CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Operating Activities:
Net Income	$ 88.9	$ 67.0
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	50.8	47.5
Deferred income taxes and investment tax credits	21.8	14.3
Changes in assets and liabilities:
Accounts receivable	(169.6)	(162.5)
Inventories	9.5	11.1
Regulatory assets and liabilities	11.2	45.6
Accounts payable	43.9	42.6
Delayed/advance customer billings, net	(5.8)	(3.5)
Taxes accrued	(30.2)	(24.9)
Other assets and liabilities	(15.4)	30.3
Other	2.5	(3.0)
Net cash provided by operating activities	7.6	64.5
Investing Activities:
Capital expenditures	(163.6)	(192.3)
Other	0.0	(0.3)
Net cash used in investing activities	(163.6)	(192.6)
Financing Activities:
Issuance of long-term debt	150.0	510.0
Repayment of long-term debt	(5.4)	(100.0)
Issuance (repayment) of short-term debt, net	48.1	(224.2)
Issuance of common stock	0.4	2.3
Dividends paid on common stock	(32.2)	(34.7)
Dividends paid on preferred stock	(3.7)	(3.7)
Other	(1.8)	(5.9)
Net cash provided by financing activities	155.4	143.8
Net (Decrease) Increase in Cash, Cash Equivalents, and Restricted Cash	(0.6)	15.7
Cash, Cash Equivalents, and Restricted Cash at Beginning of Period	4.1	5.8
Cash and Cash Equivalents at End of Period	3.5	21.5
Supplemental disclosure of cash (paid) received for:
Interest, net of amounts capitalized	(15.5)	(11.6)
Income taxes	0.1	0.0
Spire Missouri
Operating Activities:
Net Income	56.6	48.0
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	30.4	29.0
Deferred income taxes and investment tax credits	9.9	6.8
Changes in assets and liabilities:
Accounts receivable	(88.7)	(96.9)
Inventories	6.3	5.5
Regulatory assets and liabilities	7.2	32.8
Accounts payable	24.3	26.9
Delayed/advance customer billings, net	(5.6)	(2.4)
Taxes accrued	(25.7)	(21.7)
Other assets and liabilities	(8.6)	16.9
Other	0.2	0.2
Net cash provided by operating activities	6.3	45.1
Investing Activities:
Capital expenditures	(99.1)	(102.2)
Other	0.3	0.0
Net cash used in investing activities	(98.8)	(102.2)
Financing Activities:
Issuance of long-term debt	0.0	275.0
Repayment of long-term debt	0.0	(100.0)
Repayments to Spire, net	92.5	(98.3)
Dividends paid on common stock	0.0	(11.3)
Other	0.0	(1.6)
Net cash provided by financing activities	92.5	63.8
Net (Decrease) Increase in Cash, Cash Equivalents, and Restricted Cash	0.0	6.7
Cash, Cash Equivalents, and Restricted Cash at Beginning of Period	0.0	2.6
Cash and Cash Equivalents at End of Period	0.0	9.3
Supplemental disclosure of cash (paid) received for:
Interest, net of amounts capitalized	(9.6)	(7.5)
Income taxes	0.0	0.0
Spire Alabama
Operating Activities:
Net Income	13.7	13.2
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	15.0	14.3
Deferred income taxes and investment tax credits	4.8	4.5
Changes in assets and liabilities:
Accounts receivable	(37.8)	(34.3)
Inventories	(2.1)	4.2
Regulatory assets and liabilities	2.9	11.1
Accounts payable	10.4	(0.8)
Delayed/advance customer billings, net	(0.1)	(0.6)
Taxes accrued	(3.3)	(1.3)
Other assets and liabilities	(0.9)	0.6
Other	0.1	(2.7)
Net cash provided by operating activities	2.7	8.2
Investing Activities:
Capital expenditures	(40.9)	(38.7)
Other	0.0	(1.4)
Net cash used in investing activities	(40.9)	(40.1)
Financing Activities:
Issuance of long-term debt	150.0	100.0
Return of capital to Spire	(11.0)	0.0
Repayments to Spire, net	(94.4)	(61.6)
Dividends paid on common stock	(5.5)	(6.0)
Other	(0.9)	(0.5)
Net cash provided by financing activities	38.2	31.9
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 and Cash Equivalents at End of Period	0.0	0.0
Supplemental disclosure of cash (paid) received for:
Interest, net of amounts capitalized	(3.6)	(2.9)
Income taxes	$ 0.0	$ 0.0