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Commitments and Contingencies - Additional Information - Contingencies (Details)
Mar. 31, 2022
site
Spire Missouri East  
Site Contingency [Line Items]  
Number of former manufactured gas plant (MGP) sites in Missouri 3
Number of sites enrolled in Brownfields/Voluntary clean up program 2
Spire Missouri West | Previous Ownership  
Site Contingency [Line Items]  
Number of former manufactured gas plant (MGP) 6
Spire Alabama  
Site Contingency [Line Items]  
Number of former manufactured gas plant (MGP) 9
Number of former manufactured gas distribution 5
Spire Alabama | Current Ownership  
Site Contingency [Line Items]  
Number of former manufactured gas plant (MGP) 4
Number of former manufactured gas distribution 1