Spire Alabama 10-Q 5 Feb 25 2025 Q1 Quarterly report Financial data

Document And Entity Information

Document And Entity Information - shares	3 Months Ended
	Dec. 31, 2024	Jan. 31, 2025
Document Information [Line Items]
Entity Central Index Key	0001126956
Entity Registrant Name	Spire Inc.
Amendment Flag	false
Current Fiscal Year End Date	--09-30
Document Fiscal Period Focus	Q1
Document Fiscal Year Focus	2025
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Dec. 31, 2024
Document Transition Report	false
Entity File Number	1-16681
Entity Address, Address Line One	700 Market Street
Entity Address, City or Town	St. Louis
Entity Address, State or Province	MO
Entity Address, Postal Zip Code	63101
City Area Code	314
Local Phone Number	342-0500
Entity Incorporation, State or Country Code	MO
Entity Tax Identification Number	74-2976504
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		58,345,839
Spire Missouri [Member]
Document Information [Line Items]
Entity Central Index Key	0000057183
Entity Registrant Name	Spire Missouri Inc.
Amendment Flag	false
Current Fiscal Year End Date	--09-30
Document Fiscal Period Focus	Q1
Document Fiscal Year Focus	2025
Entity File Number	1-1822
Entity Address, Address Line One	700 Market Street
Entity Address, City or Town	St. Louis
Entity Address, State or Province	MO
Entity Address, Postal Zip Code	63101
City Area Code	314
Local Phone Number	342-0500
Entity Incorporation, State or Country Code	MO
Entity Tax Identification Number	43-0368139
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		26,280
Spire Alabama Inc [Member]
Document Information [Line Items]
Entity Central Index Key	0000003146
Entity Registrant Name	Spire Alabama Inc.
Amendment Flag	false
Current Fiscal Year End Date	--09-30
Document Fiscal Period Focus	Q1
Document Fiscal Year Focus	2025
Entity File Number	2-38960
Entity Address, Address Line One	605 Richard Arrington Blvd N
Entity Address, City or Town	Birmingham
Entity Address, State or Province	AL
Entity Address, Postal Zip Code	35203
City Area Code	205
Local Phone Number	326-8100
Entity Incorporation, State or Country Code	AL
Entity Tax Identification Number	63-0022000
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		1,972,052
Depositary Shares [Member]
Document Information [Line Items]
Title of 12(b) Security	Depositary Shares
Trading Symbol	SR.PRA
Security Exchange Name	NYSE
Common Stock [Member]
Document Information [Line Items]
Title of 12(b) Security	Common Stock $1.00 par value
Trading Symbol	SR
Security Exchange Name	NYSE

Condensed Consolidated Statemen

Condensed Consolidated Statements of Income (Unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Operating Revenues	$ 669.1	$ 756.6
Operating Expenses:
Natural gas	270	367
Operation and maintenance	129.3	130.7
Depreciation and amortization	72.3	67
Taxes, other than income taxes	48.7	52.7
Total Operating Expenses	520.3	617.4
Operating Income	148.8	139.2
Interest Expense, Net	48	50.6
Other Income, Net	0.6	17.5
Income Before Income Taxes	101.4	106.1
Income Tax expense	20.1	21
Net Income (Loss)	81.3	85.1
Provision for preferred dividends	3.7	3.7
Income allocated to participating securities	0.1	0.1
Net Income Available to Common Shareholders	$ 77.5	$ 81.3
Weighted Average Number of Common Shares Outstanding:
Basic (in shares)	57.7	53.5
Diluted (in shares)	57.9	53.6
Basic Earnings Per Common Share (in dollars per share)	$ 1.34	$ 1.52
Diluted Earnings Per Common Share (in dollars per share)	$ 1.34	$ 1.52
Spire Alabama Inc [Member]
Operating Revenues	$ 120.4	$ 142.1
Operating Expenses:
Natural gas	32.7	55.8
Operation and maintenance	31.9	34.2
Depreciation and amortization	17.8	17.9
Taxes, other than income taxes	8.6	10.2
Total Operating Expenses	91	118.1
Operating Income	29.4	24
Interest Expense, Net	7.8	9.3
Other Income, Net	(0.7)	0.3
Income Before Income Taxes	20.9	15
Income Tax expense	5.2	3.9
Net Income (Loss)	$ 15.7	$ 11.1

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Net Income (Loss)	$ 81.3	$ 85.1
Other Comprehensive Income (Loss), Before Tax:
Net hedging gain (loss) arising during the period	17.6	(15.4)
Amounts reclassified into net income	(1.7)	(9)
Net gain (loss) on cash flow hedging derivative instruments	15.9	(24.4)
Net gain on defined benefit pension and other postretirement plans	0.1	0.1
Net unrealized gain on available for sale securities	0	0.1
Other Comprehensive Income (Loss), Before Tax	16	(24.2)
Income Tax Expense (Benefit) Related to Items of Other Comprehensive Income (Loss)	3.7	(5.7)
Other Comprehensive Income (Loss), Net of Tax	12.3	(18.5)
Comprehensive Income	93.6	66.6
Operating Revenues	669.1	756.6
Operating Expenses:
Natural gas	270	367
Operation and maintenance	129.3	130.7
Depreciation and amortization	72.3	67
Taxes, other than income taxes	48.7	52.7
Total Operating Expenses	520.3	617.4
Operating Income	148.8	139.2
Interest Expense, Net	48	50.6
Other Income, Net	0.6	17.5
Income Before Income Taxes	101.4	106.1
Income Tax expense	20.1	21
Net Income (Loss)	81.3	85.1
Other Comprehensive Income, Net of Tax	12.3	(18.5)
Comprehensive Income	93.6	66.6
Spire Missouri [Member]
Net Income (Loss)	53.4	57
Other Comprehensive Income (Loss), Before Tax:
Other Comprehensive Income (Loss), Net of Tax	0.1	0.1
Comprehensive Income	53.5	57.1
Operating Revenues	457.5	535.4
Operating Expenses:
Natural gas	213.6	292.6
Operation and maintenance	76.2	74.9
Depreciation and amortization	45.7	42.1
Taxes, other than income taxes	36.6	38.5
Total Operating Expenses	372.1	448.1
Operating Income	85.4	87.3
Interest Expense, Net	25.3	27.9
Other Income, Net	1.5	7.2
Income Before Income Taxes	61.6	66.6
Income Tax expense	8.2	9.6
Net Income (Loss)	53.4	57
Other Comprehensive Income, Net of Tax	0.1	0.1
Comprehensive Income	$ 53.5	$ 57.1

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Millions	Dec. 31, 2024	Sep. 30, 2024	Dec. 31, 2023
ASSETS
Utility Plant	$ 8,946.3	$ 8,779.1	$ 8,345
Less: Accumulated depreciation and amortization	2,570.3	2,535.8	2,467.3
Net Utility Plant	6,376	6,243.3	5,877.7
Non-utility Property (net of accumulated depreciation and amortization of $103.9, $96.8 and $76.5 at December 31, 2024, September 30, 2024, and December 31, 2023, respectively)	982.5	955.3	687.1
Other Investments	118.5	115.3	105.5
Total Other Property and Investments	1,101	1,070.6	792.6
Current Assets:
Cash and cash equivalents	11.5	4.5	4.8
Accounts receivable:
Utility	379.6	196.3	428.8
Other	172.3	112.5	150.6
Allowance for credit losses	(34.7)	(31.4)	(35.4)
Delayed customer billings	18.4	12	22
Inventories:
Natural gas	187	208.6	220.6
Propane gas	8.6	8.6	8.6
Materials and supplies	47	46.7	47.4
Regulatory assets	89.6	115.4	256.4
Prepayments	41.5	47.6	43.3
Other	67.2	50.5	72.8
Total Current Assets	988	771.3	1,219.9
Deferred Charges and Other Assets:
Goodwill	1,171.6	1,171.6	1,171.6
Regulatory assets	1,288.4	1,251.8	1,266.9
Other	350.8	352.1	303
Total Deferred Charges and Other Assets	2,810.8	2,775.5	2,741.5
Total Assets	11,275.8	10,860.7	10,631.7
Capitalization:
Common stock (par value $1.00 per share; 70.0 million shares authorized; 58.3 million, 57.7 million, and 55.0 million shares issued and outstanding at December 31, 2024, September 30, 2024, and December 31, 2023, respectively)	58.3	57.7	55
Paid-in capital	1,933.7	1,902.2	1,727.4
Retained earnings	1,050.5	1,018.7	997.3
Accumulated other comprehensive income (loss)	24.4	12.1	29.1
Total Shareholders' Equity	3,308.9	3,232.7	3,050.8
Temporary equity	8.4	8.6	14.8
Long-term debt (less current portion)	3,697.7	3,704.4	3,247.8
Total Capitalization	7,015	6,945.7	6,313.4
Current Liabilities:
Current portion of long-term debt	42.5	42	457
Notes payable	1,158	947	1,047.5
Accounts payable	292.3	237.2	293.8
Advance customer billings	59.2	48.4	25
Wages and compensation accrued	28.7	51.5	26.1
Customer deposits	31.6	29.9	28.8
Taxes accrued	61.4	105.2	64.9
Regulatory liabilities	51	49.5	7.1
Other current liabilities	266.5	193.2	260.3
Total Current Liabilities	1,991.2	1,703.9	2,210.5
Deferred Credits and Other Liabilities:
Deferred income taxes	838.3	808.4	760.6
Pension and postretirement benefit costs	126.6	146.7	135.5
Asset retirement obligations	586	579.9	583.6
Regulatory liabilities	577.2	535.5	487.2
Other noncurrent liabilities	141.5	140.6	140.9
Total Deferred Credits and Other Liabilities	2,269.6	2,211.1	2,107.8
Commitments and Contingencies (Note 11)
Total Capitalization and Liabilities	11,275.8	10,860.7	10,631.7
Depositary Shares [Member]
Capitalization:
Preferred stock ($25.00 par value per share; 10.0 million depositary shares authorized, issued and outstanding at December 31, 2024, September 30, 2024, and December 31, 2023)	242	242	242
Spire Missouri [Member]
ASSETS
Utility Plant	5,555.5	5,420.2	5,080.2
Less: Accumulated depreciation and amortization	1,104.5	1,086	1,063.7
Net Utility Plant	4,451	4,334.2	4,016.5
Total Other Property and Investments	72.9	70.1	67.9
Accounts receivable:
Other	23.8	22.2	22.2
Allowance for credit losses	(27.9)	(24.9)	(28.9)
Delayed customer billings	9.1	5.7	16.8
Inventories:
Natural gas	120.1	129.6	141.8
Propane gas	8.6	8.6	8.6
Materials and supplies	24.3	24.4	24.6
Regulatory assets	56.7	84	212.9
Prepayments	23.2	27.2	22.8
Total Current Assets	537.2	432.5	757.4
Deferred Charges and Other Assets:
Goodwill	210.2	210.2	210.2
Regulatory assets	619.7	588	630.8
Other	194.3	193.6	146
Total Deferred Charges and Other Assets	1,024.2	991.8	987
Total Assets	6,085.3	5,828.6	5,828.8
Capitalization:
Paid-in capital and common stock	887.1	854.9	854.9
Retained earnings	1,164.2	1,110.8	1,049.4
Accumulated other comprehensive income (loss)	(1.9)	(2)	(2.4)
Total Shareholders' Equity	2,049.4	1,963.7	1,901.9
Long-term debt (less current portion)	1,803.6	1,803.4	1,485.8
Total Capitalization	3,853	3,767.1	3,387.7
Current Liabilities:
Current portion of long-term debt	0	0	300
Advance customer billings	42.4	35.5	14.3
Wages and compensation accrued	16.2	24.2	14.4
Customer deposits	6.5	6.1	5.9
Taxes accrued	25.3	60.2	26.4
Regulatory liabilities	17.4	10.2	0
Other current liabilities	104.6	50.6	111.1
Total Current Liabilities	908.6	781.7	1,218.4
Deferred Credits and Other Liabilities:
Deferred income taxes	581.7	567.6	545.8
Pension and postretirement benefit costs	91.1	110	102
Asset retirement obligations	96.6	95.7	112.2
Regulatory liabilities	486	443.3	404.5
Other noncurrent liabilities	68.3	63.2	58.2
Total Deferred Credits and Other Liabilities	1,323.7	1,279.8	1,222.7
Commitments and Contingencies (Note 11)
Total Capitalization and Liabilities	6,085.3	5,828.6	5,828.8
Spire Missouri [Member] | Nonrelated Party [Member]
Accounts receivable:
Utility	296.5	152.9	335.5
Current Liabilities:
Accounts payable	107.3	92	106.6
Spire Missouri [Member] | Related Party [Member]
Accounts receivable:
Utility	2.8	2.8	1.1
Current Liabilities:
Notes payable	580.9	495.3	633.3
Accounts payable	8	7.6	6.4
Spire Alabama Inc [Member]
ASSETS
Utility Plant	2,995.8	2,966.6	2,879.8
Less: Accumulated depreciation and amortization	1,353.5	1,336.6	1,289.1
Net Utility Plant	1,642.3	1,630	1,590.7
Total Other Property and Investments	0.1	0.1	0
Current Assets:
Cash and cash equivalents	0	1.5	0
Accounts receivable:
Other	5.6	6.1	5.7
Allowance for credit losses	(6)	(5.7)	(5.7)
Delayed customer billings	8.6	5.7	4.6
Inventories:
Natural gas	31.7	37.3	40.7
Materials and supplies	19	18.7	18.9
Regulatory assets	17.4	19.2	31
Prepayments	8.3	10.7	6.8
Total Current Assets	150.4	129.4	175.8
Deferred Charges and Other Assets:
Regulatory assets	647.3	642	612.6
Other	95	94.8	84.2
Total Deferred Charges and Other Assets	742.3	736.8	696.8
Total Assets	2,535.1	2,496.3	2,463.3
Capitalization:
Paid-in capital and common stock	279.4	279.4	284.9
Retained earnings	677.1	668.9	639.2
Total Shareholders' Equity	956.5	948.3	924.1
Long-term debt (less current portion)	711.4	711.3	746
Total Capitalization	1,667.9	1,659.6	1,670.1
Current Liabilities:
Current portion of long-term debt	35	35	0
Advance customer billings	14.6	10.9	8.8
Wages and compensation accrued	4.4	7.2	3.6
Customer deposits	21.9	20.8	20
Taxes accrued	31.2	34.8	32.6
Regulatory liabilities	27.7	33.8	0
Other current liabilities	17.4	13.8	18.2
Total Current Liabilities	273.1	249.4	249.9
Deferred Credits and Other Liabilities:
Deferred income taxes	41	35.9	13
Pension and postretirement benefit costs	26.7	28	26.5
Asset retirement obligations	473.7	468.6	455.8
Regulatory liabilities	26.9	28.3	20.7
Other noncurrent liabilities	25.8	26.5	27.3
Total Deferred Credits and Other Liabilities	594.1	587.3	543.3
Total Capitalization and Liabilities	2,535.1	2,496.3	2,463.3
Spire Alabama Inc [Member] | Nonrelated Party [Member]
Accounts receivable:
Utility	65.3	35.5	73.7
Current Liabilities:
Accounts payable	46.7	38	33.7
Spire Alabama Inc [Member] | Related Party [Member]
Accounts receivable:
Utility	0.5	0.4	0.1
Current Liabilities:
Notes payable	67	48.4	128.5
Accounts payable	$ 7.2	$ 6.7	$ 4.5

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Unaudited) (Parentheticals) - USD ($) $ in Millions	Dec. 31, 2024	Sep. 30, 2024	Dec. 31, 2023
Non-utility property, accumulated depreciation and amortization	$ 103.9	$ 96.8	$ 76.5
Common stock, par value (in dollars per share)	$ 1	$ 1	$ 1
Common stock, shares authorized (in shares)	70,000,000	70,000,000	70,000,000
Common stock, shares issued (in shares)	58,300,000	57,700,000	55,000,000
Common Stock, shares outstanding (in shares)	58,300,000	57,700,000	55,000,000
Depositary Shares [Member]
Preferred stock, par value (in dollars per share)	$ 25	$ 25	$ 25
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000	10,000,000
Preferred stock, shares issued (in shares)	10,000,000	10,000,000	10,000,000
Preferred stock, shares outstanding (in shares)	10,000,000	10,000,000	10,000,000
Spire Missouri [Member]
Common stock, par value (in dollars per share)	$ 1	$ 1	$ 1
Common stock, shares authorized (in shares)	50,000,000	50,000,000	50,000,000
Common stock, shares issued (in shares)	26,280	25,855	25,855
Common Stock, shares outstanding (in shares)	26,280	25,855	25,855
Spire Alabama Inc [Member]
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	3,000,000	3,000,000	3,000,000
Common stock, shares issued (in shares)	2,000,000	2,000,000	2,000,000
Common Stock, shares outstanding (in shares)	2,000,000	2,000,000	2,000,000

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Shareholders' Equity (Unaudited) - USD ($) $ in Millions	Total	Common Stock [Member]	Preferred Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	[1]	Spire Missouri [Member]	Spire Missouri [Member] Common Stock [Member]	Spire Missouri [Member] Additional Paid-in Capital [Member]	Spire Missouri [Member] Retained Earnings [Member]	Spire Missouri [Member] AOCI Attributable to Parent [Member]	[2]	Spire Alabama Inc [Member]	Spire Alabama Inc [Member] Common Stock [Member]	Spire Alabama Inc [Member] Additional Paid-in Capital [Member]	Spire Alabama Inc [Member] Retained Earnings [Member]
Balance (in shares) at Sep. 30, 2023		53,170,224							25,855						1,972,052
Balance at Sep. 30, 2023	$ 2,917.3	$ 53.2	$ 242	$ 1,616.5	$ 958	$ 47.6		$ 1,844.8	$ 0.1	$ 854.8	$ 992.4	$ (2.5)		$ 928		$ 285.9	$ 642.1
Net Income (Loss)	85.1				85.1			57			57			11.1			11.1
Common stock issued (in shares)		1,744,549
Common stock issued	112.8	$ 1.7		111.1
Dividend reinvestment plan (in shares)		6,774
Dividend reinvestment plan	0.4			0.4
Stock-based compensation costs	0.9			0.9
Stock activity under stock-based compensation plans (in shares)		75,706
Stock activity under stock-based compensation plans		$ 0.1		(0.1)
Employees’ tax withholding for stock-based compensation (in shares)		(23,559)
Employees’ tax withholding for stock-based compensation	(1.4)			(1.4)
Temporary equity adjustment to redemption value	(1.9)				(1.9)
Return of capital to Spire														(1)		(1)
Common stock	(40.2)				(40.2)									(14)			(14)
Preferred stock	(3.7)				(3.7)
Other comprehensive income (loss), net of tax	(18.5)					(18.5)		0.1				0.1
Balance (in shares) at Dec. 31, 2023		54,973,694							25,855						1,972,052
Balance at Dec. 31, 2023	3,050.8	$ 55	242	1,727.4	997.3	29.1		1,901.9	$ 0.1	854.8	1,049.4	(2.4)		924.1		284.9	639.2
Balance (in shares) at Sep. 30, 2024		57,749,667							25,855						1,972,052
Balance at Sep. 30, 2024	3,232.7	$ 57.7	242	1,902.2	1,018.7	12.1		1,963.7	$ 0.1	854.8	1,110.8	(2)		948.3		279.4	668.9
Net Income (Loss)	81.3				81.3			53.4			53.4			15.7			15.7
Common stock issued (in shares)		542,515							425
Common stock issued	32.4	$ 0.5		31.9				32.2		32.2
Dividend reinvestment plan (in shares)		6,507
Dividend reinvestment plan	0.4			0.4
Stock-based compensation costs	1			1
Stock activity under stock-based compensation plans (in shares)		65,488
Stock activity under stock-based compensation plans		$ 0.1		(0.1)
Employees’ tax withholding for stock-based compensation (in shares)		(23,141)
Employees’ tax withholding for stock-based compensation	(1.7)			(1.7)
Temporary equity adjustment to redemption value	(0.3)				(0.3)
Common stock	(45.5)				(45.5)									(7.5)			(7.5)
Preferred stock	(3.7)				(3.7)
Other comprehensive income (loss), net of tax	12.3					12.3		0.1				0.1
Balance (in shares) at Dec. 31, 2024		58,341,036							26,280						1,972,052
Balance at Dec. 31, 2024	$ 3,308.9	$ 58.3	$ 242	$ 1,933.7	$ 1,050.5	$ 24.4		$ 2,049.4	$ 0.1	$ 887	$ 1,164.2	$ (1.9)		$ 956.5		$ 279.4	$ 677.1
[1] Accumulated other comprehensive income (loss) Accumulated other comprehensive income (loss)

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Shareholders' Equity (Unaudited) (Parentheticals) - $ / shares	3 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Statement of Stockholders' Equity [Abstract]
Common stock, dividends per share declared (in dollars per share)	$ 0.785	$ 0.755
Preferred stock dividends per share declared (in dollars per share)	$ 0.36875	$ 0.36875

Condensed Consolidated Statem_5

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Operating Activities:
Net Income	$ 81.3	$ 85.1
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	72.3	67
Deferred income taxes and investment tax credits	19.4	21
Changes in assets and liabilities:
Accounts receivable	(239.8)	(255.5)
Inventories	21.2	2.9
Regulatory assets and liabilities	36.7	91.7
Accounts payable	96.9	54
Delayed/advance customer billings, net	4.3	4
Taxes accrued	(43.8)	(42.3)
Other assets and liabilities	30.5	40.9
Other	2.1	1.2
Net cash provided by operating activities	81.1	70
Investing Activities:
Capital expenditures	(260.6)	(226.5)
Other	0.5	1.3
Net cash used in investing activities	(260.1)	(225.2)
Financing Activities:
Repayment of long-term debt	(7)	(6.6)
Issuance of short-term debt, net	211	92
Issuance of common stock	32.8	113.2
Dividends paid on common stock	(44.6)	(38.8)
Dividends paid on preferred stock	(3.7)	(3.7)
Other	(2.5)	(1.4)
Net cash provided by financing activities	186	154.7
Net Increase (Decrease) in Cash, Cash Equivalents, and Restricted Cash	7	(0.5)
Cash, Cash Equivalents, and Restricted Cash at Beginning of Period	34.9	25.8
Cash, Cash Equivalents, and Restricted Cash at End of Period	41.9	25.3
Supplemental disclosure of cash paid for:
Interest, net of amounts capitalized	(34.1)	(44.3)
Income taxes	(0.2)	(0.3)
Spire Missouri [Member]
Operating Activities:
Net Income	53.4	57
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	45.7	42.1
Deferred income taxes and investment tax credits	8	9.6
Changes in assets and liabilities:
Accounts receivable	(142.2)	(190.9)
Inventories	9.6	(9.4)
Regulatory assets and liabilities	46.5	81.6
Accounts payable	44.3	34.6
Delayed/advance customer billings, net	3.5	4.4
Taxes accrued	(34.9)	(33.9)
Other assets and liabilities	25.4	54.1
Other	0.3	0.5
Net cash provided by operating activities	59.6	49.7
Investing Activities:
Capital expenditures	(178.3)	(144.7)
Other	0.9	1.5
Net cash used in investing activities	(177.4)	(143.2)
Financing Activities:
Issuance of long-term debt	32.2	0
Borrowings from Spire, net	85.6	92.7
Net cash provided by financing activities	117.8	92.7
Net Increase (Decrease) in Cash, Cash Equivalents, and Restricted Cash	0	(0.8)
Cash, Cash Equivalents, and Restricted Cash at Beginning of Period	0	0.8
Cash, Cash Equivalents, and Restricted Cash at End of Period	0	0
Supplemental disclosure of cash paid for:
Interest, net of amounts capitalized	(20.2)	(25.7)
Income taxes	0	0
Spire Alabama Inc [Member]
Operating Activities:
Net Income	15.7	11.1
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	17.8	17.9
Deferred income taxes and investment tax credits	5.2	3.9
Changes in assets and liabilities:
Accounts receivable	(29)	(29.4)
Inventories	5.3	12
Regulatory assets and liabilities	(7)	8.5
Accounts payable	12.8	7.4
Delayed/advance customer billings, net	0.7	(0.3)
Taxes accrued	(3.6)	(2)
Other assets and liabilities	3.9	2.1
Other	0.1	0.1
Net cash provided by operating activities	21.9	31.3
Investing Activities:
Capital expenditures	(34.5)	(22.3)
Other	0	0.3
Net cash used in investing activities	(34.5)	(22)
Financing Activities:
Borrowings from Spire, net	18.6	4.5
Return of capital to Spire	0	(1)
Dividends paid on common stock	(7.5)	(14)
Net cash provided by financing activities	11.1	(10.5)
Net Increase (Decrease) in Cash, Cash Equivalents, and Restricted Cash	(1.5)	(1.2)
Cash, Cash Equivalents, and Restricted Cash at Beginning of Period	1.5	1.2
Cash, Cash Equivalents, and Restricted Cash at End of Period	0	0
Supplemental disclosure of cash paid for:
Interest, net of amounts capitalized	(9.6)	(10.9)
Income taxes	$ 0	$ 0

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Pay vs Performance Disclosure
Net Income (Loss)	$ 81.3	$ 85.1

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
	Dec. 31, 2024
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
	Dec. 31, 2024
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	1. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES BASIS OF PRESENTATION – These notes are an integral part of the accompanying unaudited financial statements of Spire Inc. (“Spire” or the “Company”) presented on a consolidated basis, Spire Missouri Inc. (“Spire Missouri”) and Spire Alabama Inc. (“Spire Alabama”). Spire Missouri, Spire Alabama and Spire EnergySouth Inc. (“Spire EnergySouth”) are wholly owned subsidiaries of Spire. Spire Missouri, Spire Alabama and the subsidiaries of Spire EnergySouth (Spire Gulf Inc. and Spire Mississippi Inc.) are collectively referred to as the “Utilities.” The accompanying unaudited financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (GAAP) for interim financial information with the instructions to Form 10-Q and Rule 10-01 of Regulation S‑X. Accordingly, they do not include all the disclosures required for complete financial statements. In the opinion of management, the accompanying unaudited financial statements include all adjustments necessary for the fair presentation of the results of operations for the periods presented. This Form 10-Q should be read in conjunction with the Notes to Financial Statements contained in Spire, Spire Missouri and Spire Alabama’s combined Annual Report on Form 10-K for the fiscal year ended September 30, 2024 . The consolidated financial position, results of operations, and cash flows of Spire include the accounts of the Company and all its subsidiaries. Transactions and balances between consolidated entities have been eliminated from the consolidated financial statements of Spire. In compliance with GAAP, transactions between Spire Missouri and Spire Alabama and their affiliates, as well as intercompany balances on their balance sheets, have not been eliminated from their separate financial statements. NATURE OF OPERATIONS – Spire has three reportable segments: Gas Utility, Gas Marketing, and Midstream. The Gas Utility segment consists of the regulated natural gas distribution operations of the Company and is the core business segment of Spire in terms of revenue and earnings. The Gas Utility segment is comprised of the operations of: Spire Missouri, serving St. Louis, Kansas City, and other areas in Missouri; Spire Alabama, serving central and northern Alabama; and the subsidiaries of Spire EnergySouth, serving the Mobile, Alabama area and south-central Mississippi. The Gas Marketing segment includes Spire’s largest gas-related business, Spire Marketing Inc. (“Spire Marketing”), which provides non-regulated natural gas services throughout the United States (U.S.). The Midstream segment includes Spire Storage, Spire STL Pipeline and Spire MoGas Pipeline, which are subsidiaries engaged in the storage and transportation of natural gas. The activities of the Company’s other subsidiaries are reported as Other and are described in Note 10 , Information by Operating Segment. Spire Missouri and Spire Alabama each have a single reportable segment. The Company’s earnings are derived primarily from its Gas Utility segment. Due to the seasonal nature of the Utilities’ business and the volumetric Spire Missouri rate design, earnings are typically concentrated during the heating season of November through April each fiscal year. As a result, the interim statements of income for Spire, Spire Missouri and Spire Alabama are not necessarily indicative of annual results or representative of succeeding quarters of the fiscal year. REGULATED OPERATIONS – The Utilities account for their regulated operations in accordance with Financial Accounting Standards Board (FASB) Accounting Standards Codification (ASC) Topic 980, Regulated Operations . This topic sets forth the application of GAAP for those companies whose rates are established by or are subject to approval by an independent third-party regulator. The provisions of this accounting guidance require, among other things, that financial statements of a regulated enterprise reflect the actions of regulators, where appropriate. These actions may result in the recognition of revenues and expenses in time periods that are different than non-regulated enterprises. When this occurs, costs are deferred as assets in the balance sheet (regulatory assets) and recorded as expenses when those amounts are reflected in rates. In addition, regulators can impose liabilities upon a regulated company for amounts previously collected from customers and for recovery of costs that are expected to be incurred in the future (regulatory liabilities). Management believes that the current regulatory environment supports the continued use of these regulatory accounting principles and that all regulatory assets and regulatory liabilities are recoverable or refundable through the regulatory process. As authorized by the Missouri Public Service Commission (MoPSC), the Mississippi Public Service Commission (MSPSC) and the Alabama Public Service Commission (APSC), the Purchased Gas Adjustment (PGA) clauses and Gas Supply Adjustment (GSA) riders allow the Utilities to pass through to customers the cost of purchased gas supplies. Regulatory assets and liabilities related to the PGA clauses and the GSA riders are both labeled Unamortized Purchased Gas Adjustments herein. See additional information about regulatory assets and liabilities in Note 5 , Regulatory Matters. DERIVATIVES – In the course of their business, certain subsidiaries of Spire enter into commitments associated with the purchase or sale of natural gas. Certain of their derivative natural gas contracts are designated as normal purchases or normal sales and, as such, are excluded from the scope of FASB ASC Topic 815, Derivatives and Hedging . Those contracts are accounted for as executory contracts and recorded on an accrual basis. Revenues and expenses from such contracts are recorded gross. Contracts not designated as normal purchases or normal sales are recorded as derivatives with changes in fair value recognized in earnings in the periods prior to physical delivery. Certain of Spire Marketing’s wholesale purchase and sale transactions are classified as trading activities for financial reporting purposes, with income and expenses presented on a net basis in natural gas expenses in the Condensed Consolidated Statements of Income. Spire also enters into cash flow hedges through execution of interest rate swap contracts to protect itself against adverse movements in interest rates. In the first quarter of fiscal 2024, considering changes in debt issuance strategy due to the interest rate environment, Spire management determined it was probable the anticipated issuance of certain debt, and therefore the hedged forecasted interest payments, would not occur. The related swap was settled, hedge accounting was discontinued, and amounts previously deferred in “Accumulated other comprehensive income” were reclassified to earnings, such that the entire realized gain of $ 8.2 was included in “Other income” for Spire Inc. in the quarter ended December 31, 2023. TRANSACTIONS WITH AFFILIATES – Transactions between affiliates of the Company have been eliminated from the consolidated financial statements of Spire. As reflected in their separate financial statements, Spire Missouri and Spire Alabama borrowed funds from the Company and incurred related interest. Spire Missouri and Spire Alabama also participated in normal intercompany shared services transactions. Spire Missouri’s and Spire Alabama’s other transactions with affiliates are presented below: Three Months Ended 2024 2023 Spire Missouri Purchases of natural gas from Spire Marketing $ 2.2 $ 5.0 Transportation services received from Spire STL Pipeline 8.1 8.2 Transportation services received from Spire MoGas Pipeline 1.8 — Natural gas storage services from Spire Storage Salt Plains LLC — 0.3 Spire Alabama Purchases of natural gas from Spire Marketing $ 4.9 $ 3.4 RESTRICTED CASH AND OTHER INVESTMENTS – In Spire’s statement of cash flows , total Cash, Cash Equivalents, and Restricted Cash included $ 30.4 , $ 30.4 and $ 20.5 of restricted cash reported in “Other Investments” on the Company’s balance sheet as of December 31, 2024, September 30, 2024 , and December 31, 2023 , respectively (in addition to amounts shown as “Cash and cash equivalents”). This restricted cash has been segregated and invested in debt securities in trust accounts based on collateral requirements for reinsurance at Spire’s risk management company. BUSINESS COMBINATIONS – On January 19, 2024, a subsidiary in Spire’s Midstream segment acquired MoGas Pipeline, an interstate natural gas pipeline, and Omega Pipeline, a connected gas distribution system in Missouri. MoGas interconnects with Spire STL Pipeline and other regional pipelines to deliver gas to Spire Missouri’s growing customer base in St. Charles, Franklin, and western St. Louis counties, among other utility, municipal, industrial and commercial customers. Omega owns and operates an approximately 75-mile natural gas distribution system within Fort Leonard Wood in south-central Missouri and is interconnected with the MoGas system. The acquisition was accounted for as a business combination in accordance with ASC 805, Business Combinations . The $ 176.1 purchase price was allocated almost entirely to property, plant and equipment based on their estimated fair value at the acquisition date and recorded as non-utility property in the consolidated balance sheet. The operating revenues and operating income of MoGas and Omega were not material to our consolidated results for the three months ended December 31, 2024 . ACCRUED CAPITAL EXPENDITURES – Accrued capital expenditures, shown in the following table, are excluded from capital expenditures in the statements of cash flows until paid. December 31, September 30, December 31, 2024 2024 2023 Spire $ 73.7 $ 116.5 $ 90.5 Spire Missouri 38.1 67.4 38.1 Spire Alabama 10.5 14.1 2.4 ACCOUNTS RECEIVABLE AND ALLOWANCE FOR CREDIT LOSSES – Trade accounts receivable are recorded at the amounts due from customers, including unbilled amounts. Accounts receivable are written off when they are deemed to be uncollectible. An allowance for expected credit losses is estimated and updated based on relevant data and trends such as accounts receivable aging, historical write-off experience, current write-off trends, economic conditions, and the impact of weather and availability of customer payment assistance on collection trends. For the Utilities, net write-offs as a percentage of revenue has historically been the best predictor of base net write-off experience over time. Management judgment is applied in the development of the allowance due to the complexity of variables and subjective nature of certain relevant factors. The accounts receivable of Spire’s non-utility businesses are evaluated separately from those of the Utilities. The allowance for credit losses for those other businesses is based on a continuous evaluation of the individual counterparty risk and is not significant for the periods presented. Activity in the allowance for credit losses is shown in the following table. Spire Spire Missouri Spire Alabama Three Months Ended December 31, 2024 2023 2024 2023 2024 2023 Allowance at beginning of period $ 31.4 $ 32.5 $ 24.9 $ 26.2 $ 5.7 $ 5.7 Provision for expected credit losses 5.1 4.1 4.1 3.6 0.8 0.3 Write-offs, net of recoveries ( 1.8 ) ( 1.2 ) ( 1.1 ) ( 0.9 ) ( 0.5 ) ( 0.3 ) Allowance at end of period $ 34.7 $ 35.4 $ 27.9 $ 28.9 $ 6.0 $ 5.7

Revenue

Revenue	3 Months Ended
	Dec. 31, 2024
Revenue from Contract with Customer [Abstract]
Revenue	2. REVE NUE The following tables show revenue disaggregated by source and customer type. Three Months Ended 2024 2023 Spire Gas Utility: Residential $ 411.5 $ 492.8 Commercial and industrial 133.7 157.9 Transportation 34.6 32.6 Off-system and other incentive 11.5 6.4 Other customer revenue 0.8 5.5 Total revenue from contracts with customers 592.1 695.2 Changes in accrued revenue under alternative revenue programs 21.4 20.0 Total Gas Utility operating revenues 613.5 715.2 Gas Marketing 33.0 36.3 Midstream 33.5 14.9 Other 4.7 4.1 Total before eliminations 684.7 770.5 Intersegment eliminations (see Note 10, Information by Operating Segment) ( 15.6 ) ( 13.9 ) Total Operating Revenues $ 669.1 $ 756.6 Spire Missouri Residential $ 321.8 $ 388.8 Commercial and industrial 93.8 110.2 Transportation 9.4 9.0 Off-system and other incentive 9.9 4.1 Other customer revenue 2.8 2.5 Total revenue from contracts with customers 437.7 514.6 Changes in accrued revenue under alternative revenue programs 19.8 20.8 Total Operating Revenues $ 457.5 $ 535.4 Three Months Ended 2024 2023 Spire Alabama Residential $ 72.4 $ 84.4 Commercial and industrial 28.9 34.7 Transportation 22.5 20.8 Off-system and other incentive 1.6 2.3 Other customer revenue ( 3.2 ) 0.9 Total revenue from contracts with customers 122.2 143.1 Changes in accrued revenue under alternative revenue programs ( 1.8 ) ( 1.0 ) Total Operating Revenues $ 120.4 $ 142.1 Gross receipts taxes associated with the Company’s natural gas utility services are imposed on the Company, Spire Missouri, and Spire Alabama and billed to its customers. The expense amounts (shown in the table below) are reported gross in the “Taxes, other than income taxes” line in the statements of income, and corresponding revenues are reported in “Operating Revenues.” Three Months Ended 2024 2023 Spire $ 26.8 $ 31.1 Spire Missouri 19.5 22.5 Spire Alabama 5.7 6.9

Earnings Per Common Share

Earnings Per Common Share	3 Months Ended
	Dec. 31, 2024
Earnings Per Share [Abstract]
Earnings Per Common Share	3. EARN INGS PER COMMON SHARE Three Months Ended 2024 2023 Basic Earnings Per Common Share: Net Income $ 81.3 $ 85.1 Less: Provision for preferred dividends 3.7 3.7 Income allocated to participating securities 0.1 0.1 Income Available to Common Shareholders $ 77.5 $ 81.3 Weighted Average Common Shares Outstanding (in millions) 57.7 53.5 Basic Earnings Per Common Share $ 1.34 $ 1.52 Diluted Earnings Per Common Share: Net Income $ 81.3 $ 85.1 Less: Provision for preferred dividends 3.7 3.7 Income allocated to participating securities 0.1 0.1 Income Available to Common Shareholders $ 77.5 $ 81.3 Weighted Average Common Shares Outstanding (in millions) 57.7 53.5 Dilutive Effect of forward sales of common stock, restricted 0.2 0.1 Weighted Average Diluted Common Shares (in millions) 57.9 53.6 Diluted Earnings Per Common Share $ 1.34 $ 1.52 * Calculation excludes certain outstanding or potential common shares 0.3 0.2

Shareholders' Equity

Shareholders' Equity	3 Months Ended
	Dec. 31, 2024
Stockholders' Equity Note [Abstract]
Shareholders' Equity	4. SHAR EHOLDERS ’ EQUITY ATM Program Under Spire’s “at-the-market” (ATM) equity distribution agreement and as authorized by its board of directors, the Company may offer and sell, from time to time, shares of its common stock (including shares of common stock that may be sold pursuant to forward sale agreements entered into in connection with the ATM equity distribution agreement). Settled sales under this ATM program are included in “Common stock issued” in the Condensed Consolidated Statements of Shareholders’ Equity. Specifically in the first quarter of fiscal 2024, on December 11, 2023, 1,744,549 shares were settled, generating $ 112.2 of net proceeds. On January 25, 2024, Spire’s board approved a new authorization for the sale of additional shares with an aggregate offering price of up to $ 200.0 through January 2027. In the second and third quarters of fiscal 2024, Spire executed forward sale agreements for a total of 542,515 shares of its common stock, which were settled in December 2024, generating $ 32.4 of net proceeds. In the fourth quarter of fiscal 2024, Spire executed forward sale agreements for 663,619 shares of its common stock, which are scheduled to be settled on or before March 31, 2025. Had these last forward agreements been settled as of December 31, 2024 , it would have generated additional net proceeds of $ 42.4 . As of December 31, 2024 , under the ATM Program, Spire may sell additional shares with an aggregate offering price of up to $ 123.6 .

Regulatory Matters

Regulatory Matters	3 Months Ended
	Dec. 31, 2024
Regulated Operations [Abstract]
Regulatory Matters	5. REGUL ATORY MATTERS As explained in Note 1 , Summary of Significant Accounting Policies, the Utilities account for regulated operations in accordance with FASB ASC Topic 980, Regulated Operations . The following regulatory assets and regulatory liabilities were reflected in the balance sheets of the Company, Spire Missouri and Spire Alabama as of December 31, 2024, September 30, 2024 , and December 31, 2023 . December 31, September 30, December 31, Spire 2024 2024 2023 Regulatory Assets: Current: Unamortized purchased gas adjustments $ 12.2 $ 28.9 $ 207.0 Other 77.4 86.5 49.4 Total Current Regulatory Assets 89.6 115.4 256.4 Noncurrent: Pension and postretirement benefit costs 248.4 237.5 255.3 Cost of removal 676.1 668.2 640.8 Future income taxes due from customers 152.4 150.7 145.6 Energy efficiency 61.3 61.0 57.5 Unamortized purchased gas adjustments — 1.2 20.3 Other 150.2 133.2 147.4 Total Noncurrent Regulatory Assets 1,288.4 1,251.8 1,266.9 Total Regulatory Assets $ 1,378.0 $ 1,367.2 $ 1,523.3 Regulatory Liabilities: Current: Unamortized purchased gas adjustments $ 39.2 $ 42.3 $ — Other 11.8 7.2 7.1 Total Current Regulatory Liabilities 51.0 49.5 7.1 Noncurrent: Deferred taxes due to customers 110.7 114.2 124.5 Pension and postretirement benefit costs 253.2 232.9 188.2 Accrued cost of removal 136.7 133.6 130.3 Unamortized purchased gas adjustments 40.4 17.2 23.7 Other 36.2 37.6 20.5 Total Noncurrent Regulatory Liabilities 577.2 535.5 487.2 Total Regulatory Liabilities $ 628.2 $ 585.0 $ 494.3 December 31, September 30, December 31, Spire Missouri 2024 2024 2023 Regulatory Assets: Current: Unamortized purchased gas adjustments $ 11.8 $ 28.1 $ 194.1 Other 44.9 55.9 18.8 Total Current Regulatory Assets 56.7 84.0 212.9 Noncurrent: Future income taxes due from customers 144.5 142.7 137.3 Pension and postretirement benefit costs 179.7 166.5 185.5 Energy efficiency 61.3 61.0 57.5 Unamortized purchased gas adjustments — 1.2 20.3 Cost of removal 97.0 97.0 97.0 Other 137.2 119.6 133.2 Total Noncurrent Regulatory Assets 619.7 588.0 630.8 Total Regulatory Assets $ 676.4 $ 672.0 $ 843.7 Regulatory Liabilities: Current: Unamortized purchased gas adjustments $ 17.4 $ 10.2 $ — Total Current Regulatory Liabilities 17.4 10.2 — Noncurrent: Deferred taxes due to customers 98.6 101.8 111.6 Pension and postretirement benefit costs 218.0 196.6 160.2 Accrued cost of removal 96.8 94.5 93.4 Unamortized purchased gas adjustments 40.4 17.2 23.7 Other 32.2 33.2 15.6 Total Noncurrent Regulatory Liabilities 486.0 443.3 404.5 Total Regulatory Liabilities $ 503.4 $ 453.5 $ 404.5 Spire Alabama Regulatory Assets: Current: Unamortized purchased gas adjustments $ — $ — $ 12.2 Other 17.4 19.2 18.8 Total Current Regulatory Assets 17.4 19.2 31.0 Noncurrent: Future income taxes due from customers 1.7 1.8 1.9 Pension and postretirement benefit costs 66.1 68.2 66.0 Cost of removal 579.1 571.2 543.7 Other 0.4 0.8 1.0 Total Noncurrent Regulatory Assets 647.3 642.0 612.6 Total Regulatory Assets $ 664.7 $ 661.2 $ 643.6 Regulatory Liabilities: Current: Unamortized purchased gas adjustments $ 20.7 $ 30.9 $ — Other 7.0 2.9 — Total Current Regulatory Liabilities 27.7 33.8 — Noncurrent: Pension and postretirement benefit costs 24.2 25.1 17.3 Other 2.7 3.2 3.4 Total Noncurrent Regulatory Liabilities 26.9 28.3 20.7 Total Regulatory Liabilities $ 54.6 $ 62.1 $ 20.7 A portion of the Company’s and Spire Missouri’s regulatory assets are not earning a return, as shown in the table below: December 31, September 30, December 31, 2024 2024 2023 Spire Pension and postretirement benefit costs $ 129.8 $ 129.7 $ 134.0 Future income taxes due from customers 150.7 148.9 143.6 Unamortized purchased gas adjustments 11.8 29.3 214.4 Other 143.1 132.5 117.0 Total Regulatory Assets Not Earning a Return $ 435.4 $ 440.4 $ 609.0 Spire Missouri Pension and postretirement benefit costs $ 129.8 $ 129.7 $ 134.0 Future income taxes due from customers 144.5 142.7 137.3 Unamortized purchased gas adjustments 11.8 29.3 214.4 Other 143.1 132.5 117.0 Total Regulatory Assets Not Earning a Return $ 429.2 $ 434.2 $ 602.7 Like all the Company’s regulatory assets, these regulatory assets as of December 31, 2024 are probable of recovery from customers in future rates. The recovery period for the future income taxes due from customers and pension and other postretirement benefit costs could be 20 years or longer, based on current Internal Revenue Service guidelines and average remaining service life of active participants, respectively. The recovery period for the PGA assets is about one year . The other items not earning a return are expected to be recovered over a period not to exceed 15 years, consistent with precedent set by the MoPSC, except for certain debt costs expected to be recovered over the related debt term (currently up to 2051). Spire Alabama does not have any regulatory assets that are not earning a return. Spire Missouri On November 12, 2024, the MoPSC approved a PGA decrease of approximately 30 % for both the eastern and western service territories of Spire Missouri effective November 15, 2024. On November 25, 2024, Spire Missouri filed a general rate case with the MoPSC that includes new proposed rates for its service areas. The case proposes an increase in base rates, reflecting recovery of system investments and operating costs necessary to maintain the safety and reliability of its natural gas distribution systems, as well as to support enhancements to customer service. Spire’s request, if approved, represents a base rate increase of $ 289.5 . Spire is already recovering $ 53.6 from customers through the Infrastructure System Replacement Surcharge (ISRS) for its eligible capital projects through August 2024, resulting in a net base rate increase request of $ 235.9 . The proposed rates are calculated on a filed rate base of $ 4,386.0 . The rate base has increased by 32 percent since Spire’s last general rate filing test year ended September 30, 2022, reflecting the significant investment made in infrastructure upgrades and other systems. Among other things, the filing proposes changes in recovery mechanisms to address the impacts of both weather and conservation, updates Spire Missouri’s cost of capital, and further aligns the tariffs of its service areas. The filing assumes a common equity ratio of 55.0 % and a 10.5 % return on equity. Certain measures, such as rate base, capital structure and operating costs may be updated over the course of the rate proceeding. In accordance with Missouri law, the MoPSC has 11 months to consider this filing. According to the procedural schedule established on January 9, 2025, the evidentiary hearing will be held August 4–13, 2025. The ISRS allows Spire Missouri expedited recovery for its investment to replace qualifying components of its infrastructure without the necessity of a formal rate case. On January 17, 2025, Spire Missouri initiated an ISRS case for approximately $ 19.0 reflecting eligible capital projects from September 2024 through February 2025 (including estimates for January and February). The MoPSC has up to six months to consider the case. Spire Alabama The Rate Stabilization and Equalization (RSE) mechanism requires Spire Alabama to file an annual rate review based on the utility’s budget for the upcoming fiscal year. Filings are reviewed by the APSC and Office of the Attorney General and approved by the APSC. Revenue requirements are calculated to include Spire Alabama’s anticipated cost of service in addition to an updated return on common equity (RCE) within the allowed range. Rates are set by allocating the revenue requirements among the volumes budgeted for each of Spire Alabama’s customer classes. In addition, the utility is subject to points of test to periodically measure whether fiscal year earnings are projected to be above the allowed RCE range. If so, a revenue adjustment is recorded and the excess is returned to customers as stipulated by the APSC as a rate reduction commonly referred to as an “RSE giveback.” In October 2023, Spire Alabama made its annual RSE rate filing presenting the utility’s budget for the fiscal year ended September 30, 2024, and new rates designed to provide an annualized revenue increase of $ 14.3 became effective January 1, 2024. At the September 30, 2024 point of test, the RCE was above the allowed range, resulting in an annualized refund of $ 4.0 accrued at year end and reflected in a rate reduction effective December 1, 2024. On October 24, 2024, Spire Alabama made its annual RSE rate filing, presenting the utility’s preliminary budget for the fiscal year ending September 30, 2025. The final budget was filed and approved on November 26, 2024. No adjustment to the rates that were effective December 1, 2024 was required. Based on results through December 31, 2024, Spire Alabama’s RCE for the year is projected to be above the allowed range as of the March point of test, and a provision of $ 4.1 reducing revenue was recorded in the first quarter in anticipation of an RSE giveback. Spire Alabama’s rate schedules for natural gas distribution charges contain a GSA rider which permits the pass-through to customers of changes in the cost of gas supply. In fiscal 2024 and 2025, GSA rate decreases were effective October 1, 2023, January 1, 2024, April 1, 2024, and October 1, 2024, primarily attributable to changes in natural gas commodity prices. Spire In addition to those discussed above for Spire Missouri and Spire Alabama, Spire is affected by the following regulatory matters. Spire Gulf operates under an interpretation of the RSE mechanism similar to that of Spire Alabama. In the fiscal year ended September 30, 2023, Spire Gulf's September RSE point of test reflected that its actual RCE exceeded the allowed RCE, resulting in an annualized refund of $ 2.0 that reduced rates effective December 1, 2023. In October 2023, Spire Gulf made its annual RSE filing, presenting the utility’s budget for the fiscal year ended September 30, 2024, and new rates designed to provide an annualized revenue increase of $ 2.7 became effective December 13, 2023. On October 25, 2024, Spire Gulf made its annual RSE rate filing, presenting the utility’s preliminary budget for the fiscal year ending September 30, 2025. The final budget was filed and approved on December 2, 2024, reflecting an approved increase in annual revenues of $ 1.3 , with new rates effective December 4, 2024. The Mississippi Public Service Commission (MSPSC) approved stipulation agreements between the Mississippi Public Utility Staff (MPUS) and Spire Mississippi that provided for increased annual revenues of $ 1.0 and $ 0.6 through rates effective on January 1, 2024 and 2025, respectively.

Financing

Financing	3 Months Ended
	Dec. 31, 2024
Debt Disclosure [Abstract]
Financing	6. FINA NCING Short-term Spire, Spire Missouri and Spire Alabama have a syndicated revolving credit facility pursuant to a loan agreement with 12 banks through October 11, 2029. The loan agreement has an aggregate credit commitment of $ 1,500.0 , including sublimits of $ 525.0 for the Spire holding company, $ 700.0 for Spire Missouri and $ 275.0 for Spire Alabama. These sublimits may be reallocated from time to time among the three borrowers within the $ 1,500.0 aggregate commitment, with commitment fees and interest margins applied for each borrower relative to its credit rating. The Spire holding company may use its line to provide for the funding needs of various subsidiaries. The agreement also contains financial covenants limiting each borrower’s consolidated total debt, including short-term debt, to no more than 70 % of its total capitalization. As defined in the line of credit, on December 31, 2024 , total debt was less than 65 % of total capitalization for each borrower. There were no borrowings against this credit facility as of December 31, 2024. Spire has a commercial paper program (“CP Program”) pursuant to which it may issue short-term, unsecured commercial paper notes. Amounts available under the CP Program may be borrowed, repaid and re-borrowed from time to time, with the aggregate face or principal amount of the notes outstanding under the CP Program at any time not to exceed $ 1,500.0 . The notes may have maturities of up to 365 days from date of issue. On January 3, 2024, Spire Missouri entered into a short-term loan agreement with several banks for a $ 200.0 unsecured term loan. Interest accrued at the one-month term secured overnight financing rate (“SOFR”) plus a SOFR adjustment of 0.10 % per annum plus a margin of 0.90 % per annum. Spire Missouri repaid $ 50.0 of this loan on April 5, 2024 and the remaining $ 150.0 balance on May 6, 2024. Information about short-term borrowings, including Spire Missouri’s and Spire Alabama’s borrowings from Spire, is presented in the following table. As of December 31, 2024 , $ 687.7 of Spire’s CP Program borrowings was used to support lending to the Utilities. Spire Spire Spire Spire CP Term Spire Spire Consol- Program Loan Note Note idated Three Months Ended December 31, 2024 Highest borrowings outstanding $ 1,198.0 $ — $ 599.0 $ 73.2 $ 1,198.0 Lowest borrowings outstanding 943.5 — 487.8 43.0 943.5 Weighted average borrowings 1,087.8 — 545.3 58.0 1,087.8 Weighted average interest rate 4.6 % 0.0 % 4.9 % 4.9 % 4.6 % As of December 31, 2024 Borrowings outstanding $ 1,158.0 $ — $ 580.9 $ 67.0 $ 1,158.0 Weighted average interest rate 4.4 % 0.0 % 4.8 % 4.8 % 4.4 % As of September 30, 2024 Borrowings outstanding $ 947.0 $ — $ 495.3 $ 48.4 $ 947.0 Weighted average interest rate 5.2 % 0.0 % 5.2 % 5.2 % 5.2 % As of December 31, 2023 Borrowings outstanding $ 1,047.5 $ — $ 633.3 $ 128.5 $ 1,047.5 Weighted average interest rate 5.7 % 0.0 % 5.7 % 5.7 % 5.7 % Long-term The long-term debt agreements of Spire, Spire Missouri and Spire Alabama contain customary financial covenants and default provisions. As of December 31, 2024, there were no events of default under these financial covenants. Interest expense shown on the statements of income is net of the capitalized interest amounts shown in the following table. Three Months Ended 2024 2023 Spire $ 6.3 $ 3.8 Spire Missouri 1.2 1.2 Spire Alabama 0.8 0.4

Fair Value of Financial Instrum

Fair Value of Financial Instruments	3 Months Ended
	Dec. 31, 2024
Fair Value Disclosures [Abstract]
Fair Value of Financial Instruments	7. FAIR VALUE OF FINANCIAL INSTRUMENTS The carrying amounts of cash and cash equivalents, notes receivable, and short-term debt approximate fair value due to the short maturity of these instruments. The fair values of long-term debt are estimated based on market prices for similar issues. Refer to Note 8 , Fair Value Measurements, for information on financial instruments measured at fair value on a recurring basis. The carrying amounts and estimated fair values of financial instruments not measured at fair value on a recurring basis are shown in the following tables, classified according to the fair value hierarchy. There were no such instruments classified as Level 3 (significant unobservable inputs) as of December 31, 2024, September 30, 2024, and December 31, 2023. Classification of Estimated Carrying Fair Quoted Significant Spire As of December 31, 2024 Cash and cash equivalents $ 11.5 $ 11.5 $ 11.5 $ — Notes payable 1,158.0 1,158.0 — 1,158.0 Long-term debt, including current portion 3,740.2 3,435.3 — 3,435.3 As of September 30, 2024 Cash and cash equivalents $ 4.5 $ 4.5 $ 4.5 $ — Notes payable 947.0 947.0 — 947.0 Long-term debt, including current portion 3,746.4 3,600.3 — 3,600.3 As of December 31, 2023 Cash and cash equivalents $ 4.8 $ 4.8 $ 4.8 $ — Notes payable 1,047.5 1,047.5 — 1,047.5 Long-term debt, including current portion 3,704.8 3,481.5 — 3,481.5 Spire Missouri As of December 31, 2024 Notes payable – associated companies $ 580.9 $ 580.9 $ — $ 580.9 Long-term debt 1,803.6 1,646.3 — 1,646.3 As of September 30, 2024 Notes payable – associated companies $ 495.3 $ 495.3 $ — $ 495.3 Long-term debt 1,803.4 1,736.9 — 1,736.9 As of December 31, 2023 Notes payable – associated companies $ 633.3 $ 633.3 $ — $ 633.3 Long-term debt, including current portion 1,785.8 1,689.5 — 1,689.5 Spire Alabama As of December 31, 2024 Notes payable – associated companies $ 67.0 $ 67.0 $ — $ 67.0 Long-term debt, including current portion 746.4 677.4 — 677.4 As of September 30, 2024 Cash and cash equivalents $ 1.5 $ 1.5 $ 1.5 $ — Notes payable – associated companies 48.4 48.4 — 48.4 Long-term debt, including current portion 746.3 711.8 — 711.8 As of December 31, 2023 Notes payable – associated companies $ 128.5 $ 128.5 $ — $ 128.5 Long-term debt 746.0 701.7 — 701.7

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Dec. 31, 2024
Fair Value Disclosures [Abstract]
Fair Value Measurements	8. FAIR VAL UE MEASUREMENTS The information presented in the following tables categorizes the assets and liabilities in the balance sheets that are accounted for at fair value on a recurring basis in periods subsequent to initial recognition. The mutual funds and bonds included in Level 1 are valued based on exchange-quoted market prices of individual securities. Derivative instruments included in Level 1 are valued using quoted market prices on the New York Mercantile Exchange (NYMEX) or the Intercontinental Exchange (ICE), and also certain natural gas commodity contracts. Derivative instruments classified in Level 2 include derivatives that are valued using broker or dealer quotation services or published benchmarks whose prices are derived principally from, or are corroborated by, observable market inputs. Also included in Level 2 are certain derivative instruments that have values that are similar to, and correlate with, quoted prices for exchange-traded instruments or in active markets. Derivative instruments included in Level 3 are valued using generally unobservable inputs that are based upon the best information available and reflect management’s assumptions about how market participants would price the asset or liability. There were no Level 3 balances as of December 31, 2024, September 30, 2024, or December 31, 2023. The Company’s policy is to recognize transfers between the levels of the fair value hierarchy, if any, as of the beginning of the interim reporting period in which circumstances change or events occur to cause the transfer. The mutual funds and bonds are included in “Other Investments” on the Company’s balance sheets. The mutual funds are included in “Other Property and Investments” on Spire Missouri’s balance sheets. Changes in their recurring valuations are recorded as unrealized gains or losses in the corresponding income statement. Derivative assets and liabilities, including receivables and payables associated with cash margin requirements, are presented net in the balance sheets when a legally enforceable netting agreement exists between the Company, Spire Missouri, or Spire Alabama and the counterparty to a derivative contract. Derivative instruments are included in the balance sheets in “Other” current or noncurrent assets or liabilities as applicable. Spire Quoted Prices Significant Effects of Total As of December 31, 2024 ASSETS Gas Utility: U.S. stock/bond mutual funds $ 24.7 $ — $ — $ 24.7 NYMEX/ICE natural gas contracts 5.9 — ( 5.9 ) — Gas Marketing: NYMEX/ICE natural gas contracts 8.8 — ( 8.8 ) — Natural gas commodity contracts — 44.1 ( 1.2 ) 42.9 Other: U.S. stock/bond mutual funds 20.8 — — 20.8 U.S. bonds 15.6 — — 15.6 Global bonds 6.0 — — 6.0 Interest rate swaps — 16.1 — 16.1 Total $ 81.8 $ 60.2 $ ( 15.9 ) $ 126.1 LIABILITIES Gas Utility: NYMEX/ICE natural gas contracts $ 6.8 $ — $ ( 6.8 ) $ — Gas Marketing: NYMEX/ICE natural gas contracts 15.1 — ( 15.1 ) — Natural gas commodity contracts — 29.1 ( 1.2 ) 27.9 Total $ 21.9 $ 29.1 $ ( 23.1 ) $ 27.9 Quoted Prices Significant Effects of Total As of September 30, 2024 ASSETS Gas Utility: U.S. stock/bond mutual funds $ 24.3 $ — $ — $ 24.3 NYMEX/ICE natural gas contracts 3.4 — ( 3.4 ) — Gas Marketing: NYMEX/ICE natural gas contracts 7.0 — ( 7.0 ) — Natural gas commodity contracts — 46.0 ( 3.5 ) 42.5 Other: U.S. stock/bond mutual funds 17.9 — — 17.9 U.S. bonds 21.9 — — 21.9 Global bonds 5.9 — — 5.9 Interest rate swaps — 0.8 — 0.8 Total $ 80.4 $ 46.8 $ ( 13.9 ) $ 113.3 LIABILITIES Gas Utility: NYMEX/ICE natural gas contracts $ 13.6 $ — $ ( 3.8 ) $ 9.8 Gas Marketing: NYMEX/ICE natural gas contracts 17.7 — ( 17.7 ) — Natural gas commodity contracts — 24.5 ( 3.5 ) 21.0 Interest rate swaps — 1.5 — 1.5 Total $ 31.3 $ 26.0 $ ( 25.0 ) $ 32.3 As of December 31, 2023 ASSETS Gas Utility: U.S. stock/bond mutual funds $ 22.0 $ — $ — $ 22.0 NYMEX/ICE natural gas contracts 4.7 — ( 4.7 ) — Gas Marketing: NYMEX/ICE natural gas contracts 13.2 — ( 13.2 ) — Natural gas commodity contracts — 45.5 ( 1.4 ) 44.1 Other: U.S. stock/bond mutual funds 14.6 — — 14.6 U.S. bonds 21.6 — — 21.6 Global bonds 1.4 — — 1.4 Interest rate swaps — 22.7 — 22.7 Total $ 77.5 $ 68.2 $ ( 19.3 ) $ 126.4 LIABILITIES Gas Utility: NYMEX/ICE natural gas contracts $ 60.7 $ — $ ( 60.7 ) $ — Gasoline and heating oil contracts — 0.4 ( 0.4 ) — Gas Marketing: NYMEX/ICE natural gas contracts 32.7 — ( 32.7 ) — Natural gas commodity contracts — 24.5 ( 1.4 ) 23.1 Other: Interest rate swaps — 2.0 — 2.0 Total $ 93.4 $ 26.9 $ ( 95.2 ) $ 25.1 Spire Missouri Quoted Prices Significant Effects of Total As of December 31, 2024 ASSETS U.S. stock/bond mutual funds $ 24.7 $ — $ — $ 24.7 NYMEX/ICE natural gas contracts 5.9 — ( 5.9 ) — Total $ 30.6 $ — $ ( 5.9 ) $ 24.7 LIABILITIES NYMEX/ICE natural gas contracts $ 6.8 $ — $ ( 6.8 ) $ — As of September 30, 2024 ASSETS U.S. stock/bond mutual funds $ 24.3 $ — $ — $ 24.3 NYMEX/ICE natural gas contracts 3.4 — ( 3.4 ) — Total $ 27.7 $ — $ ( 3.4 ) $ 24.3 LIABILITIES NYMEX/ICE natural gas contracts $ 13.6 $ — $ ( 3.8 ) $ 9.8 As of December 31, 2023 ASSETS U.S. stock/bond mutual funds $ 22.0 $ — $ — $ 22.0 NYMEX/ICE natural gas contracts 4.7 — ( 4.7 ) — Total $ 26.7 $ — $ ( 4.7 ) $ 22.0 LIABILITIES NYMEX/ICE natural gas contracts $ 60.7 $ — $ ( 60.7 ) $ — Gasoline and heating oil contracts — 0.4 ( 0.4 ) — Total $ 60.7 $ 0.4 $ ( 61.1 ) $ —

Pension Plans and Other Postret

Pension Plans and Other Postretirement Benefits	3 Months Ended
	Dec. 31, 2024
Retirement Benefits [Abstract]
Pension Plans and Other Postretirement Benefits	9. PENSION PLA NS AND OTHER POSTRETIREMENT BENEFITS Pension Plans Spire and the Utilities maintain pension plans for their employees. Spire Missouri and Spire Alabama have non-contributory, defined benefit, trusteed forms of pension plans covering the majority of their employees. Qualified plan assets are comprised of mutual and commingled funds consisting of U.S. equities with varying strategies, global equities, alternative investments, and fixed income investments. The net periodic pension cost includes components shown in the following tables. Service costs and regulatory adjustments are recorded in “Operation and maintenance” expenses while other components are presented in “Other Income, Net” in the income statement, except for Spire Alabama’s losses on lump-sum settlements. Such losses are capitalized in regulatory balances and amortized over the remaining actuarial life of individuals in the plan, and that amortization is presented in “Other Income, Net.” Three Months Ended 2024 2023 Spire Service cost – benefits earned during the period $ 4.5 $ 4.0 Interest cost on projected benefit obligation 6.0 6.8 Expected return on plan assets ( 6.5 ) ( 6.3 ) Amortization of prior service credit ( 1.1 ) ( 1.1 ) Amortization of actuarial loss 1.6 1.6 Subtotal 4.5 5.0 Regulatory adjustment 8.9 8.7 Net pension cost $ 13.4 $ 13.7 Spire Missouri Service cost – benefits earned during the period $ 2.9 $ 2.6 Interest cost on projected benefit obligation 4.0 4.8 Expected return on plan assets ( 4.5 ) ( 4.3 ) Amortization of prior service credit ( 0.5 ) ( 0.5 ) Amortization of actuarial loss 1.0 1.5 Subtotal 2.9 4.1 Regulatory adjustment 7.4 6.3 Net pension cost $ 10.3 $ 10.4 Spire Alabama Service cost – benefits earned during the period $ 1.4 $ 1.2 Interest cost on projected benefit obligation 1.3 1.3 Expected return on plan assets ( 1.3 ) ( 1.2 ) Amortization of prior service credit ( 0.6 ) ( 0.6 ) Amortization of actuarial loss 0.6 0.2 Subtotal 1.4 0.9 Regulatory adjustment 1.3 2.2 Net pension cost $ 2.7 $ 3.1 Pursuant to the provisions of Spire Missouri’s and Spire Alabama’s pension plans, pension obligations may be satisfied by monthly annuities, lump-sum cash payments, or special termination benefits. Lump-sum payments are recognized as settlements (which can result in gains or losses) only if the total of such payments exceeds the sum of service and interest costs in a specific year. Special termination benefits, when offered, are also recognized as settlements which can result in gains or losses. For the three months ended December 31, 2024 and 2023, no plans met the criteria for settlement accounting. The funding policy of the Utilities is to contribute an amount not less than the minimum required by government funding standards, nor more than the maximum deductible amount for federal income tax purposes. Fiscal 2025 contributions to Spire Missouri’s pension plans through December 31, 2024 were $ 22.3 to the qualified trusts and none to non-qualified plans. Fiscal 2025 contributions to the Spire Alabama pension plans through December 31, 2024 were $ 2.6 . Contributions totaling $ 13.2 to the qualified trusts of Spire Missouri’s pension plans are anticipated for the remainder of fiscal 2025. Contributions to Spire Alabama’s pension plans for the remainder of fiscal 2025 are anticipated to be $ 11.9 . Other Postretirement Benefits Spire and the Utilities provide certain life insurance benefits at retirement. Spire Missouri plans provide for medical insurance after early retirement until age 65. For retirements prior to January 1, 2015, certain Spire Missouri plans provided medical insurance after retirement until death. The Spire Alabama plans provide medical insurance upon retirement until death for certain retirees depending on the type of employee and the date the employee was originally hired. The net periodic postretirement benefit cost includes components shown in the following tables. Service costs and regulatory adjustments are recorded in “Operation and maintenance” expenses while other components are presented in “Other Income, Net” in the income statement, except in the event Spire Alabama incurs losses on lump-sum settlements. Any such losses are capitalized in regulatory balances and amortized over the remaining actuarial life of individuals in the plan, and that amortization is presented in “Other Income, Net.” Three Months Ended 2024 2023 Spire Service cost – benefits earned during the period $ 1.1 $ 1.1 Interest cost on accumulated postretirement benefit obligation 1.8 2.1 Expected return on plan assets ( 4.2 ) ( 4.0 ) Amortization of prior service cost — 0.1 Amortization of actuarial gain ( 1.5 ) ( 1.0 ) Subtotal ( 2.8 ) ( 1.7 ) Regulatory adjustment 1.1 0.2 Net postretirement benefit income $ ( 1.7 ) $ ( 1.5 ) Spire Missouri Service cost – benefits earned during the period $ 0.9 $ 0.9 Interest cost on accumulated postretirement benefit obligation 1.3 1.6 Expected return on plan assets ( 2.8 ) ( 2.7 ) Amortization of prior service cost 0.1 0.2 Amortization of actuarial gain ( 1.3 ) ( 0.9 ) Subtotal ( 1.8 ) ( 0.9 ) Regulatory adjustment 1.6 0.6 Net postretirement benefit income $ ( 0.2 ) $ ( 0.3 ) Spire Alabama Service cost – benefits earned during the period $ 0.2 $ 0.2 Interest cost on accumulated postretirement benefit obligation 0.5 0.5 Expected return on plan assets ( 1.3 ) ( 1.3 ) Amortization of prior service credit ( 0.1 ) ( 0.1 ) Subtotal ( 0.7 ) ( 0.7 ) Regulatory adjustment ( 0.5 ) ( 0.4 ) Net postretirement benefit income $ ( 1.2 ) $ ( 1.1 ) Missouri and Alabama state laws provide for the recovery in rates of costs accrued pursuant to GAAP provided that such costs are funded through an independent, external funding mechanism. The Utilities have established Voluntary Employees’ Beneficiary Association (VEBA) and Rabbi Trusts as external funding mechanisms. The assets of the VEBA and Rabbi Trusts consist primarily of money market securities and mutual funds invested in stocks and bonds. The Utilities’ funding policy is to contribute amounts to the trusts equal to the periodic benefit cost calculated pursuant to GAAP as recovered in rates. There have been no contributions to the postretirement plans through December 31, 2024 for Spire Missouri or Spire Alabama, and none are expected to be required for the remainder of the fiscal year.

Information by Operating Segmen

Information by Operating Segment	3 Months Ended
	Dec. 31, 2024
Segment Reporting [Abstract]
Information by Operating Segment	10. INFORMATION BY OPERATIN G SEGMENT The Company has three reportable segments: Gas Utility, Gas Marketing, and Midstream. The Gas Utility segment is the aggregation of the operations of the Utilities. The Gas Marketing segment includes the results of Spire Marketing, a subsidiary engaged in the non-regulated marketing of natural gas and related activities, including utilizing natural gas storage contracts for providing natural gas sales. The Midstream segment includes Spire Storage, Spire STL Pipeline and Spire MoGas Pipeline, which are subsidiaries engaged in the storage and transportation of natural gas. Other components of the Company’s consolidated information include Spire’s subsidiaries engaged in the operation of a natural gas liquids pipeline and risk management, among other activities, and unallocated corporate items, including certain debt and associated interest costs. Accounting policies are described in Note 1 , Summary of Significant Accounting Policies. Intersegment transactions include sales of natural gas from Spire Marketing to Spire Missouri, Spire Alabama and Spire Storage, storage services from Spire Storage to Spire Missouri and Spire Marketing, and natural gas transportation services provided by Spire STL Pipeline and Spire MoGas Pipeline to Spire Missouri and Spire Marketing. Management evaluates the performance of the operating segments based on the computation of adjusted earnings. Adjusted earnings exclude from reported net income the after-tax impacts of fair value accounting and timing adjustments associated with energy-related transactions, the impacts of acquisition, divestiture and restructuring activities, and the largely non-cash impacts of impairments and other non-recurring or unusual items such as certain regulatory, legislative, or GAAP standard-setting actions. Gas Gas Midstream Other Eliminations Consolidated Three Months Ended December 31, 2024 Revenues from external customers $ 613.5 $ 33.0 $ 22.3 $ 0.3 $ — $ 669.1 Intersegment revenues — — 11.2 4.4 ( 15.6 ) — Total Operating Revenues 613.5 33.0 33.5 4.7 ( 15.6 ) 669.1 Depreciation and amortization expense 68.1 0.4 3.7 0.1 — 72.3 Interest expense 35.1 — 1.2 24.8 ( 13.1 ) 48.0 Income tax expense (benefit) 16.1 0.8 3.8 ( 0.6 ) — 20.1 Adjusted earnings (loss) 77.8 2.2 12.0 ( 10.9 ) — 81.1 Capital expenditures 217.9 0.1 42.7 — ( 0.1 ) 260.6 Three Months Ended December 31, 2023 Revenues from external customers $ 715.2 $ 36.3 $ 5.0 $ 0.1 $ — $ 756.6 Intersegment revenues — — 9.9 4.0 ( 13.9 ) — Total Operating Revenues 715.2 36.3 14.9 4.1 ( 13.9 ) 756.6 Depreciation and amortization expense 64.2 0.4 2.3 0.1 — 67.0 Interest expense 39.0 — 1.8 24.0 ( 14.2 ) 50.6 Income tax expense 15.7 3.8 0.6 0.9 — 21.0 Adjusted earnings (loss) 75.8 7.2 2.4 ( 2.7 ) — 82.7 Capital expenditures 174.9 — 52.0 — ( 0.4 ) 226.5 The following table reconciles the Company’s adjusted earnings (loss) to net income (loss). Three Months Ended 2024 2023 Net Income $ 81.3 $ 85.1 Adjustments, pre-tax: Fair value and timing adjustments ( 0.3 ) ( 5.2 ) Acquisition and restructuring activities — 1.9 Income tax adjustments 0.1 0.9 Adjusted Earnings $ 81.1 $ 82.7 The Company’s total assets by segment were as follows: December 31, September 30, December 31, 2024 2024 2023 Total Assets: Gas Utility $ 9,075.2 $ 8,767.2 $ 8,736.7 Gas Marketing 246.1 206.1 207.0 Midstream 936.0 903.4 633.9 Other 2,872.8 2,689.8 2,755.1 Eliminations ( 1,854.3 ) ( 1,705.8 ) ( 1,701.0 ) Total Assets $ 11,275.8 $ 10,860.7 $ 10,631.7

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Dec. 31, 2024
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	11. COMMIT MENTS AND CONTINGENCIES Commitments The Company and the Utilities have entered into contracts with various counterparties, expiring on dates through calendar 2039, for the storage, transportation, and supply of natural gas. Minimum payments required under the contracts in place at December 31, 2024 , are estimated at $ 1,576.0 , $ 1,575.3 , and $ 309.9 for the Company (excluding commitments between subsidiaries), Spire Missouri, and Spire Alabama, respectively. Additional contracts are generally entered into prior to or during the heating season of November through April. The Utilities recover their costs from customers in accordance with their PGA clauses or GSA riders. Spire is a limited partner in several unconsolidated partnerships, predominantly focusing on sustainability and development initiatives tied to the natural gas utility sector. Spire committed to contribute a total of $ 25.3 of capital to the partnerships as and when requested by the respective general partners. As of December 31, 2024 , the total remaining unfunded commitment was $ 16.3 . Contingencies The Company and the Utilities account for contingencies, including environmental liabilities, in accordance with accounting standards under the loss contingency guidance of ASC Topic 450, Contingencies , when it is probable that a liability has been incurred and the amount of the loss can be reasonably estimated. In addition to matters noted below, the Company and the Utilities are involved in other litigation, claims, and investigations arising in the normal course of business. Management, after discussion with counsel, believes the final outcome will not have a material effect on the statements of income, balance sheets, and statements of cash flows of the Company, Spire Missouri, or Spire Alabama. However, there is uncertainty in the valuation of pending claims and prediction of litigation results. The Company and the Utilities own and operate natural gas distribution, transmission, and storage facilities, the operations of which are subject to various environmental laws, regulations, and interpretations. While environmental issues resulting from such operations arise in the ordinary course of business, such issues have not materially affected the Company’s or Utilities’ financial position and results of operations. As environmental laws, regulations, and their interpretations change, the Company or the Utilities may incur additional environmental liabilities that may result in additional costs, which may be material. In the natural gas industry, many gas distribution companies have incurred environmental liabilities associated with sites they or their predecessor companies formerly owned or operated where manufactured gas operations took place. The Utilities each have former manufactured gas plant (MGP) operations in their respective service territories, some of which are discussed under the Spire Missouri and Spire Alabama headings below. To the extent costs are incurred associated with environmental remediation activities, the Utilities would request authority from their respective regulators to defer such costs (less any amounts received from insurance proceeds or as contributions from other potentially responsible parties (PRPs)) and collect them through future rates. To date, costs incurred for all Spire MGP sites for investigation, remediation and monitoring have not been material. However, the amount of costs relative to future remedial actions at these and other sites is unknown and may be material. The actual future costs that Spire Missouri and Spire Alabama may incur could be materially higher or lower depending upon several factors, including whether remediation will be required, final selection and regulatory approval of any remedial actions, changing technologies and government regulations, the ultimate ability of other PRPs to pay, and any insurance recoveries. In 2020, Spire retained an outside consultant to conduct probabilistic cost modeling of its former MGP sites in Missouri and Alabama. The purpose of this analysis was to develop an estimated range of probabilistic future liability for each of their MGP sites. That analysis, completed in March 2021, provided a range of demonstrated possible future expenditures to investigate, monitor and remediate the former MGP sites. Spire Missouri and Spire Alabama have recorded their best estimates of the probable expenditures that relate to these matters. The amount remains immaterial, and Spire Missouri, Spire Alabama and the Company do not expect potential liabilities that may arise from remediating these sites to have a material impact on their future financial condition or results of operations. Spire Missouri Spire Missouri has identified three former MGP sites in the city of St. Louis, Missouri (the “City”) where costs have been incurred and claims have been asserted. Spire Missouri has enrolled two of the sites in the Missouri Department of Natural Resources (MoDNR) Brownfields/Voluntary Cleanup Program (BVCP). The third site is the result of an assertion by the United States Environmental Protection Agency (EPA). In conjunction with redevelopment of the Carondelet Coke site, Spire Missouri and another former owner of the site entered into an agreement (the “Remediation Agreement”) with the City development agencies, the developer, and an environmental consultant that obligates one of the City agencies and the environmental consultant to remediate the site and obtain a No Further Action (NFA) letter from the MoDNR. The Remediation Agreement also provides for a release of Spire Missouri and the other former site owner from certain liabilities related to the past and current environmental condition of the site and requires the developer and the environmental consultant to maintain certain insurance coverage, including remediation cost containment, premises pollution liability, and professional liability. The operative provisions of the Remediation Agreement were triggered on December 20, 2010, on which date Spire Missouri and the other former site owner, as full consideration under the Remediation Agreement, paid a small percentage of the cost of remediation of the site. The property was divided into seven parcels, and MoDNR NFA letters have been received for six of the parcels. Remediation is ongoing on the last parcel. In May 2023, Spire Missouri was approached by a real estate developer interested in purchasing the northern half of the second site, Station A, and developing the same for industrial purposes. Consequently, Spire Missouri entered into a cost sharing agreement for remedial investigation with other PRPs. The site developer, Spire Missouri and the PRPs collectively designed a site investigation plan which was submitted to the MoDNR and approved by the agency on August 27, 2024. Contracts with an environmental engineering firm are now finalized and the site investigation process will begin very soon. Additionally, in correspondence dated November 30, 2016, Region 7 of the EPA has asserted that Spire Missouri is liable under Section 107(a) of the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA) for alleged coal gas waste contamination at a third site, Station B. Spire Missouri and the site owner notified the EPA that information and data provided by the EPA to date does not rise to the level of documenting a threat to the public health or environment. As such, in March 2017 Spire Missouri requested more information from the EPA. Spire Missouri never received a response from the EPA. Spire Missouri has notified its insurers that it seeks reimbursement for costs incurred in the past and future potential liabilities associated with these MGP sites. While some of the insurers have denied coverage and reserved their rights, Spire Missouri retains the right to seek potential reimbursements from them. On March 10, 2015, Spire Missouri received a Section 104(e) information request under CERCLA from EPA Region 7 regarding the former Thompson Chemical/Superior Solvents site in the City. In turn, Spire Missouri issued a Freedom of Information Act (FOIA) request to the EPA on April 3, 2015, to identify the basis of the inquiry. The FOIA response from the EPA was received on July 15, 2015, and a response was provided to the EPA on August 15, 2015. Spire Missouri has received no further inquiry from the EPA regarding this matter. In its western service area, Spire Missouri has six owned MGP sites enrolled in the BVCP, including Joplin MGP #1, St. Joseph MGP #1, Kansas City Coal Gas Station B, Kansas City Station A Railroad area, Kansas City Coal Gas Station A, and Independence MGP #2. Source removal has been conducted at all the owned sites since 2003 with the exception of Joplin. On September 15, 2016, a request was made with the MoDNR for a restrictive covenant use limitation with respect to Joplin. Remediation efforts at the six sites are at various stages of completion, ranging from groundwater monitoring and sampling following source removal activities to the aforementioned request for the Joplin site. As part of its participation in the BVCP, Spire Missouri communicates regularly with the MoDNR with respect to its remediation efforts and monitoring activities at these sites. On May 11, 2015, MoDNR approved the next phase of investigation at the Kansas City Station A Railroad area. Spire Alabama Spire Alabama is in the chain of title of nine former MGP sites, four of which it still owns, and five former manufactured gas distribution sites, one of which it still owns. All are located in the state of Alabama. In 2011, a removal action was completed and an NFA letter was received at the Huntsville MGP site pursuant to an Administrative Settlement Agreement and Order on Consent among the EPA, Spire Alabama and the current site owner. In 2012, Spire Alabama responded to an EPA Request for Information Pursuant to Section 104 of CERCLA relating to the 35th Avenue Superfund Site located in North Birmingham, Jefferson County, Alabama. Spire Alabama was identified as a PRP under CERCLA for the cleanup of the site or costs the EPA incurs in cleaning up the site. At this point, Spire Alabama has not been provided information that would allow it to determine the extent, if any, of its potential liability with respect to the 35th Avenue Superfund Site and vigorously denies its inclusion as a PRP. Assessments were performed by the EPA of the former MGP sites in Gadsden and Anniston, and NFA letters were received after each assessment. Spire In addition to those discussed above for Spire Missouri and Spire Alabama, Spire is aware of the following contingent matter. Spire Marketing, along with many natural gas industry participants, faced the unprecedented effects of Winter Storm Uri in February 2021. Numerous natural gas producers and midstream operators were unable to deliver natural gas to market as they experienced wellhead freeze-offs, power outages and equipment failure due to the extreme weather. These events resulted in supply curtailments, and related notices of force majeure to excuse performance, from and to certain counterparties. Further, these events made Spire Marketing subject to various commercial disputes, all of which have been settled and reflected in the financial statements in previous periods. As a result of participating in the Oklahoma natural gas market, Spire Marketing has become subject, along with other market participants, to a complaint filed in January 2025 by the State of Oklahoma related to its transactions with various counterparties in the state during this period. The Company’s management is currently assessing this matter but does not believe it will have a material impact on the Company’s financial position, results of operations or cash flow.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Dec. 31, 2024
Accounting Policies [Abstract]
Basis of Presentation	BASIS OF PRESENTATION – These notes are an integral part of the accompanying unaudited financial statements of Spire Inc. (“Spire” or the “Company”) presented on a consolidated basis, Spire Missouri Inc. (“Spire Missouri”) and Spire Alabama Inc. (“Spire Alabama”). Spire Missouri, Spire Alabama and Spire EnergySouth Inc. (“Spire EnergySouth”) are wholly owned subsidiaries of Spire. Spire Missouri, Spire Alabama and the subsidiaries of Spire EnergySouth (Spire Gulf Inc. and Spire Mississippi Inc.) are collectively referred to as the “Utilities.” The accompanying unaudited financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (GAAP) for interim financial information with the instructions to Form 10-Q and Rule 10-01 of Regulation S‑X. Accordingly, they do not include all the disclosures required for complete financial statements. In the opinion of management, the accompanying unaudited financial statements include all adjustments necessary for the fair presentation of the results of operations for the periods presented. This Form 10-Q should be read in conjunction with the Notes to Financial Statements contained in Spire, Spire Missouri and Spire Alabama’s combined Annual Report on Form 10-K for the fiscal year ended September 30, 2024 . The consolidated financial position, results of operations, and cash flows of Spire include the accounts of the Company and all its subsidiaries. Transactions and balances between consolidated entities have been eliminated from the consolidated financial statements of Spire. In compliance with GAAP, transactions between Spire Missouri and Spire Alabama and their affiliates, as well as intercompany balances on their balance sheets, have not been eliminated from their separate financial statements. NATURE OF OPERATIONS – Spire has three reportable segments: Gas Utility, Gas Marketing, and Midstream. The Gas Utility segment consists of the regulated natural gas distribution operations of the Company and is the core business segment of Spire in terms of revenue and earnings. The Gas Utility segment is comprised of the operations of: Spire Missouri, serving St. Louis, Kansas City, and other areas in Missouri; Spire Alabama, serving central and northern Alabama; and the subsidiaries of Spire EnergySouth, serving the Mobile, Alabama area and south-central Mississippi. The Gas Marketing segment includes Spire’s largest gas-related business, Spire Marketing Inc. (“Spire Marketing”), which provides non-regulated natural gas services throughout the United States (U.S.). The Midstream segment includes Spire Storage, Spire STL Pipeline and Spire MoGas Pipeline, which are subsidiaries engaged in the storage and transportation of natural gas. The activities of the Company’s other subsidiaries are reported as Other and are described in Note 10 , Information by Operating Segment. Spire Missouri and Spire Alabama each have a single reportable segment. The Company’s earnings are derived primarily from its Gas Utility segment. Due to the seasonal nature of the Utilities’ business and the volumetric Spire Missouri rate design, earnings are typically concentrated during the heating season of November through April each fiscal year. As a result, the interim statements of income for Spire, Spire Missouri and Spire Alabama are not necessarily indicative of annual results or representative of succeeding quarters of the fiscal year. REGULATED OPERATIONS – The Utilities account for their regulated operations in accordance with Financial Accounting Standards Board (FASB) Accounting Standards Codification (ASC) Topic 980, Regulated Operations . This topic sets forth the application of GAAP for those companies whose rates are established by or are subject to approval by an independent third-party regulator. The provisions of this accounting guidance require, among other things, that financial statements of a regulated enterprise reflect the actions of regulators, where appropriate. These actions may result in the recognition of revenues and expenses in time periods that are different than non-regulated enterprises. When this occurs, costs are deferred as assets in the balance sheet (regulatory assets) and recorded as expenses when those amounts are reflected in rates. In addition, regulators can impose liabilities upon a regulated company for amounts previously collected from customers and for recovery of costs that are expected to be incurred in the future (regulatory liabilities). Management believes that the current regulatory environment supports the continued use of these regulatory accounting principles and that all regulatory assets and regulatory liabilities are recoverable or refundable through the regulatory process. As authorized by the Missouri Public Service Commission (MoPSC), the Mississippi Public Service Commission (MSPSC) and the Alabama Public Service Commission (APSC), the Purchased Gas Adjustment (PGA) clauses and Gas Supply Adjustment (GSA) riders allow the Utilities to pass through to customers the cost of purchased gas supplies. Regulatory assets and liabilities related to the PGA clauses and the GSA riders are both labeled Unamortized Purchased Gas Adjustments herein. See additional information about regulatory assets and liabilities in Note 5 , Regulatory Matters.
Regulated Operations	REGULATED OPERATIONS – The Utilities account for their regulated operations in accordance with Financial Accounting Standards Board (FASB) Accounting Standards Codification (ASC) Topic 980, Regulated Operations . This topic sets forth the application of GAAP for those companies whose rates are established by or are subject to approval by an independent third-party regulator. The provisions of this accounting guidance require, among other things, that financial statements of a regulated enterprise reflect the actions of regulators, where appropriate. These actions may result in the recognition of revenues and expenses in time periods that are different than non-regulated enterprises. When this occurs, costs are deferred as assets in the balance sheet (regulatory assets) and recorded as expenses when those amounts are reflected in rates. In addition, regulators can impose liabilities upon a regulated company for amounts previously collected from customers and for recovery of costs that are expected to be incurred in the future (regulatory liabilities). Management believes that the current regulatory environment supports the continued use of these regulatory accounting principles and that all regulatory assets and regulatory liabilities are recoverable or refundable through the regulatory process. As authorized by the Missouri Public Service Commission (MoPSC), the Mississippi Public Service Commission (MSPSC) and the Alabama Public Service Commission (APSC), the Purchased Gas Adjustment (PGA) clauses and Gas Supply Adjustment (GSA) riders allow the Utilities to pass through to customers the cost of purchased gas supplies. Regulatory assets and liabilities related to the PGA clauses and the GSA riders are both labeled Unamortized Purchased Gas Adjustments herein. See additional information about regulatory assets and liabilities in Note 5 , Regulatory Matters.
Derivatives	DERIVATIVES – In the course of their business, certain subsidiaries of Spire enter into commitments associated with the purchase or sale of natural gas. Certain of their derivative natural gas contracts are designated as normal purchases or normal sales and, as such, are excluded from the scope of FASB ASC Topic 815, Derivatives and Hedging . Those contracts are accounted for as executory contracts and recorded on an accrual basis. Revenues and expenses from such contracts are recorded gross. Contracts not designated as normal purchases or normal sales are recorded as derivatives with changes in fair value recognized in earnings in the periods prior to physical delivery. Certain of Spire Marketing’s wholesale purchase and sale transactions are classified as trading activities for financial reporting purposes, with income and expenses presented on a net basis in natural gas expenses in the Condensed Consolidated Statements of Income. Spire also enters into cash flow hedges through execution of interest rate swap contracts to protect itself against adverse movements in interest rates. In the first quarter of fiscal 2024, considering changes in debt issuance strategy due to the interest rate environment, Spire management determined it was probable the anticipated issuance of certain debt, and therefore the hedged forecasted interest payments, would not occur. The related swap was settled, hedge accounting was discontinued, and amounts previously deferred in “Accumulated other comprehensive income” were reclassified to earnings, such that the entire realized gain of $ 8.2 was included in “Other income” for Spire Inc. in the quarter ended December 31, 2023.
Transaction with Affiliates	TRANSACTIONS WITH AFFILIATES – Transactions between affiliates of the Company have been eliminated from the consolidated financial statements of Spire. As reflected in their separate financial statements, Spire Missouri and Spire Alabama borrowed funds from the Company and incurred related interest. Spire Missouri and Spire Alabama also participated in normal intercompany shared services transactions. Spire Missouri’s and Spire Alabama’s other transactions with affiliates are presented below: Three Months Ended 2024 2023 Spire Missouri Purchases of natural gas from Spire Marketing $ 2.2 $ 5.0 Transportation services received from Spire STL Pipeline 8.1 8.2 Transportation services received from Spire MoGas Pipeline 1.8 — Natural gas storage services from Spire Storage Salt Plains LLC — 0.3 Spire Alabama Purchases of natural gas from Spire Marketing $ 4.9 $ 3.4
Restricted Cash and Other Investments	RESTRICTED CASH AND OTHER INVESTMENTS – In Spire’s statement of cash flows , total Cash, Cash Equivalents, and Restricted Cash included $ 30.4 , $ 30.4 and $ 20.5 of restricted cash reported in “Other Investments” on the Company’s balance sheet as of December 31, 2024, September 30, 2024 , and December 31, 2023 , respectively (in addition to amounts shown as “Cash and cash equivalents”). This restricted cash has been segregated and invested in debt securities in trust accounts based on collateral requirements for reinsurance at Spire’s risk management company.
Business Combinations	BUSINESS COMBINATIONS – On January 19, 2024, a subsidiary in Spire’s Midstream segment acquired MoGas Pipeline, an interstate natural gas pipeline, and Omega Pipeline, a connected gas distribution system in Missouri. MoGas interconnects with Spire STL Pipeline and other regional pipelines to deliver gas to Spire Missouri’s growing customer base in St. Charles, Franklin, and western St. Louis counties, among other utility, municipal, industrial and commercial customers. Omega owns and operates an approximately 75-mile natural gas distribution system within Fort Leonard Wood in south-central Missouri and is interconnected with the MoGas system. The acquisition was accounted for as a business combination in accordance with ASC 805, Business Combinations . The $ 176.1 purchase price was allocated almost entirely to property, plant and equipment based on their estimated fair value at the acquisition date and recorded as non-utility property in the consolidated balance sheet. The operating revenues and operating income of MoGas and Omega were not material to our consolidated results for the three months ended December 31, 2024 .
Accured Capital Expenditures	ACCRUED CAPITAL EXPENDITURES – Accrued capital expenditures, shown in the following table, are excluded from capital expenditures in the statements of cash flows until paid. December 31, September 30, December 31, 2024 2024 2023 Spire $ 73.7 $ 116.5 $ 90.5 Spire Missouri 38.1 67.4 38.1 Spire Alabama 10.5 14.1 2.4
Accounts Receivable and Allowance for Credit Losses	ACCOUNTS RECEIVABLE AND ALLOWANCE FOR CREDIT LOSSES – Trade accounts receivable are recorded at the amounts due from customers, including unbilled amounts. Accounts receivable are written off when they are deemed to be uncollectible. An allowance for expected credit losses is estimated and updated based on relevant data and trends such as accounts receivable aging, historical write-off experience, current write-off trends, economic conditions, and the impact of weather and availability of customer payment assistance on collection trends. For the Utilities, net write-offs as a percentage of revenue has historically been the best predictor of base net write-off experience over time. Management judgment is applied in the development of the allowance due to the complexity of variables and subjective nature of certain relevant factors. The accounts receivable of Spire’s non-utility businesses are evaluated separately from those of the Utilities. The allowance for credit losses for those other businesses is based on a continuous evaluation of the individual counterparty risk and is not significant for the periods presented. Activity in the allowance for credit losses is shown in the following table. Spire Spire Missouri Spire Alabama Three Months Ended December 31, 2024 2023 2024 2023 2024 2023 Allowance at beginning of period $ 31.4 $ 32.5 $ 24.9 $ 26.2 $ 5.7 $ 5.7 Provision for expected credit losses 5.1 4.1 4.1 3.6 0.8 0.3 Write-offs, net of recoveries ( 1.8 ) ( 1.2 ) ( 1.1 ) ( 0.9 ) ( 0.5 ) ( 0.3 ) Allowance at end of period $ 34.7 $ 35.4 $ 27.9 $ 28.9 $ 6.0 $ 5.7

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	3 Months Ended
	Dec. 31, 2024
Accounting Policies [Abstract]
Schedule of Related Party Transactions	Three Months Ended 2024 2023 Spire Missouri Purchases of natural gas from Spire Marketing $ 2.2 $ 5.0 Transportation services received from Spire STL Pipeline 8.1 8.2 Transportation services received from Spire MoGas Pipeline 1.8 — Natural gas storage services from Spire Storage Salt Plains LLC — 0.3 Spire Alabama Purchases of natural gas from Spire Marketing $ 4.9 $ 3.4
Schedule Of Capital Expenditure Excluded From Statement Of Cash Flow	December 31, September 30, December 31, 2024 2024 2023 Spire $ 73.7 $ 116.5 $ 90.5 Spire Missouri 38.1 67.4 38.1 Spire Alabama 10.5 14.1 2.4
Accounts Receivable, Allowance for Credit Loss	Spire Spire Missouri Spire Alabama Three Months Ended December 31, 2024 2023 2024 2023 2024 2023 Allowance at beginning of period $ 31.4 $ 32.5 $ 24.9 $ 26.2 $ 5.7 $ 5.7 Provision for expected credit losses 5.1 4.1 4.1 3.6 0.8 0.3 Write-offs, net of recoveries ( 1.8 ) ( 1.2 ) ( 1.1 ) ( 0.9 ) ( 0.5 ) ( 0.3 ) Allowance at end of period $ 34.7 $ 35.4 $ 27.9 $ 28.9 $ 6.0 $ 5.7

Revenue (Tables)

Revenue (Tables)	3 Months Ended
	Dec. 31, 2024
Revenue from Contract with Customer [Abstract]
Schedule of Revenue Disaggregated by Source and Customer Type	The following tables show revenue disaggregated by source and customer type. Three Months Ended 2024 2023 Spire Gas Utility: Residential $ 411.5 $ 492.8 Commercial and industrial 133.7 157.9 Transportation 34.6 32.6 Off-system and other incentive 11.5 6.4 Other customer revenue 0.8 5.5 Total revenue from contracts with customers 592.1 695.2 Changes in accrued revenue under alternative revenue programs 21.4 20.0 Total Gas Utility operating revenues 613.5 715.2 Gas Marketing 33.0 36.3 Midstream 33.5 14.9 Other 4.7 4.1 Total before eliminations 684.7 770.5 Intersegment eliminations (see Note 10, Information by Operating Segment) ( 15.6 ) ( 13.9 ) Total Operating Revenues $ 669.1 $ 756.6 Spire Missouri Residential $ 321.8 $ 388.8 Commercial and industrial 93.8 110.2 Transportation 9.4 9.0 Off-system and other incentive 9.9 4.1 Other customer revenue 2.8 2.5 Total revenue from contracts with customers 437.7 514.6 Changes in accrued revenue under alternative revenue programs 19.8 20.8 Total Operating Revenues $ 457.5 $ 535.4 Three Months Ended 2024 2023 Spire Alabama Residential $ 72.4 $ 84.4 Commercial and industrial 28.9 34.7 Transportation 22.5 20.8 Off-system and other incentive 1.6 2.3 Other customer revenue ( 3.2 ) 0.9 Total revenue from contracts with customers 122.2 143.1 Changes in accrued revenue under alternative revenue programs ( 1.8 ) ( 1.0 ) Total Operating Revenues $ 120.4 $ 142.1
Schedule of Gross Receipts Taxes Associated Revenue	Three Months Ended 2024 2023 Spire $ 26.8 $ 31.1 Spire Missouri 19.5 22.5 Spire Alabama 5.7 6.9

Earnings Per Common Share (Tabl

Earnings Per Common Share (Tables)	3 Months Ended
	Dec. 31, 2024
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted	Three Months Ended 2024 2023 Basic Earnings Per Common Share: Net Income $ 81.3 $ 85.1 Less: Provision for preferred dividends 3.7 3.7 Income allocated to participating securities 0.1 0.1 Income Available to Common Shareholders $ 77.5 $ 81.3 Weighted Average Common Shares Outstanding (in millions) 57.7 53.5 Basic Earnings Per Common Share $ 1.34 $ 1.52 Diluted Earnings Per Common Share: Net Income $ 81.3 $ 85.1 Less: Provision for preferred dividends 3.7 3.7 Income allocated to participating securities 0.1 0.1 Income Available to Common Shareholders $ 77.5 $ 81.3 Weighted Average Common Shares Outstanding (in millions) 57.7 53.5 Dilutive Effect of forward sales of common stock, restricted 0.2 0.1 Weighted Average Diluted Common Shares (in millions) 57.9 53.6 Diluted Earnings Per Common Share $ 1.34 $ 1.52 * Calculation excludes certain outstanding or potential common shares 0.3 0.2

Regulatory Matters (Tables)

Regulatory Matters (Tables)	3 Months Ended
	Dec. 31, 2024
Regulated Operations [Abstract]
Schedule of Regulatory Assets and Liabilities	The following regulatory assets and regulatory liabilities were reflected in the balance sheets of the Company, Spire Missouri and Spire Alabama as of December 31, 2024, September 30, 2024 , and December 31, 2023 . December 31, September 30, December 31, Spire 2024 2024 2023 Regulatory Assets: Current: Unamortized purchased gas adjustments $ 12.2 $ 28.9 $ 207.0 Other 77.4 86.5 49.4 Total Current Regulatory Assets 89.6 115.4 256.4 Noncurrent: Pension and postretirement benefit costs 248.4 237.5 255.3 Cost of removal 676.1 668.2 640.8 Future income taxes due from customers 152.4 150.7 145.6 Energy efficiency 61.3 61.0 57.5 Unamortized purchased gas adjustments — 1.2 20.3 Other 150.2 133.2 147.4 Total Noncurrent Regulatory Assets 1,288.4 1,251.8 1,266.9 Total Regulatory Assets $ 1,378.0 $ 1,367.2 $ 1,523.3 Regulatory Liabilities: Current: Unamortized purchased gas adjustments $ 39.2 $ 42.3 $ — Other 11.8 7.2 7.1 Total Current Regulatory Liabilities 51.0 49.5 7.1 Noncurrent: Deferred taxes due to customers 110.7 114.2 124.5 Pension and postretirement benefit costs 253.2 232.9 188.2 Accrued cost of removal 136.7 133.6 130.3 Unamortized purchased gas adjustments 40.4 17.2 23.7 Other 36.2 37.6 20.5 Total Noncurrent Regulatory Liabilities 577.2 535.5 487.2 Total Regulatory Liabilities $ 628.2 $ 585.0 $ 494.3 December 31, September 30, December 31, Spire Missouri 2024 2024 2023 Regulatory Assets: Current: Unamortized purchased gas adjustments $ 11.8 $ 28.1 $ 194.1 Other 44.9 55.9 18.8 Total Current Regulatory Assets 56.7 84.0 212.9 Noncurrent: Future income taxes due from customers 144.5 142.7 137.3 Pension and postretirement benefit costs 179.7 166.5 185.5 Energy efficiency 61.3 61.0 57.5 Unamortized purchased gas adjustments — 1.2 20.3 Cost of removal 97.0 97.0 97.0 Other 137.2 119.6 133.2 Total Noncurrent Regulatory Assets 619.7 588.0 630.8 Total Regulatory Assets $ 676.4 $ 672.0 $ 843.7 Regulatory Liabilities: Current: Unamortized purchased gas adjustments $ 17.4 $ 10.2 $ — Total Current Regulatory Liabilities 17.4 10.2 — Noncurrent: Deferred taxes due to customers 98.6 101.8 111.6 Pension and postretirement benefit costs 218.0 196.6 160.2 Accrued cost of removal 96.8 94.5 93.4 Unamortized purchased gas adjustments 40.4 17.2 23.7 Other 32.2 33.2 15.6 Total Noncurrent Regulatory Liabilities 486.0 443.3 404.5 Total Regulatory Liabilities $ 503.4 $ 453.5 $ 404.5 Spire Alabama Regulatory Assets: Current: Unamortized purchased gas adjustments $ — $ — $ 12.2 Other 17.4 19.2 18.8 Total Current Regulatory Assets 17.4 19.2 31.0 Noncurrent: Future income taxes due from customers 1.7 1.8 1.9 Pension and postretirement benefit costs 66.1 68.2 66.0 Cost of removal 579.1 571.2 543.7 Other 0.4 0.8 1.0 Total Noncurrent Regulatory Assets 647.3 642.0 612.6 Total Regulatory Assets $ 664.7 $ 661.2 $ 643.6 Regulatory Liabilities: Current: Unamortized purchased gas adjustments $ 20.7 $ 30.9 $ — Other 7.0 2.9 — Total Current Regulatory Liabilities 27.7 33.8 — Noncurrent: Pension and postretirement benefit costs 24.2 25.1 17.3 Other 2.7 3.2 3.4 Total Noncurrent Regulatory Liabilities 26.9 28.3 20.7 Total Regulatory Liabilities $ 54.6 $ 62.1 $ 20.7
Schedule of Regulatory Assets Not Earning Return	A portion of the Company’s and Spire Missouri’s regulatory assets are not earning a return, as shown in the table below: December 31, September 30, December 31, 2024 2024 2023 Spire Pension and postretirement benefit costs $ 129.8 $ 129.7 $ 134.0 Future income taxes due from customers 150.7 148.9 143.6 Unamortized purchased gas adjustments 11.8 29.3 214.4 Other 143.1 132.5 117.0 Total Regulatory Assets Not Earning a Return $ 435.4 $ 440.4 $ 609.0 Spire Missouri Pension and postretirement benefit costs $ 129.8 $ 129.7 $ 134.0 Future income taxes due from customers 144.5 142.7 137.3 Unamortized purchased gas adjustments 11.8 29.3 214.4 Other 143.1 132.5 117.0 Total Regulatory Assets Not Earning a Return $ 429.2 $ 434.2 $ 602.7

Financing (Tables)

Financing (Tables)	3 Months Ended
	Dec. 31, 2024
Debt Disclosure [Abstract]
Schedule of Short-Term Debt	Spire Spire Spire Spire CP Term Spire Spire Consol- Program Loan Note Note idated Three Months Ended December 31, 2024 Highest borrowings outstanding $ 1,198.0 $ — $ 599.0 $ 73.2 $ 1,198.0 Lowest borrowings outstanding 943.5 — 487.8 43.0 943.5 Weighted average borrowings 1,087.8 — 545.3 58.0 1,087.8 Weighted average interest rate 4.6 % 0.0 % 4.9 % 4.9 % 4.6 % As of December 31, 2024 Borrowings outstanding $ 1,158.0 $ — $ 580.9 $ 67.0 $ 1,158.0 Weighted average interest rate 4.4 % 0.0 % 4.8 % 4.8 % 4.4 % As of September 30, 2024 Borrowings outstanding $ 947.0 $ — $ 495.3 $ 48.4 $ 947.0 Weighted average interest rate 5.2 % 0.0 % 5.2 % 5.2 % 5.2 % As of December 31, 2023 Borrowings outstanding $ 1,047.5 $ — $ 633.3 $ 128.5 $ 1,047.5 Weighted average interest rate 5.7 % 0.0 % 5.7 % 5.7 % 5.7 %
Summary of Capitalized Interest	Three Months Ended 2024 2023 Spire $ 6.3 $ 3.8 Spire Missouri 1.2 1.2 Spire Alabama 0.8 0.4

Fair Value of Financial Instr_2

Fair Value of Financial Instruments (Tables)	3 Months Ended
	Dec. 31, 2024
Fair Value Disclosures [Abstract]
Summary of Estimated Fair Value of Financial Instruments Not Measured at Fair Value on Recurring Basis	The carrying amounts and estimated fair values of financial instruments not measured at fair value on a recurring basis are shown in the following tables, classified according to the fair value hierarchy. There were no such instruments classified as Level 3 (significant unobservable inputs) as of December 31, 2024, September 30, 2024, and December 31, 2023. Classification of Estimated Carrying Fair Quoted Significant Spire As of December 31, 2024 Cash and cash equivalents $ 11.5 $ 11.5 $ 11.5 $ — Notes payable 1,158.0 1,158.0 — 1,158.0 Long-term debt, including current portion 3,740.2 3,435.3 — 3,435.3 As of September 30, 2024 Cash and cash equivalents $ 4.5 $ 4.5 $ 4.5 $ — Notes payable 947.0 947.0 — 947.0 Long-term debt, including current portion 3,746.4 3,600.3 — 3,600.3 As of December 31, 2023 Cash and cash equivalents $ 4.8 $ 4.8 $ 4.8 $ — Notes payable 1,047.5 1,047.5 — 1,047.5 Long-term debt, including current portion 3,704.8 3,481.5 — 3,481.5 Spire Missouri As of December 31, 2024 Notes payable – associated companies $ 580.9 $ 580.9 $ — $ 580.9 Long-term debt 1,803.6 1,646.3 — 1,646.3 As of September 30, 2024 Notes payable – associated companies $ 495.3 $ 495.3 $ — $ 495.3 Long-term debt 1,803.4 1,736.9 — 1,736.9 As of December 31, 2023 Notes payable – associated companies $ 633.3 $ 633.3 $ — $ 633.3 Long-term debt, including current portion 1,785.8 1,689.5 — 1,689.5 Spire Alabama As of December 31, 2024 Notes payable – associated companies $ 67.0 $ 67.0 $ — $ 67.0 Long-term debt, including current portion 746.4 677.4 — 677.4 As of September 30, 2024 Cash and cash equivalents $ 1.5 $ 1.5 $ 1.5 $ — Notes payable – associated companies 48.4 48.4 — 48.4 Long-term debt, including current portion 746.3 711.8 — 711.8 As of December 31, 2023 Notes payable – associated companies $ 128.5 $ 128.5 $ — $ 128.5 Long-term debt 746.0 701.7 — 701.7

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Dec. 31, 2024
Fair Value Disclosures [Abstract]
Schedule of Derivative Assets and Liabilities, Including Receivables and Payables	Quoted Prices Significant Effects of Total As of December 31, 2024 ASSETS Gas Utility: U.S. stock/bond mutual funds $ 24.7 $ — $ — $ 24.7 NYMEX/ICE natural gas contracts 5.9 — ( 5.9 ) — Gas Marketing: NYMEX/ICE natural gas contracts 8.8 — ( 8.8 ) — Natural gas commodity contracts — 44.1 ( 1.2 ) 42.9 Other: U.S. stock/bond mutual funds 20.8 — — 20.8 U.S. bonds 15.6 — — 15.6 Global bonds 6.0 — — 6.0 Interest rate swaps — 16.1 — 16.1 Total $ 81.8 $ 60.2 $ ( 15.9 ) $ 126.1 LIABILITIES Gas Utility: NYMEX/ICE natural gas contracts $ 6.8 $ — $ ( 6.8 ) $ — Gas Marketing: NYMEX/ICE natural gas contracts 15.1 — ( 15.1 ) — Natural gas commodity contracts — 29.1 ( 1.2 ) 27.9 Total $ 21.9 $ 29.1 $ ( 23.1 ) $ 27.9 Quoted Prices Significant Effects of Total As of September 30, 2024 ASSETS Gas Utility: U.S. stock/bond mutual funds $ 24.3 $ — $ — $ 24.3 NYMEX/ICE natural gas contracts 3.4 — ( 3.4 ) — Gas Marketing: NYMEX/ICE natural gas contracts 7.0 — ( 7.0 ) — Natural gas commodity contracts — 46.0 ( 3.5 ) 42.5 Other: U.S. stock/bond mutual funds 17.9 — — 17.9 U.S. bonds 21.9 — — 21.9 Global bonds 5.9 — — 5.9 Interest rate swaps — 0.8 — 0.8 Total $ 80.4 $ 46.8 $ ( 13.9 ) $ 113.3 LIABILITIES Gas Utility: NYMEX/ICE natural gas contracts $ 13.6 $ — $ ( 3.8 ) $ 9.8 Gas Marketing: NYMEX/ICE natural gas contracts 17.7 — ( 17.7 ) — Natural gas commodity contracts — 24.5 ( 3.5 ) 21.0 Interest rate swaps — 1.5 — 1.5 Total $ 31.3 $ 26.0 $ ( 25.0 ) $ 32.3 As of December 31, 2023 ASSETS Gas Utility: U.S. stock/bond mutual funds $ 22.0 $ — $ — $ 22.0 NYMEX/ICE natural gas contracts 4.7 — ( 4.7 ) — Gas Marketing: NYMEX/ICE natural gas contracts 13.2 — ( 13.2 ) — Natural gas commodity contracts — 45.5 ( 1.4 ) 44.1 Other: U.S. stock/bond mutual funds 14.6 — — 14.6 U.S. bonds 21.6 — — 21.6 Global bonds 1.4 — — 1.4 Interest rate swaps — 22.7 — 22.7 Total $ 77.5 $ 68.2 $ ( 19.3 ) $ 126.4 LIABILITIES Gas Utility: NYMEX/ICE natural gas contracts $ 60.7 $ — $ ( 60.7 ) $ — Gasoline and heating oil contracts — 0.4 ( 0.4 ) — Gas Marketing: NYMEX/ICE natural gas contracts 32.7 — ( 32.7 ) — Natural gas commodity contracts — 24.5 ( 1.4 ) 23.1 Other: Interest rate swaps — 2.0 — 2.0 Total $ 93.4 $ 26.9 $ ( 95.2 ) $ 25.1 Quoted Prices Significant Effects of Total As of December 31, 2024 ASSETS U.S. stock/bond mutual funds $ 24.7 $ — $ — $ 24.7 NYMEX/ICE natural gas contracts 5.9 — ( 5.9 ) — Total $ 30.6 $ — $ ( 5.9 ) $ 24.7 LIABILITIES NYMEX/ICE natural gas contracts $ 6.8 $ — $ ( 6.8 ) $ — As of September 30, 2024 ASSETS U.S. stock/bond mutual funds $ 24.3 $ — $ — $ 24.3 NYMEX/ICE natural gas contracts 3.4 — ( 3.4 ) — Total $ 27.7 $ — $ ( 3.4 ) $ 24.3 LIABILITIES NYMEX/ICE natural gas contracts $ 13.6 $ — $ ( 3.8 ) $ 9.8 As of December 31, 2023 ASSETS U.S. stock/bond mutual funds $ 22.0 $ — $ — $ 22.0 NYMEX/ICE natural gas contracts 4.7 — ( 4.7 ) — Total $ 26.7 $ — $ ( 4.7 ) $ 22.0 LIABILITIES NYMEX/ICE natural gas contracts $ 60.7 $ — $ ( 60.7 ) $ — Gasoline and heating oil contracts — 0.4 ( 0.4 ) — Total $ 60.7 $ 0.4 $ ( 61.1 ) $ —

Pension Plans and Other Postr_2

Pension Plans and Other Postretirement Benefits (Tables)	3 Months Ended
	Dec. 31, 2024
Retirement Benefits [Abstract]
Schedule of Net Benefit Costs	Three Months Ended 2024 2023 Spire Service cost – benefits earned during the period $ 4.5 $ 4.0 Interest cost on projected benefit obligation 6.0 6.8 Expected return on plan assets ( 6.5 ) ( 6.3 ) Amortization of prior service credit ( 1.1 ) ( 1.1 ) Amortization of actuarial loss 1.6 1.6 Subtotal 4.5 5.0 Regulatory adjustment 8.9 8.7 Net pension cost $ 13.4 $ 13.7 Spire Missouri Service cost – benefits earned during the period $ 2.9 $ 2.6 Interest cost on projected benefit obligation 4.0 4.8 Expected return on plan assets ( 4.5 ) ( 4.3 ) Amortization of prior service credit ( 0.5 ) ( 0.5 ) Amortization of actuarial loss 1.0 1.5 Subtotal 2.9 4.1 Regulatory adjustment 7.4 6.3 Net pension cost $ 10.3 $ 10.4 Spire Alabama Service cost – benefits earned during the period $ 1.4 $ 1.2 Interest cost on projected benefit obligation 1.3 1.3 Expected return on plan assets ( 1.3 ) ( 1.2 ) Amortization of prior service credit ( 0.6 ) ( 0.6 ) Amortization of actuarial loss 0.6 0.2 Subtotal 1.4 0.9 Regulatory adjustment 1.3 2.2 Net pension cost $ 2.7 $ 3.1 Three Months Ended 2024 2023 Spire Service cost – benefits earned during the period $ 1.1 $ 1.1 Interest cost on accumulated postretirement benefit obligation 1.8 2.1 Expected return on plan assets ( 4.2 ) ( 4.0 ) Amortization of prior service cost — 0.1 Amortization of actuarial gain ( 1.5 ) ( 1.0 ) Subtotal ( 2.8 ) ( 1.7 ) Regulatory adjustment 1.1 0.2 Net postretirement benefit income $ ( 1.7 ) $ ( 1.5 ) Spire Missouri Service cost – benefits earned during the period $ 0.9 $ 0.9 Interest cost on accumulated postretirement benefit obligation 1.3 1.6 Expected return on plan assets ( 2.8 ) ( 2.7 ) Amortization of prior service cost 0.1 0.2 Amortization of actuarial gain ( 1.3 ) ( 0.9 ) Subtotal ( 1.8 ) ( 0.9 ) Regulatory adjustment 1.6 0.6 Net postretirement benefit income $ ( 0.2 ) $ ( 0.3 ) Spire Alabama Service cost – benefits earned during the period $ 0.2 $ 0.2 Interest cost on accumulated postretirement benefit obligation 0.5 0.5 Expected return on plan assets ( 1.3 ) ( 1.3 ) Amortization of prior service credit ( 0.1 ) ( 0.1 ) Subtotal ( 0.7 ) ( 0.7 ) Regulatory adjustment ( 0.5 ) ( 0.4 ) Net postretirement benefit income $ ( 1.2 ) $ ( 1.1 )

Information by Operating Segm_2

Information by Operating Segment (Tables)	3 Months Ended
	Dec. 31, 2024
Segment Reporting [Abstract]
Segment Information by Segment	Gas Gas Midstream Other Eliminations Consolidated Three Months Ended December 31, 2024 Revenues from external customers $ 613.5 $ 33.0 $ 22.3 $ 0.3 $ — $ 669.1 Intersegment revenues — — 11.2 4.4 ( 15.6 ) — Total Operating Revenues 613.5 33.0 33.5 4.7 ( 15.6 ) 669.1 Depreciation and amortization expense 68.1 0.4 3.7 0.1 — 72.3 Interest expense 35.1 — 1.2 24.8 ( 13.1 ) 48.0 Income tax expense (benefit) 16.1 0.8 3.8 ( 0.6 ) — 20.1 Adjusted earnings (loss) 77.8 2.2 12.0 ( 10.9 ) — 81.1 Capital expenditures 217.9 0.1 42.7 — ( 0.1 ) 260.6 Three Months Ended December 31, 2023 Revenues from external customers $ 715.2 $ 36.3 $ 5.0 $ 0.1 $ — $ 756.6 Intersegment revenues — — 9.9 4.0 ( 13.9 ) — Total Operating Revenues 715.2 36.3 14.9 4.1 ( 13.9 ) 756.6 Depreciation and amortization expense 64.2 0.4 2.3 0.1 — 67.0 Interest expense 39.0 — 1.8 24.0 ( 14.2 ) 50.6 Income tax expense 15.7 3.8 0.6 0.9 — 21.0 Adjusted earnings (loss) 75.8 7.2 2.4 ( 2.7 ) — 82.7 Capital expenditures 174.9 — 52.0 — ( 0.4 ) 226.5
Reconciliation of Adjusted Earnings (Loss) to Net Income (Loss)	The following table reconciles the Company’s adjusted earnings (loss) to net income (loss). Three Months Ended 2024 2023 Net Income $ 81.3 $ 85.1 Adjustments, pre-tax: Fair value and timing adjustments ( 0.3 ) ( 5.2 ) Acquisition and restructuring activities — 1.9 Income tax adjustments 0.1 0.9 Adjusted Earnings $ 81.1 $ 82.7
Total Assets by Segment	The Company’s total assets by segment were as follows: December 31, September 30, December 31, 2024 2024 2023 Total Assets: Gas Utility $ 9,075.2 $ 8,767.2 $ 8,736.7 Gas Marketing 246.1 206.1 207.0 Midstream 936.0 903.4 633.9 Other 2,872.8 2,689.8 2,755.1 Eliminations ( 1,854.3 ) ( 1,705.8 ) ( 1,701.0 ) Total Assets $ 11,275.8 $ 10,860.7 $ 10,631.7

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Additional Information (Details) $ in Millions		3 Months Ended
	Jan. 19, 2024 USD ($)	Dec. 31, 2024 USD ($) Segment	Dec. 31, 2023 USD ($)	Sep. 30, 2024 USD ($)
Accounting Policies [Line Items]
Number of reportable segments | Segment		3
Restricted cash		$ 30.4	$ 20.5	$ 30.4
MoGas Pipeline [Member]
Accounting Policies [Line Items]
Payments to acquire businesses, gross	$ 176.1
Other Income [Member]
Accounting Policies [Line Items]
Gain on discontinuation of cash flow hdge due to forecasted transaction probable of not occurring			$ 8.2

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Transactions with Affiliates (Details) - Affiliated Entity [Member] - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Regulated Operation [Member] | Spire Marketing [Member] | Spire Missouri [Member]
Related Party Transaction [Line Items]
Purchases of natural gas from Spire Marketing	$ 2.2	$ 5
Regulated Operation [Member] | Spire Marketing [Member] | Spire Alabama Inc [Member]
Related Party Transaction [Line Items]
Purchases of natural gas from Spire Marketing	4.9	3.4
Unregulated Operation [Member] | Spire S T L Pipeline L L C [Member] | Spire Missouri [Member]
Related Party Transaction [Line Items]
Transaction amount	8.1	8.2
Unregulated Operation [Member] | Spire MoGas Pipeline [Member] | Spire Missouri [Member]
Related Party Transaction [Line Items]
Transaction amount	1.8	0
Unregulated Operation [Member] | Spire Storage Salt Plains LLC [Member] | Spire Missouri [Member]
Related Party Transaction [Line Items]
Transaction amount	$ 0	$ 0.3

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Accrued Capital Expenditures Excluded from Capital Expenditures in the Statements of Cash Flows (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Sep. 30, 2024
Accounting Policies [Line Items]
Accrued capital expenditures	$ 73.7	$ 90.5	$ 116.5
Spire Missouri [Member]
Accounting Policies [Line Items]
Accrued capital expenditures	38.1	38.1	67.4
Spire Alabama Inc [Member]
Accounting Policies [Line Items]
Accrued capital expenditures	$ 10.5	$ 2.4	$ 14.1

Summary of Significant Accoun_7

Summary of Significant Accounting Policies - Activity in the Allowance for Credit Losses (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Accounting Policies [Line Items]
Allowance at beginning of period	$ 31.4	$ 32.5
Provision for expected credit losses	5.1	4.1
Write-offs, net of recoveries	(1.8)	(1.2)
Allowance at end of period	34.7	35.4
Spire Missouri [Member]
Accounting Policies [Line Items]
Allowance at beginning of period	24.9	26.2
Provision for expected credit losses	4.1	3.6
Write-offs, net of recoveries	(1.1)	(0.9)
Allowance at end of period	27.9	28.9
Spire Alabama Inc [Member]
Accounting Policies [Line Items]
Allowance at beginning of period	5.7	5.7
Provision for expected credit losses	0.8	0.3
Write-offs, net of recoveries	(0.5)	(0.3)
Allowance at end of period	$ 6	$ 5.7

Revenue - Schedule of Revenue D

Revenue - Schedule of Revenue Disaggregated by Source and Customer Type (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Disaggregation of Revenue [Line Items]
Operating Revenues	$ 669.1	$ 756.6
Consolidation, Eliminations [Member]
Disaggregation of Revenue [Line Items]
Operating Revenues	(15.6)	(13.9)
Gas Utility [Member] | Operating Segments [Member]
Disaggregation of Revenue [Line Items]
Operating Revenues	613.5	715.2
Gas Marketing [Member] | Operating Segments [Member]
Disaggregation of Revenue [Line Items]
Operating Revenues	33	36.3
Midstream [Member] | Operating Segments [Member]
Disaggregation of Revenue [Line Items]
Operating Revenues	33.5	14.9
Other Operating Segment [Member]
Disaggregation of Revenue [Line Items]
Operating Revenues	4.7	4.1
Spire Missouri [Member]
Disaggregation of Revenue [Line Items]
Changes in accrued revenue under alternative revenue programs	19.8	20.8
Operating Revenues	457.5	535.4
Spire Missouri [Member] | Gas Utility [Member] | Operating Segments [Member]
Disaggregation of Revenue [Line Items]
Revenue	437.7	514.6
Spire Missouri [Member] | Gas Utility [Member] | Operating Segments [Member] | Residential [Member]
Disaggregation of Revenue [Line Items]
Revenue	321.8	388.8
Spire Missouri [Member] | Gas Utility [Member] | Operating Segments [Member] | Commercial and Industrial [Member]
Disaggregation of Revenue [Line Items]
Revenue	93.8	110.2
Spire Missouri [Member] | Gas Utility [Member] | Operating Segments [Member] | Transportation [Member]
Disaggregation of Revenue [Line Items]
Revenue	9.4	9
Spire Missouri [Member] | Gas Utility [Member] | Operating Segments [Member] | Off-system and Other Incentive [Member]
Disaggregation of Revenue [Line Items]
Revenue	9.9	4.1
Spire Missouri [Member] | Gas Utility [Member] | Operating Segments [Member] | Other Customer Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue	2.8	2.5
Spire Alabama Inc [Member]
Disaggregation of Revenue [Line Items]
Changes in accrued revenue under alternative revenue programs	(1.8)	(1)
Operating Revenues	120.4	142.1
Spire Alabama Inc [Member] | Gas Utility [Member] | Operating Segments [Member]
Disaggregation of Revenue [Line Items]
Revenue	122.2	143.1
Spire Alabama Inc [Member] | Gas Utility [Member] | Operating Segments [Member] | Residential [Member]
Disaggregation of Revenue [Line Items]
Revenue	72.4	84.4
Spire Alabama Inc [Member] | Gas Utility [Member] | Operating Segments [Member] | Commercial and Industrial [Member]
Disaggregation of Revenue [Line Items]
Revenue	28.9	34.7
Spire Alabama Inc [Member] | Gas Utility [Member] | Operating Segments [Member] | Transportation [Member]
Disaggregation of Revenue [Line Items]
Revenue	22.5	20.8
Spire Alabama Inc [Member] | Gas Utility [Member] | Operating Segments [Member] | Off-system and Other Incentive [Member]
Disaggregation of Revenue [Line Items]
Revenue	1.6	2.3
Spire Alabama Inc [Member] | Gas Utility [Member] | Operating Segments [Member] | Other Customer Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue	(3.2)	0.9
Spire [Member]
Disaggregation of Revenue [Line Items]
Operating Revenues	669.1	756.6
Spire [Member] | Operating Segments [Member]
Disaggregation of Revenue [Line Items]
Operating Revenues	684.7	770.5
Spire [Member] | Consolidation, Eliminations [Member]
Disaggregation of Revenue [Line Items]
Operating Revenues	(15.6)	(13.9)
Spire [Member] | Gas Utility [Member] | Operating Segments [Member]
Disaggregation of Revenue [Line Items]
Revenue	592.1	695.2
Changes in accrued revenue under alternative revenue programs	21.4	20
Total Gas Utility operating revenues	613.5	715.2
Spire [Member] | Gas Utility [Member] | Operating Segments [Member] | Residential [Member]
Disaggregation of Revenue [Line Items]
Revenue	411.5	492.8
Spire [Member] | Gas Utility [Member] | Operating Segments [Member] | Commercial and Industrial [Member]
Disaggregation of Revenue [Line Items]
Revenue	133.7	157.9
Spire [Member] | Gas Utility [Member] | Operating Segments [Member] | Transportation [Member]
Disaggregation of Revenue [Line Items]
Revenue	34.6	32.6
Spire [Member] | Gas Utility [Member] | Operating Segments [Member] | Off-system and Other Incentive [Member]
Disaggregation of Revenue [Line Items]
Revenue	11.5	6.4
Spire [Member] | Gas Utility [Member] | Operating Segments [Member] | Other Customer Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue	0.8	5.5
Spire [Member] | Gas Marketing [Member] | Operating Segments [Member]
Disaggregation of Revenue [Line Items]
Unregulated Operating Revenue	33	36.3
Spire [Member] | Midstream [Member] | Operating Segments [Member]
Disaggregation of Revenue [Line Items]
Unregulated Operating Revenue	33.5	14.9
Spire [Member] | Other Operating Segment [Member] | Operating Segments [Member]
Disaggregation of Revenue [Line Items]
Unregulated Operating Revenue	$ 4.7	$ 4.1

Revenue - Schedule of Gross Rec

Revenue - Schedule of Gross Receipts Taxes Associated Revenue (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Disaggregation of Revenue [Line Items]
Gross receipts tax amounts	$ 26.8	$ 31.1
Spire Missouri [Member]
Disaggregation of Revenue [Line Items]
Gross receipts tax amounts	19.5	22.5
Spire Alabama Inc [Member]
Disaggregation of Revenue [Line Items]
Gross receipts tax amounts	$ 5.7	$ 6.9

Earnings Per Common Share - Sch

Earnings Per Common Share - Schedule of Earnings Per Share, Basic and Diluted (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions		3 Months Ended
		Dec. 31, 2024	Dec. 31, 2023
Earnings Per Share [Abstract]
Net Income (Loss)		$ 81.3	$ 85.1
Less: Provision for preferred dividends		3.7	3.7
Income allocated to participating securities		0.1	0.1
Net Income Available to Common Shareholders		$ 77.5	$ 81.3
Weighted Average Common Shares Outstanding (in millions)		57.7	53.5
Basic Earnings Per Common Share		$ 1.34	$ 1.52
Dilutive Effect of forward sales of common stock, restricted stock and restricted stock units (in millions)	[1]	0.2	0.1
Weighted Average Diluted Common Shares (in millions)		57.9	53.6
Diluted Earnings Per Common Share		$ 1.34	$ 1.52
[1] * Calculation excludes certain outstanding or potential common shares 0.3 0.2

Earnings Per Common Share - S_2

Earnings Per Common Share - Schedule of Earnings Per Share, Basic and Diluted (Parenthetical) (Details) - shares shares in Millions	3 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Earnings Per Share [Abstract]
* Calculation excludes certain outstanding or potential common shares (shown in millions by period at the right) attributable to (1) forward sales of common stock, (2) stock units subject to performance or market conditions and (3) restricted stock, which could have a dilutive effect in the future (in shares)	0.3	0.2

Shareholders' Equity - Addition

Shareholders' Equity - Additional Information (Details) - At The Market Program [Member] - USD ($) $ in Millions		1 Months Ended	3 Months Ended	6 Months Ended
	Dec. 11, 2023	Dec. 31, 2024	Sep. 30, 2024	Jun. 30, 2024	Jan. 25, 2024
Subsidiary or Equity Method Investee [Line Items]
Forward sales agreements, shares settled (in shares)	1,744,549	542,515
Proceeds from shares settled	$ 112.2	$ 32.4
Sale of stock, maximum aggregate offering price		123.6			$ 200
Forward sales agreements, shares (in shares)			663,619	542,515
Forward sales agreements, proceeds if settled		$ 42.4

Regulatory Matters - Schedule o

Regulatory Matters - Schedule of Regulatory Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2024	Sep. 30, 2024	Dec. 31, 2023
Schedule Of Regulatory Assets and Liabilities [Line Items]
Regulatory Assets, Current	$ 89.6	$ 115.4	$ 256.4
Regulatory Assets, Noncurrent	1,288.4	1,251.8	1,266.9
Total Regulatory Assets	1,378	1,367.2	1,523.3
Regulatory Liabilities, Current	51	49.5	7.1
Regulatory Liabilities, Noncurrent	577.2	535.5	487.2
Total Regulatory Liabilities	628.2	585	494.3
Spire Missouri [Member]
Schedule Of Regulatory Assets and Liabilities [Line Items]
Regulatory Assets, Current	56.7	84	212.9
Regulatory Assets, Noncurrent	619.7	588	630.8
Total Regulatory Assets	676.4	672	843.7
Regulatory Liabilities, Current	17.4	10.2	0
Regulatory Liabilities, Noncurrent	486	443.3	404.5
Total Regulatory Liabilities	503.4	453.5	404.5
Spire Alabama Inc [Member]
Schedule Of Regulatory Assets and Liabilities [Line Items]
Regulatory Assets, Current	17.4	19.2	31
Regulatory Assets, Noncurrent	647.3	642	612.6
Total Regulatory Assets	664.7	661.2	643.6
Regulatory Liabilities, Current	27.7	33.8	0
Regulatory Liabilities, Noncurrent	26.9	28.3	20.7
Total Regulatory Liabilities	54.6	62.1	20.7
Unamortized Purchased Gas Adjustments [Member]
Schedule Of Regulatory Assets and Liabilities [Line Items]
Regulatory Assets, Current	12.2	28.9	207
Regulatory Assets, Noncurrent	0	1.2	20.3
Regulatory Liabilities, Current	39.2	42.3	0
Regulatory Liabilities, Noncurrent	40.4	17.2	23.7
Unamortized Purchased Gas Adjustments [Member] | Spire Missouri [Member]
Schedule Of Regulatory Assets and Liabilities [Line Items]
Regulatory Assets, Current	11.8	28.1	194.1
Regulatory Assets, Noncurrent	0	1.2	20.3
Regulatory Liabilities, Current	17.4	10.2	0
Regulatory Liabilities, Noncurrent	40.4	17.2	23.7
Unamortized Purchased Gas Adjustments [Member] | Spire Alabama Inc [Member]
Schedule Of Regulatory Assets and Liabilities [Line Items]
Regulatory Assets, Current	0	0	12.2
Regulatory Liabilities, Current	20.7	30.9	0
Other [Member]
Schedule Of Regulatory Assets and Liabilities [Line Items]
Regulatory Assets, Current	77.4	86.5	49.4
Regulatory Assets, Noncurrent	150.2	133.2	147.4
Regulatory Liabilities, Current	11.8	7.2	7.1
Regulatory Liabilities, Noncurrent	36.2	37.6	20.5
Other [Member] | Spire Missouri [Member]
Schedule Of Regulatory Assets and Liabilities [Line Items]
Regulatory Assets, Current	44.9	55.9	18.8
Regulatory Assets, Noncurrent	137.2	119.6	133.2
Regulatory Liabilities, Noncurrent	32.2	33.2	15.6
Other [Member] | Spire Alabama Inc [Member]
Schedule Of Regulatory Assets and Liabilities [Line Items]
Regulatory Assets, Current	17.4	19.2	18.8
Regulatory Assets, Noncurrent	0.4	0.8	1
Regulatory Liabilities, Current	7	2.9	0
Regulatory Liabilities, Noncurrent	2.7	3.2	3.4
Pension and Postretirement Benefit Costs [Member]
Schedule Of Regulatory Assets and Liabilities [Line Items]
Regulatory Assets, Noncurrent	248.4	237.5	255.3
Regulatory Liabilities, Noncurrent	253.2	232.9	188.2
Pension and Postretirement Benefit Costs [Member] | Spire Missouri [Member]
Schedule Of Regulatory Assets and Liabilities [Line Items]
Regulatory Assets, Noncurrent	179.7	166.5	185.5
Regulatory Liabilities, Noncurrent	218	196.6	160.2
Pension and Postretirement Benefit Costs [Member] | Spire Alabama Inc [Member]
Schedule Of Regulatory Assets and Liabilities [Line Items]
Regulatory Assets, Noncurrent	66.1	68.2	66
Regulatory Liabilities, Noncurrent	24.2	25.1	17.3
Cost of Removal [Member]
Schedule Of Regulatory Assets and Liabilities [Line Items]
Regulatory Assets, Noncurrent	676.1	668.2	640.8
Regulatory Liabilities, Noncurrent	136.7	133.6	130.3
Cost of Removal [Member] | Spire Missouri [Member]
Schedule Of Regulatory Assets and Liabilities [Line Items]
Regulatory Assets, Noncurrent	97	97	97
Regulatory Liabilities, Noncurrent	96.8	94.5	93.4
Cost of Removal [Member] | Spire Alabama Inc [Member]
Schedule Of Regulatory Assets and Liabilities [Line Items]
Regulatory Assets, Noncurrent	579.1	571.2	543.7
Future Income Taxes Due from Customers [Member]
Schedule Of Regulatory Assets and Liabilities [Line Items]
Regulatory Assets, Noncurrent	152.4	150.7	145.6
Future Income Taxes Due from Customers [Member] | Spire Missouri [Member]
Schedule Of Regulatory Assets and Liabilities [Line Items]
Regulatory Assets, Noncurrent	144.5	142.7	137.3
Future Income Taxes Due from Customers [Member] | Spire Alabama Inc [Member]
Schedule Of Regulatory Assets and Liabilities [Line Items]
Regulatory Assets, Noncurrent	1.7	1.8	1.9
Energy Efficiency [Member]
Schedule Of Regulatory Assets and Liabilities [Line Items]
Regulatory Assets, Noncurrent	61.3	61	57.5
Energy Efficiency [Member] | Spire Missouri [Member]
Schedule Of Regulatory Assets and Liabilities [Line Items]
Regulatory Assets, Noncurrent	61.3	61	57.5
Deferred Taxes Due to Customers [Member]
Schedule Of Regulatory Assets and Liabilities [Line Items]
Regulatory Liabilities, Noncurrent	110.7	114.2	124.5
Deferred Taxes Due to Customers [Member] | Spire Missouri [Member]
Schedule Of Regulatory Assets and Liabilities [Line Items]
Regulatory Liabilities, Noncurrent	$ 98.6	$ 101.8	$ 111.6

Regulatory Matters - Schedule_2

Regulatory Matters - Schedule of Regulatory Assets Not Earning Return (Details) - USD ($) $ in Millions	Dec. 31, 2024	Sep. 30, 2024	Dec. 31, 2023
Regulatory Asset [Line Items]
Regulatory assets not earning a return	$ 435.4	$ 440.4	$ 609
Spire Missouri [Member]
Regulatory Asset [Line Items]
Regulatory assets not earning a return	429.2	434.2	602.7
Pension and Postretirement Benefit Costs [Member]
Regulatory Asset [Line Items]
Regulatory assets not earning a return	129.8	129.7	134
Pension and Postretirement Benefit Costs [Member] | Spire Missouri [Member]
Regulatory Asset [Line Items]
Regulatory assets not earning a return	129.8	129.7	134
Future Income Taxes Due from Customers [Member]
Regulatory Asset [Line Items]
Regulatory assets not earning a return	150.7	148.9	143.6
Future Income Taxes Due from Customers [Member] | Spire Missouri [Member]
Regulatory Asset [Line Items]
Regulatory assets not earning a return	144.5	142.7	137.3
Unamortized Purchased Gas Adjustments [Member]
Regulatory Asset [Line Items]
Regulatory assets not earning a return	11.8	29.3	214.4
Unamortized Purchased Gas Adjustments [Member] | Spire Missouri [Member]
Regulatory Asset [Line Items]
Regulatory assets not earning a return	11.8	29.3	214.4
Other [Member]
Regulatory Asset [Line Items]
Regulatory assets not earning a return	143.1	132.5	117
Other [Member] | Spire Missouri [Member]
Regulatory Asset [Line Items]
Regulatory assets not earning a return	$ 143.1	$ 132.5	$ 117

Regulatory Matters - Additional

Regulatory Matters - Additional Information (Details) - USD ($) $ in Millions

1 Months Ended

3 Months Ended

26 Months Ended

Jan. 17, 2025

Jan. 01, 2025

Dec. 04, 2024

Dec. 01, 2024

Nov. 25, 2024

Jan. 01, 2024

Dec. 13, 2023

Dec. 01, 2023

Aug. 31, 2024

Dec. 31, 2024

Nov. 25, 2024

Nov. 15, 2024

Spire Alabama Inc [Member] | Alabama Public Service Commission [Member]

Public Utilities, General Disclosures [Line Items]

Public utilities, approved rate, increase (decrease) annualized revenue

$ (4)

$ 14.3

$ (4.1)

Spire Gulf [Member]

Public Utilities, General Disclosures [Line Items]

Public utilities, approved rate, increase (decrease) annualized revenue

$ 1.3

$ 2.7

$ (2)

Spire Mississippi [Member] | Missouri Public Service Commission [Member]

Public Utilities, General Disclosures [Line Items]

Public utilities, approved rate, increase (decrease) annualized revenue

$ 1

Spire Mississippi [Member] | Missouri Public Service Commission [Member] | Subsequent Event [Member]

Public Utilities, General Disclosures [Line Items]

Public utilities, approved rate, increase (decrease) annualized revenue

$ 0.6

Spire Missouri [Member]

Public Utilities, General Disclosures [Line Items]

Regulatory asset, percentage change of tariff

30%

Public utilities, request rate increase (decrease), amount

$ 235.9

Public utility rate base amount

$ 4,386

Public utility, rate base, percentage change

32%

Public utilities, requested equity, percentage

55%

Public utilities, requested return on equity, percentage

10.50%

Public utilities, requested rate increase (decrease), amount

$ 289.5

Spire Missouri [Member] | Infrastructure System Replacement Surcharge [Member]

Public Utilities, General Disclosures [Line Items]

Public utilities, approved rate increase (decrease), amount

$ 53.6

Spire Missouri [Member] | Infrastructure System Replacement Surcharge [Member] | Subsequent Event [Member]

Public Utilities, General Disclosures [Line Items]

Public utilities, requested rate increase (decrease), amount

$ 19

Future Income Taxes Due From Customers and Pension and Other Postretirement Benefit Costs [Member]

Public Utilities, General Disclosures [Line Items]

Remaining recovery period of regulatory assets for which no return on investment during recovery period is provided (Year)

20 years

PGA Assets [Member]

Public Utilities, General Disclosures [Line Items]

Remaining recovery period of regulatory assets for which no return on investment during recovery period is provided (Year)

1 year

PGA Assets Not Earning a Return [Member]

Public Utilities, General Disclosures [Line Items]

Remaining recovery period of regulatory assets for which no return on investment during recovery period is provided (Year)

15 years

Financing - Additional Informat

Financing - Additional Information (Details) - USD ($)	May 06, 2024	Apr. 05, 2024	Jan. 03, 2024	Dec. 31, 2024	Sep. 30, 2024	Dec. 31, 2023
Short-Term Debt [Line Items]
Notes outstanding				$ 1,158,000,000	$ 947,000,000	$ 1,047,500,000
Commercial Paper [Member] | Parent Company [Member]
Short-Term Debt [Line Items]
Notes outstanding				1,158,000,000	$ 947,000,000	$ 1,047,500,000
Short term borrowings used to support lending to utilities				687,700,000
Maximum [Member] | Commercial Paper [Member]
Short-Term Debt [Line Items]
Notes outstanding				1,500,000,000
Spire Missouri [Member] | Loans Payable [Member]
Short-Term Debt [Line Items]
Debt Instrument face amount			$ 200,000,000
Repayments of Debt	$ 150,000,000	$ 50,000,000
Spire Missouri [Member] | Loans Payable [Member] | SOFR [Member]
Short-Term Debt [Line Items]
Debt instrument basis spread on variable rate			0.10%
Spire Missouri [Member] | Loans Payable [Member] | Adjusted SOFR [Member[
Short-Term Debt [Line Items]
Debt instrument basis spread on variable rate			0.90%
Revolving Credit Facility [Member]
Short-Term Debt [Line Items]
Line of credit facility maximum borrowing capacity				$ 1,500,000,000
Line of credit facility covenant percentage of total capitalization				65%
Long-term line of credit				$ 0
Revolving Credit Facility [Member] | Maximum [Member]
Short-Term Debt [Line Items]
Line of credit facility covenant percentage of total capitalization				70%
Revolving Credit Facility [Member] | Spire [Member]
Short-Term Debt [Line Items]
Line of credit facility maximum borrowing capacity				$ 525,000,000
Revolving Credit Facility [Member] | Spire Missouri [Member]
Short-Term Debt [Line Items]
Line of credit facility maximum borrowing capacity				700,000,000
Revolving Credit Facility [Member] | Spire Alabama Inc [Member]
Short-Term Debt [Line Items]
Line of credit facility maximum borrowing capacity				$ 275,000,000

Financing - Schedule of Short-t

Financing - Schedule of Short-term Borrowings (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2024	Sep. 30, 2024	Dec. 31, 2023
Short-Term Debt [Line Items]
Highest borrowings outstanding	$ 1,198
Lowest borrowings outstanding	943.5
Weighted average borrowings	$ 1,087.8
Weighted average interest rate	4.60%
Borrowings outstanding	$ 1,158	$ 947	$ 1,047.5
Weighted average interest rate	4.40%	5.20%	5.70%
Term Loan [Member] | Spire Missouri [Member]
Short-Term Debt [Line Items]
Highest borrowings outstanding	$ 0
Lowest borrowings outstanding	0
Weighted average borrowings	$ 0
Weighted average interest rate	0%
Borrowings outstanding	$ 0	$ 0	$ 0
Weighted average interest rate	0%	0%	0%
Spire Note [Member] | Spire Missouri [Member]
Short-Term Debt [Line Items]
Highest borrowings outstanding	$ 599
Lowest borrowings outstanding	487.8
Weighted average borrowings	$ 545.3
Weighted average interest rate	4.90%
Borrowings outstanding	$ 580.9	$ 495.3	$ 633.3
Weighted average interest rate	4.80%	5.20%	5.70%
Spire Note [Member] | Spire Alabama Inc [Member]
Short-Term Debt [Line Items]
Highest borrowings outstanding	$ 73.2
Lowest borrowings outstanding	43
Weighted average borrowings	$ 58
Weighted average interest rate	4.90%
Borrowings outstanding	$ 67	$ 48.4	$ 128.5
Weighted average interest rate	4.80%	5.20%	5.70%
Parent Company [Member] | Commercial Paper [Member]
Short-Term Debt [Line Items]
Highest borrowings outstanding	$ 1,198
Lowest borrowings outstanding	943.5
Weighted average borrowings	$ 1,087.8
Weighted average interest rate	4.60%
Borrowings outstanding	$ 1,158	$ 947	$ 1,047.5
Weighted average interest rate	4.40%	5.20%	5.70%

Financing - Summary of Capitali

Financing - Summary of Capitalized Interest Expense (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Debt Instrument [Line Items]
Interest Costs Capitalized	$ 6.3	$ 3.8
Spire Missouri [Member]
Debt Instrument [Line Items]
Interest Costs Capitalized	1.2	1.2
Spire Alabama Inc [Member]
Debt Instrument [Line Items]
Interest Costs Capitalized	$ 0.8	$ 0.4

Fair Value of Financial Instr_3

Fair Value of Financial Instruments - Schedule of Estimated Fair Value of Financial Instruments Not Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Millions	Dec. 31, 2024	Sep. 30, 2024	Dec. 31, 2023
Reported Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	$ 11.5	$ 4.5	$ 4.8
Notes payable	1,158	947	1,047.5
Long-term debt, including current portion	3,740.2	3,746.4	3,704.8
Reported Value Measurement [Member] | Spire Missouri [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, including current portion	1,803.6	1,803.4	1,785.8
Notes payable – associated companies	580.9	495.3	633.3
Reported Value Measurement [Member] | Spire Alabama Inc [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	67	1.5
Long-term debt, including current portion	746.4	746.3	746
Notes payable – associated companies		48.4	128.5
Estimate of Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	11.5	4.5	4.8
Notes payable	1,158	947	1,047.5
Long-term debt, including current portion	3,435.3	3,600.3	3,481.5
Estimate of Fair Value Measurement [Member] | Spire Missouri [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, including current portion	1,646.3	1,736.9	1,689.5
Notes payable – associated companies	580.9	495.3	633.3
Estimate of Fair Value Measurement [Member] | Spire Alabama Inc [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	67	1.5
Long-term debt, including current portion	677.4	711.8	701.7
Notes payable – associated companies		48.4	128.5
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	11.5	4.5	4.8
Notes payable	0	0	0
Long-term debt, including current portion	0	0	0
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member] | Spire Missouri [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, including current portion	0	0	0
Notes payable – associated companies	0	0	0
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member] | Spire Alabama Inc [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	0	1.5
Long-term debt, including current portion	0	0	0
Notes payable – associated companies		0	0
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	0	0	0
Notes payable	1,158	947	1,047.5
Long-term debt, including current portion	3,435.3	3,600.3	3,481.5
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Spire Missouri [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, including current portion	1,646.3	1,736.9	1,689.5
Notes payable – associated companies	580.9	495.3	633.3
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Spire Alabama Inc [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	67	0
Long-term debt, including current portion	$ 677.4	711.8	701.7
Notes payable – associated companies		$ 48.4	$ 128.5

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Derivative Assets and Liabilities, Including Receivables and Payables (Details) - Fair Value, Recurring [Member] - USD ($) $ in Millions	Dec. 31, 2024	Sep. 30, 2024	Dec. 31, 2023
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Effects of netting, asset	$ (15.9)	$ (13.9)	$ (19.3)
Derivative Assets	126.1	113.3	126.4
Effects of netting, liability	(23.1)	(25)	(95.2)
Derivative Liabilities	27.9	32.3	25.1
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset fair value gross asset	81.8	80.4	77.5
Derivative liability fair value gross liability	21.9	31.3	93.4
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset fair value gross asset	60.2	46.8	68.2
Derivative liability fair value gross liability	29.1	26	26.9
U S Stock And Bond Mutual Funds [Member] | Gas Utility [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Effects of netting, asset	0	0	0
Derivative Assets	24.7	24.3	22
U S Stock And Bond Mutual Funds [Member] | Other Operating Segment [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Effects of netting, asset	0	0	0
Derivative Assets	20.8	17.9	14.6
U S Stock And Bond Mutual Funds [Member] | Fair Value, Inputs, Level 1 [Member] | Gas Utility [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset fair value gross asset	24.7	24.3	22
U S Stock And Bond Mutual Funds [Member] | Fair Value, Inputs, Level 1 [Member] | Other Operating Segment [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset fair value gross asset	20.8	17.9	14.6
U S Stock And Bond Mutual Funds [Member] | Fair Value, Inputs, Level 2 [Member] | Gas Utility [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset fair value gross asset	0	0	0
U S Stock And Bond Mutual Funds [Member] | Fair Value, Inputs, Level 2 [Member] | Other Operating Segment [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset fair value gross asset	0	0	0
N Y M E X And I C E Natural Gas Contracts [Member] | Gas Utility [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Effects of netting, asset	(5.9)	(3.4)	(4.7)
Derivative Assets	0	0	0
Effects of netting, liability	(6.8)	(3.8)	(60.7)
Derivative Liabilities	0	9.8	0
N Y M E X And I C E Natural Gas Contracts [Member] | Gas Marketing [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Effects of netting, asset	(8.8)	(7)	(13.2)
Derivative Assets	0	0	0
Effects of netting, liability	(15.1)	(17.7)	(32.7)
Derivative Liabilities	0	0	0
N Y M E X And I C E Natural Gas Contracts [Member] | Fair Value, Inputs, Level 1 [Member] | Gas Utility [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset fair value gross asset	5.9	3.4	4.7
Derivative liability fair value gross liability	6.8	13.6	60.7
N Y M E X And I C E Natural Gas Contracts [Member] | Fair Value, Inputs, Level 1 [Member] | Gas Marketing [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset fair value gross asset	8.8	7	13.2
Derivative liability fair value gross liability	15.1	17.7	32.7
N Y M E X And I C E Natural Gas Contracts [Member] | Fair Value, Inputs, Level 2 [Member] | Gas Utility [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset fair value gross asset	0	0	0
Derivative liability fair value gross liability	0	0	0
N Y M E X And I C E Natural Gas Contracts [Member] | Fair Value, Inputs, Level 2 [Member] | Gas Marketing [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset fair value gross asset	0	0	0
Derivative liability fair value gross liability	0	0	0
Gasoline And Heating Oil Contracts [Member] | Gas Utility [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Effects of netting, liability			(0.4)
Derivative Liabilities			0
Gasoline And Heating Oil Contracts [Member] | Fair Value, Inputs, Level 1 [Member] | Gas Utility [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability fair value gross liability			0
Gasoline And Heating Oil Contracts [Member] | Fair Value, Inputs, Level 2 [Member] | Gas Utility [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability fair value gross liability			0.4
Natural Gas Commodity Contracts [Member] | Gas Marketing [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Effects of netting, asset	(1.2)	(3.5)	(1.4)
Derivative Assets	42.9	42.5	44.1
Effects of netting, liability	(1.2)	(3.5)	(1.4)
Derivative Liabilities	27.9	21	23.1
Natural Gas Commodity Contracts [Member] | Fair Value, Inputs, Level 1 [Member] | Gas Marketing [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset fair value gross asset	0	0	0
Derivative liability fair value gross liability	0	0	0
Natural Gas Commodity Contracts [Member] | Fair Value, Inputs, Level 2 [Member] | Gas Marketing [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset fair value gross asset	44.1	46	45.5
Derivative liability fair value gross liability	29.1	24.5	24.5
U.S. Bonds [Member] | Other Operating Segment [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Effects of netting, asset	0	0	0
Derivative Assets	15.6	21.9	21.6
U.S. Bonds [Member] | Fair Value, Inputs, Level 1 [Member] | Other Operating Segment [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset fair value gross asset	15.6	21.9	21.6
U.S. Bonds [Member] | Fair Value, Inputs, Level 2 [Member] | Other Operating Segment [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset fair value gross asset	0	0	0
Global Bonds [Member] | Other Operating Segment [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Effects of netting, asset	0	0	0
Derivative Assets	6	5.9	1.4
Global Bonds [Member] | Fair Value, Inputs, Level 1 [Member] | Other Operating Segment [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset fair value gross asset	6	5.9	1.4
Global Bonds [Member] | Fair Value, Inputs, Level 2 [Member] | Other Operating Segment [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset fair value gross asset	0	0	0
Interest Rate Swap [Member] | Gas Marketing [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Effects of netting, liability		0
Derivative Liabilities		1.5
Interest Rate Swap [Member] | Other Operating Segment [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Effects of netting, asset	0	0	0
Derivative Assets	16.1	0.8	22.7
Effects of netting, liability			0
Derivative Liabilities			2
Interest Rate Swap [Member] | Fair Value, Inputs, Level 1 [Member] | Gas Marketing [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability fair value gross liability		0
Interest Rate Swap [Member] | Fair Value, Inputs, Level 1 [Member] | Other Operating Segment [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset fair value gross asset	0	0	0
Derivative liability fair value gross liability			0
Interest Rate Swap [Member] | Fair Value, Inputs, Level 2 [Member] | Gas Marketing [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability fair value gross liability		1.5
Interest Rate Swap [Member] | Fair Value, Inputs, Level 2 [Member] | Other Operating Segment [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset fair value gross asset	16.1	0.8	22.7
Derivative liability fair value gross liability			2
Spire Missouri [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Effects of netting, asset	(5.9)	(3.4)	(4.7)
Derivative Assets	24.7	24.3	22
Effects of netting, liability			(61.1)
Derivative Liabilities			0
Spire Missouri [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset fair value gross asset	30.6	27.7	26.7
Derivative liability fair value gross liability			60.7
Spire Missouri [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset fair value gross asset	0	0	0
Derivative liability fair value gross liability			0.4
Spire Missouri [Member] | U S Stock And Bond Mutual Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Effects of netting, asset	0	0	0
Derivative Assets	24.7	24.3	22
Spire Missouri [Member] | U S Stock And Bond Mutual Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset fair value gross asset	24.7	24.3	22
Spire Missouri [Member] | U S Stock And Bond Mutual Funds [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset fair value gross asset	0	0	0
Spire Missouri [Member] | N Y M E X And I C E Natural Gas Contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Effects of netting, asset	(5.9)	(3.4)	(4.7)
Derivative Assets	0	0	0
Effects of netting, liability	(6.8)	(3.8)	(60.7)
Derivative Liabilities	0	9.8	0
Spire Missouri [Member] | N Y M E X And I C E Natural Gas Contracts [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset fair value gross asset	5.9	3.4	4.7
Derivative liability fair value gross liability	6.8	13.6	60.7
Spire Missouri [Member] | N Y M E X And I C E Natural Gas Contracts [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset fair value gross asset	0	0	0
Derivative liability fair value gross liability	$ 0	$ 0	0
Spire Missouri [Member] | Gasoline And Heating Oil Contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Effects of netting, liability			(0.4)
Derivative Liabilities			0
Spire Missouri [Member] | Gasoline And Heating Oil Contracts [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability fair value gross liability			0
Spire Missouri [Member] | Gasoline And Heating Oil Contracts [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability fair value gross liability			$ 0.4

Pension Plans and Other Postr_3

Pension Plans and Other Postretirement Benefits - Additional Information (Details)	3 Months Ended
	Dec. 31, 2024 USD ($)
Spire Missouri [Member] | Pension Plan [Member] | Qualified Plan [Member]
Defined benefit plan, plan assets, contributions by employer	$ 22,300,000
Anticipated contributions to pension plans qualified trusts	13,200,000
Spire Missouri [Member] | Pension Plan [Member] | Nonqualified Plan [Member]
Defined benefit plan, plan assets, contributions by employer	0
Spire Missouri [Member] | Other Postretirement Benefits Plan [Member]
Defined benefit plan, plan assets, contributions by employer	0
Anticipated contributions to pension plans qualified trusts	0
Spire Alabama Inc [Member] | Pension Plan [Member]
Defined benefit plan, plan assets, contributions by employer	2,600,000
Anticipated contributions to pension plans qualified trusts	11,900,000
Spire Alabama Inc [Member] | Other Postretirement Benefits Plan [Member]
Defined benefit plan, plan assets, contributions by employer	0
Anticipated contributions to pension plans qualified trusts	$ 0

Pension Plans and Other Postr_4

Pension Plans and Other Postretirement Benefits - Net Pension Costs (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Pension Plan [Member]
Service cost – benefits earned during the period	$ 4.5	$ 4
Interest cost on projected benefit obligation	6	6.8
Expected return on plan assets	(6.5)	(6.3)
Amortization of prior service credit	(1.1)	(1.1)
Amortization of actuarial gain (loss)	1.6	1.6
Subtotal	4.5	5
Regulatory adjustment	8.9	8.7
Net pension cost	13.4	13.7
Pension Plan [Member] | Spire Missouri [Member]
Service cost – benefits earned during the period	2.9	2.6
Interest cost on projected benefit obligation	4	4.8
Expected return on plan assets	(4.5)	(4.3)
Amortization of prior service credit	(0.5)	(0.5)
Amortization of actuarial gain (loss)	1	1.5
Subtotal	2.9	4.1
Regulatory adjustment	7.4	6.3
Net pension cost	10.3	10.4
Pension Plan [Member] | Spire Alabama Inc [Member]
Service cost – benefits earned during the period	1.4	1.2
Interest cost on projected benefit obligation	1.3	1.3
Expected return on plan assets	(1.3)	(1.2)
Amortization of prior service credit	(0.6)	(0.6)
Amortization of actuarial gain (loss)	0.6	0.2
Subtotal	1.4	0.9
Regulatory adjustment	1.3	2.2
Net pension cost	2.7	3.1
Other Postretirement Benefits Plan [Member]
Service cost – benefits earned during the period	1.1	1.1
Interest cost on projected benefit obligation	1.8	2.1
Expected return on plan assets	(4.2)	(4)
Amortization of prior service credit	0	0.1
Amortization of actuarial gain (loss)	(1.5)	(1)
Subtotal	(2.8)	(1.7)
Regulatory adjustment	1.1	0.2
Net pension cost	(1.7)	(1.5)
Other Postretirement Benefits Plan [Member] | Spire Missouri [Member]
Service cost – benefits earned during the period	0.9	0.9
Interest cost on projected benefit obligation	1.3	1.6
Expected return on plan assets	(2.8)	(2.7)
Amortization of prior service credit	0.1	0.2
Amortization of actuarial gain (loss)	(1.3)	(0.9)
Subtotal	(1.8)	(0.9)
Regulatory adjustment	1.6	0.6
Net pension cost	(0.2)	(0.3)
Other Postretirement Benefits Plan [Member] | Spire Alabama Inc [Member]
Service cost – benefits earned during the period	0.2	0.2
Interest cost on projected benefit obligation	0.5	0.5
Expected return on plan assets	(1.3)	(1.3)
Amortization of prior service credit	(0.1)	(0.1)
Subtotal	(0.7)	(0.7)
Regulatory adjustment	(0.5)	(0.4)
Net pension cost	$ (1.2)	$ (1.1)

Information by Operating Segm_3

Information by Operating Segment - Additional Information (Details)	3 Months Ended
	Dec. 31, 2024 Segment
Segment Reporting [Abstract]
Number of reportable segments	3

Information by Operating Segm_4

Information by Operating Segment - Segment Information by Segment (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Segment Reporting Information [Line Items]
Revenues from external customers	$ 669.1	$ 756.6
Intersegment revenues	0	0
Total Operating Revenues	669.1	756.6
Depreciation and amortization expense	72.3	67
Interest expense	48	50.6
Income tax expense (benefit)	20.1	21
Adjusted earnings (loss)	81.1	82.7
Capital expenditures	260.6	226.5
Other Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenues from external customers	0.3	0.1
Intersegment revenues	4.4	4
Total Operating Revenues	4.7	4.1
Depreciation and amortization expense	0.1	0.1
Interest expense	24.8	24
Income tax expense (benefit)	(0.6)	0.9
Adjusted earnings (loss)	(10.9)	(2.7)
Capital expenditures	0	0
Operating Segments [Member] | Gas Utility [Member]
Segment Reporting Information [Line Items]
Revenues from external customers	613.5	715.2
Intersegment revenues	0	0
Total Operating Revenues	613.5	715.2
Depreciation and amortization expense	68.1	64.2
Interest expense	35.1	39
Income tax expense (benefit)	16.1	15.7
Adjusted earnings (loss)	77.8	75.8
Capital expenditures	217.9	174.9
Operating Segments [Member] | Gas Marketing [Member]
Segment Reporting Information [Line Items]
Revenues from external customers	33	36.3
Intersegment revenues	0	0
Total Operating Revenues	33	36.3
Depreciation and amortization expense	0.4	0.4
Interest expense	0	0
Income tax expense (benefit)	0.8	3.8
Adjusted earnings (loss)	2.2	7.2
Capital expenditures	0.1	0
Operating Segments [Member] | Midstream [Member]
Segment Reporting Information [Line Items]
Revenues from external customers	22.3	5
Intersegment revenues	11.2	9.9
Total Operating Revenues	33.5	14.9
Depreciation and amortization expense	3.7	2.3
Interest expense	1.2	1.8
Income tax expense (benefit)	3.8	0.6
Adjusted earnings (loss)	12	2.4
Capital expenditures	42.7	52
Consolidation, Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues from external customers	0	0
Intersegment revenues	(15.6)	(13.9)
Total Operating Revenues	(15.6)	(13.9)
Depreciation and amortization expense	0	0
Interest expense	(13.1)	(14.2)
Income tax expense (benefit)	0	0
Adjusted earnings (loss)	0	0
Capital expenditures	$ (0.1)	$ (0.4)

Information by Operating Segm_5

Information by Operating Segment - Reconciliation of Adjusted Earnings (Loss) to Net Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Segment Reconciliation [Abstract]
Net Income	$ 81.3	$ 85.1
Fair value and timing adjustments	(0.3)	(5.2)
Acquisition and restructuring activities	0	1.9
Income tax adjustments	0.1	0.9
Adjusted Earnings	$ 81.1	$ 82.7

Information by Operating Segm_6

Information by Operating Segment - Total Assets by Segment (Details) - USD ($) $ in Millions	Dec. 31, 2024	Sep. 30, 2024	Dec. 31, 2023
Segment Reporting Information [Line Items]
Total Assets	$ 11,275.8	$ 10,860.7	$ 10,631.7
Operating Segments [Member] | Gas Utility [Member]
Segment Reporting Information [Line Items]
Total Assets	9,075.2	8,767.2	8,736.7
Operating Segments [Member] | Gas Marketing [Member]
Segment Reporting Information [Line Items]
Total Assets	246.1	206.1	207
Operating Segments [Member] | Midstream [Member]
Segment Reporting Information [Line Items]
Total Assets	936	903.4	633.9
Operating Segments [Member] | Other Operating Segment [Member]
Segment Reporting Information [Line Items]
Total Assets	2,872.8	2,689.8	2,755.1
Consolidation, Eliminations [Member]
Segment Reporting Information [Line Items]
Total Assets	$ (1,854.3)	$ (1,705.8)	$ (1,701)

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) $ in Millions	3 Months Ended
	Dec. 31, 2024 USD ($)
Long-Term Purchase Commitment [Line Items]
Long-term purchase commitment, amount	$ 1,576
Capital committed to contribute to partnership	25.3
Remaining unfunded capital commitment	16.3
Spire Missouri [Member]
Long-Term Purchase Commitment [Line Items]
Long-term purchase commitment, amount	1,575.3
Spire Alabama Inc [Member]
Long-Term Purchase Commitment [Line Items]
Long-term purchase commitment, amount	$ 309.9