CONDENSED CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (UNAUDITED) - USD ($) $ in Millions |
Total |
Common Stock [Member] |
Preferred Stock [Member] |
Additional Paid-in Capital [Member] |
Retained Earnings [Member] |
AOCI Attributable to Parent [Member] |
[1] | Spire Missouri [Member] |
Spire Missouri [Member]
Common Stock [Member]
|
Spire Missouri [Member]
Additional Paid-in Capital [Member]
|
Spire Missouri [Member]
Retained Earnings [Member]
|
Spire Missouri [Member]
AOCI Attributable to Parent [Member]
|
[2] | Spire Alabama Inc [Member] |
Spire Alabama Inc [Member]
Common Stock [Member]
|
Spire Alabama Inc [Member]
Additional Paid-in Capital [Member]
|
Spire Alabama Inc [Member]
Retained Earnings [Member]
|
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|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Balance (in shares) at Sep. 30, 2024 | 57,749,667 | 25,855 | 1,972,052 | ||||||||||||||||||
| Balance at Sep. 30, 2024 | $ 3,232.7 | $ 57.7 | $ 242.0 | $ 1,902.2 | $ 1,018.7 | $ 12.1 | $ 1,963.7 | $ 0.1 | $ 854.8 | $ 1,110.8 | $ (2.0) | $ 948.3 | $ 279.4 | $ 668.9 | |||||||
| Net Income | 290.6 | 290.6 | 166.3 | 166.3 | 85.7 | 85.7 | |||||||||||||||
| Common stock issued (in shares) | 1,206,134 | 967 | |||||||||||||||||||
| Common stock issued | 74.8 | $ 1.2 | 73.6 | 74.4 | 74.4 | ||||||||||||||||
| Dividend reinvestment plan (in shares) | 11,966 | ||||||||||||||||||||
| Dividend reinvestment plan | 0.8 | 0.8 | |||||||||||||||||||
| Stock-based compensation costs | 2.8 | 2.8 | |||||||||||||||||||
| Stock activity under stock-based compensation plans (in shares) | 72,093 | ||||||||||||||||||||
| Stock activity under stock-based compensation plans | $ 0.1 | (0.1) | |||||||||||||||||||
| Employees’ tax withholding for stock-based compensation (in shares) | (25,263) | ||||||||||||||||||||
| Employees’ tax withholding for stock-based compensation | (1.9) | (1.9) | |||||||||||||||||||
| Temporary equity adjustment to redemption value | (2.3) | (2.3) | |||||||||||||||||||
| Return of capital to Spire | (30.0) | (30.0) | |||||||||||||||||||
| Common stock, dividends | (92.0) | (92.0) | (14.0) | (14.0) | |||||||||||||||||
| Preferred stock, dividends | (7.4) | (7.4) | |||||||||||||||||||
| Other comprehensive income (loss), net of tax | 10.6 | 10.6 | 0.6 | 0.6 | |||||||||||||||||
| Balance (in shares) at Mar. 31, 2025 | 59,014,597 | 26,822 | 1,972,052 | ||||||||||||||||||
| Balance at Mar. 31, 2025 | 3,508.7 | $ 59.0 | 242.0 | 1,977.4 | 1,207.6 | 22.7 | 2,205.0 | $ 0.1 | 929.2 | 1,277.1 | (1.4) | 990.0 | 249.4 | 740.6 | |||||||
| Balance (in shares) at Dec. 31, 2024 | 58,341,036 | 26,280 | 1,972,052 | ||||||||||||||||||
| Balance at Dec. 31, 2024 | 3,308.9 | $ 58.3 | 242.0 | 1,933.7 | 1,050.5 | 24.4 | 2,049.4 | $ 0.1 | 887.0 | 1,164.2 | (1.9) | 956.5 | 279.4 | 677.1 | |||||||
| Net Income | 209.3 | 209.3 | 112.9 | 112.9 | 70.0 | 70.0 | |||||||||||||||
| Common stock issued (in shares) | 663,619 | 542 | |||||||||||||||||||
| Common stock issued | 42.4 | $ 0.7 | 41.7 | 42.2 | 42.2 | ||||||||||||||||
| Dividend reinvestment plan (in shares) | 5,459 | ||||||||||||||||||||
| Dividend reinvestment plan | 0.4 | 0.4 | |||||||||||||||||||
| Stock-based compensation costs | 1.8 | 1.8 | |||||||||||||||||||
| Stock activity under stock-based compensation plans (in shares) | 6,605 | ||||||||||||||||||||
| Employees’ tax withholding for stock-based compensation (in shares) | (2,122) | ||||||||||||||||||||
| Employees’ tax withholding for stock-based compensation | (0.2) | (0.2) | |||||||||||||||||||
| Temporary equity adjustment to redemption value | (2.0) | (2.0) | |||||||||||||||||||
| Return of capital to Spire | (30.0) | (30.0) | |||||||||||||||||||
| Common stock, dividends | (46.5) | (46.5) | (6.5) | (6.5) | |||||||||||||||||
| Preferred stock, dividends | (3.7) | (3.7) | |||||||||||||||||||
| Other comprehensive income (loss), net of tax | (1.7) | (1.7) | 0.5 | 0.5 | |||||||||||||||||
| Balance (in shares) at Mar. 31, 2025 | 59,014,597 | 26,822 | 1,972,052 | ||||||||||||||||||
| Balance at Mar. 31, 2025 | 3,508.7 | $ 59.0 | 242.0 | 1,977.4 | 1,207.6 | 22.7 | 2,205.0 | $ 0.1 | 929.2 | 1,277.1 | (1.4) | 990.0 | 249.4 | 740.6 | |||||||
| Balance (in shares) at Sep. 30, 2025 | 59,025,961 | 26,822 | 1,972,052 | ||||||||||||||||||
| Balance at Sep. 30, 2025 | 3,389.4 | $ 59.0 | 242.0 | 1,981.4 | 1,087.6 | 19.4 | 2,167.7 | $ 0.1 | 929.2 | 1,239.1 | (0.7) | 978.1 | 242.9 | 735.2 | |||||||
| Net Income | 377.2 | 377.2 | 227.4 | 227.4 | 91.6 | 91.6 | |||||||||||||||
| Dividend reinvestment plan (in shares) | 8,877 | ||||||||||||||||||||
| Dividend reinvestment plan | 0.5 | 0.5 | |||||||||||||||||||
| Stock-based compensation costs | 4.4 | 4.4 | |||||||||||||||||||
| Stock activity under stock-based compensation plans (in shares) | 98,851 | ||||||||||||||||||||
| Stock activity under stock-based compensation plans | $ 0.1 | (0.1) | |||||||||||||||||||
| Employees’ tax withholding for stock-based compensation (in shares) | (23,872) | ||||||||||||||||||||
| Employees’ tax withholding for stock-based compensation | (2.0) | (2.0) | |||||||||||||||||||
| Temporary equity adjustment to redemption value | (3.8) | (3.8) | |||||||||||||||||||
| Redemption of preferred shares | (242.0) | (242.0) | |||||||||||||||||||
| Return of capital to Spire | (2.4) | (2.4) | |||||||||||||||||||
| Preferred share redemption cost | (8.0) | (8.0) | |||||||||||||||||||
| Common stock, dividends | (99.3) | (99.3) | (9.9) | (9.9) | (42.1) | (42.1) | |||||||||||||||
| Preferred stock, dividends | (3.7) | (3.7) | |||||||||||||||||||
| Other comprehensive income (loss), net of tax | 5.1 | 5.1 | 0.1 | 0.1 | |||||||||||||||||
| Balance (in shares) at Mar. 31, 2026 | 59,109,817 | 26,822 | 1,972,052 | ||||||||||||||||||
| Balance at Mar. 31, 2026 | 3,417.8 | $ 59.1 | 1,984.2 | 1,350.0 | 24.5 | 2,385.3 | $ 0.1 | 929.2 | 1,456.6 | (0.6) | 1,025.2 | 240.5 | 784.7 | ||||||||
| Balance (in shares) at Dec. 31, 2025 | 59,095,121 | 26,822 | 1,972,052 | ||||||||||||||||||
| Balance at Dec. 31, 2025 | 3,432.7 | $ 59.1 | 242.0 | 1,981.8 | 1,127.7 | 22.1 | 2,239.9 | $ 0.1 | 929.2 | 1,311.3 | (0.7) | 981.7 | 242.9 | 738.8 | |||||||
| Net Income | 282.2 | 282.2 | 150.2 | 150.2 | 72.0 | 72.0 | |||||||||||||||
| Dividend reinvestment plan (in shares) | 4,475 | ||||||||||||||||||||
| Dividend reinvestment plan | 0.2 | 0.2 | |||||||||||||||||||
| Stock-based compensation costs | 2.2 | 2.2 | |||||||||||||||||||
| Stock activity under stock-based compensation plans (in shares) | 12,096 | ||||||||||||||||||||
| Employees’ tax withholding for stock-based compensation (in shares) | (1,875) | ||||||||||||||||||||
| Temporary equity adjustment to redemption value | (1.3) | (1.3) | |||||||||||||||||||
| Redemption of preferred shares | (242.0) | $ (242.0) | |||||||||||||||||||
| Return of capital to Spire | (2.4) | (2.4) | |||||||||||||||||||
| Preferred share redemption cost | (8.0) | (8.0) | |||||||||||||||||||
| Common stock, dividends | (50.6) | (50.6) | (4.9) | (4.9) | (26.1) | (26.1) | |||||||||||||||
| Other comprehensive income (loss), net of tax | 2.4 | 2.4 | 0.1 | 0.1 | |||||||||||||||||
| Balance (in shares) at Mar. 31, 2026 | 59,109,817 | 26,822 | 1,972,052 | ||||||||||||||||||
| Balance at Mar. 31, 2026 | $ 3,417.8 | $ 59.1 | $ 1,984.2 | $ 1,350.0 | $ 24.5 | $ 2,385.3 | $ 0.1 | $ 929.2 | $ 1,456.6 | $ (0.6) | $ 1,025.2 | $ 240.5 | $ 784.7 | ||||||||
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