	Gain Loss On Fair Value Hedges Recognized In Earnings GainLossOnFairValueHedgesRecognizedInEarnings	54517000	USD
CY2010	ato	Fair Value Hedge Basis Ineffectiveness FairValueHedgeBasisIneffectiveness	-1272000	USD
CY2010	ato	Fair Value Hedge Timing Ineffectiveness FairValueHedgeTimingIneffectiveness	55789000	USD
CY2012	us-gaap	Cash Flow Hedge Gain Loss Reclassified To Cost Of Sales Net CashFlowHedgeGainLossReclassifiedToCostOfSalesNet	-62678000	USD
CY2012	us-gaap	Gain Loss On Cash Flow Hedge Ineffectiveness Net GainLossOnCashFlowHedgeIneffectivenessNet	-1369000	USD
CY2012	ato	Cash Flow Hedge Gain Loss Included In Revenue Net CashFlowHedgeGainLossIncludedInRevenueNet	-64047000	USD
CY2012	us-gaap	Cash Flow Hedge Gain Loss Reclassified To Interest Expense Net CashFlowHedgeGainLossReclassifiedToInterestExpenseNet	-2009000	USD
CY2012	us-gaap	Cash Flow Hedge Gain Loss Reclassified To Earnings Net CashFlowHedgeGainLossReclassifiedToEarningsNet	-66056000	USD
CY2011	us-gaap	Cash Flow Hedge Gain Loss Reclassified To Cost Of Sales Net CashFlowHedgeGainLossReclassifiedToCostOfSalesNet	-28430000	USD
CY2011	us-gaap	Gain Loss On Cash Flow Hedge Ineffectiveness Net GainLossOnCashFlowHedgeIneffectivenessNet	-1585000	USD
CY2011	ato	Cash Flow Hedge Gain Loss Included In Revenue Net CashFlowHedgeGainLossIncludedInRevenueNet	-30015000	USD
CY2011	us-gaap	Cash Flow Hedge Gain Loss Reclassified To Interest Expense Net CashFlowHedgeGainLossReclassifiedToInterestExpenseNet	-2455000	USD
CY2011	ato	Gain On Unwinding Of Treasury Lock Reclassified From Accumulated Oci To Miscellaneous Income GainOnUnwindingOfTreasuryLockReclassifiedFromAccumulatedOciToMiscellaneousIncome	27803000	USD
CY2011	us-gaap	Cash Flow Hedge Gain Loss Reclassified To Earnings Net CashFlowHedgeGainLossReclassifiedToEarningsNet	-4667000	USD
CY2010	us-gaap	Cash Flow Hedge Gain Loss Reclassified To Cost Of Sales Net CashFlowHedgeGainLossReclassifiedToCostOfSalesNet	-44809000	USD
CY2012	us-gaap	Inventory Write Down InventoryWriteDown	1700000	USD
CY2010	us-gaap	Gain Loss On Cash Flow Hedge Ineffectiveness Net GainLossOnCashFlowHedgeIneffectivenessNet	-2717000	USD
CY2010	ato	Cash Flow Hedge Gain Loss Included In Revenue Net CashFlowHedgeGainLossIncludedInRevenueNet	-47526000	USD
CY2010	us-gaap	Cash Flow Hedge Gain Loss Reclassified To Interest Expense Net CashFlowHedgeGainLossReclassifiedToInterestExpenseNet	-2678000	USD
CY2010	us-gaap	Cash Flow Hedge Gain Loss Reclassified To Earnings Net CashFlowHedgeGainLossReclassifiedToEarningsNet	-50204000	USD
CY2012	ato	Other Comprehensive Income Unrealized Gain Loss On Treasury Locks Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedGainLossOnTreasuryLocksArisingDuringPeriodNetOfTax	-11458000	USD
CY2011	ato	Other Comprehensive Income Unrealized Gain Loss On Treasury Locks Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedGainLossOnTreasuryLocksArisingDuringPeriodNetOfTax	-12720000	USD
CY2012	ato	Other Comprehensive Income Unrealized Gain Loss On Forward Commodity Contracts Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedGainLossOnForwardCommodityContractsArisingDuringPeriodNetOfTax	-30366000	USD
CY2011	ato	Other Comprehensive Income Unrealized Gain Loss On Forward Commodity Contracts Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedGainLossOnForwardCommodityContractsArisingDuringPeriodNetOfTax	-12096000	USD
CY2012	ato	Other Comprehensive Income Reclassification Adjustment On Treasury Locks Included In Net Income Net Of Tax OtherComprehensiveIncomeReclassificationAdjustmentOnTreasuryLocksIncludedInNetIncomeNetOfTax	1342000	USD
CY2011	ato	Other Comprehensive Income Reclassification Adjustment On Treasury Locks Included In Net Income Net Of Tax OtherComprehensiveIncomeReclassificationAdjustmentOnTreasuryLocksIncludedInNetIncomeNetOfTax	-15969000	USD
CY2012	ato	Other Comprehensive Income Reclassification Adjustment On Forward Commodity Contracts Included In Net Income Net Of Tax OtherComprehensiveIncomeReclassificationAdjustmentOnForwardCommodityContractsIncludedInNetIncomeNetOfTax	38232000	USD
CY2011	ato	Other Comprehensive Income Reclassification Adjustment On Forward Commodity Contracts Included In Net Income Net Of Tax OtherComprehensiveIncomeReclassificationAdjustmentOnForwardCommodityContractsIncludedInNetIncomeNetOfTax	17344000	USD
CY2012	us-gaap	Other Comprehensive Income Derivatives Qualifying As Hedges Net Of Tax Period Increase Decrease OtherComprehensiveIncomeDerivativesQualifyingAsHedgesNetOfTaxPeriodIncreaseDecrease	-2250000	USD
CY2011	us-gaap	Other Comprehensive Income Derivatives Qualifying As Hedges Net Of Tax Period Increase Decrease OtherComprehensiveIncomeDerivativesQualifyingAsHedgesNetOfTaxPeriodIncreaseDecrease	-23441000	USD
CY2012	ato	Regulated Segments Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate RegulatedSegmentsEffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.37	pure
CY2012	ato	Nonregulated Segment Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate NonregulatedSegmentEffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.39	pure
CY2012	ato	Treasury Lock Gain Loss Reclassified To Earnings TreasuryLockGainLossReclassifiedToEarnings	9727000	USD
CY2012	ato	Commodity Contract Gain Loss Reclassified To Earnings CommodityContractGainLossReclassifiedToEarnings	-8995000	USD
CY2012	ato	Total Hedge Gain Loss Reclassified To Earnings TotalHedgeGainLossReclassifiedToEarnings	732000	USD
CY2012	ato	Gain Loss On Derivative Instruments Not Designated Hedges Net Pretax GainLossOnDerivativeInstrumentsNotDesignatedHedgesNetPretax	-2500000	USD
CY2011	ato	Gain Loss On Derivative Instruments Not Designated Hedges Net Pretax GainLossOnDerivativeInstrumentsNotDesignatedHedgesNetPretax	-1400000	USD
CY2010	ato	Gain Loss On Derivative Instruments Not Designated Hedges Net Pretax GainLossOnDerivativeInstrumentsNotDesignatedHedgesNetPretax	15400000	USD
CY2012Q3	ato	Natural Gas Distribution Segement Derivative Assets NaturalGasDistributionSegementDerivativeAssets	9365000	USD
CY2012Q3	ato	Nonregulated Segement Derivative Assets NonregulatedSegementDerivativeAssets	17773000	USD
CY2012Q3	ato	Derivative Assets Fair Value DerivativeAssetsFairValue	27138000	USD
CY2012Q3	ato	Hedged Portion Of Gas Stored Underground Fair Value Disclosure HedgedPortionOfGasStoredUndergroundFairValueDisclosure	67192000	USD
CY2012Q3	us-gaap	Available For Sale Securities Equity Securities AvailableForSaleSecuritiesEquitySecurities	40212000	USD
CY2012Q3	us-gaap	Assets Fair Value Disclosure AssetsFairValueDisclosure	158728000	USD
CY2012Q3	ato	Natural Gas Distribution Segement Derivative Liabilities NaturalGasDistributionSegementDerivativeLiabilities	85625000	USD
CY2012Q3	ato	Nonregulated Segement Derivative Liabilities NonregulatedSegementDerivativeLiabilities	9221000	USD
CY2012Q3	us-gaap	Liabilities Fair Value Disclosure LiabilitiesFairValueDisclosure	94846000	USD
CY2011Q3	ato	Natural Gas Distribution Segement Derivative Assets NaturalGasDistributionSegementDerivativeAssets	1841000	USD
CY2011Q3	ato	Nonregulated Segement Derivative Assets NonregulatedSegementDerivativeAssets	17502000	USD
CY2011Q3	ato	Derivative Assets Fair Value DerivativeAssetsFairValue	19343000	USD
CY2011Q3	ato	Hedged Portion Of Gas Stored Underground Fair Value Disclosure HedgedPortionOfGasStoredUndergroundFairValueDisclosure	47940000	USD
CY2011Q3	us-gaap	Available For Sale Securities Equity Securities AvailableForSaleSecuritiesEquitySecurities	36444000	USD
CY2011Q3	us-gaap	Assets Fair Value Disclosure AssetsFairValueDisclosure	119916000	USD
CY2011Q3	ato	Natural Gas Distribution Segement Derivative Liabilities NaturalGasDistributionSegementDerivativeLiabilities	81118000	USD
CY2011Q3	ato	Nonregulated Segement Derivative Liabilities NonregulatedSegementDerivativeLiabilities	13765000	USD
CY2011Q3	us-gaap	Liabilities Fair Value Disclosure LiabilitiesFairValueDisclosure	94883000	USD
CY2011Q3	ato	Cash Collateral Right To Reclaim Cash CashCollateralRightToReclaimCash	28800000	USD
CY2011Q3	ato	Cash Held In Margin Accounts Offset Current Risk Management Liabilities CashHeldInMarginAccountsOffsetCurrentRiskManagementLiabilities	12400000	USD
CY2011Q3	ato	Cash Held In Margin Accounts Classified Current Risk Management Asset CashHeldInMarginAccountsClassifiedCurrentRiskManagementAsset	16400000	USD
CY2012Q3	ato	Cash Collateral Right To Reclaim Cash CashCollateralRightToReclaimCash	23700000	USD
CY2012Q3	ato	Cash Held In Margin Accounts Offset Current Risk Management Liabilities CashHeldInMarginAccountsOffsetCurrentRiskManagementLiabilities	5900000	USD
CY2012Q3	ato	Cash Held In Margin Accounts Classified Current Risk Management Asset CashHeldInMarginAccountsClassifiedCurrentRiskManagementAsset	17800000	USD
CY2012Q3	us-gaap	Available For Sale Equity Securities Amortized Cost Basis AvailableForSaleEquitySecuritiesAmortizedCostBasis	55339000	USD
CY2012Q3	us-gaap	Availableforsale Securities Gross Unrealized Gain AvailableforsaleSecuritiesGrossUnrealizedGain	9061000	USD
CY2011Q3	us-gaap	Availableforsale Securities Gross Unrealized Gain AvailableforsaleSecuritiesGrossUnrealizedGain	4351000	USD
CY2011Q3	us-gaap	Available For Sale Equity Securities Amortized Cost Basis AvailableForSaleEquitySecuritiesAmortizedCostBasis	48558000	USD
CY2012Q3	us-gaap	Available For Sale Securities Gross Unrealized Losses1 AvailableForSaleSecuritiesGrossUnrealizedLosses1	2000	USD
CY2011Q3	us-gaap	Available For Sale Securities Gross Unrealized Losses1 AvailableForSaleSecuritiesGrossUnrealizedLosses1	276000	USD
CY2011Q3	us-gaap	Available For Sale Securities Fair Value Disclosure AvailableForSaleSecuritiesFairValueDisclosure	52633000	USD
CY2012Q3	us-gaap	Available For Sale Securities Fair Value Disclosure AvailableForSaleSecuritiesFairValueDisclosure	64398000	USD
CY2011	ato	Asset Impairment Charges Park City AssetImpairmentChargesParkCity	11000000	USD
CY2011	ato	Asset Impairment Charges Fort Necessity AssetImpairmentChargesFortNecessity	19300000	USD
CY2012	ato	Asset Impairment Charges Park City AssetImpairmentChargesParkCity	5300000	USD
CY2012Q3	ato	Gas Gathering Assets Fair Value Nonrecurring GasGatheringAssetsFairValueNonrecurring	500000	USD
CY2012Q3	us-gaap	Debt Instrument Fair Value DebtInstrumentFairValue	2426434000	USD
CY2012	us-gaap	Disposal Group Including Discontinued Operation Description And Timing Of Disposal DisposalGroupIncludingDiscontinuedOperationDescriptionAndTimingOfDisposal	On August 1, 2012, we completed the sale of substantially all of our natural gas distribution assets located in Missouri, Illinois and Iowa to Liberty Energy (Midstates) Corp., an affiliate of Algonquin Power & Utilities Corp. for a cash price of approximately $128 million, pursuant to an asset purchase agreement executed on May 12, 2011. In connection with the sale, we recognized a pre-tax gain of approximately $9.9 million. On August 8, 2012, we entered into a definitive agreement to sell substantially all of our natural gas distribution assets located in Georgia to Liberty Energy (Georgia) Corp., an affiliate of Algonquin Power & Utilities Corp. for a cash price of approximately $141 million. The agreement contains terms and conditions customary for transactions of this type, including typical adjustments to the purchase price at closing, if applicable. The closing of the transaction is subject to the satisfaction of customary conditions including the receipt of applicable regulatory approvals, which we currently anticipate will occur in late fiscal 2013.
CY2012	ato	Discontinued Operations Operating Revenues DiscontinuedOperationsOperatingRevenues	114703000	USD
CY2012	ato	Discontinued Operations Purchased Gas Cost DiscontinuedOperationsPurchasedGasCost	62902000	USD
CY2012	ato	Discontinued Operations Gross Profit DiscontinuedOperationsGrossProfit	51801000	USD
CY2012	us-gaap	Disposal Group Including Discontinued Operation Operating Expense DisposalGroupIncludingDiscontinuedOperationOperatingExpense	24174000	USD
CY2012	us-gaap	Disposal Group Including Discontinued Operation Operating Income Loss DisposalGroupIncludingDiscontinuedOperationOperatingIncomeLoss	27627000	USD
CY2012	ato	Discontinued Operations Miscellaneous Expense DiscontinuedOperationsMiscellaneousExpense	-611000	USD
CY2011	ato	Discontinued Operations Miscellaneous Expense DiscontinuedOperationsMiscellaneousExpense	-57000	USD
CY2011	us-gaap	Disposal Group Including Discontinued Operation Operating Income Loss DisposalGroupIncludingDiscontinuedOperationOperatingIncomeLoss	30328000	USD
CY2011	us-gaap	Disposal Group Including Discontinued Operation Operating Expense DisposalGroupIncludingDiscontinuedOperationOperatingExpense	27362000	USD
CY2011	ato	Discontinued Operations Gross Profit DiscontinuedOperationsGrossProfit	57690000	USD
CY2011	ato	Discontinued Operations Purchased Gas Cost DiscontinuedOperationsPurchasedGasCost	83537000	USD
CY2011	ato	Discontinued Operations Operating Revenues DiscontinuedOperationsOperatingRevenues	141227000	USD
CY2012	us-gaap	Discontinued Operation Income Loss From Discontinued Operation During Phase Out Period Before Income Tax DiscontinuedOperationIncomeLossFromDiscontinuedOperationDuringPhaseOutPeriodBeforeIncomeTax	28238000	USD
CY2011	us-gaap	Discontinued Operation Income Loss From Discontinued Operation During Phase Out Period Before Income Tax DiscontinuedOperationIncomeLossFromDiscontinuedOperationDuringPhaseOutPeriodBeforeIncomeTax	30385000	USD
CY2010Q3	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeited In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriodWeightedAverageGrantDateFairValue	26.54
CY2012	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	33.44
CY2012	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod	-494308	shares
CY2012	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue	26.32
CY2012	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeited In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod	-39963	shares
CY2010	us-gaap	Discontinued Operation Income Loss From Discontinued Operation During Phase Out Period Before Income Tax DiscontinuedOperationIncomeLossFromDiscontinuedOperationDuringPhaseOutPeriodBeforeIncomeTax	25572000	USD
CY2010	ato	Discontinued Operations Operating Revenues DiscontinuedOperationsOperatingRevenues	128630000	USD
CY2010	ato	Discontinued Operations Purchased Gas Cost DiscontinuedOperationsPurchasedGasCost	77825000	USD
CY2010	ato	Discontinued Operations Gross Profit DiscontinuedOperationsGrossProfit	50805000	USD
CY2010	us-gaap	Disposal Group Including Discontinued Operation Operating Expense DisposalGroupIncludingDiscontinuedOperationOperatingExpense	25202000	USD
CY2010	us-gaap	Disposal Group Including Discontinued Operation Operating Income Loss DisposalGroupIncludingDiscontinuedOperationOperatingIncomeLoss	25603000	USD
CY2010	ato	Discontinued Operations Miscellaneous Expense DiscontinuedOperationsMiscellaneousExpense	31000	USD
CY2012	us-gaap	Income Loss From Discontinued Operations Net Of Tax IncomeLossFromDiscontinuedOperationsNetOfTax	24521000	USD
CY2011	us-gaap	Income Loss From Discontinued Operations Net Of Tax IncomeLossFromDiscontinuedOperationsNetOfTax	18013000	USD
CY2010	us-gaap	Income Loss From Discontinued Operations Net Of Tax IncomeLossFromDiscontinuedOperationsNetOfTax	15988000	USD
CY2012Q3	us-gaap	Disposal Group Including Discontinued Operation Property Plant And Equipment Net DisposalGroupIncludingDiscontinuedOperationPropertyPlantAndEquipmentNet	142865000	USD
CY2012Q3	ato	Disposal Group Including Discontinued Operation Gas Stored Underground DisposalGroupIncludingDiscontinuedOperationGasStoredUnderground	4688000	USD
CY2012Q3	us-gaap	Disposal Group Including Discontinued Operation Other Current Assets DisposalGroupIncludingDiscontinuedOperationOtherCurrentAssets	6931000	USD
CY2012Q3	us-gaap	Disposal Group Including Discontinued Operation Other Noncurrent Assets DisposalGroupIncludingDiscontinuedOperationOtherNoncurrentAssets	87000	USD
CY2012Q3	us-gaap	Assets Of Disposal Group Including Discontinued Operation AssetsOfDisposalGroupIncludingDiscontinuedOperation	154571000	USD
CY2012Q3	us-gaap	Disposal Group Including Discontinued Operation Accounts Payable DisposalGroupIncludingDiscontinuedOperationAccountsPayable	2114000	USD
CY2012Q3	us-gaap	Disposal Group Including Discontinued Operation Other Current Liabilities DisposalGroupIncludingDiscontinuedOperationOtherCurrentLiabilities	3776000	USD
CY2012Q3	ato	Disposal Group Including Discontinued Operation Regulatory Cost Of Removal Obligation DisposalGroupIncludingDiscontinuedOperationRegulatoryCostOfRemovalObligation	3257000	USD
CY2012Q3	us-gaap	Disposal Group Including Discontinued Operation Other Noncurrent Liabilities DisposalGroupIncludingDiscontinuedOperationOtherNoncurrentLiabilities	2426000	USD
CY2012Q3	ato	Liabilities Of Disposal Group LiabilitiesOfDisposalGroup	11573000	USD
CY2011Q3	us-gaap	Disposal Group Including Discontinued Operation Property Plant And Equipment Net DisposalGroupIncludingDiscontinuedOperationPropertyPlantAndEquipmentNet	127577000	USD
CY2011Q3	ato	Disposal Group Including Discontinued Operation Gas Stored Underground DisposalGroupIncludingDiscontinuedOperationGasStoredUnderground	11931000	USD
CY2011Q3	us-gaap	Disposal Group Including Discontinued Operation Other Current Assets DisposalGroupIncludingDiscontinuedOperationOtherCurrentAssets	786000	USD
CY2011Q3	us-gaap	Disposal Group Including Discontinued Operation Other Noncurrent Assets DisposalGroupIncludingDiscontinuedOperationOtherNoncurrentAssets	277000	USD
CY2011Q3	us-gaap	Assets Of Disposal Group Including Discontinued Operation AssetsOfDisposalGroupIncludingDiscontinuedOperation	140571000	USD
CY2011Q3	us-gaap	Disposal Group Including Discontinued Operation Accounts Payable DisposalGroupIncludingDiscontinuedOperationAccountsPayable	1917000	USD
CY2011Q3	us-gaap	Disposal Group Including Discontinued Operation Other Current Liabilities DisposalGroupIncludingDiscontinuedOperationOtherCurrentLiabilities	4877000	USD
CY2011Q3	ato	Disposal Group Including Discontinued Operation Regulatory Cost Of Removal Obligation DisposalGroupIncludingDiscontinuedOperationRegulatoryCostOfRemovalObligation	10498000	USD
CY2011Q3	us-gaap	Disposal Group Including Discontinued Operation Other Noncurrent Liabilities DisposalGroupIncludingDiscontinuedOperationOtherNoncurrentLiabilities	1153000	USD
CY2011Q3	ato	Liabilities Of Disposal Group LiabilitiesOfDisposalGroup	18445000	USD
CY2012Q3	us-gaap	Debt Instrument Unamortized Discount DebtInstrumentUnamortizedDiscount	3695000	USD
CY2011Q3	us-gaap	Debt Instrument Unamortized Discount DebtInstrumentUnamortizedDiscount	4014000	USD
CY2012Q3	ato	Authorized Commercial Paper AuthorizedCommercialPaper	750000000	USD
CY2012Q3	us-gaap	Commercial Paper CommercialPaper	310900000	USD
CY2011Q3	us-gaap	Commercial Paper CommercialPaper	206400000	USD
CY2012Q3	ato	Aem Net Working Capital AemNetWorkingCapital	136200000	USD
CY2012Q3	ato	Aem Tangible Net Worth AemTangibleNetWorth	150800000	USD
CY2012Q3	ato	Debt And Equity Securities Authorized For Issuance DebtAndEquitySecuritiesAuthorizedForIssuance	1300000000	USD
CY2012Q3	ato	Debt And Equity Securities Available For Issuance DebtAndEquitySecuritiesAvailableForIssuance	900000000	USD
CY2012Q3	ato	Ratio Of Total Debt To Total Capital RatioOfTotalDebtToTotalCapital	0.54	pure
CY2012Q3	us-gaap	Debt Instrument Carrying Amount DebtInstrumentCarryingAmount	1960131000	USD
CY2011Q3	us-gaap	Debt Instrument Carrying Amount DebtInstrumentCarryingAmount	2212565000	USD
CY2012	us-gaap	Stock Repurchased During Period Value StockRepurchasedDuringPeriodValue	12500000	USD
CY2012Q3	ato	Regulated Operations Letters Of Credit Outstanding Amount RegulatedOperationsLettersOfCreditOutstandingAmount	11500000	USD
CY2012Q3	ato	Nonregulated Operations Letters Of Credit Outstanding Amount NonregulatedOperationsLettersOfCreditOutstandingAmount	11500000	USD
CY2012	ato	Nonregulated Operations Line Of Credit Facilities Covenant Terms NonregulatedOperationsLineOfCreditFacilitiesCovenantTerms	AEM is required by the financial covenants in this facility to maintain a ratio of total liabilities to tangible net worth that does not exceed a maximum of 5 to 1. Additionally, AEM must maintain minimum levels of net working capital and net worth ranging from $20 million to $40 million.
CY2012Q3	ato	Ratio Of Liabilities To Tangible Net Worth RatioOfLiabilitiesToTangibleNetWorth	0.74 to 1
CY2012Q3	ato	Commercial Paper Weighted Average Interest Rate CommercialPaperWeightedAverageInterestRate	0.0043	pure
CY2010	ato	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number Ending Balance ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumberEndingBalance	1293960	shares
CY2010	ato	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Weighted Average Grant Date Fair Value End Of Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueEndOfPeriod	27.28
CY2012	us-gaap	Debt Instrument Covenant Description DebtInstrumentCovenantDescription	In addition to the financial covenants described above, our credit facilities and public indentures contain usual and customary covenants for our business, including covenants substantially limiting liens, substantial asset sales and mergers. Additionally, our public debt indentures relating to our senior notes and debentures, as well as our revolving credit agreements, each contain a default provision that is triggered if outstanding indebtedness arising out of any other credit agreements in amounts ranging from in excess of $15 million to in excess of $100 million becomes due by acceleration or is not paid at maturity. Further, AEM’s credit agreement contains a cross-default provision whereby AEM would be in default if it defaults on other indebtedness, as defined, by at least $250 thousand in the aggregate. Finally, AEM’s credit agreement contains a provision that would limit the amount of credit available if Atmos Energy were downgraded below an S&P rating of BBB and a Moody’s rating of Baa2. We have no other triggering events in our debt instruments that are tied to changes in specified credit ratings or stock price, nor have we entered into any transactions that would require us to issue equity, based on our credit rating or other triggering events.
CY2012	us-gaap	Debt Instrument Covenant Compliance DebtInstrumentCovenantCompliance	We were in compliance with all of our debt covenants
CY2012	ato	Regulated Operations Line Of Credit Facilities Covenant Terms RegulatedOperationsLineOfCreditFacilitiesCovenantTerms	The availability of funds under these credit facilities is subject to conditions specified in the respective credit agreements, all of which we currently satisfy. These conditions include our compliance with financial covenants and the continued accuracy of representations and warranties contained in these agreements. We are required by the financial covenants in each of these facilities to maintain, at the end of each fiscal quarter, a ratio of total debt to total capitalization of no greater than 70 percent.
CY2012Q3	us-gaap	Long Term Debt Maturities Repayments Of Principal In Next Twelve Months LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths	131000	USD
CY2012Q3	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Two LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo	0	USD
CY2012Q3	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Three LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree	500000000	USD
CY2012Q3	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Four LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour	0	USD
CY2012Q3	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Five LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive	250000000	USD
CY2012Q3	us-gaap	Long Term Debt Maturities Repayments Of Principal After Year Five LongTermDebtMaturitiesRepaymentsOfPrincipalAfterYearFive	1210000000	USD
CY2012Q3	ato	Accelerated Share Repurchases Payment AcceleratedShareRepurchasesPayment	100000000	USD
CY2010	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	12700000	USD
CY2012Q3	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Authorized ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized	8700000	shares
CY2012	us-gaap	Accelerated Share Repurchases Cash Or Stock Settlement AcceleratedShareRepurchasesCashOrStockSettlement	3,334,048
CY2011	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	11600000	USD
CY2012	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	19200000	USD
CY2012Q3	ato	Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Available ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailable	1949088	shares
CY2012	us-gaap	Stock Repurchased During Period Shares StockRepurchasedDuringPeriodShares	387991	shares
CY2012Q3	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeited In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriodWeightedAverageGrantDateFairValue	29.83
CY2012	ato	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number Ending Balance ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumberEndingBalance	1262582	shares
CY2012	ato	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Weighted Average Grant Date Fair Value End Of Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueEndOfPeriod	32.46
CY2011	ato	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number Beginning Balance ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumberBeginningBalance	1293960	shares
CY2011	ato	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Weighted Average Grant Date Fair Value Beginning Of Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueBeginningOfPeriod	27.28
CY2011	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod	491345	shares
CY2011	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	33.10
CY2011	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod	-464321	shares
CY2011	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue	27.21
CY2011	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeited In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod	-56842	shares
CY2011Q3	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeited In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriodWeightedAverageGrantDateFairValue	27.56
CY2011	ato	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number Ending Balance ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumberEndingBalance	1264142	shares
CY2011	ato	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Weighted Average Grant Date Fair Value End Of Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueEndOfPeriod	29.56
CY2010	ato	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number Beginning Balance ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumberBeginningBalance	1295841	shares
CY2010	ato	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Weighted Average Grant Date Fair Value Beginning Of Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueBeginningOfPeriod	27.23
CY2010	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod	551278	shares
CY2010	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	29.07
CY2010	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod	-493957	shares
CY2010	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue	29.24
CY2010	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeited In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod	-59202	shares
CY2012Q3	us-gaap	Stock Repurchase Program Number Of Shares Authorized To Be Repurchased StockRepurchaseProgramNumberOfSharesAuthorizedToBeRepurchased	5000000	shares
CY2012Q3	us-gaap	Stock Repurchase Program Period In Force StockRepurchaseProgramPeriodInForce	5	pure
CY2011	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Total Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue	12600000	USD
CY2010	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Total Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue	14400000	USD
CY2012Q3	us-gaap	Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized	10100000	USD
CY2012	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Total Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue	13000000	USD
CY2012	us-gaap	Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized Period For Recognition EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition	1.6	pure
CY2012	ato	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number Beginning Balance ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumberBeginningBalance	86766	shares
CY2012Q3	ato	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price Beginning Of Period ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceBeginningOfPeriod	22.16
CY2011Q3	ato	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price Beginning Of Period ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceBeginningOfPeriod	22.46
CY2011	ato	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number Beginning Balance ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumberBeginningBalance	434962	shares
CY2010	ato	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number Beginning Balance ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumberBeginningBalance	611227	shares
CY2010Q3	ato	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price Beginning Of Period ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceBeginningOfPeriod	21.88
CY2012Q3	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice	0
CY2012	us-gaap	Stock Issued During Period Shares Stock Options Exercised StockIssuedDuringPeriodSharesStockOptionsExercised	-76672	shares
CY2012Q3	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercises In Period Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice	21.79
CY2011Q3	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue	300000	USD
CY2012	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod	0	shares
CY2012Q3	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures In Period Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice	0
CY2012	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Expirations In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExpirationsInPeriod	0	shares
CY2012Q3	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Expirations In Period Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExpirationsInPeriodWeightedAverageExercisePrice	0
CY2012	ato	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number Ending Balance ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumberEndingBalance	10094	shares
CY2012Q3	ato	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price End Of Period ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceEndOfPeriod	24.95
CY2012Q3	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber	10094	shares
CY2012Q3	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice	24.95
CY2011Q3	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice	0
CY2011	us-gaap	Stock Issued During Period Shares Stock Options Exercised StockIssuedDuringPeriodSharesStockOptionsExercised	-348196	shares
CY2011Q3	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercises In Period Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice	22.54
CY2011	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod	0	shares
CY2011Q3	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures In Period Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice	0
CY2011	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Expirations In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExpirationsInPeriod	0	shares
CY2011Q3	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Expirations In Period Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExpirationsInPeriodWeightedAverageExercisePrice	0
CY2011	ato	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number Ending Balance ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumberEndingBalance	86766	shares
CY2011Q3	ato	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price End Of Period ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceEndOfPeriod	22.16
CY2011Q3	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber	86766	shares
CY2010Q3	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice	0
CY2010	us-gaap	Stock Issued During Period Shares Stock Options Exercised StockIssuedDuringPeriodSharesStockOptionsExercised	-176265	shares
CY2010Q3	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercises In Period Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice	20.44
CY2010	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod	0	shares
CY2010Q3	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures In Period Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice	0
CY2010	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Expirations In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExpirationsInPeriod	0	shares
CY2010Q3	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Expirations In Period Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExpirationsInPeriodWeightedAverageExercisePrice	0
CY2010	ato	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number Ending Balance ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumberEndingBalance	434962	shares
CY2010Q3	ato	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price End Of Period ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceEndOfPeriod	22.46
CY2010Q3	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber	434962	shares
CY2010Q3	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice	22.46
CY2011Q3	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice	22.16
CY2012	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Gross ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross	0	shares
CY2011	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Gross ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross	0	shares
CY2010	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Gross ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross	0	shares
CY2012Q3	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Outstanding Weighted Average Remaining Contractual Term1 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm1	1.7	pure
CY2011Q3	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Outstanding Weighted Average Remaining Contractual Term1 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm1	1.7	pure
CY2010Q3	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Outstanding Weighted Average Remaining Contractual Term1 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm1	1.6	pure
CY2012	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Weighted Average Remaining Contractual Term ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm	1.7	pure
CY2011	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Weighted Average Remaining Contractual Term ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm	1.7	pure
CY2010	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Weighted Average Remaining Contractual Term ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm	1.6	pure
CY2010Q3	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue	1600000	USD
CY2012Q3	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Exercisable Intrinsic Value1 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1	30000	USD
CY2011Q3	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Exercisable Intrinsic Value1 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1	300000	USD
CY2010Q3	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Exercisable Intrinsic Value1 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1	1600000	USD
CY2012Q3	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue	30000	USD
CY2012Q3	us-gaap	Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range Number Of Outstanding Options ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions	10094	shares
CY2012	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	0
CY2012	us-gaap	Employee Service Share Based Compensation Cash Received From Exercise Of Stock Options EmployeeServiceShareBasedCompensationCashReceivedFromExerciseOfStockOptions	1671000	USD
CY2012	us-gaap	Employee Service Share Based Compensation Tax Benefit Realized From Exercise Of Stock Options EmployeeServiceShareBasedCompensationTaxBenefitRealizedFromExerciseOfStockOptions	401000	USD
CY2012	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercises In Period Total Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue	256000	USD
CY2011	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	0
CY2011	us-gaap	Employee Service Share Based Compensation Cash Received From Exercise Of Stock Options EmployeeServiceShareBasedCompensationCashReceivedFromExerciseOfStockOptions	7848000	USD
CY2011	us-gaap	Employee Service Share Based Compensation Tax Benefit Realized From Exercise Of Stock Options EmployeeServiceShareBasedCompensationTaxBenefitRealizedFromExerciseOfStockOptions	1010000	USD
CY2011	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercises In Period Total Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue	1263000	USD
CY2010	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	0
CY2010	us-gaap	Employee Service Share Based Compensation Cash Received From Exercise Of Stock Options EmployeeServiceShareBasedCompensationCashReceivedFromExerciseOfStockOptions	3604000	USD
CY2010	us-gaap	Employee Service Share Based Compensation Tax Benefit Realized From Exercise Of Stock Options EmployeeServiceShareBasedCompensationTaxBenefitRealizedFromExerciseOfStockOptions	547000	USD
CY2010	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercises In Period Total Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue	239000	USD
CY2012Q3	us-gaap	Sharebased Compensation Shares Authorized Under Stock Option Plans Exercise Price Range Exercisable Options Weighted Average Exercise Price1 SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1	24.95
CY2012Q3	us-gaap	Sharebased Compensation Shares Authorized Under Stock Option Plans Exercise Price Range Exercisable Options Weighted Average Remaining Contractual Term1 SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageRemainingContractualTerm1	1.7	pure
CY2012Q3	ato	Minimum Initial Investment For Direct Stock Purchase Plan MinimumInitialInvestmentForDirectStockPurchasePlan	1250	USD
CY2012Q3	ato	Minimum Continuing Investment For Direct Stock Purchase Plan MinimumContinuingInvestmentForDirectStockPurchasePlan	25	USD
CY2012Q3	ato	Annual Maximum Investment For Direct Stock Purchase Plan AnnualMaximumInvestmentForDirectStockPurchasePlan	100000	USD
CY2012	ato	Unrecognized Transition Obligation In Net Periodic Pension Cost UnrecognizedTransitionObligationInNetPeriodicPensionCost	1709000	USD
CY2012	ato	Unrecognized Prior Service Cost In Net Periodic Pension Cost UnrecognizedPriorServiceCostInNetPeriodicPensionCost	7643000	USD
CY2012	ato	Unrecognized Actuarial Loss In Net Periodic Pension Cost UnrecognizedActuarialLossInNetPeriodicPensionCost	294447000	USD
CY2012	ato	Total Unrecognized In Net Periodic Pension Cost TotalUnrecognizedInNetPeriodicPensionCost	288513000	USD
CY2011	ato	Unrecognized Transition Obligation In Net Periodic Pension Cost UnrecognizedTransitionObligationInNetPeriodicPensionCost	3220000	USD
CY2011	ato	Unrecognized Prior Service Cost In Net Periodic Pension Cost UnrecognizedPriorServiceCostInNetPeriodicPensionCost	9234000	USD
CY2011	ato	Unrecognized Actuarial Loss In Net Periodic Pension Cost UnrecognizedActuarialLossInNetPeriodicPensionCost	260680000	USD
CY2011	ato	Total Unrecognized In Net Periodic Pension Cost TotalUnrecognizedInNetPeriodicPensionCost	254666000	USD
CY2012	us-gaap	Defined Contribution Plan Cost Recognized DefinedContributionPlanCostRecognized	10500000	USD
CY2011	us-gaap	Defined Contribution Plan Cost Recognized DefinedContributionPlanCostRecognized	10200000	USD
CY2010	us-gaap	Defined Contribution Plan Cost Recognized DefinedContributionPlanCostRecognized	9800000	USD
CY2011	ato	Defined Contribution Plan Discretionary Cost Recognized DefinedContributionPlanDiscretionaryCostRecognized	1300000	USD
CY2010	ato	Defined Contribution Plan Discretionary Cost Recognized DefinedContributionPlanDiscretionaryCostRecognized	1300000	USD
CY2012	ato	Defined Contribution Plan Discretionary Cost Recognized DefinedContributionPlanDiscretionaryCostRecognized	1200000	USD
CY2011Q3	ato	Defined Contribution Plan Percent Of Equity Securities Issued By Employer And Related Parties Included In Plan Assets DefinedContributionPlanPercentOfEquitySecuritiesIssuedByEmployerAndRelatedPartiesIncludedInPlanAssets	0.045	pure
CY2012Q3	ato	Defined Contribution Plan Percent Of Equity Securities Issued By Employer And Related Parties Included In Plan Assets DefinedContributionPlanPercentOfEquitySecuritiesIssuedByEmployerAndRelatedPartiesIncludedInPlanAssets	0.049	pure
CY2012Q3	ato	Billed Accounts Receivable BilledAccountsReceivable	177953000	USD
CY2012Q3	ato	Unbilled Revenues UnbilledRevenues	42694000	USD
CY2012Q3	us-gaap	Other Receivables OtherReceivables	23304000	USD
CY2012Q3	us-gaap	Accounts Receivable Gross Current AccountsReceivableGrossCurrent	243951000	USD
CY2011Q3	ato	Billed Accounts Receivable BilledAccountsReceivable	216145000	USD
CY2011Q3	ato	Unbilled Revenues UnbilledRevenues	48006000	USD
CY2011Q3	us-gaap	Other Receivables OtherReceivables	16592000	USD
CY2011Q3	us-gaap	Accounts Receivable Gross Current AccountsReceivableGrossCurrent	280743000	USD
CY2012Q3	us-gaap	Derivative Assets Current DerivativeAssetsCurrent	24707000	USD
CY2012Q3	us-gaap	Deferred Gas Cost DeferredGasCost	31359000	USD
CY2012Q3	us-gaap	Income Tax Receivable IncomeTaxReceivable	1291000	USD
CY2012Q3	us-gaap	Deferred Tax Assets Net Current DeferredTaxAssetsNetCurrent	27091000	USD
CY2012Q3	us-gaap	Prepaid Expense Current PrepaidExpenseCurrent	17114000	USD
CY2012Q3	us-gaap	Capital Leases Future Minimum Payments Receivable Current CapitalLeasesFutureMinimumPaymentsReceivableCurrent	168000	USD
CY2012Q3	us-gaap	Supplies Supplies	5872000	USD
CY2012Q3	ato	Other Assets Current Other OtherAssetsCurrentOther	10609000	USD
CY2011Q3	us-gaap	Derivative Assets Current DerivativeAssetsCurrent	18344000	USD
CY2011Q3	us-gaap	Deferred Gas Cost DeferredGasCost	33976000	USD
CY2011Q3	us-gaap	Income Tax Receivable IncomeTaxReceivable	9215000	USD
CY2011Q3	us-gaap	Deferred Tax Assets Net Current DeferredTaxAssetsNetCurrent	76725000	USD
CY2011Q3	us-gaap	Prepaid Expense Current PrepaidExpenseCurrent	22499000	USD
CY2011Q3	us-gaap	Capital Leases Future Minimum Payments Receivable Current CapitalLeasesFutureMinimumPaymentsReceivableCurrent	2013000	USD
CY2011Q3	us-gaap	Supplies Supplies	4113000	USD
CY2011Q3	ato	Other Assets Current Other OtherAssetsCurrentOther	9015000	USD
CY2012Q3	ato	Property Plant And Equipment Production Gross PropertyPlantAndEquipmentProductionGross	5020000	USD
CY2012Q3	ato	Property Plant And Equipment Storage Gross PropertyPlantAndEquipmentStorageGross	232260000	USD
CY2012Q3	ato	Property Plant And Equipment Transmission Gross PropertyPlantAndEquipmentTransmissionGross	1185007000	USD
CY2012Q3	ato	Property Plant And Equipment Distribution Gross PropertyPlantAndEquipmentDistributionGross	4680877000	USD
CY2012Q3	ato	Property Plant And Equipment General Gross PropertyPlantAndEquipmentGeneralGross	717568000	USD
CY2012Q3	ato	Property Plant And Equipment Intangible Gross PropertyPlantAndEquipmentIntangibleGross	39626000	USD
CY2011Q3	ato	Property Plant And Equipment Production Gross PropertyPlantAndEquipmentProductionGross	7412000	USD
CY2011Q3	ato	Property Plant And Equipment Storage Gross PropertyPlantAndEquipmentStorageGross	198422000	USD
CY2011Q3	ato	Property Plant And Equipment Transmission Gross PropertyPlantAndEquipmentTransmissionGross	1126509000	USD
CY2011Q3	ato	Property Plant And Equipment Distribution Gross PropertyPlantAndEquipmentDistributionGross	4496263000	USD
CY2011Q3	ato	Property Plant And Equipment General Gross PropertyPlantAndEquipmentGeneralGross	737850000	USD
CY2011Q3	ato	Property Plant And Equipment Intangible Gross PropertyPlantAndEquipmentIntangibleGross	41096000	USD
CY2012Q3	us-gaap	Marketable Securities MarketableSecurities	64398000	USD
CY2012Q3	us-gaap	Regulatory Assets Noncurrent RegulatoryAssetsNoncurrent	334551000	USD
CY2012Q3	us-gaap	Deferred Finance Costs Noncurrent Net DeferredFinanceCostsNoncurrentNet	35101000	USD
CY2012Q3	us-gaap	Derivative Assets Noncurrent DerivativeAssetsNoncurrent	2283000	USD
CY2012Q3	ato	Other Assets Noncurrent Other OtherAssetsNoncurrentOther	14929000	USD
CY2011Q3	us-gaap	Marketable Securities MarketableSecurities	52633000	USD
CY2011Q3	us-gaap	Regulatory Assets Noncurrent RegulatoryAssetsNoncurrent	278920000	USD
CY2011Q3	us-gaap	Deferred Finance Costs Noncurrent Net DeferredFinanceCostsNoncurrentNet	35149000	USD
CY2011Q3	us-gaap	Derivative Assets Noncurrent DerivativeAssetsNoncurrent	998000	USD
CY2011Q3	ato	Other Assets Noncurrent Other OtherAssetsNoncurrentOther	16093000	USD
CY2012Q3	us-gaap	Customer Deposits Current CustomerDepositsCurrent	100926000	USD
CY2012Q3	us-gaap	Accrued Employee Benefits Current AccruedEmployeeBenefitsCurrent	37675000	USD
CY2012Q3	ato	Deferred Gas Cost Liability DeferredGasCostLiability	23072000	USD
CY2012Q3	us-gaap	Interest Payable Current InterestPayableCurrent	34451000	USD
CY2012Q3	us-gaap	Derivative Liabilities Current DerivativeLiabilitiesCurrent	85381000	USD
CY2012Q3	us-gaap	Taxes Payable Current TaxesPayableCurrent	64319000	USD
CY2012Q3	us-gaap	Pension And Other Postretirement Defined Benefit Plans Current Liabilities PensionAndOtherPostretirementDefinedBenefitPlansCurrentLiabilities	39625000	USD
CY2012Q3	ato	Regulatory Cost Of Removal Liability Current RegulatoryCostOfRemovalLiabilityCurrent	78525000	USD
CY2012Q3	ato	Other Liabilities Current Other OtherLiabilitiesCurrentOther	14118000	USD
CY2011Q3	us-gaap	Customer Deposits Current CustomerDepositsCurrent	106743000	USD
CY2011Q3	us-gaap	Accrued Employee Benefits Current AccruedEmployeeBenefitsCurrent	38558000	USD
CY2011Q3	ato	Deferred Gas Cost Liability DeferredGasCostLiability	8130000	USD
CY2011Q3	us-gaap	Interest Payable Current InterestPayableCurrent	37557000	USD
CY2011Q3	us-gaap	Derivative Liabilities Current DerivativeLiabilitiesCurrent	15453000	USD
CY2011Q3	us-gaap	Taxes Payable Current TaxesPayableCurrent	57853000	USD
CY2011Q3	us-gaap	Pension And Other Postretirement Defined Benefit Plans Current Liabilities PensionAndOtherPostretirementDefinedBenefitPlansCurrentLiabilities	33036000	USD
CY2011Q3	ato	Regulatory Cost Of Removal Liability Current RegulatoryCostOfRemovalLiabilityCurrent	35078000	USD
CY2012	us-gaap	Incremental Common Shares Attributable To Participating Nonvested Shares With Non Forfeitable Dividend Rights IncrementalCommonSharesAttributableToParticipatingNonvestedSharesWithNonForfeitableDividendRights	1022000	shares
CY2011	us-gaap	Incremental Common Shares Attributable To Participating Nonvested Shares With Non Forfeitable Dividend Rights IncrementalCommonSharesAttributableToParticipatingNonvestedSharesWithNonForfeitableDividendRights	451000	shares
CY2010	us-gaap	Incremental Common Shares Attributable To Participating Nonvested Shares With Non Forfeitable Dividend Rights IncrementalCommonSharesAttributableToParticipatingNonvestedSharesWithNonForfeitableDividendRights	570000	shares
CY2011Q3	ato	Other Liabilities Current Other OtherLiabilitiesCurrentOther	16710000	USD
CY2012Q3	us-gaap	Other Postretirement Defined Benefit Plan Liabilities Noncurrent OtherPostretirementDefinedBenefitPlanLiabilitiesNoncurrent	221231000	USD
CY2012Q3	us-gaap	Defined Benefit Pension Plan Liabilities Noncurrent DefinedBenefitPensionPlanLiabilitiesNoncurrent	235965000	USD
CY2012Q3	us-gaap	Customer Advances For Construction CustomerAdvancesForConstruction	12937000	USD
CY2012Q3	us-gaap	Regulatory Liability Noncurrent RegulatoryLiabilityNoncurrent	5638000	USD
CY2012Q3	us-gaap	Asset Retirement Obligations Noncurrent AssetRetirementObligationsNoncurrent	10394000	USD
CY2011Q3	us-gaap	Other Postretirement Defined Benefit Plan Liabilities Noncurrent OtherPostretirementDefinedBenefitPlanLiabilitiesNoncurrent	202709000	USD
CY2011Q3	us-gaap	Defined Benefit Pension Plan Liabilities Noncurrent DefinedBenefitPensionPlanLiabilitiesNoncurrent	236227000	USD
CY2011Q3	us-gaap	Customer Advances For Construction CustomerAdvancesForConstruction	13967000	USD
CY2011Q3	us-gaap	Regulatory Liability Noncurrent RegulatoryLiabilityNoncurrent	13823000	USD
CY2011Q3	us-gaap	Asset Retirement Obligations Noncurrent AssetRetirementObligationsNoncurrent	13574000	USD
CY2012	ato	Amount Of Dilutive Securities Stock Options And Restrictive Stock Units Discontinued Operations AmountOfDilutiveSecuritiesStockOptionsAndRestrictiveStockUnitsDiscontinuedOperations	0	USD
CY2011	ato	Amount Of Dilutive Securities Stock Options And Restrictive Stock Units Discontinued Operations AmountOfDilutiveSecuritiesStockOptionsAndRestrictiveStockUnitsDiscontinuedOperations	0	USD
CY2010	ato	Amount Of Dilutive Securities Stock Options And Restrictive Stock Units Discontinued Operations AmountOfDilutiveSecuritiesStockOptionsAndRestrictiveStockUnitsDiscontinuedOperations	0	USD
CY2012	ato	Net Income Loss From Discontinued Operations Available To Common Stockholders Diluted NetIncomeLossFromDiscontinuedOperationsAvailableToCommonStockholdersDiluted	24420000	USD
CY2011	ato	Net Income Loss From Discontinued Operations Available To Common Stockholders Diluted NetIncomeLossFromDiscontinuedOperationsAvailableToCommonStockholdersDiluted	17825000	USD
CY2010	ato	Net Income Loss From Discontinued Operations Available To Common Stockholders Diluted NetIncomeLossFromDiscontinuedOperationsAvailableToCommonStockholdersDiluted	15824000	USD
CY2012Q3	us-gaap	Derivative Liabilities Noncurrent DerivativeLiabilitiesNoncurrent	9206000	USD
CY2011Q3	us-gaap	Derivative Liabilities Noncurrent DerivativeLiabilitiesNoncurrent	78089000	USD
CY2012Q3	ato	Other Liabilities Noncurrent Other OtherLiabilitiesNoncurrentOther	12555000	USD
CY2011Q3	ato	Other Liabilities Noncurrent Other OtherLiabilitiesNoncurrentOther	6306000	USD
CY2012	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	191403000	USD
CY2011	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	187608000	USD
CY2010	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	187908000	USD
CY2012	ato	Undistributed Earnings From Discontinued Operations Allocated To Participating Securities UndistributedEarningsFromDiscontinuedOperationsAllocatedToParticipatingSecurities	101000	USD
CY2011	ato	Undistributed Earnings From Discontinued Operations Allocated To Participating Securities UndistributedEarningsFromDiscontinuedOperationsAllocatedToParticipatingSecurities	188000	USD
CY2010	ato	Undistributed Earnings From Discontinued Operations Allocated To Participating Securities UndistributedEarningsFromDiscontinuedOperationsAllocatedToParticipatingSecurities	164000	USD
CY2012	ato	Net Income Loss From Discontinued Operations Available To Common Stockholders Basic NetIncomeLossFromDiscontinuedOperationsAvailableToCommonStockholdersBasic	24420000	USD
CY2011	ato	Net Income Loss From Discontinued Operations Available To Common Stockholders Basic NetIncomeLossFromDiscontinuedOperationsAvailableToCommonStockholdersBasic	17825000	USD
CY2012	ato	Incremental Common Shares Attributable To Participating Nonvested Shares With Non Forfeitable Dividend Rights Discontinued Operations IncrementalCommonSharesAttributableToParticipatingNonvestedSharesWithNonForfeitableDividendRightsDiscontinuedOperations	1022000	shares
CY2011	ato	Incremental Common Shares Attributable To Participating Nonvested Shares With Non Forfeitable Dividend Rights Discontinued Operations IncrementalCommonSharesAttributableToParticipatingNonvestedSharesWithNonForfeitableDividendRightsDiscontinuedOperations	451000	shares
CY2010	ato	Incremental Common Shares Attributable To Participating Nonvested Shares With Non Forfeitable Dividend Rights Discontinued Operations IncrementalCommonSharesAttributableToParticipatingNonvestedSharesWithNonForfeitableDividendRightsDiscontinuedOperations	570000	shares
CY2012	ato	Weighted Average Number Of Diluted Shares Outstanding Discontinued Operations WeightedAverageNumberOfDilutedSharesOutstandingDiscontinuedOperations	91172000	shares
CY2011	ato	Weighted Average Number Of Diluted Shares Outstanding Discontinued Operations WeightedAverageNumberOfDilutedSharesOutstandingDiscontinuedOperations	90652000	shares
CY2010	ato	Weighted Average Number Of Diluted Shares Outstanding Discontinued Operations WeightedAverageNumberOfDilutedSharesOutstandingDiscontinuedOperations	92422000	shares
CY2012	us-gaap	Amount Of Dilutive Securities Stock Options And Restrictive Stock Units AmountOfDilutiveSecuritiesStockOptionsAndRestrictiveStockUnits	4000	USD
CY2012	us-gaap	Undistributed Earnings Allocated To Participating Securities UndistributedEarningsAllocatedToParticipatingSecurities	793000	USD
CY2011	us-gaap	Undistributed Earnings Allocated To Participating Securities UndistributedEarningsAllocatedToParticipatingSecurities	1980000	USD
CY2010	us-gaap	Undistributed Earnings Allocated To Participating Securities UndistributedEarningsAllocatedToParticipatingSecurities	1943000	USD
CY2012	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	631000	USD
CY2011	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	-13298000	USD
CY2010	ato	Net Income Loss From Discontinued Operations Available To Common Stockholders Basic NetIncomeLossFromDiscontinuedOperationsAvailableToCommonStockholdersBasic	15824000	USD
CY2011	us-gaap	Amount Of Dilutive Securities Stock Options And Restrictive Stock Units AmountOfDilutiveSecuritiesStockOptionsAndRestrictiveStockUnits	4000	USD
CY2010	us-gaap	Amount Of Dilutive Securities Stock Options And Restrictive Stock Units AmountOfDilutiveSecuritiesStockOptionsAndRestrictiveStockUnits	5000	USD
CY2012	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	191407000	USD
CY2011	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	187612000	USD
CY2010	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	187913000	USD
CY2010	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	-70884000	USD
CY2012	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	6888000	USD
CY2011	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	6841000	USD
CY2010	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	6849000	USD
CY2012	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	103971000	USD
CY2011	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	107950000	USD
CY2010	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	172690000	USD
CY2012	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	-13237000	USD
CY2011	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	5498000	USD
CY2010	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	10831000	USD
CY2012	ato	Investment Tax Credits InvestmentTaxCredits	-27000	USD
CY2010	ato	Investment Tax Credits InvestmentTaxCredits	-283000	USD
CY2011	ato	Investment Tax Credits InvestmentTaxCredits	-172000	USD
CY2012	us-gaap	Income Tax Reconciliation Nondeductible Expense Other IncomeTaxReconciliationNondeductibleExpenseOther	66000	USD
CY2010	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	108169000	USD
CY2012	us-gaap	Income Tax Reconciliation Deductions Dividends IncomeTaxReconciliationDeductionsDividends	2096000	USD
CY2011	us-gaap	Income Tax Reconciliation Deductions Dividends IncomeTaxReconciliationDeductionsDividends	1930000	USD
CY2010	us-gaap	Income Tax Reconciliation Deductions Dividends IncomeTaxReconciliationDeductionsDividends	1785000	USD
CY2012	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	-5958000	USD
CY2011	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	8109000	USD
CY2010	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	11493000	USD
CY2012	us-gaap	Income Tax Reconciliation Other Adjustments IncomeTaxReconciliationOtherAdjustments	2735000	USD
CY2011	us-gaap	Income Tax Reconciliation Other Adjustments IncomeTaxReconciliationOtherAdjustments	-445000	USD
CY2010	us-gaap	Income Tax Reconciliation Other Adjustments IncomeTaxReconciliationOtherAdjustments	1222000	USD
CY2012	us-gaap	Income Tax Reconciliation Tax Settlements Domestic IncomeTaxReconciliationTaxSettlementsDomestic	1831000	USD
CY2011	us-gaap	Income Tax Reconciliation Tax Settlements Domestic IncomeTaxReconciliationTaxSettlementsDomestic	-4950000	USD
CY2010	us-gaap	Income Tax Reconciliation Tax Settlements Domestic IncomeTaxReconciliationTaxSettlementsDomestic	0	USD
CY2012	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	101648000	USD
CY2011	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	103743000	USD
CY2011	us-gaap	Income Tax Reconciliation Nondeductible Expense Other IncomeTaxReconciliationNondeductibleExpenseOther	2292000	USD
CY2010	us-gaap	Income Tax Reconciliation Nondeductible Expense Other IncomeTaxReconciliationNondeductibleExpenseOther	104000	USD
CY2012Q3	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Accrued Liabilities DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAccruedLiabilities	7906000	USD
CY2011Q3	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Accrued Liabilities DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAccruedLiabilities	10327000	USD
CY2012Q3	ato	Deferred Tax Assets Customer Advances DeferredTaxAssetsCustomerAdvances	4721000	USD
CY2011Q3	ato	Deferred Tax Assets Customer Advances DeferredTaxAssetsCustomerAdvances	5271000	USD
CY2012Q3	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Other DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsOther	48513000	USD
CY2011Q3	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Other DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsOther	43924000	USD
CY2012Q3	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Postretirement Benefits DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsPostretirementBenefits	62802000	USD
CY2011Q3	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Postretirement Benefits DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsPostretirementBenefits	62274000	USD
CY2012Q3	us-gaap	Deferred Tax Assets Hedging Transactions DeferredTaxAssetsHedgingTransactions	25448000	USD
CY2011Q3	us-gaap	Deferred Tax Assets Hedging Transactions DeferredTaxAssetsHedgingTransactions	20060000	USD
CY2012Q3	us-gaap	Deferred Tax Assets Tax Credit Carryforwards General Business DeferredTaxAssetsTaxCreditCarryforwardsGeneralBusiness	14000	USD
CY2011Q3	us-gaap	Deferred Tax Assets Tax Credit Carryforwards General Business DeferredTaxAssetsTaxCreditCarryforwardsGeneralBusiness	120000	USD
CY2012Q3	ato	Total Estimated Purchase Commitments TotalEstimatedPurchaseCommitments	333839000	USD
CY2012Q3	ato	Deferred Tax Assets Operating Loss And Credit Carryforwards DeferredTaxAssetsOperatingLossAndCreditCarryforwards	164419000	USD
CY2011Q3	ato	Deferred Tax Assets Operating Loss And Credit Carryforwards DeferredTaxAssetsOperatingLossAndCreditCarryforwards	95293000	USD
CY2012Q3	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	7223000	USD
CY2011Q3	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	3529000	USD
CY2012Q3	us-gaap	Deferred Tax Assets Net DeferredTaxAssetsNet	323388000	USD
CY2011Q3	us-gaap	Deferred Tax Assets Net DeferredTaxAssetsNet	248837000	USD
CY2012Q3	us-gaap	Deferred Tax Liabilities Property Plant And Equipment DeferredTaxLiabilitiesPropertyPlantAndEquipment	1254698000	USD
CY2011Q3	us-gaap	Deferred Tax Liabilities Property Plant And Equipment DeferredTaxLiabilitiesPropertyPlantAndEquipment	1108063000	USD
CY2012Q3	us-gaap	Deferred Tax Liabilities Prepaid Pension Costs DeferredTaxLiabilitiesPrepaidPensionCosts	32812000	USD
CY2011Q3	us-gaap	Deferred Tax Liabilities Prepaid Pension Costs DeferredTaxLiabilitiesPrepaidPensionCosts	7533000	USD
CY2012Q3	us-gaap	Deferred Tax Liabilities Other DeferredTaxLiabilitiesOther	2065000	USD
CY2011Q3	us-gaap	Deferred Tax Liabilities Other DeferredTaxLiabilitiesOther	3039000	USD
CY2012Q3	us-gaap	Deferred Tax Liabilities DeferredTaxLiabilities	1311381000	USD
CY2011Q3	us-gaap	Deferred Tax Liabilities DeferredTaxLiabilities	1132205000	USD
CY2012Q3	us-gaap	Deferred Tax Assets Liabilities Net DeferredTaxAssetsLiabilitiesNet	-987993000	USD
CY2011Q3	us-gaap	Deferred Tax Assets Liabilities Net DeferredTaxAssetsLiabilitiesNet	-883368000	USD
CY2012Q3	ato	Deferred Tax Assets Deferred Credits DeferredTaxAssetsDeferredCredits	140000	USD
CY2011Q3	ato	Deferred Tax Assets Deferred Credits DeferredTaxAssetsDeferredCredits	325000	USD
CY2012Q3	us-gaap	Deferred Tax Assets Unrealized Losses On Availablefor Sale Securities Gross DeferredTaxAssetsUnrealizedLossesOnAvailableforSaleSecuritiesGross	2342000	USD
CY2011Q3	us-gaap	Deferred Tax Assets Unrealized Losses On Availablefor Sale Securities Gross DeferredTaxAssetsUnrealizedLossesOnAvailableforSaleSecuritiesGross	8039000	USD
CY2011Q3	us-gaap	Deferred Tax Liabilities Regulatory Assets DeferredTaxLiabilitiesRegulatoryAssets	13570000	USD
CY2012Q3	us-gaap	Deferred Tax Liabilities Regulatory Assets DeferredTaxLiabilitiesRegulatoryAssets	21806000	USD
CY2012Q3	us-gaap	Income Tax Examination Liability Recorded IncomeTaxExaminationLiabilityRecorded	1800000	USD
CY2012	us-gaap	Unrecognized Tax Benefits Income Tax Penalties And Interest Expense UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestExpense	10000	USD
CY2011	us-gaap	Unrecognized Tax Benefits Income Tax Penalties And Interest Expense UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestExpense	10000	USD
CY2010	us-gaap	Unrecognized Tax Benefits Income Tax Penalties And Interest Expense UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestExpense	500000	USD
CY2011Q3	us-gaap	Income Tax Examination Liability Recorded IncomeTaxExaminationLiabilityRecorded	6700000	USD
CY2012	us-gaap	Other Information Pertaining To Income Taxes OtherInformationPertainingToIncomeTaxes	results for fiscal 2012 were favorably impacted by a state tax benefit of $13.6 million.  Due to the completion of the sale of our Missouri, Iowa and Illinois service areas in the fiscal fourth quarter, the Company updated its analysis of the tax rate at which deferred taxes would reverse in the future to reflect the sale of these service areas.  The updated analysis supported a reduction in the deferred tax rate which when applied to the balance of taxable income deferred to future periods resulted in a reduction of the Company’s overall deferred tax liability.
CY2012	ato	Description Of Pending Litigation DescriptionOfPendingLitigation	Since April 2009, Atmos Energy and two subsidiaries of AEH, Atmos Energy Marketing, LLC (AEM) and Atmos Gathering Company, LLC (AGC) (collectively, the Atmos Entities), have been involved in a lawsuit filed in the Circuit Court of Edmonson County, Kentucky related to our Park City Gathering Project. The dispute which gave rise to the litigation involves the amount of royalties due from a third party producer to landowners (who own the mineral rights) for natural gas produced from the landowners’ properties. The third party producer was operating pursuant to leases between the landowners and certain investors/working interest owners. The third party producer filed a petition in bankruptcy, which was subsequently dismissed due to the lack of meaningful assets to reorganize or liquidate. Although certain Atmos Energy companies entered into contracts with the third party producer to gather, treat and ultimately sell natural gas produced from the landowners’ properties, no Atmos Energy company had a contractual relationship with the landowners or the investors/working interest owners. After the lawsuit was filed, the landowners were successful in terminating for non-payment of royalties the leases related to the production of natural gas from their properties. Subsequent to termination, the investors/working interest owners under such leases filed additional claims against us for the termination of the leases. During the trial, the landowners and the investors/working interest owners requested an award of compensatory damages plus punitive damages against us. On December 17, 2010, the jury returned a verdict in favor of the landowners and investor/working interest owners and awarded compensatory damages of $3.8 million and punitive damages of $27.5 million payable by Atmos Energy and the two AEH subsidiaries. A hearing was held on February 28, 2011 to hear a number of motions, including a motion to dismiss the jury verdict and a motion for a new trial. The motions to dismiss the jury verdict and for a new trial were denied. However, the total punitive damages award was reduced from $27.5 million to $24.7 million. On October 17, 2011, we filed our brief of appellants with the Kentucky Court of Appeals (Court), appealing the verdict of the trial court. The appellees in this case subsequently filed their appellees’ brief with the Court on January 16, 2012, with our reply brief being filed with the Court on March 19, 2012. Oral arguments were held in the case on August 27, 2012; however, the Court has yet to render a decision. In addition, in a related development, on July 12, 2011, the Atmos Entities filed a lawsuit in the United States District Court, Western District of Kentucky, Atmos Energy Corporation et al.vs. Resource Energy Technologies, LLC and Robert Thorpe and John F. Charles, against the third party producer and its affiliates to recover all costs, including attorneys’ fees, incurred by the Atmos Entities, which are associated with the defense and appeal of the case discussed above as well as for all damages awarded to the plaintiffs in such case against the Atmos Entities. The total amount of damages being claimed in the lawsuit is “open-ended” since the appellate process and related costs are ongoing. This lawsuit is based upon the indemnification provisions agreed to by the third party producer in favor of Atmos Gathering that are contained in an agreement entered into between Atmos Gathering and the third party producer in May 2009. The defendants filed a motion to dismiss the case on August 25, 2011, with Atmos Energy filing a brief in response to such motion on September 19, 2011. On March 27, 2012 the court denied the motion to dismiss. Since that time, we have been engaged in discovery activities in this case. We have accrued what we believe is an adequate amount for the anticipated resolution of this matter; however, the amount accrued is less than the amount of the verdict. The Company does not have insurance coverage that could mitigate any losses that may arise from the resolution of this matter; however, we believe that the final outcome will not have a material adverse effect on our financial condition, results of operations or cash flows.
CY2012Q3	ato	Long Term Purchase Commitment Minimum Quantity Required One To Three Years LongTermPurchaseCommitmentMinimumQuantityRequiredOneToThreeYears	29.0	Bcf
CY2012	ato	Significant Purchase Commitment Amount Description SignificantPurchaseCommitmentAmountDescription	978800000	USD
CY2011	ato	Significant Purchase Commitment Amount Description SignificantPurchaseCommitmentAmountDescription	1498600000	USD
CY2010	ato	Significant Purchase Commitment Amount Description SignificantPurchaseCommitmentAmountDescription	1562800000	USD
CY2012Q3	ato	Significant Purchase Commitment Remaining Minimum Amount Committed Next Fiscal Year SignificantPurchaseCommitmentRemainingMinimumAmountCommittedNextFiscalYear	259235000	USD
CY2012Q3	ato	Significant Purchase Commitment Remaining Minimum Amount Committed Second Fiscal Year SignificantPurchaseCommitmentRemainingMinimumAmountCommittedSecondFiscalYear	74604000	USD
CY2012Q3	ato	Significant Purchase Commitment Remaining Minimum Amount Committed Third Fiscal Year SignificantPurchaseCommitmentRemainingMinimumAmountCommittedThirdFiscalYear	0	USD
CY2012Q3	ato	Significant Purchase Commitment Remaining Minimum Amount Committed Fourth Fiscal Year SignificantPurchaseCommitmentRemainingMinimumAmountCommittedFourthFiscalYear	0	USD
CY2012Q3	ato	Significant Purchase Commitment Remaining Minimum Amount Committed Fifth Fiscal Year SignificantPurchaseCommitmentRemainingMinimumAmountCommittedFifthFiscalYear	0	USD
CY2012Q3	ato	Significant Purchase Commitment Remaining Minimum Amount Committed Thereafter SignificantPurchaseCommitmentRemainingMinimumAmountCommittedThereafter	0	USD
CY2012Q3	ato	Contractual Demand Fees Demand Fees Due Next Fiscal Year ContractualDemandFeesDemandFeesDueNextFiscalYear	19456000	USD
CY2012Q3	ato	Contractual Demand Fees Demand Fees Due Second Fiscal Year ContractualDemandFeesDemandFeesDueSecondFiscalYear	10554000	USD
CY2012Q3	ato	Contractual Demand Fees Demand Fees Due Third Fiscal Year ContractualDemandFeesDemandFeesDueThirdFiscalYear	4504000	USD
CY2012Q3	ato	Contractual Demand Fees Demand Fees Due Fourth Fiscal Year ContractualDemandFeesDemandFeesDueFourthFiscalYear	278000	USD
CY2012Q3	ato	Contractual Demand Fees Demand Fees Due Fifth Fiscal Year ContractualDemandFeesDemandFeesDueFifthFiscalYear	37000	USD
CY2012Q3	ato	Contractual Demand Fees Demand Fees Due Thereafter ContractualDemandFeesDemandFeesDueThereafter	128000	USD
CY2012Q3	ato	Total Estimated Contractual Demand Fees TotalEstimatedContractualDemandFees	34957000	USD
CY2012	us-gaap	Loss Contingency Settlement Agreement Consideration LossContingencySettlementAgreementConsideration	In December 2007, the Company received data requests from the Division of Investigations of the Office of Enforcement of the Federal Energy Regulatory Commission (the "Commission") in connection with its investigation into possible violations of the Commission’s posting and competitive bidding regulations for pre-arranged released firm capacity on natural gas pipelines. The Company and the Commission entered into a stipulation and consent agreement, which was approved by the Commission on December 9, 2011, thereby resolving this investigation. The Commission’s findings of violations were limited to the nonregulated operations of the Company. Under the terms of the agreement, the Company paid to the United States Treasury a total civil penalty of approximately $6.4 million and to energy assistance programs approximately $5.6 million in disgorgement of unjust profits plus interest for violations identified during the investigation. The resolution of this matter did not have a material adverse impact on the Company’s financial position, results of operations or cash flows and none of the payments were charged to any of the Company’s customers. In addition, none of the services the Company provides to any of its regulated or nonregulated customers were affected by the agreement.
CY2012	ato	Steel Service Line Replacement Cost SteelServiceLineReplacementCost	116300000	USD
CY2011Q3	us-gaap	Capital Leased Assets Gross CapitalLeasedAssetsGross	1300000	USD
CY2011	ato	Capital Leases Accumulated Depreciation CapitalLeasesAccumulatedDepreciation	900000	USD
CY2012Q3	us-gaap	Capital Leased Assets Gross CapitalLeasedAssetsGross	1300000	USD
CY2012	ato	Capital Leases Accumulated Depreciation CapitalLeasesAccumulatedDepreciation	900000	USD
CY2012Q3	us-gaap	Capital Leases Future Minimum Payments Due Current CapitalLeasesFutureMinimumPaymentsDueCurrent	186000	USD
CY2012Q3	us-gaap	Capital Leases Future Minimum Payments Due In Two Years CapitalLeasesFutureMinimumPaymentsDueInTwoYears	186000	USD
CY2012Q3	us-gaap	Capital Leases Future Minimum Payments Due In Three Years CapitalLeasesFutureMinimumPaymentsDueInThreeYears	186000	USD
CY2012Q3	us-gaap	Capital Leases Future Minimum Payments Due In Four Years CapitalLeasesFutureMinimumPaymentsDueInFourYears	186000	USD
CY2012Q3	us-gaap	Capital Leases Future Minimum Payments Due In Five Years CapitalLeasesFutureMinimumPaymentsDueInFiveYears	186000	USD
CY2012Q3	us-gaap	Capital Leases Future Minimum Payments Due Thereafter CapitalLeasesFutureMinimumPaymentsDueThereafter	78000	USD
CY2012Q3	us-gaap	Capital Leases Future Minimum Payments Due CapitalLeasesFutureMinimumPaymentsDue	1008000	USD
CY2012Q3	ato	Capital Lease Interest Included In Lease Payments CapitalLeaseInterestIncludedInLeasePayments	286000	USD
CY2012Q3	us-gaap	Capital Leases Future Minimum Payments Present Value Of Net Minimum Payments CapitalLeasesFutureMinimumPaymentsPresentValueOfNetMinimumPayments	722000	USD
CY2012Q3	us-gaap	Operating Leases Future Minimum Payments Due Current OperatingLeasesFutureMinimumPaymentsDueCurrent	17571000	USD
CY2012Q3	us-gaap	Operating Leases Future Minimum Payments Due In Two Years OperatingLeasesFutureMinimumPaymentsDueInTwoYears	17215000	USD
CY2012Q3	us-gaap	Operating Leases Future Minimum Payments Due In Three Years OperatingLeasesFutureMinimumPaymentsDueInThreeYears	15940000	USD
CY2012Q3	us-gaap	Operating Leases Future Minimum Payments Due In Four Years OperatingLeasesFutureMinimumPaymentsDueInFourYears	15036000	USD
CY2012Q3	us-gaap	Operating Leases Future Minimum Payments Due In Five Years OperatingLeasesFutureMinimumPaymentsDueInFiveYears	14597000	USD
CY2012Q3	us-gaap	Operating Leases Future Minimum Payments Due Thereafter OperatingLeasesFutureMinimumPaymentsDueThereafter	100632000	USD
CY2012Q3	us-gaap	Operating Leases Future Minimum Payments Due OperatingLeasesFutureMinimumPaymentsDue	180991000	USD
CY2010Q3	ato	Lease And Rental Expense1 LeaseAndRentalExpense1	36700000	USD
CY2011Q3	ato	Lease And Rental Expense1 LeaseAndRentalExpense1	35500000	USD
CY2012Q3	ato	Lease And Rental Expense1 LeaseAndRentalExpense1	33600000	USD
CY2012Q3	ato	Percentage Of Aem Investment Grade Customers PercentageOfAemInvestmentGradeCustomers	0.60	pure
CY2011Q3	ato	Percentage Of Aem Investment Grade Customers PercentageOfAemInvestmentGradeCustomers	0.54	pure
CY2012Q3	ato	Percentage Of Aem Non Investment Grade Customers PercentageOfAemNonInvestmentGradeCustomers	0.40	pure
CY2011Q3	ato	Percentage Of Aem Non Investment Grade Customers PercentageOfAemNonInvestmentGradeCustomers	0.46	pure
CY2012Q3	ato	Percentage Of Total Aem Customers PercentageOfTotalAemCustomers	1.00	pure
CY2011Q3	ato	Percentage Of Total Aem Customers PercentageOfTotalAemCustomers	1.00	pure
CY2012Q3	ato	Investment Grade Counterparty Credit Exposure InvestmentGradeCounterpartyCreditExposure	4000	USD
CY2012Q3	ato	Non Investment Grade Counterparty Credit Exposure NonInvestmentGradeCounterpartyCreditExposure	0	USD
CY2012Q3	ato	Total Counterparty Credit Exposure TotalCounterpartyCreditExposure	4000	USD
CY2012	us-gaap	Interest Paid InterestPaid	150606000	USD
CY2011	us-gaap	Interest Paid InterestPaid	157976000	USD
CY2010	us-gaap	Interest Paid InterestPaid	161925000	USD
CY2012	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	-432000	USD
CY2011	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	-8329000	USD
CY2010	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	-63677000	USD
CY2012	us-gaap	Revenues From External Customers RevenuesFromExternalCustomers	3438483000	USD
CY2012	us-gaap	Revenues From Transactions With Other Operating Segments Of Same Entity RevenuesFromTransactionsWithOtherOperatingSegmentsOfSameEntity	0	USD
CY2011	us-gaap	Revenues From External Customers RevenuesFromExternalCustomers	4286435000	USD
CY2011	us-gaap	Revenues From Transactions With Other Operating Segments Of Same Entity RevenuesFromTransactionsWithOtherOperatingSegmentsOfSameEntity	0	USD
CY2010	us-gaap	Revenues From External Customers RevenuesFromExternalCustomers	4661060000	USD
CY2010	us-gaap	Revenues From Transactions With Other Operating Segments Of Same Entity RevenuesFromTransactionsWithOtherOperatingSegmentsOfSameEntity	0	USD
CY2011Q3	ato	Segment Reporting Information Other Current Liabilities SegmentReportingInformationOtherCurrentLiabilities	643315000	USD
CY2011Q3	ato	Intercompany Payables IntercompanyPayables	0	USD
CY2011Q3	ato	Segment Reporting Information Other Noncurrent Liabilities SegmentReportingInformationOtherNoncurrentLiabilities	486606000	USD
CY2011Q4	us-gaap	Gross Profit GrossProfit	355392000	USD
CY2011Q4	us-gaap	Operating Income Loss OperatingIncomeLoss	139471000	USD
CY2012	ato	Gas Sales Revenue Residential GasSalesRevenueResidential	1351479000	USD
CY2011	ato	Gas Sales Revenue Residential GasSalesRevenueResidential	1535887000	USD
CY2010	ato	Gas Sales Revenue Residential GasSalesRevenueResidential	1751186000	USD
CY2012	ato	Gas Sales Revenue Commercial GasSalesRevenueCommercial	587651000	USD
CY2011	ato	Gas Sales Revenue Commercial GasSalesRevenueCommercial	685380000	USD
CY2010	ato	Gas Sales Revenue Commercial GasSalesRevenueCommercial	775714000	USD
CY2012	ato	Gas Sales Revenue Industrial GasSalesRevenueIndustrial	71960000	USD
CY2011	ato	Gas Sales Revenue Industrial GasSalesRevenueIndustrial	96636000	USD
CY2010	ato	Gas Sales Revenue Industrial GasSalesRevenueIndustrial	101814000	USD
CY2012	ato	Gas Sales Revenue Public Authority And Other GasSalesRevenuePublicAuthorityAndOther	54334000	USD
CY2011	ato	Gas Sales Revenue Public Authority And Other GasSalesRevenuePublicAuthorityAndOther	68676000	USD
CY2010	ato	Gas Sales Revenue Public Authority And Other GasSalesRevenuePublicAuthorityAndOther	69944000	USD
CY2012	ato	Gas Sales Revenue GasSalesRevenue	2065424000	USD
CY2011	ato	Gas Sales Revenue GasSalesRevenue	2386579000	USD
CY2010	ato	Gas Sales Revenue GasSalesRevenue	2698658000	USD
CY2012	ato	Gas Transportation Revenue GasTransportationRevenue	53924000	USD
CY2011	ato	Gas Transportation Revenue GasTransportationRevenue	57331000	USD
CY2010	ato	Gas Transportation Revenue GasTransportationRevenue	56539000	USD
CY2012	ato	Gas Revenue Other GasRevenueOther	25028000	USD
CY2011	ato	Gas Revenue Other GasRevenueOther	25871000	USD
CY2010	ato	Gas Revenue Other GasRevenueOther	27796000	USD
CY2012Q3	ato	Investment In Subsidaries InvestmentInSubsidaries	0	USD
CY2012Q3	ato	Segment Reporting Information Other Current Assets SegmentReportingInformationOtherCurrentAssets	739016000	USD
CY2012Q3	ato	Intercompany Receivables IntercompanyReceivables	0	USD
CY2012Q3	us-gaap	Finite Lived Intangible Assets Net FiniteLivedIntangibleAssetsNet	164000	USD
CY2012Q3	us-gaap	Goodwill Goodwill	740683000	USD
CY2012Q3	ato	Segment Reporting Information Other Noncurrent Assets SegmentReportingInformationOtherNoncurrentAssets	448979000	USD
CY2012Q3	ato	Segment Reporting Information Other Current Liabilities SegmentReportingInformationOtherCurrentLiabilities	619513000	USD
CY2012Q3	ato	Intercompany Payables IntercompanyPayables	0	USD
CY2012Q3	ato	Segment Reporting Information Other Noncurrent Liabilities SegmentReportingInformationOtherNoncurrentLiabilities	498720000	USD
CY2011Q3	ato	Investment In Subsidaries InvestmentInSubsidaries	0	USD
CY2011Q3	ato	Segment Reporting Information Other Current Assets SegmentReportingInformationOtherCurrentAssets	861190000	USD
CY2011Q3	ato	Intercompany Receivables IntercompanyReceivables	0	USD
CY2011Q3	us-gaap	Finite Lived Intangible Assets Net FiniteLivedIntangibleAssetsNet	207000	USD
CY2011Q3	us-gaap	Goodwill Goodwill	740000000	USD
CY2011Q3	ato	Segment Reporting Information Other Noncurrent Assets SegmentReportingInformationOtherNoncurrentAssets	382795000	USD
CY2011Q4	us-gaap	Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest	62384000	USD
CY2011Q4	us-gaap	Discontinued Operation Income Loss From Discontinued Operation During Phase Out Period Net Of Tax DiscontinuedOperationIncomeLossFromDiscontinuedOperationDuringPhaseOutPeriodNetOfTax	6123000	USD
CY2011Q4	us-gaap	Net Income Loss NetIncomeLoss	68507000	USD
CY2011Q4	us-gaap	Income Loss From Continuing Operations Per Basic Share IncomeLossFromContinuingOperationsPerBasicShare	0.68
CY2011Q4	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Basic Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicShare	0.07
CY2011Q4	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.75
CY2011Q4	us-gaap	Income Loss From Continuing Operations Per Diluted Share IncomeLossFromContinuingOperationsPerDilutedShare	0.68
CY2011Q4	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Diluted Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare	0.07
CY2011Q4	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.75
CY2012Q1	us-gaap	Gross Profit GrossProfit	425787000	USD
CY2012Q1	us-gaap	Operating Income Loss OperatingIncomeLoss	202432000	USD
CY2012Q1	us-gaap	Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest	102084000	USD
CY2012Q1	us-gaap	Discontinued Operation Income Loss From Discontinued Operation During Phase Out Period Net Of Tax DiscontinuedOperationIncomeLossFromDiscontinuedOperationDuringPhaseOutPeriodNetOfTax	7027000	USD
CY2012Q1	us-gaap	Net Income Loss NetIncomeLoss	109111000	USD
CY2012Q1	us-gaap	Income Loss From Continuing Operations Per Basic Share IncomeLossFromContinuingOperationsPerBasicShare	1.12
CY2012Q1	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Basic Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicShare	0.08
CY2012Q1	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.20
CY2012Q1	us-gaap	Income Loss From Continuing Operations Per Diluted Share IncomeLossFromContinuingOperationsPerDilutedShare	1.12
CY2012Q1	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Diluted Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare	0.08
CY2012Q1	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.20
CY2012Q2	us-gaap	Gross Profit GrossProfit	293171000	USD
CY2012Q2	us-gaap	Operating Income Loss OperatingIncomeLoss	81546000	USD
CY2012Q2	us-gaap	Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest	28014000	USD
CY2012Q2	us-gaap	Discontinued Operation Income Loss From Discontinued Operation During Phase Out Period Net Of Tax DiscontinuedOperationIncomeLossFromDiscontinuedOperationDuringPhaseOutPeriodNetOfTax	3118000	USD
CY2012Q2	us-gaap	Net Income Loss NetIncomeLoss	31132000	USD
CY2012Q2	us-gaap	Income Loss From Continuing Operations Per Basic Share IncomeLossFromContinuingOperationsPerBasicShare	0.31
CY2012Q2	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Basic Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicShare	0.03
CY2012Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.34
CY2012Q2	us-gaap	Income Loss From Continuing Operations Per Diluted Share IncomeLossFromContinuingOperationsPerDilutedShare	0.31
CY2012Q2	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Diluted Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare	0.03
CY2012Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.34
CY2012Q3	us-gaap	Gross Profit GrossProfit	249389000	USD
CY2012Q3	us-gaap	Operating Income Loss OperatingIncomeLoss	22791000	USD
CY2012Q3	us-gaap	Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest	-286000	USD
CY2012Q3	us-gaap	Discontinued Operation Income Loss From Discontinued Operation During Phase Out Period Net Of Tax DiscontinuedOperationIncomeLossFromDiscontinuedOperationDuringPhaseOutPeriodNetOfTax	1904000	USD
CY2012Q3	us-gaap	Net Income Loss NetIncomeLoss	7967000	USD
CY2012Q3	us-gaap	Income Loss From Continuing Operations Per Basic Share IncomeLossFromContinuingOperationsPerBasicShare	0.00
CY2012Q3	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Basic Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicShare	0.09
CY2012Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.09
CY2012Q3	us-gaap	Income Loss From Continuing Operations Per Diluted Share IncomeLossFromContinuingOperationsPerDilutedShare	0.00
CY2012Q3	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Diluted Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare	0.09
CY2012Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.09
CY2010Q4	us-gaap	Gross Profit GrossProfit	357582000	USD
CY2010Q4	us-gaap	Operating Income Loss OperatingIncomeLoss	150773000	USD
CY2010Q4	us-gaap	Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest	68208000	USD
CY2010Q4	us-gaap	Discontinued Operation Income Loss From Discontinued Operation During Phase Out Period Net Of Tax DiscontinuedOperationIncomeLossFromDiscontinuedOperationDuringPhaseOutPeriodNetOfTax	5789000	USD
CY2010Q4	us-gaap	Net Income Loss NetIncomeLoss	73997000	USD
CY2010Q4	us-gaap	Income Loss From Continuing Operations Per Basic Share IncomeLossFromContinuingOperationsPerBasicShare	0.75
CY2010Q4	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Basic Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicShare	0.06
CY2010Q4	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.81
CY2010Q4	us-gaap	Income Loss From Continuing Operations Per Diluted Share IncomeLossFromContinuingOperationsPerDilutedShare	0.75
CY2010Q4	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Diluted Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare	0.06
CY2010Q4	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.81
CY2011Q1	us-gaap	Gross Profit GrossProfit	444466000	USD
CY2011Q1	us-gaap	Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest	124293000	USD
CY2011Q1	us-gaap	Discontinued Operation Income Loss From Discontinued Operation During Phase Out Period Net Of Tax DiscontinuedOperationIncomeLossFromDiscontinuedOperationDuringPhaseOutPeriodNetOfTax	7916000	USD
CY2011Q1	us-gaap	Net Income Loss NetIncomeLoss	132209000	USD
CY2011Q1	us-gaap	Income Loss From Continuing Operations Per Basic Share IncomeLossFromContinuingOperationsPerBasicShare	1.36
CY2011Q1	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Basic Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicShare	0.09
CY2011Q1	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.45
CY2011Q1	us-gaap	Income Loss From Continuing Operations Per Diluted Share IncomeLossFromContinuingOperationsPerDilutedShare	1.36
CY2011Q1	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Diluted Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare	0.09
CY2011Q1	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.45
CY2011Q2	us-gaap	Gross Profit GrossProfit	261612000	USD
CY2011Q2	us-gaap	Discontinued Operation Income Loss From Discontinued Operation During Phase Out Period Net Of Tax DiscontinuedOperationIncomeLossFromDiscontinuedOperationDuringPhaseOutPeriodNetOfTax	2584000	USD
CY2011Q2	us-gaap	Net Income Loss NetIncomeLoss	-566000	USD
CY2011Q2	us-gaap	Income Loss From Continuing Operations Per Basic Share IncomeLossFromContinuingOperationsPerBasicShare	-0.04
CY2011Q2	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Basic Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicShare	0.03
CY2011Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	-0.01
CY2011Q2	us-gaap	Income Loss From Continuing Operations Per Diluted Share IncomeLossFromContinuingOperationsPerDilutedShare	-0.04
CY2011Q2	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Diluted Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare	0.03
CY2011Q2	us-gaap	Operating Income Loss OperatingIncomeLoss	31394000	USD
CY2011Q3	us-gaap	Operating Income Loss OperatingIncomeLoss	39195000	USD
CY2011Q2	us-gaap	Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest	-3150000	USD
CY2011Q3	us-gaap	Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest	237000	USD
CY2011Q3	us-gaap	Discontinued Operation Income Loss From Discontinued Operation During Phase Out Period Net Of Tax DiscontinuedOperationIncomeLossFromDiscontinuedOperationDuringPhaseOutPeriodNetOfTax	1724000	USD
CY2011Q4	us-gaap	Regulated And Unregulated Operating Revenue RegulatedAndUnregulatedOperatingRevenue	1083994000	USD
CY2011Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	-0.01
CY2011Q3	us-gaap	Gross Profit GrossProfit	237160000	USD
CY2011Q3	us-gaap	Net Income Loss NetIncomeLoss	1961000	USD
CY2011Q3	us-gaap	Income Loss From Continuing Operations Per Basic Share IncomeLossFromContinuingOperationsPerBasicShare	0.00
CY2011Q3	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Basic Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicShare	0.02
CY2011Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.02
CY2011Q3	us-gaap	Income Loss From Continuing Operations Per Diluted Share IncomeLossFromContinuingOperationsPerDilutedShare	0.00
CY2011Q3	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Diluted Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare	0.02
CY2011Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.02
CY2011Q4	us-gaap	Discontinued Operation Gain Loss On Disposal Of Discontinued Operation Net Of Tax DiscontinuedOperationGainLossOnDisposalOfDiscontinuedOperationNetOfTax	0	USD
CY2012Q1	us-gaap	Discontinued Operation Gain Loss On Disposal Of Discontinued Operation Net Of Tax DiscontinuedOperationGainLossOnDisposalOfDiscontinuedOperationNetOfTax	0	USD
CY2012Q2	us-gaap	Discontinued Operation Gain Loss On Disposal Of Discontinued Operation Net Of Tax DiscontinuedOperationGainLossOnDisposalOfDiscontinuedOperationNetOfTax	0	USD
CY2012Q3	us-gaap	Discontinued Operation Gain Loss On Disposal Of Discontinued Operation Net Of Tax DiscontinuedOperationGainLossOnDisposalOfDiscontinuedOperationNetOfTax	6349000	USD
CY2012Q1	us-gaap	Regulated And Unregulated Operating Revenue RegulatedAndUnregulatedOperatingRevenue	1225509000	USD
CY2012Q2	us-gaap	Regulated And Unregulated Operating Revenue RegulatedAndUnregulatedOperatingRevenue	576414000	USD
CY2012Q3	us-gaap	Regulated And Unregulated Operating Revenue RegulatedAndUnregulatedOperatingRevenue	552566000	USD
CY2010Q4	us-gaap	Regulated And Unregulated Operating Revenue RegulatedAndUnregulatedOperatingRevenue	1117226000	USD
CY2011Q1	us-gaap	Regulated And Unregulated Operating Revenue RegulatedAndUnregulatedOperatingRevenue	1556374000	USD
CY2011Q2	us-gaap	Regulated And Unregulated Operating Revenue RegulatedAndUnregulatedOperatingRevenue	833168000	USD
CY2011Q3	us-gaap	Regulated And Unregulated Operating Revenue RegulatedAndUnregulatedOperatingRevenue	779667000	USD
CY2011Q1	us-gaap	Operating Income Loss OperatingIncomeLoss	204624000	USD
CY2011Q4	us-gaap	Quarterly Financial Information Explanatory Disclosure QuarterlyFinancialInformationExplanatoryDisclosure	Operating revenues for natural gas distribution, gross profit and operating income are shown net of discontinued operations from our Georgia operations of $17.2 million, $7.5 million and $4.9 million, which were not previously reported as discontinued operations.
CY2012Q1	us-gaap	Quarterly Financial Information Explanatory Disclosure QuarterlyFinancialInformationExplanatoryDisclosure	Operating revenues for natural gas distribution, gross profit and operating income are shown net of discontinued operations from our Georgia operations of $17.9 million, $8.5 million and $5.9 million, which were not previously reported as discontinued operations.
CY2012Q2	us-gaap	Quarterly Financial Information Explanatory Disclosure QuarterlyFinancialInformationExplanatoryDisclosure	Operating revenues for natural gas distribution, gross profit and operating income are shown net of discontinued operations from our Georgia operations of $9.4 million, $5.6 million and $3.2 million, which were not previously reported as discontinued operations.
CY2010Q4	us-gaap	Quarterly Financial Information Explanatory Disclosure QuarterlyFinancialInformationExplanatoryDisclosure	Operating revenues for natural gas distribution, gross profit and operating income are shown net of discontinued operations from our Georgia operations of $16.0 million, $7.1 million and $4.5 million, which were not previously reported as discontinued operations.
CY2011Q1	us-gaap	Quarterly Financial Information Explanatory Disclosure QuarterlyFinancialInformationExplanatoryDisclosure	Operating revenues for natural gas distribution, gross profit and operating income are shown net of discontinued operations from our Georgia operations of $25.1 million, $9.2 million and $6.6 million, which were not previously reported as discontinued operations.
CY2011Q2	us-gaap	Quarterly Financial Information Explanatory Disclosure QuarterlyFinancialInformationExplanatoryDisclosure	Operating revenues for natural gas distribution, gross profit and operating income are shown net of discontinued operations from our Georgia operations of $10.4 million, $5.2 million and $2.7 million, which were not previously reported as discontinued operations.
CY2011Q3	us-gaap	Quarterly Financial Information Explanatory Disclosure QuarterlyFinancialInformationExplanatoryDisclosure	Operating revenues for natural gas distribution, gross profit and operating income are shown net of discontinued operations from our Georgia operations of $9.6 million, $4.9 million and $2.1 million, which were not previously reported as discontinued operations.

Files In Submission

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$ATO
Atmos Energy Corp Stock $ato

2011 Q3 Form 10-K Financial Statement

#000119312512466518 Filed on November 13, 2012

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$ATO Atmos Energy Corp Stock $ato

2011 Q3 Form 10-K Financial Statement

#000119312512466518 Filed on November 13, 2012

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$ATO
Atmos Energy Corp Stock $ato