XML 59 R47.htm IDEA: XBRL DOCUMENT v3.23.2
Note 9 - Pension Plans and Other Postretirement Benefits (Details Textual) - USD ($)
$ in Thousands
3 Months Ended 6 Months Ended 9 Months Ended 12 Months Ended
Dec. 26, 2022
Dec. 23, 2021
Dec. 22, 2021
Jun. 30, 2023
Dec. 31, 2022
Jun. 30, 2022
Mar. 31, 2022
Mar. 31, 2023
Mar. 31, 2022
Jun. 30, 2023
Jun. 30, 2022
Sep. 30, 2023
Sep. 30, 2022
Feb. 28, 2022
Sep. 30, 2021
Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Remeasurement due to Settlement             $ 0     $ 0          
Regulatory Asset, Total       $ 1,514,500   $ 1,357,600       1,514,500 $ 1,357,600   $ 1,467,800    
Regulatory Liability       433,600   392,200       433,600 392,200   421,900    
Pension Plan [Member]                              
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement       (0)   (17,800)       (8,600) (29,500)        
Spire Alabama Inc [Member]                              
Regulatory Asset, Total       620,600   567,000       620,600 567,000   595,100    
Regulatory Liability       20,800   24,000       20,800 24,000   $ 23,000    
Spire Alabama Inc [Member] | Pension Plan [Member]                              
Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Remeasurement due to Settlement         $ 27,500 3,600     $ 17,400            
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement       (0) $ (8,600) $ (500)     $ (4,900) (8,600) $ (5,400)        
Defined Benefit Plan, Plan Assets, Contributions by Employer       25,000                      
Spire Alabama Inc [Member] | Pension Plan One [Member]                              
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate           13.00%   12.30%     13.00%       3.60%
Defined Benefit Plan, Benefit Obligation, Settlement Losses Amortized Over Remaining Actuarial Life (Year)                       13 years 4 months 24 days      
Spire Alabama Inc [Member] | Pension Plan Two [Member]                              
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate           11.10% 3.10%   3.10%   11.10%   5.65% 3.60% 3.00%
Defined Benefit Plan, Benefit Obligation, Settlement Losses Amortized Over Remaining Actuarial Life (Year)               12 years 7 months 6 days       12 years 4 months 24 days      
Spire Alabama Inc [Member] | Other Postretirement Benefits Plan [Member]                              
Defined Benefit Plan, Plan Assets, Contributions by Employer                     $ 0        
Anticipated Contributions to Pension Plans Qualified Trusts                     0        
Spire Missouri [Member]                              
Regulatory Asset, Total       854,100   $ 754,500       854,100 754,500   $ 835,700    
Regulatory Liability       346,100   300,800       346,100 300,800   $ 331,800    
Spire Missouri [Member] | Pension Costs [Member] | Missouri West [Member]                              
Regulatory Asset, Total   $ 4,400 $ 5,500                        
Spire Missouri [Member] | Pension Costs [Member] | Missouri East [Member]                              
Regulatory Asset, Total $ 29,900 32,400 29,000                        
Spire Missouri [Member] | Pension and Other Postretirement Plans Costs [Member] | Missouri West [Member]                              
Regulatory Liabilities For Which No Return On Investment During Recovery Period Is Provided 800 $ 1,100 $ 3,300                        
Remaining Recovery Period of Regulatory Liabilities for which No Return on Investment During Recovery Period is Provided (Year)   8 years 8 years                        
Spire Missouri [Member] | Pension and Other Postretirement Plans Costs [Member] | Missouri East [Member]                              
Regulatory Assets for Which No Return on Investment During Recovery Period Is Provided 6,900 $ 11,000 $ 21,600                        
Remaining Recovery Period of Regulatory Assets for which No Return on Investment During Recovery Period is Provided (Year)     8 years                        
Additional Remaining Recovery Period of Regulatory Assets for Which No Return on Investment During Recovery Period Is Provided (Year)   8 years                          
Spire Missouri [Member] | Pension Plan [Member]                              
Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Remeasurement due to Settlement           47,400     $ 21,600            
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement       (0)   $ (17,300)     $ (6,800) (0) $ (24,100)        
Anticipated Contributions to Pension Plans Qualified Trusts       $ 2,800                      
Spire Missouri [Member] | Pension Plan [Member] | Qualified Plan [Member]                              
Defined Benefit Plan, Plan Assets, Contributions by Employer                   29,700          
Spire Missouri [Member] | Pension Plan [Member] | Nonqualified Plan [Member]                              
Defined Benefit Plan, Plan Assets, Contributions by Employer                   $ 0          
Spire Missouri [Member] | Pension Plan One [Member]                              
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate         5.60% 4.55% 3.60%   3.60%   4.55%   5.70% 3.60% 3.00%
Spire Missouri [Member] | Other Postretirement Benefits Plan [Member]                              
Postretirement Benefit Plans, Recovery in Rates Base Allowance   $ 8,600                          
Spire Missouri [Member] | Other Postretirement Benefits Plan [Member] | Missouri West [Member]                              
Regulatory Liability 100                            
Spire Missouri [Member] | Other Postretirement Benefits Plan [Member] | Missouri East [Member]                              
Regulatory Liability $ 900