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Document and Entity Information
Feb. 09, 2026
Document And Entity Information [Line Items]  
Amendment Flag false
Entity Central Index Key 0001126956
Document Type 8-K
Document Period End Date Feb. 09, 2026
Entity File Number 1-16681
Entity Registrant Name Spire Inc.
Entity Address, Address Line One 700 Market Street
Entity Address, City or Town St. Louis
Entity Address, State or Province MO
Entity Address, Postal Zip Code 63101
City Area Code 314
Local Phone Number 342-0500
Entity Incorporation State Country Code MO
Entity Tax Identification Number 74-2976504
Written Communications false
Soliciting Material false
Pre Commencement Tender Offer false
Pre Commencement Issuer Tender Offer false
Entity Emerging Growth Company false
Common Stock [Member]  
Document And Entity Information [Line Items]  
Security 12b Title Common Stock $1.00 par value
Trading Symbol SR
Security Exchange Name NYSE
Series A Preferred Stock [Member]  
Document And Entity Information [Line Items]  
Security 12b Title Depositary Shares, each representing a 1/1,000th interest in a share of 5.90% Series A Cumulative Redeemable Perpetual Preferred Stock, par value
Trading Symbol SR.PRA
Security Exchange Name NYSE
Junior Notes [Member]  
Document And Entity Information [Line Items]  
Security 12b Title 6.375% Junior Subordinated Notes due 2086
Trading Symbol SRJN
Security Exchange Name NYSE