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v3.23.1

Note 16 - Commitments and Contingencies (Details Textual) $ in Millions | 12 Months Ended
--- | ---
Sep. 30, 2022 USD ($)
Long-Term Purchase Commitment, Amount | $ 2,107.1
Capital Committed to Contribute to Partnership | 10.0
Contributed Capital, Total | 1.9
Spire Missouri [Member] |
Long-Term Purchase Commitment, Amount | 1,224.7
Spire Alabama Inc [Member] |
Long-Term Purchase Commitment, Amount | $ 723.1

X
- Definition Amount of capital committed to partnership. + References No definition available. + Details
Name: | sr_CapitalCommittedToContributeToPartnership
Namespace Prefix: | sr_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of capital contributed in total. + References No definition available. + Details
Name: | sr_ContributedCapitalTotal
Namespace Prefix: | sr_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The minimum amount the entity agreed to spend under the long-term purchase commitment. + References No definition available. + Details
Name: | us-gaap_LongTermPurchaseCommitmentAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

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

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