Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Millions		3 Months Ended
		Dec. 31, 2023		Dec. 31, 2022
Net Income		$ 85.1		$ 91.0
Other Comprehensive Loss, Before Tax:
Net hedging loss arising during the period		(15.4)		(3.0)
Amounts reclassified into net income		(9.0)		(0.3)
Net loss on cash flow hedging derivative instruments		(24.4)		(3.3)
Net gain on defined benefit pension and other postretirement plans		0.1		0.1
Net unrealized gain on available for sale securities		0.1		0.0
Other Comprehensive Loss, Before Tax		(24.2)		(3.2)
Income Tax Benefit Related to Items of Other Comprehensive Loss		(5.7)		(0.8)
Other Comprehensive Loss, Net of Tax		(18.5)		(2.4)
Comprehensive Income		66.6		88.6
Operating Revenues		756.6		814.0
Operating Expenses:
Natural gas		367.0		419.2
Operation and maintenance		130.7		132.1
Depreciation and amortization		67.0		62.1
Taxes, other than income taxes		52.7		50.4
Total Operating Expenses		617.4		663.8
Operating Income		139.2		150.2
Interest Expense, Net		50.6		43.6
Other Income, Net		17.5		6.0
Income Before Income Taxes		106.1		112.6
Income Tax Expense		21.0		21.6
Net Income		85.1		91.0
Other Comprehensive Income, Net of Tax		(18.5)		(2.4)
Comprehensive Income		66.6		88.6
Spire Missouri [Member]
Net Income		57.0	[1]	47.3
Other Comprehensive Loss, Before Tax:
Other Comprehensive Loss, Net of Tax	[1]	0.1		0.1
Comprehensive Income		57.1		47.4
Operating Revenues		535.4		541.2
Operating Expenses:
Natural gas		292.6		316.7
Operation and maintenance		74.9		77.1
Depreciation and amortization		42.1		38.6
Taxes, other than income taxes		38.5		36.4
Total Operating Expenses		448.1		468.8
Operating Income		87.3		72.4
Interest Expense, Net		27.9		22.0
Other Income, Net		7.2		5.0
Income Before Income Taxes		66.6		55.4
Income Tax Expense		9.6		8.1
Net Income		57.0	[1]	47.3
Other Comprehensive Income, Net of Tax	[1]	0.1		0.1
Comprehensive Income		$ 57.1		$ 47.4

[1] Accumulated other comprehensive income (loss)