v3.26.1
Document and Entity Information
Mar. 31, 2026
Document Information [Line Items]  
Document Type 8-K/A
Document Period End Date Mar. 31, 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
Amendment Flag true
Entity Central Index Key 0001126956
Common Stock [Member]  
Document Information [Line Items]  
Title of 12(b) Security Common Stock $1.00 par value
Trading Symbol SR
Security Exchange Name NYSE
6.375% Junior Subordinated Notes due 2086 [Member]  
Document Information [Line Items]  
Title of 12(b) Security 6.375% Junior Subordinated Notes
Trading Symbol SRJN
Security Exchange Name NYSE