Condensed Consolidated Statements of Income (Unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2023	Mar. 31, 2022
Operating Revenues	$ 1,123.4	$ 880.9	$ 1,937.4	$ 1,436.3
Operating Expenses:
Natural gas	586.5	392.0	1,005.7	641.2
Operation and maintenance	132.1	113.2	264.2	229.6
Depreciation and amortization	62.6	58.9	124.7	115.8
Taxes, other than income taxes	81.9	71.6	132.3	109.2
Total Operating Expenses	863.1	635.7	1,526.9	1,095.8
Operating Income	260.3	245.2	410.5	340.5
Interest Expense, Net	47.2	27.5	90.8	56.1
Other Income (Expense), Net	7.0	(3.4)	13.0	4.0
Income Before Income Taxes	220.1	214.3	332.7	288.4
Income Tax Expense	40.9	40.7	62.5	59.1
Net Income	179.2	173.6	270.2	229.3
Provision for preferred dividends	3.7	3.7	7.4	7.4
Income allocated to participating securities	0.4	0.2	0.5	0.3
Net Income Available to Common Shareholders	$ 175.1	$ 169.7	$ 262.3	$ 221.6
Weighted Average Number of Common Shares Outstanding:
Basic (in shares)	52.5	51.8	52.5	51.7
Diluted (in shares)	52.6	51.9	52.6	51.8
Basic Earnings Per Common Share (in dollars per share)	$ 3.33	$ 3.27	$ 5.00	$ 4.28
Diluted Earnings Per Common Share (in dollars per share)	$ 3.33	$ 3.27	$ 4.99	$ 4.28
Operating Revenues	$ 1,123.4	$ 880.9	$ 1,937.4	$ 1,436.3
Spire Alabama Inc [Member]
Operating Revenues	218.3	204.1	370.7	330.7
Operating Expenses:
Natural gas	61.8	52.1	131.2	97.6
Operation and maintenance	34.5	32.9	69.6	67.4
Depreciation and amortization	17.0	16.7	34.0	33.2
Taxes, other than income taxes	16.1	14.5	26.7	23.5
Total Operating Expenses	129.4	116.2	261.5	221.7
Operating Income	88.9	87.9	109.2	109.0
Interest Expense, Net	9.0	4.7	17.3	9.8
Other Income (Expense), Net	0.3	0.1	0.7	0.5
Income Before Income Taxes	80.2	83.3	92.6	99.7
Income Tax Expense	20.2	20.9	23.4	25.1
Net Income	60.0	62.4	69.2	74.6
Weighted Average Number of Common Shares Outstanding:
Operating Revenues	$ 218.3	$ 204.1	$ 370.7	$ 330.7