Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Millions		3 Months Ended
		Dec. 31, 2022	Sep. 30, 2022	Dec. 31, 2021	Sep. 30, 2021
Operating Activities:
Net Income		$ 91.0	$ 91.0	$ 55.7	$ 55.7
Adjustments to reconcile net income to net cash used in operating activities:
Depreciation and amortization		62.1		56.9
Deferred income taxes and investment tax credits		21.6		18.4
Changes in assets and liabilities:
Accounts receivable		(156.9)		(152.8)
Inventories		49.7		(20.5)
Regulatory assets and liabilities		(90.1)		(187.3)
Accounts payable		(96.7)		42.9
Delayed/advance customer billings, net		(7.2)		(2.9)
Taxes accrued		(32.1)		(31.4)
Other assets and liabilities		(15.6)		(9.6)
Other		3.4		0.7
Net cash used in operating activities		(170.8)		(229.9)
Delayed/advance customer billings, net		(7.2)		(2.9)
Investing Activities:
Capital expenditures		(154.8)		(145.7)
Other		3.1		2.6
Net cash used in investing activities		(151.7)		(143.1)
Financing Activities:
Issuance of long-term debt		205.0		300.0
Repayment of long-term debt		(31.2)		(55.8)
Issuance of short-term debt, net		189.5		174.0
Issuance of common stock		0.4		0.4
Dividends paid on common stock		(36.3)		(34.6)
Dividends paid on preferred stock		(3.7)		(3.7)
Other financing activities		(2.7)		(3.4)
Net cash provided by financing activities		321.0		376.9
Net (Decrease) Increase in Cash, Cash Equivalents, and Restricted Cash		(1.5)		3.9
Cash, Cash Equivalents, and Restricted Cash at Beginning of Period		20.5		11.3
Cash, Cash Equivalents, and Restricted Cash at End of Period		19.0	20.5	15.2	11.3
Supplemental disclosure of cash paid for:
Interest, net of amounts capitalized		(36.9)		(23.3)
Income taxes		(0.3)		(0.2)
Spire Missouri [Member]
Operating Activities:
Net Income	[1]	47.3		45.3
Adjustments to reconcile net income to net cash used in operating activities:
Depreciation and amortization		38.6		34.2
Deferred income taxes and investment tax credits		8.1		11.5
Changes in assets and liabilities:
Accounts receivable		(208.5)		(74.9)
Inventories		24.4		(11.1)
Regulatory assets and liabilities		(61.5)		(161.3)
Accounts payable		66.4		38.3
Delayed/advance customer billings, net		(7.1)		(2.0)
Taxes accrued		(26.2)		(25.8)
Other assets and liabilities		13.2		3.8
Other		0.4		0.2
Net cash used in operating activities		(104.9)		(141.8)
Delayed/advance customer billings, net		(7.1)		(2.0)
Investing Activities:
Capital expenditures		(102.0)		(96.3)
Other		1.0		0.4
Net cash used in investing activities		(101.0)		(95.9)
Financing Activities:
Issuance of long-term debt		0.0		300.0
Other financing activities		0.0		(1.7)
Net cash provided by financing activities		205.9		237.7
Net (Decrease) Increase in Cash, Cash Equivalents, and Restricted Cash		0.0		0.0
Cash, Cash Equivalents, and Restricted Cash at Beginning of Period		0.0		0.0
Cash, Cash Equivalents, and Restricted Cash at End of Period		0.0	0.0	0.0	0.0
Borrowings from (repayments to) Spire, net		205.9		(60.6)
Supplemental disclosure of cash paid for:
Interest, net of amounts capitalized		(21.0)		(15.3)
Income taxes		0.0		0.0
Spire Alabama Inc [Member]
Operating Activities:
Net Income		9.2		12.2
Adjustments to reconcile net income to net cash used in operating activities:
Depreciation and amortization		17.0		16.5
Deferred income taxes and investment tax credits		3.2		4.2
Changes in assets and liabilities:
Accounts receivable		(29.5)		(36.5)
Inventories		5.6		(11.1)
Regulatory assets and liabilities		(29.7)		(21.4)
Accounts payable		10.9		15.8
Delayed/advance customer billings, net		(0.1)		(0.9)
Taxes accrued		(2.5)		(3.2)
Other assets and liabilities		15.1		(2.0)
Other		0.1		(0.2)
Net cash used in operating activities		(0.7)		(26.6)
Delayed/advance customer billings, net		(0.1)		(0.9)
Investing Activities:
Capital expenditures		(38.2)		(34.7)
Other		0.1		0.6
Net cash used in investing activities		(38.1)		(34.1)
Financing Activities:
Issuance of long-term debt		175.0		0.0
Repayment of long-term debt		0.0		(50.0)
Dividends paid on common stock		(11.0)		(8.0)
Other financing activities		(1.0)		0.0
Net cash provided by financing activities		36.4		60.7
Net (Decrease) Increase in Cash, Cash Equivalents, and Restricted Cash		(2.4)		0.0
Cash, Cash Equivalents, and Restricted Cash at Beginning of Period		2.4		0.0
Cash, Cash Equivalents, and Restricted Cash at End of Period		0.0	$ 2.4	0.0	$ 0.0
Borrowings from (repayments to) Spire, net		(115.1)		124.7
Return of capital to Spire		(11.5)		(6.0)
Supplemental disclosure of cash paid for:
Interest, net of amounts capitalized		(5.8)		(5.2)
Income taxes		$ 0.0		$ 0.0

[1] Accumulated other comprehensive income (loss)