$ATO
Atmos Energy Corp Stock $ato

$ato Overview Financials Valuation SEC Filings Company Website

2021 Q3 Form 10-K Financial Statement

#000073180221000040 Filed on November 12, 2021

Income Statement

Concept	2021 Q3	2021	2020 Q3
Revenue	$568.4M	$3.407B	$474.9M
YoY Change	19.68%	20.78%	7.04%
Cost Of Revenue	$83.78M	$1.033B	$18.00M
YoY Change	365.43%	56.74%	31.39%
Gross Profit	$484.6M	$2.375B	$456.9M
YoY Change	6.06%	9.83%	6.26%
Gross Profit Margin	85.26%	69.69%	96.21%
Selling, General & Admin
YoY Change
% of Gross Profit
Research & Development
YoY Change
% of Gross Profit
Depreciation & Amortization	$124.7M	$478.0M	$111.7M
YoY Change	11.65%	11.2%	10.59%
% of Gross Profit	25.73%	20.13%	24.45%
Operating Expenses	$393.6M	$1.470B	$356.1M
YoY Change	10.54%	9.84%	4.64%
Operating Profit	$90.96M	$905.0M	$100.8M
YoY Change	-9.8%	9.82%	12.41%
Interest Expense	-$14.49M	$83.55M	-$15.50M
YoY Change	-6.54%	-1.09%	-46.18%
% of Operating Profit	-15.92%	9.23%	-15.37%
Other Income/Expense, Net	-$16.94M	-$2.145M	-$2.000M
YoY Change	746.9%	-129.91%	-121.51%
Pretax Income	$59.54M	$819.3M	$83.40M
YoY Change	-28.61%	9.71%	18.8%
Income Tax	$10.82M	$153.7M	$18.10M
% Of Pretax Income	18.17%	18.76%	21.7%
Net Earnings	$48.72M	$665.6M	$65.33M
YoY Change	-25.43%	10.66%	11.86%
Net Earnings / Revenue	8.57%	19.53%	13.76%
Basic Earnings Per Share		$5.12	$0.53
Diluted Earnings Per Share	$370.1K	$5.12	$0.53
COMMON SHARES
Basic Shares Outstanding	130.8M shares	129.8M shares	123.4M shares
Diluted Shares Outstanding		129.8M shares

Balance Sheet

Concept	2021 Q3	2021	2020 Q3
SHORT-TERM ASSETS
Cash & Short-Term Investments	$224.8M	$116.7M	$124.8M
YoY Change	80.18%	455.82%	399.04%
Cash & Equivalents	$116.7M	$116.7M	$20.81M
Short-Term Investments	$108.1M		$104.0M
Other Short-Term Assets	$2.201B	$2.185B	$107.9M
YoY Change	1939.67%	2063.69%	48.28%
Inventory	$178.1M	$193.7M	$112.0M
Prepaid Expenses	$48.77M		$40.34M
Receivables	$343.0M	$270.1M	$230.6M
Other Receivables	$0.00	$72.82M	$0.00
Total Short-Term Assets	$2.839B	$2.839B	$471.3M
YoY Change	502.37%	502.7%	2.89%
LONG-TERM ASSETS
Property, Plant & Equipment	$15.29B	$15.29B	$13.58B
YoY Change	12.55%	12.55%	15.22%
Goodwill	$731.3M		$731.3M
YoY Change	0.0%		0.08%
Intangibles
YoY Change
Long-Term Investments		$108.1M
YoY Change		3.91%
Other Assets	$974.7M	$644.2M	$801.2M
YoY Change	21.66%	37.06%	104.79%
Total Long-Term Assets	$16.77B	$16.77B	$14.89B
YoY Change	12.64%	12.64%	15.32%
TOTAL ASSETS
Total Short-Term Assets	$2.839B	$2.839B	$471.3M
Total Long-Term Assets	$16.77B	$16.77B	$14.89B
Total Assets	$19.61B	$19.61B	$15.36B
YoY Change	27.67%	27.67%	14.9%
SHORT-TERM LIABILITIES
YoY Change
Accounts Payable	$423.2M	$224.9M	$236.0M
YoY Change	79.33%	59.48%	-10.94%
Accrued Expenses	$37.69M	$341.7M	$36.00M
YoY Change	4.69%	41.79%
Deferred Revenue	$49.72M		$56.49M
YoY Change	-11.97%		3.42%
Short-Term Debt	$0.00	$0.00	$0.00
YoY Change			-100.0%
Long-Term Debt Due	$2.400B	$2.400B	$0.00
YoY Change
Total Short-Term Liabilities	$3.510B	$3.510B	$782.4M
YoY Change	348.66%	348.89%	-35.31%
LONG-TERM LIABILITIES
Long-Term Debt	$4.930B	$4.930B	$4.532B
YoY Change	8.79%	8.79%	28.41%
Other Long-Term Liabilities	$537.5M	$1.555B	$642.1M
YoY Change	-16.3%	-13.44%	60.45%
Total Long-Term Liabilities	$537.5M	$6.486B	$642.1M
YoY Change	-16.3%	2.47%	-83.66%
TOTAL LIABILITIES
Total Short-Term Liabilities	$3.510B	$3.510B	$782.4M
Total Long-Term Liabilities	$537.5M	$6.486B	$642.1M
Total Liabilities	$4.048B	$11.70B	$1.425B
YoY Change	184.15%	36.58%	-72.28%
SHAREHOLDERS EQUITY
Retained Earnings	$2.813B		$2.471B
YoY Change	13.83%		14.82%
Common Stock	$5.024B		$4.378B
YoY Change	14.77%		17.91%
Preferred Stock
YoY Change
Treasury Stock (at cost)
YoY Change
Treasury Stock Shares
Shareholders Equity	$7.907B	$7.907B	$6.791B
YoY Change
Total Liabilities & Shareholders Equity	$19.61B	$19.61B	$15.36B
YoY Change	27.67%	27.67%	14.9%

Cashflow Statement

Concept	2021 Q3	2021	2020 Q3
OPERATING ACTIVITIES
Net Income	$48.72M	$665.6M	$65.33M
YoY Change	-25.43%	10.66%	11.86%
Depreciation, Depletion And Amortization	$124.7M	$478.0M	$111.7M
YoY Change	11.65%	11.2%	10.59%
Cash From Operating Activities	$74.22M	-$1.084B	$142.5M
YoY Change	-47.92%	-204.46%	-10.88%
INVESTING ACTIVITIES
Capital Expenditures	-$611.6M	-$1.970B	-$530.0M
YoY Change	15.39%	1.75%	7.22%
Acquisitions
YoY Change
Other Investing Activities	$242.0K	-$11.96M	$4.800M
YoY Change	-94.96%	23.69%	-20.0%
Cash From Investing Activities	-$611.3M	-$1.964B	-$525.2M
YoY Change	16.4%	1.98%	7.56%
FINANCING ACTIVITIES
Cash Dividend Paid
YoY Change
Common Stock Issuance & Retirement, Net		$606.7M
YoY Change		-2.82%
Debt Paid & Issued, Net		$0.00
YoY Change
Cash From Financing Activities	129.2M	$3.144B	195.5M
YoY Change	-33.9%	255.73%	-36.28%
NET CHANGE
Cash From Operating Activities	74.22M	-$1.084B	142.5M
Cash From Investing Activities	-611.3M	-$1.964B	-525.2M
Cash From Financing Activities	129.2M	$3.144B	195.5M
Net Change In Cash	-407.9M	$95.92M	-187.2M
YoY Change	117.89%	-2663.2%	766.67%
FREE CASH FLOW
Cash From Operating Activities	$74.22M	-$1.084B	$142.5M
Capital Expenditures	-$611.6M	-$1.970B	-$530.0M
Free Cash Flow	$685.8M	$885.3M	$672.5M
YoY Change	1.98%	-70.23%	2.8%

Facts In Submission

Frame	Concept Type	Concept / XBRL Key	Value	Unit
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CY2021	dei	Document Fiscal Year Focus DocumentFiscalYearFocus	2021
CY2021	dei	Document Fiscal Period Focus DocumentFiscalPeriodFocus	FY
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CY2020Q3	us-gaap	Operating Lease Right Of Use Asset Statement Of Financial Position Extensible List OperatingLeaseRightOfUseAssetStatementOfFinancialPositionExtensibleList	http://fasb.org/us-gaap/2021-01-31#OtherAssetsNoncurrent
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CY2021Q3	us-gaap	Finance Lease Liability Current Statement Of Financial Position Extensible List FinanceLeaseLiabilityCurrentStatementOfFinancialPositionExtensibleList	http://fasb.org/us-gaap/2021-01-31#LongTermDebtAndCapitalLeaseObligationsCurrent
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CY2021	dei	Document Type DocumentType	10-K
CY2021	dei	Document Annual Report DocumentAnnualReport	true
CY2021	dei	Document Period End Date DocumentPeriodEndDate	2021-09-30
CY2021	dei	Current Fiscal Year End Date CurrentFiscalYearEndDate	--09-30
CY2021	dei	Document Transition Report DocumentTransitionReport	false
CY2021	dei	Entity File Number EntityFileNumber	1-10042
CY2021	dei	Entity Registrant Name EntityRegistrantName	Atmos Energy Corp
CY2021	dei	Entity Incorporation State Country Code EntityIncorporationStateCountryCode	TX
CY2021	dei	Entity Tax Identification Number EntityTaxIdentificationNumber	75-1743247
CY2021	dei	Entity Address Address Line1 EntityAddressAddressLine1	1800 Three Lincoln Centre
CY2021	dei	Entity Address Address Line2 EntityAddressAddressLine2	5430 LBJ Freeway
CY2021	dei	Entity Address City Or Town EntityAddressCityOrTown	Dallas
CY2021	dei	Entity Address State Or Province EntityAddressStateOrProvince	TX
CY2021	dei	Entity Address Postal Zip Code EntityAddressPostalZipCode	75240
CY2021	dei	City Area Code CityAreaCode	972
CY2021	dei	Local Phone Number LocalPhoneNumber	934-9227
CY2021	dei	Security12b Title Security12bTitle	Common stock
CY2021	dei	Trading Symbol TradingSymbol	ATO
CY2021	dei	Security Exchange Name SecurityExchangeName	NYSE
CY2021	dei	Entity Well Known Seasoned Issuer EntityWellKnownSeasonedIssuer	Yes
CY2021	dei	Entity Voluntary Filers EntityVoluntaryFilers	No
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CY2021	dei	Entity Filer Category EntityFilerCategory	Large Accelerated Filer
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CY2019	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	117461000	shares
CY2021	us-gaap	Income Loss From Continuing Operations IncomeLossFromContinuingOperations	665563000	USD
CY2020	us-gaap	Income Loss From Continuing Operations IncomeLossFromContinuingOperations	601443000	USD
CY2019	us-gaap	Income Loss From Continuing Operations IncomeLossFromContinuingOperations	511406000	USD
CY2021	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	-55000	USD
CY2020	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	32000	USD
CY2019	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	64000	USD
CY2021	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Net Of Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax	-191000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Net Of Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax	106000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Net Of Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax	218000	USD
CY2021	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss After Reclassification Tax Parent OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationTaxParent	36875000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss After Reclassification Tax Parent OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationTaxParent	17198000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss After Reclassification Tax Parent OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationTaxParent	-6782000	USD
CY2021	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss After Reclassification And Tax Parent OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTaxParent	127583000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss After Reclassification And Tax Parent OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTaxParent	56888000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss After Reclassification And Tax Parent OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTaxParent	-22944000	USD
CY2021	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	127392000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	56994000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	-22726000	USD
CY2021	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	792955000	USD
CY2020	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	658437000	USD
CY2019	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	488680000	USD
CY2018Q3	us-gaap	Stockholders Equity StockholdersEquity	4769951000	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	511406000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-22726000	USD
CY2019	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	2.10
CY2019	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	245717000	USD
CY2019	us-gaap	Stock Issued During Period Value New Issues StockIssuedDuringPeriodValueNewIssues	694103000	USD
CY2019	us-gaap	Stock Issued During Period Value Other StockIssuedDuringPeriodValueOther	11071000	USD
CY2019	us-gaap	Stock Issued During Period Value Employee Benefit Plan StockIssuedDuringPeriodValueEmployeeBenefitPlan	8252000	USD
CY2019	us-gaap	Stock Issued During Period Value Restricted Stock Award Net Of Forfeitures StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures	2948000	USD
CY2019	us-gaap	Stock Issued During Period Value Share Based Compensation StockIssuedDuringPeriodValueShareBasedCompensation	20935000	USD
CY2019Q3	us-gaap	Stockholders Equity StockholdersEquity	5750223000	USD
CY2020	us-gaap	Net Income Loss NetIncomeLoss	601443000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	56994000	USD
CY2020	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	2.30
CY2020	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	282444000	USD
CY2020	us-gaap	Stock Issued During Period Value New Issues StockIssuedDuringPeriodValueNewIssues	624302000	USD
CY2020	us-gaap	Stock Issued During Period Value Other StockIssuedDuringPeriodValueOther	11326000	USD
CY2020	us-gaap	Stock Issued During Period Value Employee Benefit Plan StockIssuedDuringPeriodValueEmployeeBenefitPlan	8222000	USD
CY2020	us-gaap	Stock Issued During Period Value Restricted Stock Award Net Of Forfeitures StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures	2749000	USD
CY2020	us-gaap	Stock Issued During Period Value Share Based Compensation StockIssuedDuringPeriodValueShareBasedCompensation	18388000	USD
CY2020Q3	us-gaap	Stockholders Equity StockholdersEquity	6791203000	USD
CY2021	us-gaap	Net Income Loss NetIncomeLoss	665563000	USD
CY2021	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	127392000	USD
CY2021	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	2.50
CY2021	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	323904000	USD
CY2021	us-gaap	Stock Issued During Period Value New Issues StockIssuedDuringPeriodValueNewIssues	606667000	USD
CY2021	us-gaap	Stock Issued During Period Value Other StockIssuedDuringPeriodValueOther	7715000	USD
CY2021	us-gaap	Stock Issued During Period Value Employee Benefit Plan StockIssuedDuringPeriodValueEmployeeBenefitPlan	8126000	USD
CY2021	us-gaap	Stock Issued During Period Value Restricted Stock Award Net Of Forfeitures StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures	3092000	USD
CY2021	us-gaap	Stock Issued During Period Value Share Based Compensation StockIssuedDuringPeriodValueShareBasedCompensation	21035000	USD
CY2021Q3	us-gaap	Stockholders Equity StockholdersEquity	7906889000	USD
CY2021	us-gaap	Net Income Loss NetIncomeLoss	665563000	USD
CY2020	us-gaap	Net Income Loss NetIncomeLoss	601443000	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	511406000	USD
CY2019	us-gaap	Share Based Compensation ShareBasedCompensation	11121000	USD
CY2021	us-gaap	Amortization Of Financing Costs And Discounts AmortizationOfFinancingCostsAndDiscounts	14030000	USD
CY2021	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	477977000	USD
CY2020	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	429828000	USD
CY2019	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	391456000	USD
CY2021	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	155355000	USD
CY2020	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	155322000	USD
CY2019	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	132004000	USD
CY2021	ato	One Time Income Tax Benefit OneTimeIncomeTaxBenefit	0	USD
CY2020	ato	One Time Income Tax Benefit OneTimeIncomeTaxBenefit	-20962000	USD
CY2019	ato	One Time Income Tax Benefit OneTimeIncomeTaxBenefit	0	USD
CY2021	us-gaap	Share Based Compensation ShareBasedCompensation	11255000	USD
CY2020	us-gaap	Share Based Compensation ShareBasedCompensation	9583000	USD
CY2020	us-gaap	Amortization Of Financing Costs And Discounts AmortizationOfFinancingCostsAndDiscounts	11543000	USD
CY2019	us-gaap	Amortization Of Financing Costs And Discounts AmortizationOfFinancingCostsAndDiscounts	9464000	USD
CY2021	us-gaap	Public Utilities Allowance For Funds Used During Construction Capitalized Cost Of Equity PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedCostOfEquity	32749000	USD
CY2020	us-gaap	Public Utilities Allowance For Funds Used During Construction Capitalized Cost Of Equity PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedCostOfEquity	23493000	USD
CY2019	us-gaap	Public Utilities Allowance For Funds Used During Construction Capitalized Cost Of Equity PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedCostOfEquity	11165000	USD
CY2021	us-gaap	Other Noncash Income Expense OtherNoncashIncomeExpense	-3731000	USD
CY2020	us-gaap	Other Noncash Income Expense OtherNoncashIncomeExpense	-8411000	USD
CY2019	us-gaap	Other Noncash Income Expense OtherNoncashIncomeExpense	-1169000	USD
CY2021	us-gaap	Increase Decrease In Accounts Receivable IncreaseDecreaseInAccountsReceivable	113665000	USD
CY2020	us-gaap	Increase Decrease In Accounts Receivable IncreaseDecreaseInAccountsReceivable	-7167000	USD
CY2019	us-gaap	Increase Decrease In Accounts Receivable IncreaseDecreaseInAccountsReceivable	-18724000	USD
CY2021	us-gaap	Increase Decrease In Inventories IncreaseDecreaseInInventories	66166000	USD
CY2020	us-gaap	Increase Decrease In Inventories IncreaseDecreaseInInventories	-18188000	USD
CY2019	us-gaap	Increase Decrease In Inventories IncreaseDecreaseInInventories	-35594000	USD
CY2021	ato	Increase Decrease In Regulatory Assets Current IncreaseDecreaseInRegulatoryAssetsCurrent	2003659000	USD
CY2020	ato	Increase Decrease In Regulatory Assets Current IncreaseDecreaseInRegulatoryAssetsCurrent	0	USD
CY2019	ato	Increase Decrease In Regulatory Assets Current IncreaseDecreaseInRegulatoryAssetsCurrent	0	USD
CY2021	us-gaap	Increase Decrease In Other Current Assets IncreaseDecreaseInOtherCurrentAssets	84705000	USD
CY2020	us-gaap	Increase Decrease In Other Current Assets IncreaseDecreaseInOtherCurrentAssets	35878000	USD
CY2019	us-gaap	Increase Decrease In Other Current Assets IncreaseDecreaseInOtherCurrentAssets	26590000	USD
CY2021	ato	Increase Decrease In Regulatory Assets Noncurrent IncreaseDecreaseInRegulatoryAssetsNoncurrent	76652000	USD
CY2020	ato	Increase Decrease In Regulatory Assets Noncurrent IncreaseDecreaseInRegulatoryAssetsNoncurrent	0	USD
CY2019	ato	Increase Decrease In Regulatory Assets Noncurrent IncreaseDecreaseInRegulatoryAssetsNoncurrent	0	USD
CY2021	us-gaap	Increase Decrease In Other Noncurrent Assets IncreaseDecreaseInOtherNoncurrentAssets	-136809000	USD
CY2020	us-gaap	Increase Decrease In Other Noncurrent Assets IncreaseDecreaseInOtherNoncurrentAssets	31935000	USD
CY2019	us-gaap	Increase Decrease In Other Noncurrent Assets IncreaseDecreaseInOtherNoncurrentAssets	58403000	USD
CY2021	us-gaap	Increase Decrease In Accounts Payable And Accrued Liabilities IncreaseDecreaseInAccountsPayableAndAccruedLiabilities	104242000	USD
CY2020	us-gaap	Increase Decrease In Accounts Payable And Accrued Liabilities IncreaseDecreaseInAccountsPayableAndAccruedLiabilities	7359000	USD
CY2019	us-gaap	Increase Decrease In Accounts Payable And Accrued Liabilities IncreaseDecreaseInAccountsPayableAndAccruedLiabilities	9908000	USD
CY2021	us-gaap	Increase Decrease In Other Current Liabilities IncreaseDecreaseInOtherCurrentLiabilities	-166268000	USD
CY2020	us-gaap	Increase Decrease In Other Current Liabilities IncreaseDecreaseInOtherCurrentLiabilities	-129543000	USD
CY2019	us-gaap	Increase Decrease In Other Current Liabilities IncreaseDecreaseInOtherCurrentLiabilities	-103895000	USD
CY2021	us-gaap	Increase Decrease In Other Noncurrent Liabilities IncreaseDecreaseInOtherNoncurrentLiabilities	-109349000	USD
CY2020	us-gaap	Increase Decrease In Other Noncurrent Liabilities IncreaseDecreaseInOtherNoncurrentLiabilities	30966000	USD
CY2019	us-gaap	Increase Decrease In Other Noncurrent Liabilities IncreaseDecreaseInOtherNoncurrentLiabilities	47976000	USD
CY2021	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	-1084251000	USD
CY2020	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	1037999000	USD
CY2019	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	968769000	USD
CY2021	us-gaap	Payments To Acquire Productive Assets PaymentsToAcquireProductiveAssets	1969540000	USD
CY2020	us-gaap	Payments To Acquire Productive Assets PaymentsToAcquireProductiveAssets	1935676000	USD
CY2019	us-gaap	Payments To Acquire Productive Assets PaymentsToAcquireProductiveAssets	1693477000	USD
CY2021	us-gaap	Cash Provided By Used In Investing Activities Discontinued Operations CashProvidedByUsedInInvestingActivitiesDiscontinuedOperations	0	USD
CY2020	us-gaap	Cash Provided By Used In Investing Activities Discontinued Operations CashProvidedByUsedInInvestingActivitiesDiscontinuedOperations	0	USD
CY2019	us-gaap	Cash Provided By Used In Investing Activities Discontinued Operations CashProvidedByUsedInInvestingActivitiesDiscontinuedOperations	4000000	USD
CY2021	us-gaap	Payments To Acquire Investments PaymentsToAcquireInvestments	49879000	USD
CY2020	us-gaap	Payments To Acquire Investments PaymentsToAcquireInvestments	50517000	USD
CY2019	us-gaap	Payments To Acquire Investments PaymentsToAcquireInvestments	29153000	USD
CY2021	us-gaap	Proceeds From Sale Of Trading Securities Heldforinvestment ProceedsFromSaleOfTradingSecuritiesHeldforinvestment	14957000	USD
CY2020	us-gaap	Proceeds From Sale Of Trading Securities Heldforinvestment ProceedsFromSaleOfTradingSecuritiesHeldforinvestment	32339000	USD
CY2019	us-gaap	Proceeds From Sale Of Trading Securities Heldforinvestment ProceedsFromSaleOfTradingSecuritiesHeldforinvestment	6070000	USD
CY2021	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	28850000	USD
CY2020	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	18669000	USD
CY2019	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	20299000	USD
CY2021	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	-11957000	USD
CY2020	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	-9667000	USD
CY2019	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	-8601000	USD
CY2021	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-1963655000	USD
CY2020	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-1925518000	USD
CY2019	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-1683660000	USD
CY2021	us-gaap	Proceeds From Repayments Of Short Term Debt ProceedsFromRepaymentsOfShortTermDebt	0	USD
CY2020	us-gaap	Proceeds From Repayments Of Short Term Debt ProceedsFromRepaymentsOfShortTermDebt	-464915000	USD
CY2019	us-gaap	Proceeds From Repayments Of Short Term Debt ProceedsFromRepaymentsOfShortTermDebt	-110865000	USD
CY2021	us-gaap	Proceeds From Issuance Of Long Term Debt ProceedsFromIssuanceOfLongTermDebt	2797346000	USD
CY2020	us-gaap	Proceeds From Issuance Of Long Term Debt ProceedsFromIssuanceOfLongTermDebt	999450000	USD
CY2019	us-gaap	Proceeds From Issuance Of Long Term Debt ProceedsFromIssuanceOfLongTermDebt	1045221000	USD
CY2021	us-gaap	Proceeds From Issuance Of Common Stock ProceedsFromIssuanceOfCommonStock	606667000	USD
CY2020	us-gaap	Proceeds From Issuance Of Common Stock ProceedsFromIssuanceOfCommonStock	624302000	USD
CY2019	us-gaap	Proceeds From Issuance Of Common Stock ProceedsFromIssuanceOfCommonStock	694103000	USD
CY2021	us-gaap	Proceeds From Stock Plans ProceedsFromStockPlans	15841000	USD
CY2020	us-gaap	Proceeds From Stock Plans ProceedsFromStockPlans	19548000	USD
CY2019	us-gaap	Proceeds From Stock Plans ProceedsFromStockPlans	19323000	USD
CY2020	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	0	USD
CY2019	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	575000000	USD
CY2021	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	323904000	USD
CY2021	us-gaap	Payments For Proceeds From Hedge Financing Activities PaymentsForProceedsFromHedgeFinancingActivities	-62159000	USD
CY2020	us-gaap	Payments For Proceeds From Hedge Financing Activities PaymentsForProceedsFromHedgeFinancingActivities	4426000	USD
CY2019	us-gaap	Payments For Proceeds From Hedge Financing Activities PaymentsForProceedsFromHedgeFinancingActivities	90141000	USD
CY2021	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	0	USD
CY2020	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	282444000	USD
CY2019	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	245717000	USD
CY2021	us-gaap	Payments Of Debt Issuance Costs PaymentsOfDebtIssuanceCosts	14288000	USD
CY2020	us-gaap	Payments Of Debt Issuance Costs PaymentsOfDebtIssuanceCosts	7738000	USD
CY2019	us-gaap	Payments Of Debt Issuance Costs PaymentsOfDebtIssuanceCosts	11254000	USD
CY2021	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	3143821000	USD
CY2020	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	883777000	USD
CY2019	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	725670000	USD
CY2021	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	95915000	USD
CY2020	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	-3742000	USD
CY2020Q3	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	20808000	USD
CY2019Q3	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	24550000	USD
CY2019	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	10779000	USD
CY2018Q3	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	13771000	USD
CY2021Q3	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	116723000	USD
CY2020Q3	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	20808000	USD
CY2019Q3	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	24550000	USD
CY2021	us-gaap	Nature Of Operations NatureOfOperations	Nature of Business<div style="margin-top:5pt;text-indent:24.75pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Atmos Energy Corporation (Atmos Energy or the “Company”) and its subsidiaries are engaged in the regulated natural gas distribution and pipeline and storage businesses. Through our distribution business, we deliver natural gas through sales and transportation arrangements to over three million residential, commercial, public-authority and industrial customers through our six regulated distribution divisions in the service areas described below:</span></div><div><table style="border-collapse:collapse;display:inline-table;margin-bottom:5pt;vertical-align:text-bottom;width:99.853%"><tr><td style="width:1.0%"/><td style="width:47.069%"/><td style="width:0.1%"/><td style="width:1.0%"/><td style="width:2.560%"/><td style="width:0.1%"/><td style="width:1.0%"/><td style="width:47.071%"/><td style="width:0.1%"/></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:100%">Division</span></td><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%"> </span></td><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:100%">Service Area</span></td></tr><tr><td colspan="3" style="border-top:1pt solid #000000;padding:2px 1pt;text-align:left;vertical-align:top"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Atmos Energy Colorado-Kansas Division</span></td><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%"> </span></td><td colspan="3" style="border-top:1pt solid #000000;padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Colorado, Kansas</span></td></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:top"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Atmos Energy Kentucky/Mid-States Division</span></td><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%"> </span></td><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><div><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Kentucky, Tennessee, Virginia</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:6.5pt;font-weight:400;line-height:100%;position:relative;top:-3.5pt;vertical-align:baseline">(1)</span></div></td></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:top"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Atmos Energy Louisiana Division</span></td><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%"> </span></td><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Louisiana</span></td></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:top"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Atmos Energy Mid-Tex Division</span></td><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%"> </span></td><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Texas, including the Dallas/Fort Worth metropolitan area</span></td></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:top"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Atmos Energy Mississippi Division</span></td><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%"> </span></td><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Mississippi</span></td></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:top"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Atmos Energy West Texas Division</span></td><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%"> </span></td><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">West Texas</span></td></tr></table><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:6pt;font-weight:400;line-height:120%"> </span></div><div style="padding-left:24.75pt;text-indent:-18pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%">(1)</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%;padding-left:8.68pt">Denotes location where we have more limited service areas.</span></div><div style="margin-top:4pt;text-indent:24.75pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">In addition, we transport natural gas for others through our distribution system. Our distribution business is subject to federal and state regulation and/or regulation by local authorities in each of the states in which our distribution divisions operate. Our corporate headquarters and shared-services function are located in Dallas, Texas, and our customer support centers are located in Amarillo and Waco, Texas.</span></div>Our pipeline and storage business, which is also subject to federal and state regulation, consists of the pipeline and storage operations of our Atmos Pipeline–Texas (APT) Division and our natural gas transmission business in Louisiana. The APT division provides transportation and storage services to our Mid-Tex Division, other third-party local distribution companies, industrial and electric generation customers, as well as marketers and producers. As part of its pipeline operations, APT manages five underground storage facilities in Texas. We also provide ancillary services customary to the pipeline industry including parking arrangements, lending and sales of inventory on hand. Our natural gas transmission operations in Louisiana are comprised of a 21-mile pipeline located in the New Orleans, Louisiana area that is primarily used to aggregate gas supply for our distribution division in Louisiana under a long-term contract and on a more limited basis, to third parties.
CY2021Q3	ato	Number Of Customers Regulated Distribution NumberOfCustomersRegulatedDistribution	3000000	customer
CY2021Q3	ato	Number Of Divisions Regulated Distribution NumberOfDivisionsRegulatedDistribution	6	regulated_distribution_division
CY2021	us-gaap	Use Of Estimates UseOfEstimates	<span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-style:italic;font-weight:700;line-height:120%">Use of estimates</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%"> — The preparation of financial statements in conformity with accounting principles generally accepted in the United States 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, unbilled revenues, contingency accruals, pension and postretirement obligations, deferred income taxes, impairment of long-lived assets, risk management and trading activities, fair value measurements and the valuation of goodwill and other long-lived assets. Actual results could differ from those estimates.</span>
CY2021Q3	us-gaap	Regulatory Assets RegulatoryAssets	2521441000	USD
CY2020Q3	us-gaap	Regulatory Assets RegulatoryAssets	414641000	USD
CY2021Q3	us-gaap	Regulatory Liabilities RegulatoryLiabilities	1424195000	USD
CY2020Q3	us-gaap	Regulatory Liabilities RegulatoryLiabilities	1367013000	USD
CY2021	us-gaap	Public Utilities Allowance For Funds Used During Construction Capitalized Interest PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedInterest	11414000	USD
CY2020	us-gaap	Public Utilities Allowance For Funds Used During Construction Capitalized Interest PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedInterest	8436000	USD
CY2019	us-gaap	Public Utilities Property Plant And Equipment Disclosure Of Composite Depreciation Rate For Plants In Service PublicUtilitiesPropertyPlantAndEquipmentDisclosureOfCompositeDepreciationRateForPlantsInService	0.031
CY2019	us-gaap	Public Utilities Allowance For Funds Used During Construction Capitalized Interest PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedInterest	7643000	USD
CY2021	us-gaap	Public Utilities Allowance For Funds Used During Construction Capitalized Cost Of Equity PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedCostOfEquity	32749000	USD
CY2020	us-gaap	Public Utilities Allowance For Funds Used During Construction Capitalized Cost Of Equity PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedCostOfEquity	23493000	USD
CY2019	us-gaap	Public Utilities Allowance For Funds Used During Construction Capitalized Cost Of Equity PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedCostOfEquity	11165000	USD
CY2021	us-gaap	Public Utilities Allowance For Funds Used During Construction Additions PublicUtilitiesAllowanceForFundsUsedDuringConstructionAdditions	44163000	USD
CY2020	us-gaap	Public Utilities Allowance For Funds Used During Construction Additions PublicUtilitiesAllowanceForFundsUsedDuringConstructionAdditions	31929000	USD
CY2019	us-gaap	Public Utilities Allowance For Funds Used During Construction Additions PublicUtilitiesAllowanceForFundsUsedDuringConstructionAdditions	18808000	USD
CY2021	us-gaap	Public Utilities Property Plant And Equipment Disclosure Of Composite Depreciation Rate For Plants In Service PublicUtilitiesPropertyPlantAndEquipmentDisclosureOfCompositeDepreciationRateForPlantsInService	0.03
CY2020	us-gaap	Public Utilities Property Plant And Equipment Disclosure Of Composite Depreciation Rate For Plants In Service PublicUtilitiesPropertyPlantAndEquipmentDisclosureOfCompositeDepreciationRateForPlantsInService	0.03
CY2021Q3	us-gaap	Asset Retirement Obligation AssetRetirementObligation	18400000	USD
CY2020Q3	us-gaap	Asset Retirement Obligation AssetRetirementObligation	20300000	USD
CY2021Q3	ato	Asset Retirement Costs In Property Plant And Equipment AssetRetirementCostsInPropertyPlantAndEquipment	12800000	USD
CY2020Q3	ato	Asset Retirement Costs In Property Plant And Equipment AssetRetirementCostsInPropertyPlantAndEquipment	14400000	USD
CY2021	us-gaap	Derivatives Reporting Of Derivative Activity DerivativesReportingOfDerivativeActivity	<div style="margin-top:5pt;text-indent:24.75pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-style:italic;font-weight:700;line-height:120%">Financial instruments and hedging activities</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%"> — We use financial instruments to mitigate commodity price risk in our distribution and pipeline and storage segments and to mitigate interest rate risk. The objectives and strategies for using financial instruments have been tailored to our business and are discussed in Note 15 to the consolidated financial statements.</span></div><div style="margin-top:5pt;text-indent:24.75pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">We record all of our financial instruments on the balance sheet at fair value</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-style:italic;font-weight:400;line-height:120%">,</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%"> with the exception of normal purchases and normal sales that are expected to result in physical delivery, with changes in fair value ultimately recorded in the statement of comprehensive income. 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. We record the cash flow impact of our financial instruments in operating cash flows based upon their balance sheet classification.</span></div><div style="margin-top:5pt;text-indent:24.75pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">The timing of when changes in fair value of our financial instruments are recorded in the statement of comprehensive income 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 statement of comprehensive income as they occur.</span></div><div style="margin-top:6pt;text-indent:11.25pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-style:italic;font-weight:400;line-height:120%">Financial Instruments Associated with Commodity Price Risk</span></div><div style="margin-top:5pt;text-indent:24.75pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">In our distribution segment, the costs associated with and the realized 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 statements of comprehensive 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 United States. Accordingly, there is no earnings impact on our distribution segment as a result of the use of these financial instruments.</span></div><div style="margin-top:6pt;text-indent:11.25pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-style:italic;font-weight:400;line-height:120%">Financial Instruments Associated with Interest Rate Risk</span></div><div style="margin-top:5pt;text-indent:24.75pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">In connection with the planned issuance of long-term debt, we may use financial instruments to manage interest rate risk. We currently manage this risk through the use of forward starting interest rate swaps to fix the Treasury yield component of the interest cost associated with anticipated financings. We designate these financial instruments as cash flow hedges at the time the agreements are executed. Unrealized gains and losses associated with the instruments are recorded as a component of accumulated other comprehensive income (loss). When the instruments settle, the realized gain or loss is recorded as a component of accumulated other comprehensive income (loss) and recognized as a component of interest charges over the life of the related financing arrangement. As of September 30, 2021 and 2020, no cash was required to be held in margin accounts.</span></div>
CY2020Q3	ato	Derivative Cash Collateral DerivativeCashCollateral	0	USD
CY2021Q3	ato	Derivative Cash Collateral DerivativeCashCollateral	0	USD
CY2021	ato	Self Insured Retention Deductible SelfInsuredRetentionDeductible	1000000	USD
CY2021	us-gaap	Number Of Operating Segments NumberOfOperatingSegments	2	segment
CY2021Q3	us-gaap	Number Of States In Which Entity Operates NumberOfStatesInWhichEntityOperates	8	state
CY2021	us-gaap	Revenues Revenues	3407490000	USD
CY2021	us-gaap	Revenues Revenues	3407490000	USD
CY2021	us-gaap	Cost Of Revenue CostOfRevenue	1032717000	USD
CY2021	us-gaap	Other Selling General And Administrative Expense OtherSellingGeneralAndAdministrativeExpense	679019000	USD
CY2021	us-gaap	Depreciation And Amortization DepreciationAndAmortization	477977000	USD
CY2021	us-gaap	Taxes Other TaxesOther	312779000	USD
CY2021	us-gaap	Operating Income Loss OperatingIncomeLoss	904998000	USD
CY2021	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	-2145000	USD
CY2021	us-gaap	Interest Expense InterestExpense	83554000	USD
CY2021	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	819299000	USD
CY2021	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	153736000	USD
CY2021	us-gaap	Income Loss From Continuing Operations IncomeLossFromContinuingOperations	665563000	USD
CY2021	us-gaap	Payments To Acquire Productive Assets PaymentsToAcquireProductiveAssets	1969540000	USD
CY2020	us-gaap	Revenues Revenues	2821137000	USD
CY2020	us-gaap	Revenues Revenues	2821137000	USD
CY2020	us-gaap	Cost Of Revenue CostOfRevenue	658854000	USD
CY2020	us-gaap	Other Selling General And Administrative Expense OtherSellingGeneralAndAdministrativeExpense	629601000	USD
CY2020	us-gaap	Depreciation And Amortization DepreciationAndAmortization	429828000	USD
CY2020	us-gaap	Taxes Other TaxesOther	278755000	USD
CY2020	us-gaap	Operating Income Loss OperatingIncomeLoss	824099000	USD
CY2020	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	7171000	USD
CY2020	us-gaap	Interest Expense InterestExpense	84474000	USD
CY2020	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	746796000	USD
CY2020	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	145353000	USD
CY2020	us-gaap	Income Loss From Continuing Operations IncomeLossFromContinuingOperations	601443000	USD
CY2020	us-gaap	Payments To Acquire Productive Assets PaymentsToAcquireProductiveAssets	1935676000	USD
CY2019	us-gaap	Revenues Revenues	2901848000	USD
CY2019	us-gaap	Revenues Revenues	2901848000	USD
CY2019	us-gaap	Cost Of Revenue CostOfRevenue	858837000	USD
CY2019	us-gaap	Other Selling General And Administrative Expense OtherSellingGeneralAndAdministrativeExpense	630308000	USD
CY2019	us-gaap	Depreciation And Amortization DepreciationAndAmortization	391456000	USD
CY2019	us-gaap	Taxes Other TaxesOther	275189000	USD
CY2019	us-gaap	Operating Income Loss OperatingIncomeLoss	746058000	USD
CY2019	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	7404000	USD
CY2019	us-gaap	Interest Expense InterestExpense	103153000	USD
CY2019	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	650309000	USD
CY2019	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	138903000	USD
CY2019	us-gaap	Income Loss From Continuing Operations IncomeLossFromContinuingOperations	511406000	USD
CY2019	us-gaap	Payments To Acquire Productive Assets PaymentsToAcquireProductiveAssets	1693477000	USD
CY2021	us-gaap	Revenues Revenues	3407490000	USD
CY2020	us-gaap	Revenues Revenues	2821137000	USD
CY2019	us-gaap	Revenues Revenues	2901848000	USD
CY2021Q3	us-gaap	Public Utilities Property Plant And Equipment Net PublicUtilitiesPropertyPlantAndEquipmentNet	15063970000	USD
CY2021Q3	us-gaap	Assets Assets	19608662000	USD
CY2020Q3	us-gaap	Public Utilities Property Plant And Equipment Net PublicUtilitiesPropertyPlantAndEquipmentNet	13355347000	USD
CY2020Q3	us-gaap	Assets Assets	15359032000	USD
CY2021	us-gaap	Net Income Loss NetIncomeLoss	665563000	USD
CY2020	us-gaap	Net Income Loss NetIncomeLoss	601443000	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	511406000	USD
CY2021	us-gaap	Undistributed Earnings Loss Allocated To Participating Securities Basic UndistributedEarningsLossAllocatedToParticipatingSecuritiesBasic	465000	USD
CY2020	us-gaap	Undistributed Earnings Loss Allocated To Participating Securities Basic UndistributedEarningsLossAllocatedToParticipatingSecuritiesBasic	444000	USD
CY2019	us-gaap	Undistributed Earnings Loss Allocated To Participating Securities Basic UndistributedEarningsLossAllocatedToParticipatingSecuritiesBasic	416000	USD
CY2021	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	665098000	USD
CY2020	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	600999000	USD
CY2019	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	510990000	USD
CY2021	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	129779000	shares
CY2020	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	122788000	shares
CY2019	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	117200000	shares
CY2021	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	5.12
CY2020	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	4.89
CY2019	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	4.36
CY2021	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	665098000	USD
CY2020	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	600999000	USD
CY2019	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	510990000	USD
CY2021	us-gaap	Amount Of Dilutive Securities Stock Options And Restrictive Stock Units AmountOfDilutiveSecuritiesStockOptionsAndRestrictiveStockUnits	0	USD
CY2020	us-gaap	Amount Of Dilutive Securities Stock Options And Restrictive Stock Units AmountOfDilutiveSecuritiesStockOptionsAndRestrictiveStockUnits	0	USD
CY2019	us-gaap	Amount Of Dilutive Securities Stock Options And Restrictive Stock Units AmountOfDilutiveSecuritiesStockOptionsAndRestrictiveStockUnits	0	USD
CY2021	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	665098000	USD
CY2020	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	600999000	USD
CY2019	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	510990000	USD
CY2021	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	129779000	shares
CY2020	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	122788000	shares
CY2019	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	117200000	shares
CY2021	us-gaap	Incremental Common Shares Attributable To Equity Forward Agreements IncrementalCommonSharesAttributableToEquityForwardAgreements	55000	shares
CY2020	us-gaap	Incremental Common Shares Attributable To Equity Forward Agreements IncrementalCommonSharesAttributableToEquityForwardAgreements	84000	shares
CY2019	us-gaap	Incremental Common Shares Attributable To Equity Forward Agreements IncrementalCommonSharesAttributableToEquityForwardAgreements	261000	shares
CY2021	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	129834000	shares
CY2020	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	122872000	shares
CY2019	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	117461000	shares
CY2021	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	5.12
CY2020	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	4.89
CY2019	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	4.35
CY2021	ato	Percent Of Customers Whose Gas Cost Portion Of Bill Excluded From Allowance For Uncollectable Account PercentOfCustomersWhoseGasCostPortionOfBillExcludedFromAllowanceForUncollectableAccount	0.79
CY2018Q3	us-gaap	Allowance For Doubtful Accounts Receivable Current AllowanceForDoubtfulAccountsReceivableCurrent	14795000	USD
CY2019	us-gaap	Provision For Doubtful Accounts ProvisionForDoubtfulAccounts	18106000	USD
CY2019	us-gaap	Allowance For Doubtful Accounts Receivable Write Offs AllowanceForDoubtfulAccountsReceivableWriteOffs	19575000	USD
CY2019	us-gaap	Allowance For Doubtful Accounts Receivable Recoveries AllowanceForDoubtfulAccountsReceivableRecoveries	2573000	USD
CY2019Q3	us-gaap	Allowance For Doubtful Accounts Receivable Current AllowanceForDoubtfulAccountsReceivableCurrent	15899000	USD
CY2020	us-gaap	Provision For Doubtful Accounts ProvisionForDoubtfulAccounts	24796000	USD
CY2020	us-gaap	Allowance For Doubtful Accounts Receivable Write Offs AllowanceForDoubtfulAccountsReceivableWriteOffs	12698000	USD
CY2020	us-gaap	Allowance For Doubtful Accounts Receivable Recoveries AllowanceForDoubtfulAccountsReceivableRecoveries	1952000	USD
CY2020Q3	us-gaap	Allowance For Doubtful Accounts Receivable Current AllowanceForDoubtfulAccountsReceivableCurrent	29949000	USD
CY2021	us-gaap	Provision For Doubtful Accounts ProvisionForDoubtfulAccounts	43807000	USD
CY2021	us-gaap	Allowance For Doubtful Accounts Receivable Write Offs AllowanceForDoubtfulAccountsReceivableWriteOffs	11019000	USD
CY2021	us-gaap	Allowance For Doubtful Accounts Receivable Recoveries AllowanceForDoubtfulAccountsReceivableRecoveries	1734000	USD
CY2021Q3	us-gaap	Allowance For Doubtful Accounts Receivable Current AllowanceForDoubtfulAccountsReceivableCurrent	64471000	USD
CY2021Q3	us-gaap	Finance Lease Weighted Average Remaining Lease Term1 FinanceLeaseWeightedAverageRemainingLeaseTerm1	P19Y
CY2020Q3	us-gaap	Finance Lease Weighted Average Remaining Lease Term1 FinanceLeaseWeightedAverageRemainingLeaseTerm1	P19Y1M6D
CY2021Q3	us-gaap	Operating Lease Weighted Average Remaining Lease Term1 OperatingLeaseWeightedAverageRemainingLeaseTerm1	P10Y2M12D
CY2020Q3	us-gaap	Operating Lease Weighted Average Remaining Lease Term1 OperatingLeaseWeightedAverageRemainingLeaseTerm1	P10Y7M6D
CY2021Q3	us-gaap	Finance Lease Weighted Average Discount Rate Percent FinanceLeaseWeightedAverageDiscountRatePercent	0.057
CY2020Q3	us-gaap	Finance Lease Weighted Average Discount Rate Percent FinanceLeaseWeightedAverageDiscountRatePercent	0.080
CY2021Q3	us-gaap	Operating Lease Weighted Average Discount Rate Percent OperatingLeaseWeightedAverageDiscountRatePercent	0.028
CY2020Q3	us-gaap	Operating Lease Weighted Average Discount Rate Percent OperatingLeaseWeightedAverageDiscountRatePercent	0.029
CY2021	ato	Finance Lease Cost FinanceLeaseCost	1334000	USD
CY2020	ato	Finance Lease Cost FinanceLeaseCost	622000	USD
CY2021	us-gaap	Operating Lease Cost OperatingLeaseCost	42349000	USD
CY2020	us-gaap	Operating Lease Cost OperatingLeaseCost	40887000	USD
CY2021	us-gaap	Lease Cost LeaseCost	43683000	USD
CY2020	us-gaap	Lease Cost LeaseCost	41509000	USD
CY2021Q3	us-gaap	Finance Lease Right Of Use Asset FinanceLeaseRightOfUseAsset	18252000	USD
CY2020Q3	us-gaap	Finance Lease Right Of Use Asset FinanceLeaseRightOfUseAsset	8480000	USD
CY2021Q3	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	222446000	USD
CY2020Q3	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	227146000	USD
CY2021Q3	ato	Right Of Use Asset Finance Leaseand Operating Lease RightOfUseAssetFinanceLeaseandOperatingLease	240698000	USD
CY2020Q3	ato	Right Of Use Asset Finance Leaseand Operating Lease RightOfUseAssetFinanceLeaseandOperatingLease	235626000	USD
CY2021Q3	us-gaap	Finance Lease Liability Current FinanceLeaseLiabilityCurrent	452000	USD
CY2020Q3	us-gaap	Finance Lease Liability Current FinanceLeaseLiabilityCurrent	165000	USD
CY2021Q3	us-gaap	Operating Lease Liability Current OperatingLeaseLiabilityCurrent	37688000	USD
CY2020Q3	us-gaap	Operating Lease Liability Current OperatingLeaseLiabilityCurrent	35716000	USD
CY2021Q3	us-gaap	Finance Lease Liability Noncurrent FinanceLeaseLiabilityNoncurrent	18287000	USD
CY2020Q3	us-gaap	Finance Lease Liability Noncurrent FinanceLeaseLiabilityNoncurrent	8466000	USD
CY2021Q3	us-gaap	Operating Lease Liability Noncurrent OperatingLeaseLiabilityNoncurrent	194745000	USD
CY2020Q3	us-gaap	Operating Lease Liability Noncurrent OperatingLeaseLiabilityNoncurrent	201071000	USD
CY2021Q3	ato	Lease Liability LeaseLiability	251172000	USD
CY2020Q3	ato	Lease Liability LeaseLiability	245418000	USD
CY2021	us-gaap	Operating Lease Payments OperatingLeasePayments	42013000	USD
CY2020	us-gaap	Operating Lease Payments OperatingLeasePayments	37758000	USD
CY2021	us-gaap	Right Of Use Asset Obtained In Exchange For Finance Lease Liability RightOfUseAssetObtainedInExchangeForFinanceLeaseLiability	10333000	USD
CY2020	us-gaap	Right Of Use Asset Obtained In Exchange For Finance Lease Liability RightOfUseAssetObtainedInExchangeForFinanceLeaseLiability	6083000	USD
CY2021	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	25690000	USD
CY2020	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	34169000	USD
CY2021Q3	ato	Lessee Liability Payments Due Next Rolling Twelve Months LesseeLiabilityPaymentsDueNextRollingTwelveMonths	43164000	USD
CY2021Q3	us-gaap	Finance Lease Liability Payments Due In Next Rolling Twelve Months FinanceLeaseLiabilityPaymentsDueInNextRollingTwelveMonths	1342000	USD
CY2021Q3	us-gaap	Lessee Operating Lease Liability Payments Due Next Rolling Twelve Months LesseeOperatingLeaseLiabilityPaymentsDueNextRollingTwelveMonths	41822000	USD
CY2021Q3	ato	Lessee Liability Payments Due Next Rolling Two Years LesseeLiabilityPaymentsDueNextRollingTwoYears	38690000	USD
CY2021Q3	us-gaap	Finance Lease Liability Payments Due In Rolling Year Two FinanceLeaseLiabilityPaymentsDueInRollingYearTwo	1365000	USD
CY2021Q3	us-gaap	Lessee Operating Lease Liability Payments Due In Rolling Year Two LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearTwo	37325000	USD
CY2021Q3	ato	Lessee Liability Payments Due Next Rolling Three Years LesseeLiabilityPaymentsDueNextRollingThreeYears	32106000	USD
CY2021Q3	us-gaap	Finance Lease Liability Payments Due In Rolling Year Three FinanceLeaseLiabilityPaymentsDueInRollingYearThree	1388000	USD
CY2021Q3	us-gaap	Lessee Operating Lease Liability Payments Due In Rolling Year Three LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearThree	30718000	USD
CY2021Q3	ato	Lessee Liability Payments Due Next Rolling Four Years LesseeLiabilityPaymentsDueNextRollingFourYears	23927000	USD
CY2021Q3	us-gaap	Finance Lease Liability Payments Due In Rolling Year Four FinanceLeaseLiabilityPaymentsDueInRollingYearFour	1411000	USD
CY2021Q3	us-gaap	Lessee Operating Lease Liability Payments Due In Rolling Year Four LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFour	22516000	USD
CY2021Q3	ato	Lessee Liability Payments Due Next Rolling Five Years LesseeLiabilityPaymentsDueNextRollingFiveYears	18278000	USD
CY2021Q3	us-gaap	Finance Lease Liability Payments Due In Rolling Year Five FinanceLeaseLiabilityPaymentsDueInRollingYearFive	1435000	USD
CY2021Q3	us-gaap	Lessee Operating Lease Liability Payments Due In Rolling Year Five LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFive	16843000	USD
CY2021Q3	ato	Lessee Liability Payments Due After Rolling Five Years LesseeLiabilityPaymentsDueAfterRollingFiveYears	144718000	USD
CY2021Q3	us-gaap	Finance Lease Liability Payments Due In Rolling After Year Five FinanceLeaseLiabilityPaymentsDueInRollingAfterYearFive	22868000	USD
CY2021Q3	us-gaap	Lessee Operating Lease Liability Payments Due After Rolling Year Five LesseeOperatingLeaseLiabilityPaymentsDueAfterRollingYearFive	121850000	USD
CY2021Q3	ato	Lease Liability Lease Payments LeaseLiabilityLeasePayments	300883000	USD
CY2021Q3	us-gaap	Finance Lease Liability Payments Due FinanceLeaseLiabilityPaymentsDue	29809000	USD
CY2021Q3	us-gaap	Lessee Operating Lease Liability Payments Due LesseeOperatingLeaseLiabilityPaymentsDue	271074000	USD
CY2021Q3	ato	Lease Liability Imputed Interest LeaseLiabilityImputedInterest	49711000	USD
CY2021Q3	us-gaap	Finance Lease Liability Undiscounted Excess Amount FinanceLeaseLiabilityUndiscountedExcessAmount	11070000	USD
CY2021Q3	us-gaap	Lessee Operating Lease Liability Undiscounted Excess Amount LesseeOperatingLeaseLiabilityUndiscountedExcessAmount	38641000	USD
CY2021Q3	ato	Lease Liability LeaseLiability	251172000	USD
CY2021Q3	us-gaap	Finance Lease Liability FinanceLeaseLiability	18739000	USD
CY2021Q3	us-gaap	Operating Lease Liability OperatingLeaseLiability	232433000	USD
CY2021Q3	ato	Lease Liability Current LeaseLiabilityCurrent	38140000	USD
CY2021Q3	us-gaap	Finance Lease Liability Current FinanceLeaseLiabilityCurrent	452000	USD
CY2021Q3	us-gaap	Operating Lease Liability Current OperatingLeaseLiabilityCurrent	37688000	USD
CY2021Q3	ato	Lease Liability Noncurrent LeaseLiabilityNoncurrent	213032000	USD
CY2021Q3	us-gaap	Finance Lease Liability Noncurrent FinanceLeaseLiabilityNoncurrent	18287000	USD
CY2021Q3	us-gaap	Operating Lease Liability Noncurrent OperatingLeaseLiabilityNoncurrent	194745000	USD
CY2021Q3	ato	Lease Liability LeaseLiability	251172000	USD
CY2021Q3	us-gaap	Finance Lease Liability FinanceLeaseLiability	18739000	USD
CY2021Q3	us-gaap	Operating Lease Liability OperatingLeaseLiability	232433000	USD
CY2019	us-gaap	Operating Leases Rent Expense Net OperatingLeasesRentExpenseNet	40400000	USD
CY2021Q3	us-gaap	Finance Lease Liability FinanceLeaseLiability	18739000	USD
CY2020Q3	us-gaap	Finance Lease Liability FinanceLeaseLiability	8631000	USD
CY2021Q3	us-gaap	Long Term Debt And Capital Lease Obligations Including Current Maturities LongTermDebtAndCapitalLeaseObligationsIncludingCurrentMaturities	7378739000	USD
CY2020Q3	us-gaap	Long Term Debt And Capital Lease Obligations Including Current Maturities LongTermDebtAndCapitalLeaseObligationsIncludingCurrentMaturities	4568631000	USD
CY2021Q3	us-gaap	Debt Instrument Unamortized Discount Premium Net DebtInstrumentUnamortizedDiscountPremiumNet	2811000	USD
CY2020Q3	us-gaap	Debt Instrument Unamortized Discount Premium Net DebtInstrumentUnamortizedDiscountPremiumNet	583000	USD
CY2021Q3	us-gaap	Deferred Finance Costs Net DeferredFinanceCostsNet	45271000	USD
CY2020Q3	us-gaap	Deferred Finance Costs Net DeferredFinanceCostsNet	36104000	USD
CY2021Q3	us-gaap	Long Term Debt And Capital Lease Obligations Current LongTermDebtAndCapitalLeaseObligationsCurrent	2400452000	USD
CY2020Q3	us-gaap	Long Term Debt And Capital Lease Obligations Current LongTermDebtAndCapitalLeaseObligationsCurrent	165000	USD
CY2021Q3	us-gaap	Long Term Debt And Capital Lease Obligations LongTermDebtAndCapitalLeaseObligations	4930205000	USD
CY2020Q3	us-gaap	Long Term Debt And Capital Lease Obligations LongTermDebtAndCapitalLeaseObligations	4531779000	USD
CY2021Q3	us-gaap	Long Term Debt Maturities Repayments Of Principal In Next Twelve Months LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths	2400000000	USD
CY2021Q3	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Two LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo	0	USD
CY2021Q3	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Three LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree	0	USD
CY2021Q3	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Four LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour	10000000	USD
CY2021Q3	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Five LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive	0	USD
CY2021Q3	us-gaap	Long Term Debt Maturities Repayments Of Principal After Year Five LongTermDebtMaturitiesRepaymentsOfPrincipalAfterYearFive	4950000000	USD
CY2021Q3	us-gaap	Debt Instrument Carrying Amount DebtInstrumentCarryingAmount	7360000000	USD
CY2021	us-gaap	Public Utilities Approved Debt Capital Structure Percentage PublicUtilitiesApprovedDebtCapitalStructurePercentage	0.70
CY2021	ato	Public Utilities Actual Debt Capital Structure Percentage PublicUtilitiesActualDebtCapitalStructurePercentage	0.49
CY2021Q3	us-gaap	Forward Contract Indexed To Issuers Equity Settlement Alternatives Cash At Fair Value ForwardContractIndexedToIssuersEquitySettlementAlternativesCashAtFairValue	302000000	USD
CY2021Q3	us-gaap	Forward Contract Indexed To Issuers Equity Settlement Alternatives Shares At Fair Value ForwardContractIndexedToIssuersEquitySettlementAlternativesSharesAtFairValue	3071724	shares
CY2021Q3	us-gaap	Forward Contract Indexed To Issuers Equity Settlement Alternatives Cash At Fair Value ForwardContractIndexedToIssuersEquitySettlementAlternativesCashAtFairValue	301984000	USD
CY2021	us-gaap	Forward Contract Indexed To Issuers Equity Forward Rate ForwardContractIndexedToIssuersEquityForwardRate	98.31
CY2021	us-gaap	Other Comprehensive Income Loss Before Reclassifications Net Of Tax OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax	122826000	USD
CY2021	us-gaap	Reclassification From Accumulated Other Comprehensive Income Current Period Net Of Tax ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax	-4566000	USD
CY2021	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	127392000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Before Reclassifications Net Of Tax OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax	53349000	USD
CY2020	us-gaap	Reclassification From Accumulated Other Comprehensive Income Current Period Net Of Tax ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax	-3645000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	56994000	USD
CY2021Q1	us-gaap	Utilities Operating Expense Gas And Petroleum Purchased UtilitiesOperatingExpenseGasAndPetroleumPurchased	2300000000	USD
CY2021Q3	us-gaap	Public Utilities Amount Of Allowance For Earnings On Equity Capitalized For Rate Making Purposes PublicUtilitiesAmountOfAllowanceForEarningsOnEquityCapitalizedForRateMakingPurposes	2800000	USD
CY2021	us-gaap	Remaining Recovery Period Of Regulatory Assets For Which No Return On Investment During Recovery Period Is Provided1 RemainingRecoveryPeriodOfRegulatoryAssetsForWhichNoReturnOnInvestmentDuringRecoveryPeriodIsProvided1	P15Y
CY2021	us-gaap	Defined Benefit Plan Plan Amendments DefinedBenefitPlanPlanAmendments	34732000	USD
CY2020	us-gaap	Defined Benefit Plan Plan Amendments DefinedBenefitPlanPlanAmendments	0	USD
CY2021	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	24100000	USD
CY2020	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	21100000	USD
CY2019	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	23900000	USD
CY2021	us-gaap	Employee Service Share Based Compensation Allocation Of Recognized Period Costs Capitalized Amount EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsCapitalizedAmount	12900000	USD
CY2020	us-gaap	Employee Service Share Based Compensation Allocation Of Recognized Period Costs Capitalized Amount EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsCapitalizedAmount	11600000	USD
CY2019	us-gaap	Employee Service Share Based Compensation Allocation Of Recognized Period Costs Capitalized Amount EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsCapitalizedAmount	12800000	USD
CY2021Q3	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Authorized ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized	11200000	shares
CY2021Q3	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Available For Grant ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant	1100000	shares
CY2021	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Award Requisite Service Period1 ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardRequisiteServicePeriod1	P3Y
CY2021	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Award Requisite Service Period1 ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardRequisiteServicePeriod1	P3Y
CY2021	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Award Requisite Service Period1 ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardRequisiteServicePeriod1	P3Y
CY2020Q3	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber	443279	shares
CY2020Q3	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue	99.28
CY2019Q3	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber	503072	shares
CY2019Q3	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue	91.66
CY2018Q3	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber	538592	shares
CY2018Q3	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue	80.91
CY2021	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod	223954	shares
CY2021	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	102.68
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod	199985	shares
CY2020	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	102.34
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod	241472	shares
CY2019	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	98.25
CY2021	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod	271435	shares
CY2021	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	97.44
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod	242975	shares
CY2020	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	85.66
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod	269347	shares
CY2019	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	76.71
CY2021	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeited In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod	17671	shares
CY2021	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeitures Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue	101.48
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeited In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod	16803	shares
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeitures Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue	96.87
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeited In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod	7645	shares
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeitures Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue	86.37
CY2021Q3	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber	378127	shares
CY2021Q3	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue	102.45
CY2020Q3	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber	443279	shares
CY2020Q3	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue	99.28
CY2019Q3	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber	503072	shares
CY2019Q3	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue	91.66
CY2021Q3	us-gaap	Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized	13800000	USD
CY2021	us-gaap	Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized Period For Recognition1 EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1	P1Y8M12D
CY2021	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Total Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue	26300000	USD
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Total Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue	20700000	USD
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Total Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue	20500000	USD
CY2021Q3	ato	Minimum Initial Investment For Direct Stock Purchase Plan MinimumInitialInvestmentForDirectStockPurchasePlan	1250	USD
CY2021Q3	ato	Minimum Continuing Investment For Direct Stock Purchase Plan MinimumContinuingInvestmentForDirectStockPurchasePlan	25	USD
CY2021Q3	ato	Annual Maximum Investment For Direct Stock Purchase Plan AnnualMaximumInvestmentForDirectStockPurchasePlan	100000	USD
CY2021Q3	us-gaap	Accounts Receivable Gross Current AccountsReceivableGrossCurrent	407438000	USD
CY2020Q3	us-gaap	Accounts Receivable Gross Current AccountsReceivableGrossCurrent	260544000	USD
CY2021Q3	us-gaap	Allowance For Doubtful Accounts Receivable Current AllowanceForDoubtfulAccountsReceivableCurrent	64471000	USD
CY2020Q3	us-gaap	Allowance For Doubtful Accounts Receivable Current AllowanceForDoubtfulAccountsReceivableCurrent	29949000	USD
CY2021Q3	us-gaap	Accounts Receivable Net Current AccountsReceivableNetCurrent	342967000	USD
CY2020Q3	us-gaap	Accounts Receivable Net Current AccountsReceivableNetCurrent	230595000	USD
CY2021Q3	us-gaap	Deferred Gas Cost DeferredGasCost	66395000	USD
CY2020Q3	us-gaap	Deferred Gas Cost DeferredGasCost	40593000	USD
CY2021Q3	ato	Unusual Or Infrequent Events Incremental Costs Capitalized Current UnusualOrInfrequentEventsIncrementalCostsCapitalizedCurrent	2011719000	USD
CY2020Q3	ato	Unusual Or Infrequent Events Incremental Costs Capitalized Current UnusualOrInfrequentEventsIncrementalCostsCapitalizedCurrent	0	USD
CY2021Q3	us-gaap	Prepaid Expense Current PrepaidExpenseCurrent	48766000	USD
CY2020Q3	us-gaap	Prepaid Expense Current PrepaidExpenseCurrent	40340000	USD
CY2021Q3	us-gaap	Supplies Supplies	15581000	USD
CY2020Q3	us-gaap	Supplies Supplies	6829000	USD
CY2021Q3	us-gaap	Derivative Assets Current DerivativeAssetsCurrent	55073000	USD
CY2020Q3	us-gaap	Derivative Assets Current DerivativeAssetsCurrent	5687000	USD
CY2021Q3	us-gaap	Other Assets Miscellaneous Current OtherAssetsMiscellaneousCurrent	3375000	USD
CY2020Q3	us-gaap	Other Assets Miscellaneous Current OtherAssetsMiscellaneousCurrent	14456000	USD
CY2021Q3	us-gaap	Other Assets Current OtherAssetsCurrent	2200909000	USD
CY2020Q3	us-gaap	Other Assets Current OtherAssetsCurrent	107905000	USD
CY2021Q3	ato	Unusual Or Infrequent Events Incremental Costs Capitalized Gas Purchase Current UnusualOrInfrequentEventsIncrementalCostsCapitalizedGasPurchaseCurrent	2003700000	USD
CY2021Q3	ato	Unusual Or Infrequent Events Incremental Costs Capitalized Current Deferred Carrying Costs UnusualOrInfrequentEventsIncrementalCostsCapitalizedCurrentDeferredCarryingCosts	8000000	USD
CY2021Q3	ato	Public Utilities Property Plantand Equipment Storage PublicUtilitiesPropertyPlantandEquipmentStorage	539972000	USD
CY2020Q3	ato	Public Utilities Property Plantand Equipment Storage PublicUtilitiesPropertyPlantandEquipmentStorage	530985000	USD
CY2021Q3	us-gaap	Public Utilities Property Plant And Equipment Transmission PublicUtilitiesPropertyPlantAndEquipmentTransmission	3725347000	USD
CY2020Q3	us-gaap	Public Utilities Property Plant And Equipment Transmission PublicUtilitiesPropertyPlantAndEquipmentTransmission	3459765000	USD
CY2021Q3	us-gaap	Public Utilities Property Plant And Equipment Distribution PublicUtilitiesPropertyPlantAndEquipmentDistribution	12085654000	USD
CY2020Q3	us-gaap	Public Utilities Property Plant And Equipment Distribution PublicUtilitiesPropertyPlantAndEquipmentDistribution	10680495000	USD
CY2021Q3	us-gaap	Public Utilities Property Plant And Equipment Common PublicUtilitiesPropertyPlantAndEquipmentCommon	868962000	USD
CY2020Q3	us-gaap	Public Utilities Property Plant And Equipment Common PublicUtilitiesPropertyPlantAndEquipmentCommon	829624000	USD
CY2021Q3	us-gaap	Public Utilities Property Plant And Equipment Other Property Plant And Equipment PublicUtilitiesPropertyPlantAndEquipmentOtherPropertyPlantAndEquipment	38612000	USD
CY2020Q3	us-gaap	Public Utilities Property Plant And Equipment Other Property Plant And Equipment PublicUtilitiesPropertyPlantAndEquipmentOtherPropertyPlantAndEquipment	38297000	USD
CY2021Q3	ato	Public Utilities Property Plantand Equipment Plantin Service Excluding Construction Workin Progress PublicUtilitiesPropertyPlantandEquipmentPlantinServiceExcludingConstructionWorkinProgress	17258547000	USD
CY2020Q3	ato	Public Utilities Property Plantand Equipment Plantin Service Excluding Construction Workin Progress PublicUtilitiesPropertyPlantandEquipmentPlantinServiceExcludingConstructionWorkinProgress	15539166000	USD
CY2021Q3	us-gaap	Public Utilities Property Plant And Equipment Construction Work In Progress PublicUtilitiesPropertyPlantAndEquipmentConstructionWorkInProgress	626551000	USD
CY2020Q3	us-gaap	Public Utilities Property Plant And Equipment Construction Work In Progress PublicUtilitiesPropertyPlantAndEquipmentConstructionWorkInProgress	418055000	USD
CY2021Q3	us-gaap	Public Utilities Property Plant And Equipment Plant In Service PublicUtilitiesPropertyPlantAndEquipmentPlantInService	17885098000	USD
CY2020Q3	us-gaap	Public Utilities Property Plant And Equipment Plant In Service PublicUtilitiesPropertyPlantAndEquipmentPlantInService	15957221000	USD
CY2021Q3	us-gaap	Public Utilities Property Plant And Equipment Accumulated Depreciation PublicUtilitiesPropertyPlantAndEquipmentAccumulatedDepreciation	2821128000	USD
CY2020Q3	us-gaap	Public Utilities Property Plant And Equipment Accumulated Depreciation PublicUtilitiesPropertyPlantAndEquipmentAccumulatedDepreciation	2601874000	USD
CY2021Q3	us-gaap	Public Utilities Property Plant And Equipment Net PublicUtilitiesPropertyPlantAndEquipmentNet	15063970000	USD
CY2020Q3	us-gaap	Public Utilities Property Plant And Equipment Net PublicUtilitiesPropertyPlantAndEquipmentNet	13355347000	USD
CY2021Q3	us-gaap	Public Utilities Property Plant And Equipment Amount Of Acquisition Adjustments1 PublicUtilitiesPropertyPlantAndEquipmentAmountOfAcquisitionAdjustments1	-28500000	USD
CY2020Q3	us-gaap	Public Utilities Property Plant And Equipment Amount Of Acquisition Adjustments1 PublicUtilitiesPropertyPlantAndEquipmentAmountOfAcquisitionAdjustments1	-37800000	USD
CY2021Q3	us-gaap	Marketable Securities MarketableSecurities	108071000	USD
CY2020Q3	us-gaap	Marketable Securities MarketableSecurities	103952000	USD
CY2021Q3	us-gaap	Regulatory Assets Noncurrent RegulatoryAssetsNoncurrent	351843000	USD
CY2020Q3	us-gaap	Regulatory Assets Noncurrent RegulatoryAssetsNoncurrent	371707000	USD
CY2021Q3	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	222446000	USD
CY2020Q3	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	227146000	USD
CY2021Q3	ato	Unusual Or Infrequent Events Incremental Costs Capitalized Noncurrent UnusualOrInfrequentEventsIncrementalCostsCapitalizedNoncurrent	89009000	USD
CY2020Q3	ato	Unusual Or Infrequent Events Incremental Costs Capitalized Noncurrent UnusualOrInfrequentEventsIncrementalCostsCapitalizedNoncurrent	0	USD
CY2021Q3	us-gaap	Derivative Assets Noncurrent DerivativeAssetsNoncurrent	175613000	USD
CY2020Q3	us-gaap	Derivative Assets Noncurrent DerivativeAssetsNoncurrent	74991000	USD
CY2021Q3	us-gaap	Other Assets Miscellaneous Noncurrent OtherAssetsMiscellaneousNoncurrent	27738000	USD
CY2020Q3	us-gaap	Other Assets Miscellaneous Noncurrent OtherAssetsMiscellaneousNoncurrent	23374000	USD
CY2021Q3	us-gaap	Other Assets Noncurrent OtherAssetsNoncurrent	974720000	USD
CY2020Q3	us-gaap	Other Assets Noncurrent OtherAssetsNoncurrent	801170000	USD
CY2021Q3	ato	Unusual Or Infrequent Events Incremental Costs Capitalized Gas Purchase Non Current UnusualOrInfrequentEventsIncrementalCostsCapitalizedGasPurchaseNonCurrent	76700000	USD
CY2021Q3	ato	Unusual Or Infrequent Events Incremental Costs Capitalized Non Current Deferred Carrying Costs UnusualOrInfrequentEventsIncrementalCostsCapitalizedNonCurrentDeferredCarryingCosts	12300000	USD
CY2021Q3	us-gaap	Accrued Liabilities Current And Noncurrent AccruedLiabilitiesCurrentAndNoncurrent	97650000	USD
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CY2020Q3	us-gaap	Accounts Payable Current And Noncurrent AccountsPayableCurrentAndNoncurrent	141075000	USD
CY2021Q3	ato	Accrued Gas Payable AccruedGasPayable	100699000	USD
CY2020Q3	ato	Accrued Gas Payable AccruedGasPayable	42054000	USD
CY2021Q3	us-gaap	Accounts Payable And Accrued Liabilities Current And Noncurrent AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent	423222000	USD
CY2020Q3	us-gaap	Accounts Payable And Accrued Liabilities Current And Noncurrent AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent	235775000	USD
CY2021Q3	us-gaap	Contract With Customer Liability Current ContractWithCustomerLiabilityCurrent	49722000	USD
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CY2021Q3	us-gaap	Refundable Gas Costs RefundableGasCosts	52553000	USD
CY2020Q3	us-gaap	Refundable Gas Costs RefundableGasCosts	19985000	USD
CY2021Q3	us-gaap	Operating Lease Liability Current OperatingLeaseLiabilityCurrent	37688000	USD
CY2020Q3	us-gaap	Operating Lease Liability Current OperatingLeaseLiabilityCurrent	35716000	USD
CY2021Q3	us-gaap	Interest Payable Current InterestPayableCurrent	55164000	USD
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CY2021Q3	us-gaap	Derivative Liabilities Current DerivativeLiabilitiesCurrent	5269000	USD
CY2020Q3	us-gaap	Derivative Liabilities Current DerivativeLiabilitiesCurrent	2015000	USD
CY2021Q3	us-gaap	Taxes Payable Current TaxesPayableCurrent	160986000	USD
CY2020Q3	us-gaap	Taxes Payable Current TaxesPayableCurrent	148292000	USD
CY2021Q3	us-gaap	Pension And Other Postretirement Defined Benefit Plans Current Liabilities PensionAndOtherPostretirementDefinedBenefitPlansCurrentLiabilities	4863000	USD
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CY2021Q3	ato	Regulatory Cost Of Removal Liability Current RegulatoryCostOfRemovalLiabilityCurrent	72823000	USD
CY2020Q3	us-gaap	Other Liabilities Current OtherLiabilitiesCurrent	546461000	USD
CY2021Q3	ato	Regulatory Clause Revenues Over Recoveredcurrent RegulatoryClauseRevenuesOverRecoveredcurrent	22694000	USD
CY2020Q3	ato	Regulatory Clause Revenues Over Recoveredcurrent RegulatoryClauseRevenuesOverRecoveredcurrent	43893000	USD
CY2021Q3	us-gaap	Regulatory Liability Current RegulatoryLiabilityCurrent	155857000	USD
CY2020Q3	us-gaap	Regulatory Liability Current RegulatoryLiabilityCurrent	20887000	USD
CY2021Q3	ato	Other Liabilities Current Other OtherLiabilitiesCurrentOther	18545000	USD
CY2020Q3	ato	Other Liabilities Current Other OtherLiabilitiesCurrentOther	14060000	USD
CY2021Q3	us-gaap	Other Liabilities Current OtherLiabilitiesCurrent	686681000	USD
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CY2021Q3	us-gaap	Operating Lease Liability Noncurrent OperatingLeaseLiabilityNoncurrent	194745000	USD
CY2020Q3	us-gaap	Operating Lease Liability Noncurrent OperatingLeaseLiabilityNoncurrent	201071000	USD
CY2021Q3	us-gaap	Contract With Customer Liability Noncurrent ContractWithCustomerLiabilityNoncurrent	9879000	USD
CY2020Q3	ato	Regulatory Clause Revenues Over Recoveredlongterm RegulatoryClauseRevenuesOverRecoveredlongterm	13486000	USD
CY2020Q3	us-gaap	Contract With Customer Liability Noncurrent ContractWithCustomerLiabilityNoncurrent	10060000	USD
CY2021Q3	us-gaap	Regulatory Liability Noncurrent RegulatoryLiabilityNoncurrent	75506000	USD
CY2020Q3	us-gaap	Regulatory Liability Noncurrent RegulatoryLiabilityNoncurrent	17838000	USD
CY2021Q3	us-gaap	Asset Retirement Obligations Noncurrent AssetRetirementObligationsNoncurrent	18373000	USD
CY2020Q3	us-gaap	Asset Retirement Obligations Noncurrent AssetRetirementObligationsNoncurrent	20348000	USD
CY2021Q3	ato	Regulatory Clause Revenues Over Recoveredlongterm RegulatoryClauseRevenuesOverRecoveredlongterm	8416000	USD
CY2021Q3	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	32792000	USD
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CY2021Q3	ato	Other Liabilities Noncurrent Other OtherLiabilitiesNoncurrentOther	12161000	USD
CY2020Q3	ato	Other Liabilities Noncurrent Other OtherLiabilitiesNoncurrentOther	11101000	USD
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CY2020Q3	us-gaap	Other Liabilities Noncurrent OtherLiabilitiesNoncurrent	642128000	USD
CY2021	us-gaap	Public Utilities Allowance For Funds Used During Construction Capitalized Cost Of Equity PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedCostOfEquity	32749000	USD
CY2020	us-gaap	Public Utilities Allowance For Funds Used During Construction Capitalized Cost Of Equity PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedCostOfEquity	23493000	USD
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CY2021	ato	Performance Based Rate Program Income Loss PerformanceBasedRateProgramIncomeLoss	6362000	USD
CY2020	ato	Performance Based Rate Program Income Loss PerformanceBasedRateProgramIncomeLoss	6771000	USD
CY2019	ato	Performance Based Rate Program Income Loss PerformanceBasedRateProgramIncomeLoss	6737000	USD
CY2021	ato	Pension And Other Postretirement Non Service Credit Cost PensionAndOtherPostretirementNonServiceCreditCost	-19238000	USD
CY2020	ato	Pension And Other Postretirement Non Service Credit Cost PensionAndOtherPostretirementNonServiceCreditCost	-3189000	USD
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CY2019	us-gaap	Interest Income Expense Nonoperating Net InterestIncomeExpenseNonoperatingNet	4160000	USD
CY2021	ato	Charitable Contributions CharitableContributions	14460000	USD
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CY2019	ato	Charitable Contributions CharitableContributions	4771000	USD
CY2021	ato	Miscellaneous Non Operating Income Expense MiscellaneousNonOperatingIncomeExpense	-9702000	USD
CY2020	ato	Miscellaneous Non Operating Income Expense MiscellaneousNonOperatingIncomeExpense	-11108000	USD
CY2019	ato	Miscellaneous Non Operating Income Expense MiscellaneousNonOperatingIncomeExpense	-12903000	USD
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CY2020	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	7171000	USD
CY2019	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	7404000	USD
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CY2019	us-gaap	Interest Paid InterestPaid	184852000	USD
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CY2019	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	11467000	USD
CY2021	us-gaap	Capital Expenditures Incurred But Not Yet Paid CapitalExpendituresIncurredButNotYetPaid	184786000	USD
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CY2019	us-gaap	Capital Expenditures Incurred But Not Yet Paid CapitalExpendituresIncurredButNotYetPaid	149993000	USD
CY2021	us-gaap	Interest Paid Net InterestPaidNet	81900000	USD
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CY2019	us-gaap	Interest Paid Net InterestPaidNet	91300000	USD
CY2021Q1	us-gaap	Litigation Settlement Expense LitigationSettlementExpense	1600000	USD
CY2021	us-gaap	Long Term Purchase Commitment Minimum Volume Required LongTermPurchaseCommitmentMinimumVolumeRequired	11.9	Bcf
CY2021	ato	Significant Purchase Commitment Amount SignificantPurchaseCommitmentAmount	149400000	USD
CY2020	ato	Significant Purchase Commitment Amount SignificantPurchaseCommitmentAmount	58500000	USD
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CY2019	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	138903000	USD
CY2020	us-gaap	Income Tax Reconciliation Change In Enacted Tax Rate IncomeTaxReconciliationChangeInEnactedTaxRate	-21000000	USD
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CY2019	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	138903000	USD
CY2021	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.210
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CY2021Q3	us-gaap	Deferred Tax Assets Hedging Transactions DeferredTaxAssetsHedgingTransactions	0	USD
CY2020Q3	us-gaap	Deferred Tax Assets Hedging Transactions DeferredTaxAssetsHedgingTransactions	16719000	USD
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CY2021Q3	ato	Deferred Tax Assets Charitable Contributionand Other Tax Credit Carryforwards DeferredTaxAssetsCharitableContributionandOtherTaxCreditCarryforwards	7712000	USD
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CY2021Q3	us-gaap	Deferred Tax Assets Valuation Allowance DeferredTaxAssetsValuationAllowance	663000	USD
CY2020Q3	us-gaap	Deferred Tax Assets Valuation Allowance DeferredTaxAssetsValuationAllowance	1102000	USD
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CY2020Q3	ato	Deferred Tax Liability Gas Cost Adjustments DeferredTaxLiabilityGasCostAdjustments	23209000	USD
CY2021Q3	ato	Deferred Liabilities Winter Storm Uri DeferredLiabilitiesWinterStormUri	471025000	USD
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CY2021Q3	ato	Deferred Tax Assets Deferred Credits DeferredTaxAssetsDeferredCredits	4181000	USD
CY2020Q3	ato	Deferred Tax Assets Deferred Credits DeferredTaxAssetsDeferredCredits	2537000	USD
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CY2021Q3	ato	Deferred Tax Assets Operating Loss Carryforwards Domestic Impact State And Local DeferredTaxAssetsOperatingLossCarryforwardsDomesticImpactStateAndLocal	500000	USD
CY2021	us-gaap	Unrecognized Tax Benefits Period Increase Decrease UnrecognizedTaxBenefitsPeriodIncreaseDecrease	32800000	USD
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CY2021Q3	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	32792000	USD
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CY2021Q3	us-gaap	Interest Rate Cash Flow Hedge Gain Loss Reclassified To Earnings Net InterestRateCashFlowHedgeGainLossReclassifiedToEarningsNet	-5900000	USD
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CY2021Q3	ato	Accumulated Other Comprehensive Income Loss Derivatives Qualifyingas Hedges Interest Rate Agreements Realized Gain Loss Netof Tax AccumulatedOtherComprehensiveIncomeLossDerivativesQualifyingasHedgesInterestRateAgreementsRealizedGainLossNetofTax	-61700000	USD
CY2021Q3	us-gaap	Derivative Asset Fair Value Gross Liability And Obligation To Return Cash Offset DerivativeAssetFairValueGrossLiabilityAndObligationToReturnCashOffset	0	USD
CY2021Q3	us-gaap	Derivative Assets DerivativeAssets	230686000	USD
CY2021Q3	ato	Debtandequitysecurities Debtandequitysecurities	108071000	USD
CY2021Q3	us-gaap	Derivative Asset Fair Value Gross Liability And Obligation To Return Cash Offset DerivativeAssetFairValueGrossLiabilityAndObligationToReturnCashOffset	0	USD
CY2021Q3	us-gaap	Assets Fair Value Disclosure AssetsFairValueDisclosure	338757000	USD
CY2021Q3	us-gaap	Derivative Liability Fair Value Gross Asset And Right To Reclaim Cash Offset DerivativeLiabilityFairValueGrossAssetAndRightToReclaimCashOffset	0	USD
CY2021Q3	us-gaap	Derivative Liabilities DerivativeLiabilities	5269000	USD
CY2020Q3	us-gaap	Derivative Asset Fair Value Gross Liability And Obligation To Return Cash Offset DerivativeAssetFairValueGrossLiabilityAndObligationToReturnCashOffset	0	USD
CY2020Q3	us-gaap	Derivative Assets DerivativeAssets	80678000	USD
CY2020Q3	ato	Debtandequitysecurities Debtandequitysecurities	103952000	USD
CY2020Q3	us-gaap	Assets Fair Value Disclosure AssetsFairValueDisclosure	184630000	USD
CY2020Q3	us-gaap	Derivative Liability Fair Value Gross Asset And Right To Reclaim Cash Offset DerivativeLiabilityFairValueGrossAssetAndRightToReclaimCashOffset	0	USD
CY2020Q3	us-gaap	Derivative Liabilities DerivativeLiabilities	2015000	USD
CY2021Q3	us-gaap	Debt Securities Available For Sale Allowance For Credit Loss DebtSecuritiesAvailableForSaleAllowanceForCreditLoss	0	USD
CY2021Q3	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	35600000	USD
CY2020Q3	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	32600000	USD
CY2021Q3	us-gaap	Debt Instrument Carrying Amount DebtInstrumentCarryingAmount	7360000000	USD
CY2021Q3	us-gaap	Long Term Debt Fair Value LongTermDebtFairValue	8086136000	USD

Files In Submission

Name	View Source	Status
0000731802-21-000040-index-headers.html	Edgar Link	pending
0000731802-21-000040-index.html	Edgar Link	pending
0000731802-21-000040.txt	Edgar Link	pending
0000731802-21-000040-xbrl.zip	Edgar Link	pending
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ato-20210930_htm.xml	Edgar Link	completed
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$ATO
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2021 Q3 Form 10-K Financial Statement

#000073180221000040 Filed on November 12, 2021

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$ATO Atmos Energy Corp Stock $ato

2021 Q3 Form 10-K Financial Statement

#000073180221000040 Filed on November 12, 2021

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$ATO
Atmos Energy Corp Stock $ato