XML 52 R43.htm IDEA: XBRL DOCUMENT
v3.22.2

Winter Storm Uri (Details) - USD ($) | 1 Months Ended |  |  |  |  |
--- | --- | --- | --- | --- | --- | ---
Feb. 28, 2021 | Jun. 30, 2022 | May 25, 2022 | Sep. 30, 2021 | Jul. 30, 2021 | Mar. 31, 2021
Unusual or Infrequent Item, or Both [Line Items] |  |  |  |  |  |
Aggregate natural gas purchases | $ 2,300,000,000 |  |  |  |  |
Regulatory assets |  | $ 2,513,357,000 |  | $ 2,521,441,000 |  |
Winter Storm Uri incremental costs |  |  |  |  |  |
Unusual or Infrequent Item, or Both [Line Items] |  |  |  |  |  |
Regulatory assets |  | 2,107,820,000 |  | $ 2,100,728,000 |  |
Winter Storm Uri incremental costs | Winter Storm Uri |  |  |  |  |  |
Unusual or Infrequent Item, or Both [Line Items] |  |  |  |  |  |
Regulatory assets |  | 2,100,000,000 |  |  |  |
Winter Storm Uri incremental costs | Kansas | Winter Storm Uri |  |  |  |  |  |
Unusual or Infrequent Item, or Both [Line Items] |  |  |  |  |  |
Regulatory assets |  | 88,000,000 |  |  |  |
Winter Storm Uri incremental costs | Texas | Winter Storm Uri |  |  |  |  |  |
Unusual or Infrequent Item, or Both [Line Items] |  |  |  |  |  |
Regulatory assets |  | $ 2,019,800,000 |  |  |  |
Extraordinary Gas Cost | Kansas |  |  |  |  |  |
Unusual or Infrequent Item, or Both [Line Items] |  |  |  |  |  |
Regulatory assets |  |  | $ 90,200,000 |  |  |
Extraordinary Gas Cost | Texas | Winter Storm Uri |  |  |  |  |  |
Unusual or Infrequent Item, or Both [Line Items] |  |  |  |  |  |
Regulatory assets |  |  |  |  | $ 2,000,000,000 |
Senior Notes Due 2023 |  |  |  |  |  |
Unusual or Infrequent Item, or Both [Line Items] |  |  |  |  |  |
Debt instrument, face amount |  |  |  |  |  | $ 2,200,000,000
Senior Notes Due 2023 | Texas |  |  |  |  |  |
Unusual or Infrequent Item, or Both [Line Items] |  |  |  |  |  |
Debt instrument, face amount |  |  |  |  |  | 2,200,000,000
Other administrative costs |  |  |  |  |  | $ 600,000

X
- Definition Other Administrative Costs, Gross + References No definition available. + Details
Name: | ato_OtherAdministrativeCostsGross
Namespace Prefix: | ato_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Face (par) amount of debt instrument at time of issuance. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 50 -Paragraph 1B -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=124435984&loc=d3e28551-108399 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 55 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=124429444&loc=SL124452920-239629 Reference 5: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 55 -Paragraph 69C -URI http://asc.fasb.org/extlink&oid=123466577&loc=SL123495737-112612 Reference 6: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 55 -Paragraph 69B -URI http://asc.fasb.org/extlink&oid=123466577&loc=SL123495735-112612 + Details
Name: | us-gaap_DebtInstrumentFaceAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The amount for the individual regulatory asset as itemized in a table of regulatory assets as of the end of the period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 340 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6499975&loc=d3e44250-110382 + Details
Name: | us-gaap_RegulatoryAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_UnusualOrInfrequentItemLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of operating expense for purchased gas and petroleum of regulated operation. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.2(b)) -URI http://asc.fasb.org/extlink&oid=123367319&loc=SL114868664-224227 + Details
Name: | us-gaap_UtilitiesOperatingExpenseGasAndPetroleumPurchased
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | us-gaap_RegulatoryAssetAxis=us-gaap_StormCostsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_UnusualOrInfrequentItemAxis=ato_WinterStormUriMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_StatementGeographicalAxis=stpr_KS
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_StatementGeographicalAxis=stpr_TX
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RegulatoryAssetAxis=us-gaap_AssetRecoverableGasCostsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=ato_SeniorNotesDue2023Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |