Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended				9 Months Ended
	Jun. 30, 2023		Jun. 30, 2022		Jun. 30, 2023		Jun. 30, 2022
Net Income	$ (21.6)		$ (1.4)		$ 248.6		$ 227.9
Other Comprehensive Income (Loss), Before Tax:
Net hedging gain (loss) arising during the period	7.6		24.3		(2.2)		38.2
Amounts reclassified into regulatory liabilities	0.0		0.0		(17.5)		0.0
Amounts reclassified into net income	(0.8)		(0.2)		(1.6)		(0.9)
Net gain (loss) on cash flow hedging derivative instruments	6.8		24.1		(21.3)		37.3
Net gain on defined benefit pension and other postretirement plans	0.0		0.2		0.2		0.4
Net unrealized gain (loss) on available for sale securities	0.1		(0.1)		0.1		(0.3)
Other Comprehensive Income (Loss), Before Tax	6.9		24.2		(21.0)		37.4
Income Tax Expense (Benefit) Related to Items of Other Comprehensive Income (Loss)	1.6		5.7		(5.0)		8.8
Other Comprehensive Income (Loss), Net of Tax	5.3		18.5		(16.0)		28.6
Comprehensive (Loss) Income	(16.3)		17.1		232.6		256.5
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
Other Comprehensive Income, Net of Tax	5.3		18.5		(16.0)		28.6
Comprehensive (Loss) Income	(16.3)		17.1		232.6		256.5
Spire Missouri [Member]
Net Income	(13.8)	[1]	(8.4)		145.6	[1]	135.1
Other Comprehensive Income (Loss), Before Tax:
Other Comprehensive Income (Loss), Net of Tax	0.0		0.2	[1]	0.2	[1]	0.4
Comprehensive (Loss) Income	(13.8)		(8.2)		145.8		135.5
Operating Revenues	253.8		236.7		1,586.0		1,155.8
Operating Expenses:
Natural gas	105.5		94.7		887.9		538.8
Operation and maintenance	71.1		59.5		225.6		190.1
Depreciation and amortization	40.0		37.3		117.8		107.4
Taxes, other than income taxes	34.4		32.3		132.0		111.0
Total Operating Expenses	251.0		223.8		1,363.3		947.3
Operating Income	2.8		12.9		222.7		208.5
Interest Expense, Net	24.9		14.7		71.5		43.4
Other Income (Expense), Net	4.7		(9.7)		15.6		(6.2)
(Loss) Income Before Income Taxes	(17.4)		(11.5)		166.8		158.9
Income Tax (Benefit) Expense	(3.6)		(3.1)		21.2		23.8
Net (Loss) Income	(13.8)	[1]	(8.4)		145.6	[1]	135.1
Other Comprehensive Income, Net of Tax	0.0		0.2	[1]	0.2	[1]	0.4
Comprehensive (Loss) Income	$ (13.8)		$ (8.2)		$ 145.8		$ 135.5

[1] Accumulated other comprehensive income (loss)