v3.26.1
Divestitures - Schedule of Income (Loss) from Discontinued Operations, Net of Tax (Details) - Discontinued Operations, Held-for-Sale [Member] - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Mar. 31, 2026
Mar. 31, 2025
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]        
Operating Revenues $ 187.6 $ 75.0 $ 251.1 $ 126.0
Natural gas 83.4 32.3 122.3 56.9
Operation and maintenance 12.4 11.9 21.7 23.0
Depreciation and amortization 3.2 1.3 6.9 2.7
Taxes, other than income taxes 1.4 1.0 1.4 1.0
Total Operating Expenses 100.4 46.5 152.3 83.6
Operating Income 87.2 28.5 98.8 42.4
Interest Expense, Net 1.6 2.1 4.0 3.9
Income Before Income Taxes 85.6 26.4 94.8 38.5
Income Tax Expense 21.0 6.4 23.0 9.3
Net Income from discontinued operations attributable to Spire Inc. 64.6 20.0 71.8 29.2
Spire Marketing [Member]        
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]        
Operating Revenues 159.9 53.6 201.0 86.6
Natural gas 83.4 32.3 122.3 56.9
Operation and maintenance 6.0 5.6 9.1 8.6
Depreciation and amortization 0.1 0.3 0.2 0.7
Taxes, other than income taxes 0.5 0.6 0.5 0.5
Total Operating Expenses 90.0 38.8 132.1 66.7
Operating Income 69.9 14.8 68.9 19.9
Interest Expense, Net 0.0 0.0 0.0 0.0
Income Before Income Taxes 69.9 14.8 68.9 19.9
Income Tax Expense 17.5 3.7 17.2 5.0
Net Income from discontinued operations attributable to Spire Inc. 52.4 11.1 51.7 14.9
Spire Storage [Member]        
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]        
Operating Revenues 27.7 21.4 50.1 39.4
Natural gas 0.0 0.0 0.0 0.0
Operation and maintenance 6.4 6.3 12.6 14.4
Depreciation and amortization 3.1 1.0 6.7 2.0
Taxes, other than income taxes 0.9 0.4 0.9 0.5
Total Operating Expenses 10.4 7.7 20.2 16.9
Operating Income 17.3 13.7 29.9 22.5
Interest Expense, Net 1.6 2.1 4.0 3.9
Income Before Income Taxes 15.7 11.6 25.9 18.6
Income Tax Expense 3.5 2.7 5.8 4.3
Net Income from discontinued operations attributable to Spire Inc. $ 12.2 $ 8.9 $ 20.1 $ 14.3