Condensed Consolidated Statements of Income (Unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Operating Revenues	$ 418.5	$ 448.0	$ 2,355.9	$ 1,884.3
Operating Expenses:
Natural gas	169.8	203.3	1,175.5	844.5
Operation and maintenance	125.5	102.3	389.7	331.9
Depreciation and amortization	64.3	60.4	189.0	176.2
Taxes, other than income taxes	46.9	44.1	179.2	153.3
Total Operating Expenses	406.5	410.1	1,933.4	1,505.9
Operating Income	12.0	37.9	422.5	378.4
Interest Expense, Net	46.7	29.3	137.5	85.4
Other Income (Expense), Net	6.3	(12.1)	19.3	(8.1)
(Loss) Income Before Income Taxes	(28.4)	(3.5)	304.3	284.9
Income Tax (Benefit) Expense	(6.8)	(2.1)	55.7	57.0
Net (Loss) Income	(21.6)	(1.4)	248.6	227.9
Provision for preferred dividends	3.7	3.7	11.1	11.1
(Loss) income allocated to participating securities	(0.1)	0.0	0.4	0.3
Net (Loss) Income Available to Common Shareholders	$ (25.2)	$ (5.1)	$ 237.1	$ 216.5
Weighted Average Number of Common Shares Outstanding:
Basic (in shares)	52.5	52.2	52.5	51.9
Diluted (in shares)	52.5	52.2	52.6	52.0
Basic (Loss) Earnings Per Common Share (in dollars per share)	$ (0.48)	$ (0.10)	$ 4.52	$ 4.17
Diluted (Loss) Earnings Per Common Share (in dollars per share)	$ (0.48)	$ (0.10)	$ 4.51	$ 4.16
Operating Revenues	$ 418.5	$ 448.0	$ 2,355.9	$ 1,884.3
Spire Alabama Inc [Member]
Operating Revenues	113.1	115.7	483.8	446.4
Operating Expenses:
Natural gas	42.7	41.0	173.9	138.6
Operation and maintenance	33.4	29.2	103.0	96.6
Depreciation and amortization	17.5	16.9	51.5	50.1
Taxes, other than income taxes	9.3	8.6	36.0	32.1
Total Operating Expenses	102.9	95.7	364.4	317.4
Operating Income	10.2	20.0	119.4	129.0
Interest Expense, Net	8.7	5.2	26.0	15.0
Other Income (Expense), Net	0.4	(0.7)	1.1	(0.2)
(Loss) Income Before Income Taxes	1.9	14.1	94.5	113.8
Income Tax (Benefit) Expense	0.6	3.6	24.0	28.7
Net (Loss) Income	1.3	10.5	70.5	85.1
Weighted Average Number of Common Shares Outstanding:
Operating Revenues	$ 113.1	$ 115.7	$ 483.8	$ 446.4