XML 90 R70.htm IDEA: XBRL DOCUMENT
v3.25.3

Derivative Instruments and Hedging Activities - Additional Information (Details) MMBTU in Thousands, $ in Millions | 12 Months Ended
--- | ---
Sep. 30, 2025 USD ($) MMBTU
Derivative Instruments and Hedging Activities Disclosures [Line Items] |
Nonmonetary Notional Amount of Natural Gas Derivative Contracts Not Designated As Normal Purchases Or Normal Sales (Millions of Barrels of Oil Equivalent) | 278,200
Notional Amount of Non Exchange Traded Natural Gas Commodity Contracts To Be Settled In Next Twelve Months (Millions of Barrels of Oil Equivalent) | 236,700
Notional Amount of Non Exchange Traded Natural Gas Commodity Contracts To Be Settled In Year Two (Millions of Barrels of Oil Equivalent) | 29,700
Notional Amount of Non Exchange Traded Natural Gas Commodity Contracts To Be Settled In Year Three (Millions of Barrels of Oil Equivalent) | 8,200
Notional Amount of Non Exchange Traded Natural Gas Commodity Contracts To Be Settled In Year Four (Millions of Barrels of Oil Equivalent) | 3,400
Notional Amount of Non Exchange Traded Natural Gas Commodity Contracts To Be Settled In Year Five (Millions of Barrels of Oil Equivalent) | 200
AOCI, Cash Flow Hedge, Cumulative Gain (Loss), after Tax | $ | $ 10.0
Reclassification from AOCI, Current Period, before Tax, Attributable to Parent | $ | $ 2.6
Spire Missouri [Member] |
Derivative Instruments and Hedging Activities Disclosures [Line Items] |
Nonmonetary Notional Amount of Other Price Mitigation in Place Not Designated As Normal Purchases Or Normal Sales (Millions of Barrels of Oil Equivalent) | 9,780

X
- Definition Aggregate notional amount of natural gas derivative contracts not designated as normal purchases or normal sales with notional amounts expressed in nonmonetary units. For example the number of MMBtus specified in a natural gas forward purchase contract. + References No definition available. + Details
Name: | sr_NonmonetaryNotionalAmountOfNaturalGasDerivativeContractsNotDesignatedAsNormalPurchasesOrNormalSales
Namespace Prefix: | sr_
Data Type: | dtr-types:energyItemType
Balance Type: | na
Period Type: | instant

X
- Definition Aggregate notional amount of other price mitigation in place not designated as normal purchases or normal sales with notional amounts expressed in nonmonetary units. + References No definition available. + Details
Name: | sr_NonmonetaryNotionalAmountOfOtherPriceMitigationInPlaceNotDesignatedAsNormalPurchasesOrNormalSales
Namespace Prefix: | sr_
Data Type: | dtr-types:energyItemType
Balance Type: | na
Period Type: | instant

X
- Definition Notional amount of non-exchange traded natural gas commodity contracts to be settled in next twelve months. + References No definition available. + Details
Name: | sr_NotionalAmountOfNonExchangeTradedNaturalGasCommodityContractsToBeSettledInNextTwelveMonths
Namespace Prefix: | sr_
Data Type: | dtr-types:energyItemType
Balance Type: | na
Period Type: | instant

X
- Definition Notional amount of non-exchange traded natural gas commodity contracts to be settled in year five. + References No definition available. + Details
Name: | sr_NotionalAmountOfNonExchangeTradedNaturalGasCommodityContractsToBeSettledInYearFive
Namespace Prefix: | sr_
Data Type: | dtr-types:energyItemType
Balance Type: | na
Period Type: | instant

X
- Definition Notional amount of non-exchange traded natural gas commodity contracts to be settled in year four. + References No definition available. + Details
Name: | sr_NotionalAmountOfNonExchangeTradedNaturalGasCommodityContractsToBeSettledInYearFour
Namespace Prefix: | sr_
Data Type: | dtr-types:energyItemType
Balance Type: | na
Period Type: | instant

X
- Definition Notional amount of non-exchange traded natural gas commodity contracts to be settled in year three. + References No definition available. + Details
Name: | sr_NotionalAmountOfNonExchangeTradedNaturalGasCommodityContractsToBeSettledInYearThree
Namespace Prefix: | sr_
Data Type: | dtr-types:energyItemType
Balance Type: | na
Period Type: | instant

X
- Definition Notional amount of non-exchange traded natural gas commodity contracts to be settled in year two. + References No definition available. + Details
Name: | sr_NotionalAmountOfNonExchangeTradedNaturalGasCommodityContractsToBeSettledInYearTwo
Namespace Prefix: | sr_
Data Type: | dtr-types:energyItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amount, after tax, of accumulated gain (loss) on derivative instrument designated and qualifying as cash flow hedge included in assessment of hedge effectiveness. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 220 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 11 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482790/220-10-45-11 + Details
Name: | us-gaap_AociLossCashFlowHedgeCumulativeGainLossAfterTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
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 Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4EE -Subparagraph (d) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4EE Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4EE -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4EE Reference 3: http://www.xbrl.org/2003/role/exampleRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 55 -Paragraph 181 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480401/815-10-55-181 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4EEE -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4EEE Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4EEE -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4EEE Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4EEE -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4EEE Reference 7: http://www.xbrl.org/2003/role/disclosureRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4EE -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4EE + Details
Name: | us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount before tax of reclassification adjustments of other comprehensive income (loss) attributable to parent. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 14A -Publisher FASB -URI https://asc.fasb.org/1943274/2147482790/220-10-45-14A + Details
Name: | us-gaap_ReclassificationFromAociCurrentPeriodBeforeTaxAttributableToParent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | dei_LegalEntityAxis=sr_SpireMissouriMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |