XML 103 R95.htm IDEA: XBRL DOCUMENT
v3.23.1

Note 15 - Regulatory Matters (Details Textual) - USD ($) $ in Thousands |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1 Months Ended | 3 Months Ended | 6 Months Ended | 7 Months Ended | 12 Months Ended |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Nov. 18, 2022 | Oct. 26, 2022 | Oct. 07, 2022 | Oct. 05, 2022 | Sep. 14, 2022 | Apr. 22, 2022 | Apr. 21, 2022 | Jan. 18, 2022 | Jan. 01, 2022 | Dec. 29, 2021 | Dec. 23, 2021 | Oct. 26, 2021 | Aug. 23, 2021 | Aug. 30, 2019 | Oct. 01, 2018 | Sep. 30, 2022 | Feb. 28, 2021 | Nov. 30, 2019 | Mar. 31, 2022 | Dec. 31, 2021 | Jun. 30, 2022 | Dec. 31, 2021 | Sep. 30, 2023 | Sep. 30, 2022 | Sep. 30, 2021 | Sep. 30, 2020 | Sep. 13, 2022 | Jul. 12, 2022 | Feb. 23, 2022
Customer Share |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 75.00% |  |  |  |  |  |  |  | 75.00% |  |  |  |  |
Regulatory Asset, Current |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 355,400 |  |  |  |  |  |  |  | $ 355,400 | $ 306,500 |  |  |  |
Utilities Operating Expense, Gas and Petroleum Purchased |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 923,900 | 946,300 | $ 696,100 |  |  |
Spire S T L Pipeline L L C [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Asset Impairment Charges, Total |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 270,000 |  |  |  |  |  |  |  |  |
Revolving Credit Facility [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Line of Credit Facility, Maximum Borrowing Capacity |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,300,000 |  |  |  |  |  |  |  | 1,300,000 |  |  |  |  |
Missouri Public Service Commission [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accrued Pension Assets Added to Prepaid Pension Asset |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 9,000 |  |  |  |  |  |  |  | 9,000 |  |  |  |  |
Public Utilities, Approved Rate, Increase Decrease Annualized Revenue |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 300 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Missouri Public Service Commission [Member] | Infrastructure System Replacement Surcharge [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Requested Rate Increase (Decrease), Amount |  |  |  |  |  |  |  |  |  |  | $ 47,300 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Alabama Public Service Commission [Member] | Enhanced Stability Reserve [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Utilities Operating Expense Maintenance and Operations Self Insurance Cost Deferred Amount |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,000 |  |  |  |  |
Utilities Operating Expense Maintenance and Operations Self Insurance Cost Single Force Majeure Event Deferred Amount |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 300 |  |  |  |  |
Utilities Operating Expense Maintenance and Operations Self Insurance Cost Multiple Force Majeure Events Deferred Amount |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 400 |  |  |  |  |
Regulated Operating Revenue Variances Amount |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 400 |  |  |  |  |
Regulated Operations Enhanced Stability Reserve Term (Year) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 9 years |  |  |  |  |
Regulated Operations Enhanced Stability Reserve Underfunded Balances Amortization Term (Year) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 5 years |  |  |  |  |
Regulated Operations, Enhanced Stability Reserve, Unfunded Balances, Amortization, Annual Limitation |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 700 |  |  |  |  |
Spire Missouri [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Customer Share |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 25.00% |  |  |  |  |  |  |  | 25.00% |  |  |  |  |
Regulatory Asset, Current |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 288,100 |  |  |  |  |  |  |  | $ 288,100 | 276,300 |  |  |  |
Utilities Operating Expense, Gas and Petroleum Purchased |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 195,800 |  |  |  |  |  |  | 587,000 | 786,800 | 515,800 |  |  |
Public Utilities, Reduced Revenue Accounts Receivable Cost Of Gas and Regulatory Liabilities |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 150,000 |  |  |  |  |  |  |  |  |  |
Utilities Operating, Due From Other Parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 42,000 |  |  |  |  |  |  |  |  |  |
Public Utilities Approved Percentages of Excess Natural Gas Supply and Capacity To Retain |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 25.00% |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities Approved Percentages of Excess Natural Gas Supply and Capacity to Customers |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 75.00% |  |  |  |  |  |  |  |  |  |  |  |
Regulated Operating Revenue, Gas |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 100,000 |  |  |  |  |  |  |  |  |  |  |  |
Equity and Debt Financing, Authority Pending Approval |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 800,000
Spire Missouri [Member] | Revolving Credit Facility [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Line of Credit Facility, Maximum Borrowing Capacity |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 575,000 |  |  |  |  |  |  |  | 575,000 |  |  |  |  |
Spire Missouri [Member] | Infrastructure System Replacement Surcharge [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Loss Contingency Accrual, Provision |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 12,200 |  |  |
Regulated Operating Revenue, Pipelines |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 11,900 | $ 11,300 |  |  |  |  |  |  |
Regulated Incremental Annual Revenue From Settlement |  |  |  |  |  |  | $ 8,500 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Spire Missouri [Member] | Infrastructure System Replacement Surcharge [Member] | Subsequent Event [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulated Incremental Annual Revenue From Settlement |  |  |  | $ 10,500 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulated Operating Revenue, Total |  |  |  | $ 19,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Spire Missouri [Member] | Missouri Public Service Commission [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Approved Rate Increase (Decrease), Amount |  |  |  |  |  |  |  |  |  |  | 72,200 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Requested Rate Increase (Decrease), Amount |  |  |  |  |  |  |  |  |  |  | $ 24,900 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Deferred Amount Under Order Authorizing Accounting Treatment |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 42,800 |  |  |  |  |  |  |  | 42,800 |  |  |  |  |
Deferred Amount in Accordance With New Capitalization Rates |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 19,000 |  |  |  |  |  |  |  | 19,000 |  |  |  |  |
Public Utilities, Deferred Amount Prudent Costs in Excess of Capitalization Rates |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 18,800 |  |  |  |  |  |  |  | 18,800 |  |  |  |  |
Deferred Amount, Prudent Costs Related To I S R S Settlement |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 5,000 |  |  |  |  |  |  |  | 5,000 |  |  |  |  |
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 151,900 |  |  |  |  |
Spire Missouri [Member] | Missouri Public Service Commission [Member] | Forecast [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Pending, New Base Rate Revenue Authorized | $ 78,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Spire Missouri [Member] | Missouri Public Service Commission [Member] | Subsequent Event [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount |  |  | $ 71,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Spire Missouri [Member] | Missouri Public Service Commission [Member] | Accounting Authority Order [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Asset, Current |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 6,200 |  |  |  |  |  |  |  | 6,200 |  |  |  |  |
Spire Alabama Inc [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Asset, Current |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 56,900 |  |  |  |  |  |  |  | 56,900 | 18,800 |  |  |  |
Utilities Operating Expense, Gas and Petroleum Purchased |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 161,500 | 145,300 | $ 118,900 |  |  |
Public Utilities, Rate Increase Decrease Index Range Margin |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1.50% |  |  |  |  |  |  |  | 1.50% |  |  |  |  |
Public Utilities, Approved Point of Test Giveback Under Rate Stabilization and Equalization |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 2,200 |  |  |  |  |  |  |  | $ 2,200 | 2,200 |  |  |  |
Spire Alabama Inc [Member] | Revolving Credit Facility [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Line of Credit Facility, Maximum Borrowing Capacity |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 275,000 |  |  |  |  |  |  |  | 275,000 |  |  |  |  |
Spire Alabama Inc [Member] | Revolving Credit Facility [Member] | Spire [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Line of Credit Facility, Maximum Borrowing Capacity |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 200,000 |  |  | $ 275,000 |
Spire Alabama Inc [Member] | Maximum [Member] | Spire [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Notes Receivable, Related Parties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 25,000 |  |  |  |  |  |  |  | 25,000 |  |  |  | $ 25,000 |
Spire Alabama Inc [Member] | Alabama Public Service Commission [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Approved Rate Increase (Decrease), Amount |  |  |  |  |  |  |  |  | $ 5,300 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 8,800 |  |  |  |
Public Utilities, Requested Rate Increase (Decrease), Amount |  |  |  |  |  |  |  |  |  | $ 5,300 |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 17,200 |  |  |  |  |
Public Utilities Maximum Return on Equity Percentage of Prior Year Revenues |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 4.00% |  |  |  |  |  |  |  | 4.00% |  |  |  |  |
Public Utilities, Approved Return on Equity, Percentage |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 10.40% | 9.70% |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Rate Increase Decrease Index Range Margin |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0.10% |  |  |  |  |  |  |  | 0.10% |  |  |  |  |
Public Utilities, Equity Limitation as Percent of Total Capitalization |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 55.50% |  |  |  |  |  |  |  | 55.50% |  |  |  |  |
Public Utilities Approved Percentage of Excess Natural Gas Supply and Capacity To Retain |  |  |  |  |  | 25.00% |  |  |  |  |  |  |  |  |  |  |  | 25.00% |  |  |  |  |  |  |  |  |  |  |
Public Utilities Approved Percentage of Excess Natural Gas Supply and Capacity to Customers |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 75.00% |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Value From Capacity Release, Threshold |  |  |  |  |  | $ 1,600 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Spire Alabama Inc [Member] | Alabama Public Service Commission [Member] | Maximum [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Approved Equity Capital Structure, Percentage |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 56.50% |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Approved Return on Equity, Percentage |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 10.65% | 9.90% |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Average Common Equity Growth |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 6.00% |  |  |  |  |  |  |  |  |  |  |  |  |
Long Term Debt, Approved Amount |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 175,000 |  |
Spire Alabama Inc [Member] | Alabama Public Service Commission [Member] | Minimum [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Approved Equity Capital Structure, Percentage |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 55.50% |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Approved Return on Equity, Percentage |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 10.15% | 9.50% |  |  |  |  |  |  |  |  |  |  |  |  |
Spire Gulf [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Approved Rate Increase (Decrease), Amount |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 1,700 | 2,300 |  |  |  |
Public Utilities, Approved Return on Equity, Percentage |  |  |  |  |  |  |  |  |  |  |  | 9.95% |  |  |  |  |  |  |  |  |  |  |  | 10.70% |  |  |  |  |
Public Utilities, Rate Increase Decrease Index Range Margin |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1.50% |  |  |  |  |  |  |  | 1.50% |  |  |  |  |
Utilities Operating Expense Maintenance and Operations Self Insurance Cost Single Force Majeure Event Deferred Amount |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 100 |  |  |  |  |
Utilities Operating Expense Maintenance and Operations Self Insurance Cost Multiple Force Majeure Events Deferred Amount |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 150 |  |  |  |  |
Regulated Operating Revenue Variances Amount |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 100 |  |  |  |  |
Public Utilities, Approved Rate, Increase Decrease Annualized Revenue |  |  |  |  |  |  |  |  |  |  |  | $ 1,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Approved Rate, Net Income Benefit |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 1,600 |  |  |  |
Public Utilities, Approved Return on Equity, Pro-Rata, Percentage |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 75.00% |  |  |  |  |
Regulated Operations, Recovery of Incurred Costs, Percentage |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 90.00% |  |  |  |  |
Spire Gulf [Member] | Maximum [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Approved Return on Equity, Percentage |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 10.95% |  |  |  |  |
Spire Gulf [Member] | Minimum [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Approved Return on Equity, Percentage |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 10.45% |  |  |  |  |
Spire Gulf [Member] | Forecast [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Approved Return on Equity, Percentage |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 9.95% |  |  |  |  |  |
Spire Gulf [Member] | Forecast [Member] | Maximum [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Approved Return on Equity, Percentage |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 10.30% |  |  |  |  |  |
Spire Gulf [Member] | Forecast [Member] | Minimum [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Approved Return on Equity, Percentage |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 9.70% |  |  |  |  |  |
Spire Gulf [Member] | Subsequent Event [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Requested Rate Increase (Decrease), Amount |  | $ 3,500 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Spire Gulf [Member] | Alabama Public Service Commission [Member] | Debt Issued on October 13, 2022 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Long Term Debt, Approved Amount |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 30,000 |  |
Spire [Member] | Revolving Credit Facility [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Line of Credit Facility, Maximum Borrowing Capacity |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 450,000 |  |  |  |  |  |  |  | $ 450,000 |  |  |  |  |
Spire [Member] | Alabama Public Service Commission [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Line of Credit Facility, Maximum Borrowing Capacity |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 75,000 |  |  |  |  |  |  |  | $ 75,000 |  |  |  |  |
Spire Mississippi [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Approved Rate Increase (Decrease), Amount |  |  |  |  | $ 1,300 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Approved Return on Equity, Percentage |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 10.03% |  |  |  |  |
Public Utilities, Approved Rate, Increase Decrease Annualized Revenue |  |  |  |  |  |  |  | $ 800 |  |  |  |  | $ 1,100 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Approved Return on Equity, Excess of Allowed Return, Percentage |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1.00% |  |  |  |  |
Public Utilities, Approved Return on Equity Shortfall Percentage |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 75.00% |  |  |  |  |
Public Utilities, Approved Return On Equity, Excess, Percentage |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 50.00% |  |  |  |  |
Future Income Taxes Due From Customers and Pension and Other Postretirement Benefit Costs [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Remaining Recovery Period of Regulatory Assets for which No Return on Investment During Recovery Period is Provided (Year) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 20 years |  |  |  |  |  |  |  | 20 years |  |  |  |  |
PGA Assets [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Remaining Recovery Period of Regulatory Assets for which No Return on Investment During Recovery Period is Provided (Year) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1 year |  |  |  |  |  |  |  | 1 year |  |  |  |  |
PGA Assets Due to Filing Adjustment Factors [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Remaining Recovery Period of Regulatory Assets for which No Return on Investment During Recovery Period is Provided (Year) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 3 years |  |  |  |  |  |  |  | 3 years |  |  |  |  |
PGA Assets Not Earning A Return [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Remaining Recovery Period of Regulatory Assets for which No Return on Investment During Recovery Period is Provided (Year) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 15 years |  |  |  |  |  |  |  | 15 years |  |  |  |  |

X
- Definition Amount of accrued pension assets added to prepaid pension assets. + References No definition available. + Details
Name: | sr_AccruedPensionAssetsAddedToPrepaidPensionAsset
Namespace Prefix: | sr_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The revenue of off system sales attributable to customers. + References No definition available. + Details
Name: | sr_CustomerShare
Namespace Prefix: | sr_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Deferred amount in accordance with new capitalization rates. + References No definition available. + Details
Name: | sr_DeferredAmountInAccordanceWithNewCapitalizationRates
Namespace Prefix: | sr_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Deferred amount prudent costs related to the ISRS settlement. + References No definition available. + Details
Name: | sr_DeferredAmountPrudentCostsRelatedToISRSSettlement
Namespace Prefix: | sr_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Equity and debt financing authority pending approval. + References No definition available. + Details
Name: | sr_EquityAndDebtFinancingAuthorityPendingApproval
Namespace Prefix: | sr_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Approved amount of long-term debt. + References No definition available. + Details
Name: | sr_LongTermDebtApprovedAmount
Namespace Prefix: | sr_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Approved percentage of excess natural gas supply and capacity to customers under public utilities. + References No definition available. + Details
Name: | sr_PublicUtilitiesApprovedPercentageOfExcessNaturalGasSupplyAndCapacityToCustomers
Namespace Prefix: | sr_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Approved percentage of excess natural gas supply and capacity to retain for public utilities. + References No definition available. + Details
Name: | sr_PublicUtilitiesApprovedPercentageOfExcessNaturalGasSupplyAndCapacityToRetain
Namespace Prefix: | sr_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage of excess natural gas supply and capacity to customers for public utilities approved. + References No definition available. + Details
Name: | sr_PublicUtilitiesApprovedPercentagesOfExcessNaturalGasSupplyAndCapacityToCustomers
Namespace Prefix: | sr_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Percentage of excess natural gas supply and capacity to retain for public utilities approved. + References No definition available. + Details
Name: | sr_PublicUtilitiesApprovedPercentagesOfExcessNaturalGasSupplyAndCapacityToRetain
Namespace Prefix: | sr_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amounts of approved point of test giveback under rate stabilization and equalization for public utilities. + References No definition available. + Details
Name: | sr_PublicUtilitiesApprovedPointOfTestGivebackUnderRateStabilizationAndEqualization
Namespace Prefix: | sr_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Public Utilities, Approved Rate Increase (Decrease), Annualized Revenue + References No definition available. + Details
Name: | sr_PublicUtilitiesApprovedRateIncreaseDecreaseAnnualizedRevenue
Namespace Prefix: | sr_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Represents approved rate of net income benefit under public utilities. + References No definition available. + Details
Name: | sr_PublicUtilitiesApprovedRateNetIncomeBenefit
Namespace Prefix: | sr_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Percentage of excess of allowed return of approved return on equity of public utilities. + References No definition available. + Details
Name: | sr_PublicUtilitiesApprovedReturnOnEquityExcessOfAllowedReturnPercentage
Namespace Prefix: | sr_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage of excess of approved return on equity for public utilities. + References No definition available. + Details
Name: | sr_PublicUtilitiesApprovedReturnOnEquityExcessPercentage
Namespace Prefix: | sr_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Pro-rata percentage of approved return on equity under public utilities. + References No definition available. + Details
Name: | sr_PublicUtilitiesApprovedReturnOnEquityProrataPercentage
Namespace Prefix: | sr_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage of shortfall for approved return on equity of public utilities. + References No definition available. + Details
Name: | sr_PublicUtilitiesApprovedReturnOnEquityShortfallPercentage
Namespace Prefix: | sr_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents average common equity growth limited with public utilities. + References No definition available. + Details
Name: | sr_PublicUtilitiesAverageCommonEquityGrowth
Namespace Prefix: | sr_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Public utilities deferred amount prudent costs in excess of capitalization rates. + References No definition available. + Details
Name: | sr_PublicUtilitiesDeferredAmountPrudentCostsInExcessOfCapitalizationRates
Namespace Prefix: | sr_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Public utilities deferred amount under order authorizing accounting treatment. + References No definition available. + Details
Name: | sr_PublicUtilitiesDeferredAmountUnderOrderAuthorizingAccountingTreatment
Namespace Prefix: | sr_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Represents equity limitation as a percentage of total capitalization by regulatory agency. + References No definition available. + Details
Name: | sr_PublicUtilitiesEquityLimitationAsPercentOfTotalCapitalization
Namespace Prefix: | sr_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Percentage of prior year revenues for maximum return on equity under public utilities. + References No definition available. + Details
Name: | sr_PublicUtilitiesMaximumReturnOnEquityPercentageOfPriorYearRevenues
Namespace Prefix: | sr_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amount of public utility's new base rate revenue authorized that has not been aprroved. + References No definition available. + Details
Name: | sr_PublicUtilitiesPendingNewBaseRateRevenueAuthorized
Namespace Prefix: | sr_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Represents rate increase decrease index range margin for public utilities. + References No definition available. + Details
Name: | sr_PublicUtilitiesRateIncreaseDecreaseIndexRangeMargin
Namespace Prefix: | sr_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Public utilities reduced revenue, accounts receivable, cost of gas and regulatory liabilities. + References No definition available. + Details
Name: | sr_PublicUtilitiesReducedRevenueAccountsReceivableCostOfGasAndRegulatoryLiabilities
Namespace Prefix: | sr_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Represents the threshold value from capacity release with regulatory agency. + References No definition available. + Details
Name: | sr_PublicUtilitiesValueFromCapacityReleaseThreshold
Namespace Prefix: | sr_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Regulated incremental annual revenue from settlement. + References No definition available. + Details
Name: | sr_RegulatedIncrementalAnnualRevenueFromSettlement
Namespace Prefix: | sr_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Variance amount of revenue for regulated operating. + References No definition available. + Details
Name: | sr_RegulatedOperatingRevenueVariancesAmount
Namespace Prefix: | sr_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Duration of regulated operations enhanced stability reserve term. + References No definition available. + Details
Name: | sr_RegulatedOperationsEnhancedStabilityReserveTerm
Namespace Prefix: | sr_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amortization term of underfunded balances of enhanced stability reserve under regulated operations. + References No definition available. + Details
Name: | sr_RegulatedOperationsEnhancedStabilityReserveUnderfundedBalancesAmortizationTerm
Namespace Prefix: | sr_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of annual limitation of amortization of unfunded balances for enhanced stability reserve under regulated operations. + References No definition available. + Details
Name: | sr_RegulatedOperationsEnhancedStabilityReserveUnfundedBalancesAmortizationAnnualLimitation
Namespace Prefix: | sr_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Percentage of recovery of incurred costs under regulated operations. + References No definition available. + Details
Name: | sr_RegulatedOperationsRecoveryOfIncurredCostsPercentage
Namespace Prefix: | sr_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of receivables from other parties. + References No definition available. + Details
Name: | sr_UtilitiesOperatingDueFromOtherParties
Namespace Prefix: | sr_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amounts of maintenance and operations and self insurance cost for utilities operating expense. + References No definition available. + Details
Name: | sr_UtilitiesOperatingExpenseMaintenanceAndOperationsSelfInsuranceCostDeferredAmount
Namespace Prefix: | sr_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of maintenance and operations self insurance cost of multiple force majeure events as utilities operating expense. + References No definition available. + Details
Name: | sr_UtilitiesOperatingExpenseMaintenanceAndOperationsSelfInsuranceCostMultipleForceMajeureEventsDeferredAmount
Namespace Prefix: | sr_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of maintenance and operations self insurance cost of single force majeure event as utilities operating expense. + References No definition available. + Details
Name: | sr_UtilitiesOperatingExpenseMaintenanceAndOperationsSelfInsuranceCostSingleForceMajeureEventDeferredAmount
Namespace Prefix: | sr_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 45 -Paragraph 28 -Subparagraph (b) -SubTopic 10 -Topic 230 -Publisher FASB -URI https://asc.fasb.org//1943274/2147482740/230-10-45-28 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 45 -Paragraph 4 -Publisher FASB -URI https://asc.fasb.org//1943274/2147482130/360-10-45-4 + Details
Name: | us-gaap_AssetImpairmentCharges
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.19(b),22(b)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1 + Details
Name: | us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount charged against operating income increasing loss contingency liability, after adjustments to reduce previously estimated charges. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 450 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org//1943274/2147483076/450-20-50-1 + Details
Name: | us-gaap_LossContingencyAccrualProvision
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition For an unclassified balance sheet, amounts due from parties associated with the reporting entity as evidenced by a written promise to pay. + References No definition available. + Details
Name: | us-gaap_NotesReceivableRelatedParties
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Percentage of public utility's approved equity to capital, including debt and equity. + References No definition available. + Details
Name: | us-gaap_PublicUtilitiesApprovedEquityCapitalStructurePercentage
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of public utility's approved rate increase (decrease) by regulatory agency. + References No definition available. + Details
Name: | us-gaap_PublicUtilitiesApprovedRateIncreaseDecreaseAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Percentage of public utility's approved return on equity. + References No definition available. + Details
Name: | us-gaap_PublicUtilitiesApprovedReturnOnEquityPercentage
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of public utility's amended requested rate increase (decrease) with regulatory agency. + References No definition available. + Details
Name: | us-gaap_PublicUtilitiesRequestedRateIncreaseDecreaseAmendedAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of public utility's requested rate increase (decrease) with regulatory agency. + References No definition available. + Details
Name: | us-gaap_PublicUtilitiesRequestedRateIncreaseDecreaseAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The total amount of regulated operating revenues recognized during the period. + References No definition available. + Details
Name: | us-gaap_RegulatedOperatingRevenue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The amount of regulated gas operating revenues recognized during the period. + References No definition available. + Details
Name: | us-gaap_RegulatedOperatingRevenueGas
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The amount of regulated pipeline operating revenues recognized during the period. + References No definition available. + Details
Name: | us-gaap_RegulatedOperatingRevenuePipelines
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Carrying amount as of the balance sheet date of capitalized costs of regulated entities that are expected to be recovered through revenue sources within one year or the normal operating cycle, if longer. Such costs are capitalized if they meet both of the following criteria: a. It is probable that future revenue in an amount at least equal to the capitalized cost will result from inclusion of that cost in allowable costs for rate-making purposes. b. Based on available evidence, the future revenue will be provided to permit recovery of the previously incurred cost rather than to provide for expected levels of similar future costs. If the revenue will be provided through an automatic rate-adjustment clause, this criterion requires that the regulator's intent clearly be to permit recovery of the previously incurred cost. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 980 -SubTopic 340 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481878/980-340-50-1 + Details
Name: | us-gaap_RegulatoryAssetsCurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Remaining recovery period of regulatory assets for which no return on investment during recovery period is provided, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 980 -SubTopic 340 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481878/980-340-50-1 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 980 -SubTopic 340 -Section 55 -Paragraph 2 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481849/980-340-55-2 + Details
Name: | us-gaap_RemainingRecoveryPeriodOfRegulatoryAssetsForWhichNoReturnOnInvestmentDuringRecoveryPeriodIsProvided1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amount of operating expense for purchased gas and petroleum of regulated operation. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 220 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.2(b)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147483621/220-10-S99-2 + Details
Name: | us-gaap_UtilitiesOperatingExpenseGasAndPetroleumPurchased
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | srt_CounterpartyNameAxis=sr_SpireSTLPipelineLLCMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CreditFacilityAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RegulatoryAgencyAxis=sr_MissouriPublicServiceCommissionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PublicUtilitiesRegulatoryProceedingAxis=sr_InfrastructureSystemReplacementSurchargeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RegulatoryAgencyAxis=sr_AlabamaPublicServiceCommissionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PublicUtilitiesRegulatoryProceedingAxis=sr_EnhancedStabilityReserveMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=sr_SpireMissouriMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_StatementScenarioAxis=srt_ScenarioForecastMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PublicUtilitiesRegulatoryProceedingAxis=sr_AccountingAuthorityOrderMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=sr_SpireAlabamaIncMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LineOfCreditFacilityAxis=sr_SpireMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_CounterpartyNameAxis=sr_SpireMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=sr_SpireGulfMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=sr_DebtIssuedOnOctober132022Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=sr_SpireMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=sr_SpireMississippiMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RegulatoryAssetAxis=sr_FutureIncomeTaxesDueFromCustomersAndPensionAndOtherPostretirementBenefitCostsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RegulatoryAssetAxis=sr_PgaAssetsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RegulatoryAssetAxis=sr_PgaAssetsDueToFilingAdjustmentFactorsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RegulatoryAssetAxis=sr_PgaAssetsNotEarningAReturnMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |