CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Operating Activities:
Net Income	$ 88.6	$ 184.6	$ 214.2
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	197.3	181.7	168.4
Impairments	148.6	0.0	0.0
Deferred income taxes and investment tax credits	9.0	31.8	(28.7)
Changes in assets and liabilities:
Accounts receivable	36.2	2.7	(32.7)
Inventories	2.6	13.6	15.5
Regulatory assets and liabilities	0.6		191.0
Accounts payable	(43.1)	(6.4)	12.6
Delayed/advance customer billings, net	7.0	12.4	(12.8)
Taxes accrued	2.9	3.5	6.4
Other assets and liabilities	12.0	31.0	(121.2)
Other	8.2	(4.0)	43.9
Net cash provided by operating activities	469.9	450.9	456.6
Investing Activities:
Capital expenditures	(638.4)	(823.3)	(499.4)
Other business acquisitions		(7.9)	(28.1)
Other	6.8	(7.1)	(4.2)
Net cash used in investing activities	(631.6)	(838.3)	(531.7)
Financing Activities:
Issuance of preferred stock		242.0
Issuance of long-term debt	510.0	230.0	75.0
Repayment of long-term debt	(147.0)	(184.1)	(105.0)
(Repayment) issuance of short-term debt, net	(95.2)	189.6	76.3
Issuance of common stock	41.1	19.5	154.7
Dividends paid on common stock	(128.0)	(119.0)	(108.7)
Dividends paid on preferred stock	(14.8)	(3.4)
Other	(6.1)	(2.8)	(3.2)
Net cash provided by financing activities	160.0	371.8	89.1
Net (Decrease) Increase in Cash, Cash Equivalents, and Restricted Cash	(1.7)	(15.6)	14.0
Cash, Cash Equivalents, and Restricted Cash at Beginning of Year	5.8	21.4	7.4
Cash, Cash Equivalents, and Restricted Cash at End of Year	4.1	5.8	21.4
Supplemental disclosure of cash paid for:
Interest, net of amounts capitalized	(100.0)	(102.4)	(95.1)
Income taxes	(2.9)	(2.7)	(1.5)
Spire Missouri
Operating Activities:
Net Income	130.2	115.0	129.3
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	118.0	111.5	102.8
Deferred income taxes and investment tax credits	17.1	13.2	(32.6)
Changes in assets and liabilities:
Accounts receivable	(3.7)	(0.3)	(2.0)
Inventories	2.7	29.0	8.4
Regulatory assets and liabilities	27.3	32.7	141.5
Accounts payable	2.3	(8.4)	(14.8)
Delayed/advance customer billings, net	13.7	13.9	(7.4)
Taxes accrued	2.7	4.4	(2.1)
Other assets and liabilities	(6.1)	(2.6)	(83.9)
Other	0.6	5.2	45.0
Net cash provided by operating activities	304.8	313.6	284.2
Investing Activities:
Capital expenditures	(356.0)	(356.9)	(295.8)
Other	1.3	1.3	4.8
Net cash used in investing activities	(354.7)	(355.6)	(291.0)
Financing Activities:
Issuance of long-term debt	275.0	100.0
Repayment of long-term debt	(107.0)	(50.0)	(100.0)
(Repayments of) borrowings from Spire	(85.2)	41.1	142.3
Dividends paid on common stock	(33.9)	(48.5)	(36.0)
Other	(1.6)
Net cash provided by financing activities	47.3	42.6	6.3
Net (Decrease) Increase in Cash, Cash Equivalents, and Restricted Cash	(2.6)	0.6	(0.5)
Cash, Cash Equivalents, and Restricted Cash at Beginning of Year	2.6	2.0	2.5
Cash, Cash Equivalents, and Restricted Cash at End of Year		2.6	2.0
Supplemental disclosure of cash paid for:
Interest, net of amounts capitalized	(46.0)	(48.7)	(45.6)
Income taxes	0.0	0.0	0.0
Spire Alabama
Operating Activities:
Net Income	65.7	60.3	1.3
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	59.3	56.2	53.2
Deferred income taxes and investment tax credits	22.0	20.5	81.6
Changes in assets and liabilities:
Accounts receivable	7.3	0.8	(16.2)
Inventories	11.9	(1.2)	(1.2)
Regulatory assets and liabilities	(23.5)	(28.2)	40.7
Accounts payable	(15.1)	4.5	4.7
Delayed/advance customer billings, net	(6.6)	(2.5)	(5.5)
Taxes accrued	0.6	(0.9)	4.9
Other assets and liabilities	18.9	34.8	(16.7)
Other	0.2	(3.2)	(0.7)
Net cash provided by operating activities	140.7	141.1	146.1
Investing Activities:
Capital expenditures	(150.4)	(174.5)	(131.7)
Other	1.6	(3.3)	(1.6)
Net cash used in investing activities	(148.8)	(177.8)	(133.3)
Financing Activities:
Issuance of long-term debt	100.0	90.0	75.0
Repayment of long-term debt	(40.0)	0.0	0.0
(Repayments of) borrowings from Spire	(7.4)	(13.8)	(27.4)
Return of capital to Spire	(20.0)	(20.0)	(30.0)
Dividends paid on common stock	(24.0)	(19.0)	(30.0)
Other	(0.5)	(0.5)	(0.5)
Net cash provided by financing activities	8.1	36.7	(12.9)
Net (Decrease) Increase in Cash, Cash Equivalents, and Restricted Cash	0.0	0.0	(0.1)
Cash, Cash Equivalents, and Restricted Cash at Beginning of Year	0.0	0.0	0.1
Cash, Cash Equivalents, and Restricted Cash at End of Year	0.0	0.0	0.0
Supplemental disclosure of cash paid for:
Interest, net of amounts capitalized	(19.0)	(19.2)	(15.1)
Income taxes	$ 0.0	$ 0.0	$ 0.0