XML 74 R57.htm IDEA: XBRL DOCUMENT v3.22.2.2
Note 6 - Long-term Debt (Details Textual) - USD ($)
$ in Millions
12 Months Ended
Dec. 07, 2021
Sep. 30, 2022
Sep. 30, 2021
Sep. 30, 2020
Oct. 13, 2022
Long-Term Debt, Gross   $ 3,258.9 $ 3,014.6    
Interest Paid, Capitalized, Investing Activities   4.5 4.4 $ 5.8  
Subsidiaries [Member]          
Long-Term Debt, Gross   205.9      
Spire Missouri [Member]          
Long-Term Debt, Gross   1,648.0 1,348.0    
Interest Paid, Capitalized, Investing Activities   0.6 0.2 0.8  
Regulatory Preferred Stock and Debt Securities Issuance Amount Authorized   800.0      
Spire Missouri [Member] | First Mortgage Bonds Due December Two Two Thousand Twenty Four [Member]          
Long-Term Debt, Gross $ 300.0        
Debt Instrument, Interest Rate, Stated Percentage 8.00%        
Spire Missouri [Member] | First Mortgage Bonds Due December Two Two Thousand Twenty Four [Member] | Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]          
Debt Instrument, Basis Spread on Variable Rate 0.50%        
Spire Missouri [Member] | Floating Rate Series Due December 2, 2024 [Member]          
Long-Term Debt, Gross   300.0      
Spire Alabama Inc [Member]          
Long-Term Debt, Gross   575.0 625.0    
Interest Paid, Capitalized, Investing Activities   $ 3.2 $ 3.2 $ 1.9  
Spire Alabama Inc [Member] | Notes Due October 15, 2029 [Member] | Subsequent Event [Member]          
Long-Term Debt, Gross         $ 90.0
Debt Instrument, Interest Rate, Stated Percentage         5.32%
Spire Alabama Inc [Member] | Notes Due October 15, 2032 [Member] | Subsequent Event [Member]          
Long-Term Debt, Gross         $ 85.0
Debt Instrument, Interest Rate, Stated Percentage         5.41%
Spire Gulf [Member] | First Mortgage Bonds Due October 15, 2037 [Member] | Subsequent Event [Member]          
Long-Term Debt, Gross         $ 30.0
Debt Instrument, Interest Rate, Stated Percentage         5.61%