Consolidated Statements of Income - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023		Sep. 30, 2022
Operating Revenues	$ 2,593.0	$ 2,666.3		$ 2,198.5
Operating Expenses:
Natural gas	1,103.3	1,260.8		923.9
Operation and maintenance	507.4	517.6		449.6
Depreciation and amortization	278.4	254.8		237.3
Taxes, other than income taxes	215.6	214.5		179.5
Total Operating Expenses	2,104.7	2,247.7		1,790.3
Operating Income	488.3	418.6		408.2
Interest Expense	201.1	185.7		119.8
Other Income (Expense), Net	22.4	23.4		(8.7)
Income Before Income Taxes	309.6	256.3		279.7
Income Tax Expense	58.7	38.8		58.9
Net Income	250.9	217.5		220.8
Provision for preferred dividends	14.8	14.8		14.8
Income allocated to participating securities	0.3	0.3		0.3
Net Income Available to Common Shareholders	235.8	202.4		205.7
Other Comprehensive Income, Net of Tax	(35.5)	0.4		43.6
Comprehensive Income	215.4	217.9		264.4
Operating Revenues	$ 2,593.0	$ 2,666.3		$ 2,198.5
Weighted Average Number of Common Shares Outstanding:
Basic (in shares)	56.1	52.5		52.0
Diluted (in shares)	56.3	52.6		52.1
Basic Earnings Per Share of Common Stock (in dollars per share)	$ 4.2	$ 3.86		$ 3.96
Diluted Earnings Per Share of Common Stock (in dollars per share)	$ 4.19	$ 3.85		$ 3.95
Operating Revenues	$ 2,593.0	$ 2,666.3		$ 2,198.5
Spire Missouri [Member]
Operating Revenues	1,737.4	1,762.9		1,321.0
Operating Expenses:
Natural gas	886.2	943.4		587.0
Operation and maintenance	287.4	296.2		255.7
Depreciation and amortization	174.0	158.7		145.3
Taxes, other than income taxes	157.7	157.5		129.0
Total Operating Expenses	1,505.3	1,555.8		1,117.0
Operating Income	232.1	207.1		204.0
Interest Expense	106.4	97.4		60.9
Other Income (Expense), Net	8.4	19.4		(6.9)
Income Before Income Taxes	134.1	129.1		136.2
Income Tax Expense	15.7	11.6		21.3
Net Income	118.4	117.5		114.9	[1]
Other Comprehensive Income, Net of Tax	0.5	0.2	[1]	1.5	[1]
Comprehensive Income	118.9	117.7		116.4
Operating Revenues	1,737.4	1,762.9		1,321.0
Weighted Average Number of Common Shares Outstanding:
Operating Revenues	1,737.4	1,762.9		1,321.0
Spire Alabama Inc [Member]
Operating Revenues	578.9	571.1		509.1
Operating Expenses:
Natural gas	189.5	202.7		161.5
Operation and maintenance	135.6	136.4		130.1
Depreciation and amortization	72.8	69.3		66.8
Taxes, other than income taxes	42.7	43.0		38.1
Total Operating Expenses	440.6	451.4		396.5
Operating Income	138.3	119.7		112.6
Interest Expense	33.1	34.9		21.3
Other Income (Expense), Net	1.8	1.5		0.4
Income Before Income Taxes	107.0	86.3		91.7
Income Tax Expense	26.9	20.3		23.2
Net Income	80.1	66.0		68.5
Operating Revenues	578.9	571.1		509.1
Weighted Average Number of Common Shares Outstanding:
Operating Revenues	$ 578.9	$ 571.1		$ 509.1

[1] Accumulated other comprehensive income (loss)