XML 65 R46.htm IDEA: XBRL DOCUMENT v3.24.3
Note 1 - Summary of Significant Accounting Policies - Transactions With Affiliates (Details) - Affiliated Entity [Member] - USD ($)
$ in Millions
12 Months Ended
Sep. 30, 2024
Sep. 30, 2023
Sep. 30, 2022
Regulated Operation [Member] | Spire Marketing [Member] | Spire Missouri [Member]      
Natural gas purchases from Spire Marketing $ 13.9 $ 57.4 $ 86.3
Transaction amount 1.7 0.4 0.0
Regulated Operation [Member] | Spire Marketing [Member] | Spire Alabama Inc [Member]      
Natural gas purchases from Spire Marketing 6.7 4.7 3.2
Transaction amount 0.0 0.0 0.5
Unregulated Operation [Member] | Spire S T L Pipeline L L C [Member] | Spire Missouri [Member]      
Transaction amount 32.5 32.0 32.0
Unregulated Operation [Member] | Spire S T L Pipeline L L C [Member] | Spire Alabama Inc [Member]      
Transaction amount 0.0 0.0 0.0
Unregulated Operation [Member] | Spire Storage Salt Plains LLC [Member] | Spire Missouri [Member]      
Transaction amount 0.7 0.7 0.0
Unregulated Operation [Member] | Spire Storage Salt Plains LLC [Member] | Spire Alabama Inc [Member]      
Transaction amount 0.0 0.0 0.0
Unregulated Operation [Member] | Spire MoGas Pipeline [Member] | Spire Missouri [Member]      
Transaction amount 4.8 0.0 0.0
Unregulated Operation [Member] | Spire MoGas Pipeline [Member] | Spire Alabama Inc [Member]      
Transaction amount $ 0.0 $ 0.0 $ 0.0