Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Operating Activities:
Net Income	$ 217.5	$ 220.8	$ 271.7
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	254.8	237.3	213.1
Deferred income taxes and investment tax credits	36.9	57.9	67.0
Changes in assets and liabilities:
Accounts receivable	334.2	(26.5)	(343.0)
Inventories	142.8	(117.2)	(111.0)
Regulatory assets and liabilities	(68.7)	(409.0)	76.6
Accounts payable	(389.2)	190.7	177.7
Delayed/advance customer billings, net	1.5	(25.5)	(12.4)
Taxes accrued	15.0	11.2	8.9
Other assets and liabilities	(117.6)	(93.5)	(116.1)
Other	13.0	8.8	17.3
Net cash provided by operating activities	440.2	55.0	249.8
Delayed/advance customer billings	1.5	(25.5)	(12.4)
Investing Activities:
Capital expenditures	(662.5)	(552.2)	(624.8)
Business acquisition	(37.0)	0.0	0.0
Other	4.0	5.5	2.8
Net cash used in investing activities	(695.5)	(546.7)	(622.0)
Financing Activities:
Issuance of long-term debt	755.0	300.0	629.1
Repayment of long-term debt	(281.2)	(55.8)	(115.4)
(Repayment) Issuance of short-term debt, net	(82.0)	365.5	24.0
Issuance of common stock	41.9	51.9	1.0
Dividends paid on common stock	(150.7)	(141.9)	(133.2)
Dividends paid on preferred stock	(14.8)	(14.8)	(14.8)
Other financing activities	(7.6)	(4.0)	(11.3)
Net cash provided by financing activities	260.6	500.9	379.4
Net Increase in Cash, Cash Equivalents, and Restricted Cash	5.3	9.2	7.2
Cash, Cash Equivalents, and Restricted Cash at Beginning of Year	20.5	11.3	4.1
Cash, Cash Equivalents, and Restricted Cash at End of Year	25.8	20.5	11.3
Supplemental disclosure of cash paid for:
Interest, net of amounts capitalized	(177.5)	(119.9)	(98.7)
Income taxes	(2.0)	(1.8)	(1.5)
Spire Missouri [Member]
Operating Activities:
Net Income	117.5	114.9	144.1	[1]
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	158.7	145.3	129.2
Deferred income taxes and investment tax credits	11.6	21.3	25.3
Changes in assets and liabilities:
Accounts receivable	16.0	163.8	(207.4)
Inventories	80.2	(45.4)	(79.0)
Regulatory assets and liabilities	(22.4)	(314.3)	35.9
Accounts payable	(45.7)	25.3	23.1
Delayed/advance customer billings, net	2.2	(26.4)	(13.0)
Taxes accrued	9.7	9.3	2.1
Other assets and liabilities	(108.4)	(48.0)	(115.0)
Other	1.7	1.4	0.7
Net cash provided by operating activities	221.1	47.2	(54.0)
Delayed/advance customer billings	2.2	(26.4)	(13.0)
Investing Activities:
Capital expenditures	(447.5)	(354.1)	(382.6)
Other	4.1	3.6	1.3
Net cash used in investing activities	(443.4)	(350.5)	(381.3)
Financing Activities:
Issuance of long-term debt	400.0	300.0	304.1
Repayment of long-term debt	(250.0)	0.0	(55.0)
(Repayment) Issuance of short-term debt, net	0.0	(250.0)	250.0
Issuance of common stock	38.7	51.1	0.0
Dividends paid on common stock	(57.0)	0.0	0.0
Other financing activities	(3.9)	(2.2)	(3.5)
Net cash provided by financing activities	223.1	303.3	435.3
Net Increase in Cash, Cash Equivalents, and Restricted Cash	0.8	0.0	0.0
Cash, Cash Equivalents, and Restricted Cash at Beginning of Year	0.0	0.0	0.0
Cash, Cash Equivalents, and Restricted Cash at End of Year	0.8	0.0	0.0
Borrowings from (repayments to) Spire, net	95.3	204.4	(60.3)
(Repayments to) borrowings from Spire, net	95.3	204.4	(60.3)
Supplemental disclosure of cash paid for:
Interest, net of amounts capitalized	(93.8)	(58.9)	(45.9)
Income taxes	(0.2)	0.0	0.0
Spire Alabama Inc [Member]
Operating Activities:
Net Income	66.0	68.5	73.8
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	69.3	66.8	62.1
Deferred income taxes and investment tax credits	20.3	23.2	25.0
Changes in assets and liabilities:
Accounts receivable	27.1	(21.2)	(17.8)
Inventories	17.2	(42.5)	(15.4)
Regulatory assets and liabilities	(49.5)	(101.7)	29.2
Accounts payable	(42.3)	26.3	14.0
Delayed/advance customer billings, net	(0.6)	0.5	0.5
Taxes accrued	3.3	0.8	2.5
Other assets and liabilities	18.7	(3.7)	(37.8)
Other	0.4	0.2	0.3
Net cash provided by operating activities	129.9	17.2	136.4
Delayed/advance customer billings	(0.6)	0.5	0.5
Investing Activities:
Capital expenditures	(117.6)	(141.5)	(169.8)
Other	1.3	0.8	0.7
Net cash used in investing activities	(116.3)	(140.7)	(169.1)
Financing Activities:
Issuance of long-term debt	175.0	0.0	150.0
Repayment of long-term debt	0.0	(50.0)	0.0
Dividends paid on common stock	(21.0)	(24.0)	(22.0)
Other financing activities	(1.0)	0.0	(0.9)
Net cash provided by financing activities	(14.8)	125.9	32.7
Net Increase in Cash, Cash Equivalents, and Restricted Cash	(1.2)	2.4	0.0
Cash, Cash Equivalents, and Restricted Cash at Beginning of Year	2.4	0.0	0.0
Cash, Cash Equivalents, and Restricted Cash at End of Year	1.2	2.4	0.0
Borrowings from (repayments to) Spire, net	(136.8)	211.9	(72.4)
(Repayments to) borrowings from Spire, net	(136.8)	211.9	(72.4)
Return of capital to Spire	(31.0)	(12.0)	(22.0)
Supplemental disclosure of cash paid for:
Interest, net of amounts capitalized	(30.1)	(21.0)	(17.9)
Income taxes	$ 0.0	$ 0.0	$ 0.0

[1] Accumulated other comprehensive income (loss)