Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Mar. 31, 2025	Mar. 31, 2024
Net Income (Loss)	$ 209.3	$ 204.3	$ 290.6	$ 289.4
Other Comprehensive (Loss) Income, Before Tax:
Net hedging (loss) gain arising during the period	(5.4)	9.1	12.2	(6.3)
Amounts reclassified into net income	(0.7)	(0.6)	(2.4)	(9.6)
Net (loss) gain on cash flow hedging derivative instruments	(6.1)	8.5	9.8	(15.9)
Net gain on defined benefit pension and other postretirement plans	0.5	0.0	0.6	0.1
Net unrealized gain on available for sale securities	0.0	0.0	0.0	0.1
Other Comprehensive (Loss) Income , Before Tax	(5.6)	8.5	10.4	(15.7)
(Benefit) Tax Expense Related to Items of Other Comprehensive (Loss) Income	(3.9)	2.0	(0.2)	(3.7)
Other Comprehensive (Loss) Income, Net of Tax	(1.7)	6.5	10.6	(12.0)
Comprehensive Income	207.6	210.8	301.2	277.4
Operating Revenues	1,051.3	1,128.5	1,720.4	1,885.1
Operating Expenses:
Natural gas	454.9	540.8	724.9	907.8
Operation and maintenance	139.4	137.8	268.7	268.5
Depreciation and amortization	73.7	68.9	146.0	135.9
Taxes, other than income taxes	76.9	82.4	125.6	135.1
Total Operating Expenses	744.9	829.9	1,265.2	1,447.3
Operating Income	306.4	298.6	455.2	437.8
Interest Expense, Net	47.4	52.2	95.4	102.8
Other Income, Net	3.0	7.3	3.6	24.8
Income Before Income Taxes	262.0	253.7	363.4	359.8
Income Tax Expense	52.7	49.4	72.8	70.4
Net Income (Loss)	209.3	204.3	290.6	289.4
Other Comprehensive Income, Net of Tax	(1.7)	6.5	10.6	(12.0)
Comprehensive Income	207.6	210.8	301.2	277.4
Spire Missouri [Member]
Net Income (Loss)	112.9	105.2	166.3	162.2
Other Comprehensive (Loss) Income, Before Tax:
Other Comprehensive (Loss) Income, Net of Tax	0.5	0.0	0.6	0.1
Comprehensive Income	113.4	105.2	166.9	162.3
Operating Revenues	671.6	766.5	1,129.1	1,301.9
Operating Expenses:
Natural gas	337.4	443.7	551.0	736.3
Operation and maintenance	77.8	78.6	154.0	153.5
Depreciation and amortization	47.0	43.1	92.7	85.2
Taxes, other than income taxes	55.4	59.8	92.0	98.3
Total Operating Expenses	517.6	625.2	889.7	1,073.3
Operating Income	154.0	141.3	239.4	228.6
Interest Expense, Net	24.7	27.7	50.0	55.6
Other Income, Net	1.5	5.7	3.0	12.9
Income Before Income Taxes	130.8	119.3	192.4	185.9
Income Tax Expense	17.9	14.1	26.1	23.7
Net Income (Loss)	112.9	105.2	166.3	162.2
Other Comprehensive Income, Net of Tax	0.5	0.0	0.6	0.1
Comprehensive Income	$ 113.4	$ 105.2	$ 166.9	$ 162.3