Spire (SR) 10-Q 8 May 20 2020 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Mar. 31, 2020	May 05, 2020
Entity Information [Line Items]
Entity Registrant Name	Spire Inc
Entity Central Index Key	0001126956
Current Fiscal Year End Date	--09-30
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 Common Stock, Shares Outstanding (in shares)		51,235,146
Document Period End Date	Mar. 31, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q2
Document Type	10-Q
Amendment Flag	false
Entity Shell Company	false
Entity File Number	1-16681
Entity Tax Identification Number	74-2976504
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
Document Quarterly Report	true
Document Transition Report	false
Spire Missouri Inc
Entity Information [Line Items]
Entity Registrant Name	Spire Missouri Inc
Entity Central Index Key	0000057183
Current Fiscal Year End Date	--09-30
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 Common Stock, Shares Outstanding (in shares)		24,577
Document Period End Date	Mar. 31, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q2
Document Type	10-Q
Amendment Flag	false
Entity Shell Company	false
Entity File Number	1-1822
Entity Tax Identification Number	43-0368139
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
Spire Alabama Inc
Entity Information [Line Items]
Entity Registrant Name	Spire Alabama Inc
Entity Central Index Key	0000003146
Current Fiscal Year End Date	--09-30
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 Common Stock, Shares Outstanding (in shares)		1,972,052
Document Period End Date	Mar. 31, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q2
Document Type	10-Q
Amendment Flag	false
Entity Shell Company	false
Entity File Number	2-38960
Entity Tax Identification Number	63-0022000
Entity Address, Address Line One	2101 6th Avenue North
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
Common Stock $1.00 par value
Entity Information [Line Items]
Trading Symbol	SR
Title of each class	Common Stock $1.00 par value
Name of each exchange on which registered	NYSE
Depositary Shares, each representing a 1/1,000th interest in a share of 5.90% Series A Cumulative Redeemable Perpetual Preferred Stock, par value $25.00 per share
Entity Information [Line Items]
Trading Symbol	SR.PRA
Title of each class	Depositary Shares
Name of each exchange on which registered	NYSE

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF INCOME (UNAUDITED) - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Operating Revenues:
Gas Utility	$ 679.1	$ 776.7	$ 1,209.7	$ 1,350.5
Gas Marketing and other	36.4	26.8	72.7	55
Total Operating Revenues	715.5	803.5	1,282.4	1,405.5
Gas Utility
Natural and propane gas	249	337.4	463.6	589.1
Other operation and maintenance expenses	93.1	109.5	199.1	212
Depreciation and amortization	47	44.4	93.4	88.1
Taxes, other than income taxes	51.7	57.4	89.6	96.6
Total Gas Utility Operating Expenses	440.8	548.7	845.7	985.8
Gas Marketing and other	64.2	45.3	123.9	105.1
Total Operating Expenses	505	594	969.6	1,090.9
Operating Income	210.5	209.5	312.8	314.6
Interest Expense, Net	27.2	27.6	53.9	53.5
Other (Expense) Income, Net	(19.5)	6.1	(13.8)	8.9
Income Before Income Taxes	163.8	188	245.1	270
Income Tax Expense	30.2	33.4	44.5	48.1
Net Income	133.6	154.6	200.6	221.9
Provision for preferred dividends	3.7		7.4
Income allocated to participating securities	0.2	0.3	0.3	0.5
Net Income Available to Common Shareholders	$ 129.7	$ 154.3	$ 192.9	$ 221.4
Weighted Average Number of Common Shares Outstanding:
Basic	51	50.6	51	50.6
Diluted	51.1	50.8	51.1	50.8
Basic Earnings Per Common Share	$ 2.55	$ 3.05	$ 3.78	$ 4.37
Diluted Earnings Per Common Share	$ 2.54	$ 3.04	$ 3.77	$ 4.36
Spire Alabama
Operating Revenues:
Gas Utility	$ 185.5	$ 180.4	$ 311.7	$ 313.9
Total Operating Revenues	185.5	180.4	311.7	313.9
Gas Utility
Natural and propane gas	39.4	41.1	86.4	100.6
Other operation and maintenance expenses	37.1	33.4	72.3	67.8
Depreciation and amortization	14.6	13.7	28.9	27.3
Taxes, other than income taxes	13.2	12.6	22	21.5
Total Operating Expenses	104.3	100.8	209.6	217.2
Operating Income	81.2	79.6	102.1	96.7
Interest Expense, Net	5.3	5.4	10.7	10.5
Other (Expense) Income, Net	1.2	1.5	3.4	3.3
Income Before Income Taxes	77.1	75.7	94.8	89.5
Income Tax Expense	19.3	19	23.8	22.5
Net Income	$ 57.8	$ 56.7	$ 71	$ 67

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (UNAUDITED) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Net Income	$ 133.6	$ 154.6	$ 200.6	$ 221.9
Cash flow hedging derivative instruments:
Net hedging loss arising during the period	(41.1)	(7.7)	(22.2)	(18.1)
Amounts reclassified into net income	(2.2)	(0.4)	(2.5)	(0.7)
Net loss on cash flow hedging derivative instruments	(43.3)	(8.1)	(24.7)	(18.8)
Net (loss) gain on defined benefit pension and other postretirement plans	(0.1)	0.1	(0.1)	0.1
Net unrealized gain on available for sale securities		0.1		0.1
Other Comprehensive Loss, Before Tax	(43.4)	(7.9)	(24.8)	(18.6)
Income Tax Benefit Related to Items of Other Comprehensive Income (Loss)	(9.7)	(1.9)	(5.5)	(4.4)
Other Comprehensive Loss, Net of Tax	(33.7)	(6)	(19.3)	(14.2)
Comprehensive Income	99.9	148.6	181.3	207.7
Operating Revenues:
Gas Utility	679.1	776.7	1,209.7	1,350.5
Total Operating Revenues	715.5	803.5	1,282.4	1,405.5
Gas Utility
Natural and propane gas	249	337.4	463.6	589.1
Other operation and maintenance expenses	93.1	109.5	199.1	212
Depreciation and amortization	47	44.4	93.4	88.1
Taxes, other than income taxes	51.7	57.4	89.6	96.6
Total Operating Expenses	505	594	969.6	1,090.9
Operating Income	210.5	209.5	312.8	314.6
Interest Expense, Net	27.2	27.6	53.9	53.5
Other (Expense) Income, Net	(19.5)	6.1	(13.8)	8.9
Income Before Income Taxes	163.8	188	245.1	270
Income Tax Expense	30.2	33.4	44.5	48.1
Net Income	133.6	154.6	200.6	221.9
Other Comprehensive Loss, Net of Tax	(33.7)	(6)	(19.3)	(14.2)
Comprehensive Income	99.9	148.6	181.3	207.7
Spire Missouri
Net Income	74.5	80	122.5	131.2
Cash flow hedging derivative instruments:
Other Comprehensive Loss, Net of Tax	(0.2)		(0.1)
Comprehensive Income	74.3	80	122.4	131.2
Operating Revenues:
Gas Utility	457.5	556.6	831.5	969.8
Total Operating Revenues	457.5	556.6	831.5	969.8
Gas Utility
Natural and propane gas	223.6	313.8	409.4	537.2
Other operation and maintenance expenses	50.8	70.7	116.3	133.8
Depreciation and amortization	29.3	27.8	58.3	55
Taxes, other than income taxes	36.1	41.9	62.8	70
Total Operating Expenses	339.8	454.2	646.8	796
Operating Income	117.7	102.4	184.7	173.8
Interest Expense, Net	12.7	13.2	25.9	25.3
Other (Expense) Income, Net	(20.9)	2.5	(19.9)	1.8
Income Before Income Taxes	84.1	91.7	138.9	150.3
Income Tax Expense	9.6	11.7	16.4	19.1
Net Income	74.5	80	122.5	131.2
Other Comprehensive Loss, Net of Tax	(0.2)		(0.1)
Comprehensive Income	$ 74.3	$ 80	$ 122.4	$ 131.2

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED) - USD ($) $ in Millions	Mar. 31, 2020	Sep. 30, 2019	Mar. 31, 2019
ASSETS
Utility Plant	$ 6,369.4	$ 6,146.5	$ 5,856.8
Less: Accumulated depreciation and amortization	1,848.4	1,794.5	1,738.5
Net Utility Plant	4,521	4,352	4,118.3
Non-utility Property (net of accumulated depreciation and amortization of $17.5, $12.7 and $11.9 at March 31, 2020, September 30, 2019, and March 31, 2019, respectively)	547.4	477.8	329.1
Other Investments	68.1	72.3	68.4
Total Other Property and Investments	615.5	550.1	397.5
Current Assets:
Cash and cash equivalents	108.4	5.8	11.1
Accounts receivable:
Utility	248.2	139.8	318.6
Other	132.8	172.8	196.5
Allowance for doubtful accounts	(28)	(23)	(28.1)
Delayed customer billings	16.9	4.3	43.8
Inventories:
Natural gas	90.3	162.6	91.3
Propane gas	10.7	10.7	10.7
Materials and supplies	26.1	23.3	24.3
Regulatory assets	68	78.6	75.3
Prepayments	27.9	29.1	21
Other	17.5	10.5	29.1
Total Current Assets	718.8	614.5	793.6
Deferred Charges and Other Assets:
Goodwill	1,171.6	1,171.6	1,171.6
Regulatory assets	770.7	767.6	659.9
Other	220.4	163.4	132.7
Total Deferred Charges and Other Assets	2,162.7	2,102.6	1,964.2
Total Assets	8,018	7,619.2	7,273.6
Capitalization:
Preferred stock ($25.00 par value per share; 10.0 million depositary shares authorized, issued and outstanding at March 31, 2020 and September 30, 2019)	242	242	0
Common stock (par value $1.00 per share; 70.0 million shares authorized; 51.2 million, 51.0 million, and 50.7 million shares issued and outstanding at March 31, 2020, September 30, 2019, and March 31, 2019, respectively)	51.2	51	50.7
Paid-in capital and common stock	1,520.7	1,505.8	1,485.6
Retained earnings	902.3	775.5	877.5
Accumulated other comprehensive loss	(50.6)	(31.3)	(7.8)
Total Shareholders' Equity	2,665.6	2,543	2,406
Temporary equity	3.9	3.4	0
Long-term debt (less current portion)	2,484.8	2,082.6	2,041.9
Total Capitalization	5,154.3	4,629	4,447.9
Current Liabilities:
Current portion of long-term debt	5.4	40	215
Notes payable	560.6	743.2	512
Accounts payable	221.4	301.5	324.8
Advance customer billings	11.6	32.6	6.5
Wages and compensation accrued	34	45.7	32.2
Customer deposits	35.9	35.6	36.7
Taxes accrued	55.1	68.5	50.9
Regulatory liabilities	31.8	60.8	35.3
Other	196.7	140.9	123.3
Total Current Liabilities	1,152.5	1,468.8	1,336.7
Deferred Credits and Other Liabilities:
Deferred income taxes	498.1	451.4	490.2
Pension and postretirement benefit costs	272.1	264.8	178.3
Asset retirement obligations	344.7	337.6	325.5
Regulatory liabilities	472.3	399	431.3
Other	124	68.6	63.7
Total Deferred Credits and Other Liabilities	1,711.2	1,521.4	1,489
Commitments and Contingencies (Note 10)
Total Capitalization and Liabilities	8,018	7,619.2	7,273.6
Spire Missouri
ASSETS
Utility Plant	3,790.8	3,643.2	3,460.1
Less: Accumulated depreciation and amortization	795.2	764.1	736.7
Net Utility Plant	2,995.6	2,879.1	2,723.4
Other Investments	53.5	53.3	52.8
Current Assets:
Cash and cash equivalents	5.1	2.6	6.9
Accounts receivable:
Utility	169.2	94.6	231.8
Associated companies	3.7	1.4	2.4
Other	22.4	26.5	18.5
Allowance for doubtful accounts	(20.2)	(14.9)	(21.9)
Delayed customer billings	16.9	4.3	43.8
Inventories:
Natural gas	58.5	100.1	53.1
Propane gas	10.7	10.7	10.7
Materials and supplies	15.6	13.3	14.4
Regulatory assets	29.4	29.4	30
Prepayments	15.9	18.2	11.1
Total Current Assets	327.2	286.2	400.8
Deferred Charges and Other Assets:
Goodwill	210.2	210.2	210.2
Regulatory assets	512.1	507.5	433.6
Other	83.4	85.6	53
Total Deferred Charges and Other Assets	805.7	803.3	696.8
Total Assets	4,182	4,021.9	3,873.8
Capitalization:
Paid-in capital and common stock	765.1	765.1	762.8
Retained earnings	676.5	576.6	612.8
Accumulated other comprehensive loss	(2.5)	(2.4)	(1.6)
Total Shareholders' Equity	1,439.1	1,339.3	1,374
Long-term debt (less current portion)	1,098.7	925	924.7
Total Capitalization	2,537.8	2,264.3	2,298.7
Current Liabilities:
Current portion of long-term debt	0	0	50
Notes payable	185.1	0	0
Notes payable – associated companies	39.6	386.4	232.9
Accounts payable	63.8	75.7	72.6
Accounts payable – associated companies	5.2	5.5	8.1
Advance customer billings	5.4	20.8	0
Wages and compensation accrued	24.1	34.5	24.5
Customer deposits	13.2	13.4	13
Taxes accrued	26.6	36.4	27.2
Regulatory liabilities	24.3	52.3	24.2
Other	32.7	26.4	31
Total Current Liabilities	420	651.4	483.5
Deferred Credits and Other Liabilities:
Deferred income taxes	390.6	364.6	390.5
Pension and postretirement benefit costs	205	192.4	132.7
Asset retirement obligations	177.1	173.5	177.8
Regulatory liabilities	400.4	326.5	345.1
Other	51.1	49.2	45.5
Total Deferred Credits and Other Liabilities	1,224.2	1,106.2	1,091.6
Commitments and Contingencies (Note 10)
Total Capitalization and Liabilities	4,182	4,021.9	3,873.8
Spire Alabama
ASSETS
Utility Plant	2,217	2,138	2,032.5
Less: Accumulated depreciation and amortization	904.7	882.1	852.8
Net Utility Plant	1,312.3	1,255.9	1,179.7
Current Assets:
Cash and cash equivalents	0.1	0	0.1
Accounts receivable:
Utility	65.6	37.5	69.8
Associated companies	0.1	0	0.1
Other	7.8	8.5	8.4
Allowance for doubtful accounts	(6.8)	(6.3)	(3.8)
Inventories:
Natural gas	16.3	35.1	30.1
Materials and supplies	8.3	7.8	7.8
Regulatory assets	23.3	33.9	30.4
Prepayments	5.7	5.3	3.9
Other	0.3	0.4	0.2
Total Current Assets	120.7	122.2	147
Deferred Charges and Other Assets:
Regulatory assets	230.1	231.2	198.9
Deferred income taxes	57.4	81.3	79.3
Other	61	53	58.9
Total Deferred Charges and Other Assets	348.5	365.5	337.1
Total Assets	1,781.5	1,743.6	1,663.8
Capitalization:
Paid-in capital and common stock	350.9	370.9	370.9
Retained earnings	518.1	459.1	467.8
Total Shareholders' Equity	869	830	838.7
Long-term debt (less current portion)	471.7	372.2	372.1
Total Capitalization	1,340.7	1,202.2	1,210.8
Current Liabilities:
Current portion of long-term debt	0	40	40
Notes payable	50	0	0
Notes payable – associated companies	33	128.7	73.7
Accounts payable	48	56.2	54.6
Accounts payable – associated companies	4.8	1.6	3.1
Advance customer billings	5.3	10.6	5.3
Wages and compensation accrued	5.9	8	5.3
Customer deposits	19.9	19.5	20.5
Taxes accrued	23	27.4	21.2
Regulatory liabilities	2.4	3.4	6.1
Other	9.7	9.2	10
Total Current Liabilities	202	304.6	239.8
Deferred Credits and Other Liabilities:
Pension and postretirement benefit costs	54.6	59.2	37.4
Asset retirement obligations	151.7	148.7	138.6
Regulatory liabilities	21.6	23	30.5
Other	10.9	5.9	6.7
Total Deferred Credits and Other Liabilities	238.8	236.8	213.2
Commitments and Contingencies (Note 10)
Total Capitalization and Liabilities	$ 1,781.5	$ 1,743.6	$ 1,663.8

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED) (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2020	Sep. 30, 2019	Mar. 31, 2019
ASSETS
Non-utility property, accumulated depreciation and amortization	$ 17.5	$ 12.7	$ 11.9
Capitalization:
Preferred stock, par value (in dollars per share)	$ 25	$ 25
Preferred stock, depositary shares authorized (in shares)	10,000,000	10,000,000
Preferred stock, depositary shares outstanding (in shares)	10,000,000	10,000,000
Preferred stock, depositary shares issued (in shares)	10,000,000	10,000,000
Common stock, par value (in dollars per share)	$ 1	$ 1	$ 1
Common stock, authorized (in shares)	70,000,000	70,000,000	70,000,000
Common stock, issued (in shares)	51,200,000	51,000,000	50,700,000
Common stock, outstanding (in shares)	51,200,000	51,000,000	50,700,000
Spire Missouri
Capitalization:
Common stock, par value (in dollars per share)	$ 1	$ 1	$ 1
Common stock, authorized (in shares)	50,000,000	50,000,000	50,000,000
Common stock, issued (in shares)	24,577	24,577	24,577
Common stock, outstanding (in shares)	24,577	24,577	24,577
Spire Alabama
Capitalization:
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01	$ 0.01
Common stock, authorized (in shares)	3,000,000	3,000,000	3,000,000
Common stock, issued (in shares)	2,000,000	2,000,000	2,000,000
Common stock, 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	Spire Missouri	Spire Alabama	Common Stock	Common StockSpire Missouri	Common StockSpire Alabama	Preferred Stock	Paid-in Capital	Paid-in CapitalSpire Missouri	Paid-in CapitalSpire Alabama	Retained Earnings	Retained EarningsSpire Missouri	Retained EarningsSpire Alabama	AOCI	[1]	AOCISpire Missouri	[1]
BALANCE at Sep. 30, 2018	$ 2,255.4	$ 1,259.9	$ 808.7	$ 50.7	$ 0.1			$ 1,482.7	$ 760.3	$ 390.9	$ 715.6	$ 501.1	$ 417.8	$ 6.4		$ (1.6)
BALANCE (in shares) at Sep. 30, 2018				50,671,903	24,577	1,972,052
Stockholders' Equity Rollforward
Net Income	221.9	131.2	67								221.9	131.2	67
Dividend reinvestment plan	0.8							0.8
Dividend reinvestment plan (in shares)				11,267
Stock-based compensation costs	4.4	2.4						4.4	2.4
Stock issued under stock-based compensation plans				$ 0.1				(0.1)
Stock issued under stock-based compensation (in shares)				87,468
Employees’ tax withholding for stock-based compensation	(2.3)			$ (0.1)				(2.2)
Employee's tax withholding for stock-based compensation (in shares)				(28,001)
Return of capital to Spire			(20)							(20)
Dividends declared on common stock	(60)	(19.5)	(17)								(60)	(19.5)	(17)
Other comprehensive loss, net of tax	(14.2)													(14.2)
BALANCE at Mar. 31, 2019	2,406	1,374	838.7	$ 50.7	$ 0.1			1,485.6	762.7	370.9	877.5	612.8	467.8	(7.8)		(1.6)
BALANCE (in shares) at Mar. 31, 2019				50,742,637	24,577	1,972,052
BALANCE at Dec. 31, 2018	2,284.6	1,302.5	810.5	$ 50.7	$ 0.1			1,482.8	761.5	390.9	752.9	542.5	419.6	(1.8)		(1.6)
BALANCE (in shares) at Dec. 31, 2018				50,724,168	24,577	1,972,052
Stockholders' Equity Rollforward
Net Income	154.6	80	56.7								154.6	80	56.7
Dividend reinvestment plan	0.4							0.4
Dividend reinvestment plan (in shares)				6,204
Stock-based compensation costs	2.4	1.2						2.4	1.2
Stock issued under stock-based compensation (in shares)				12,633
Employee's tax withholding for stock-based compensation (in shares)				(368)
Return of capital to Spire			(20)							(20)
Dividends declared on common stock	(30)	(9.7)	(8.5)								(30)	(9.7)	(8.5)
Other comprehensive loss, net of tax	(6)													(6)
BALANCE at Mar. 31, 2019	2,406	1,374	838.7	$ 50.7	$ 0.1			1,485.6	762.7	370.9	877.5	612.8	467.8	(7.8)		(1.6)
BALANCE (in shares) at Mar. 31, 2019				50,742,637	24,577	1,972,052
BALANCE at Sep. 30, 2019	2,543	1,339.3	830	$ 51	$ 0.1		$ 242	1,505.8	765	370.9	775.5	576.6	459.1	(31.3)		(2.4)
BALANCE (in shares) at Sep. 30, 2019				50,973,515	24,577	1,972,052
Stockholders' Equity Rollforward
Net Income	200.6	122.5	71								200.6	122.5	71
Common stock issued	9.5			$ 0.1				9.4
Common stock issued (in shares)				112,758
Dividend reinvestment plan	5.6							5.6
Dividend reinvestment plan (in shares)				73,883
Stock-based compensation costs	3.1							3.1
Stock issued under stock-based compensation plans				$ 0.1				(0.1)
Stock issued under stock-based compensation (in shares)				108,752
Employees’ tax withholding for stock-based compensation	(3.1)							(3.1)
Employee's tax withholding for stock-based compensation (in shares)				(39,847)
Temporary equity adjustment to redemption value	1.1										1.1
Return of capital to Spire			(20)							(20)
Dividends declared on common stock	(63.8)	(22.6)	(12)								(63.8)	(22.6)	(12)
Dividends declared on preferred stock	(11.1)										(11.1)
Other comprehensive loss, net of tax	(19.3)	(0.1)												(19.3)		(0.1)
BALANCE at Mar. 31, 2020	2,665.6	1,439.1	869	$ 51.2	$ 0.1		242	1,520.7	765	350.9	902.3	676.5	518.1	(50.6)		(2.5)
BALANCE (in shares) at Mar. 31, 2020				51,229,061	24,577	1,972,052
BALANCE at Dec. 31, 2019	2,586	1,376.1	837.2	$ 51.1	$ 0.1		242	1,506.7	765	370.9	803.1	613.3	466.3	(16.9)		(2.3)
BALANCE (in shares) at Dec. 31, 2019				51,063,460	24,577	1,972,052
Stockholders' Equity Rollforward
Net Income	133.6	74.5	57.8								133.6	74.5	57.8
Common stock issued	9.5			$ 0.1				9.4
Common stock issued (in shares)				112,758
Dividend reinvestment plan	3.3							3.3
Dividend reinvestment plan (in shares)				45,119
Stock-based compensation costs	1.5							1.5
Stock issued under stock-based compensation (in shares)				9,626
Employees’ tax withholding for stock-based compensation	(0.2)							(0.2)
Employee's tax withholding for stock-based compensation (in shares)				(1,902)
Temporary equity adjustment to redemption value	1.2										1.2
Return of capital to Spire			(20)							(20)
Dividends declared on common stock	(31.9)	(11.3)	(6)								(31.9)	(11.3)	(6)
Dividends declared on preferred stock	(3.7)										(3.7)
Other comprehensive loss, net of tax	(33.7)	(0.2)												(33.7)		(0.2)
BALANCE at Mar. 31, 2020	$ 2,665.6	$ 1,439.1	$ 869	$ 51.2	$ 0.1		$ 242	$ 1,520.7	$ 765	$ 350.9	$ 902.3	$ 676.5	$ 518.1	$ (50.6)		$ (2.5)
BALANCE (in shares) at Mar. 31, 2020				51,229,061	24,577	1,972,052
[1]	Accumulated other comprehensive income (loss)

CONDENSED CONSOLIDATED STATEM_4

CONDENSED CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (Parenthetical) - $ / shares	3 Months Ended		6 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Statement Of Stockholders Equity [Abstract]
Dividends declared on common stock (in dollars per share)	$ 0.6225	$ 0.5925	$ 1.245	$ 1.185
Dividends declared on preferred stock (in dollars per depositary share)	$ 0.36875		$ 1.10625

CONDENSED CONSOLIDATED STATEM_5

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($) $ in Millions	6 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Operating Activities:
Net Income	$ 200.6	$ 221.9
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	96.7	89.1
Deferred income taxes and investment tax credits	42.8	45.5
Changes in assets and liabilities:
Accounts receivable	(64.4)	(194.3)
Inventories	69.5	83.9
Regulatory assets and liabilities	74.7	105.9
Accounts payable	(50.5)	33.6
Delayed/advance customer billings, net	(33.6)	(53.2)
Taxes accrued	(14.1)	(12.9)
Other assets and liabilities	0.1	(20.6)
Other	(0.1)	(1.4)
Net cash provided by operating activities	321.7	297.5
Investing Activities:
Capital expenditures	(346.1)	(376.8)
Business acquisitions	0	(7.9)
Other	1.5	(1.9)
Net cash used in investing activities	(344.6)	(386.6)
Financing Activities:
Issuance of long-term debt	510	190
Repayment of long-term debt	(140)	(9.1)
Repayment of short-term debt, net	(182.6)	(41.6)
Issuance of common stock	15.2	1
Dividends paid on common stock	(63.8)	(58.8)
Dividends paid on preferred stock	(7.4)	0
Other	(5.9)	(2.7)
Net cash provided by financing activities	125.5	78.8
Net Increase (Decrease) in Cash, Cash Equivalents, and Restricted Cash	102.6	(10.3)
Cash, Cash Equivalents, and Restricted Cash at Beginning of Period	5.8	21.4
Cash and Cash Equivalents at End of Period	108.4	11.1
Supplemental disclosure of cash paid for:
Interest, net of amounts capitalized	(46.7)	(49)
Income taxes	(1.7)	(2)
Spire Missouri
Operating Activities:
Net Income	122.5	131.2
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	58.3	55
Deferred income taxes and investment tax credits	16.4	19.1
Changes in assets and liabilities:
Accounts receivable	(67.6)	(123.5)
Inventories	39.3	74.9
Regulatory assets and liabilities	59.8	107.3
Accounts payable	6.8	11.1
Delayed/advance customer billings, net	(27.9)	(46.4)
Taxes accrued	(9.8)	(4.8)
Other assets and liabilities	(1.9)	(14.4)
Other	0.3	2.6
Net cash provided by operating activities	196.2	212.1
Investing Activities:
Capital expenditures	(183.2)	(167.1)
Other	0.3	0.8
Net cash used in investing activities	(182.9)	(166.3)
Financing Activities:
Issuance of long-term debt	275	100
Repayment of long-term debt	(100)	0
Issuance of short-term debt, net	185.1	0
Repayments to Spire, net	(346.8)	(112.4)
Dividends paid on common stock	(22.6)	(28.5)
Other	(1.5)	0
Net cash provided by financing activities	(10.8)	(40.9)
Net Increase (Decrease) in Cash, Cash Equivalents, and Restricted Cash	2.5	4.9
Cash, Cash Equivalents, and Restricted Cash at Beginning of Period	2.6	2
Cash and Cash Equivalents at End of Period	5.1	6.9
Supplemental disclosure of cash paid for:
Interest, net of amounts capitalized	(21.6)	(23.8)
Income taxes	0	0
Spire Alabama
Operating Activities:
Net Income	71	67
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	28.9	27.3
Deferred income taxes and investment tax credits	23.9	22.5
Changes in assets and liabilities:
Accounts receivable	(27.9)	(33.5)
Inventories	18.3	3.7
Regulatory assets and liabilities	13.7	0.6
Accounts payable	(10.8)	4
Delayed/advance customer billings, net	(5.3)	(7.8)
Taxes accrued	(4.4)	(7.1)
Other assets and liabilities	(7.8)	8.9
Other	(2.5)	(2.4)
Net cash provided by operating activities	97.1	83.2
Investing Activities:
Capital expenditures	(75.8)	(65.7)
Other	(3)	(1.1)
Net cash used in investing activities	(78.8)	(66.8)
Financing Activities:
Issuance of long-term debt	100	90
Repayment of long-term debt	(40)	0
Issuance of short-term debt, net	50	0
Return of capital to Spire	(20)	(20)
Repayments to Spire, net	(95.7)	(68.8)
Dividends paid on common stock	(12)	(17)
Other	(0.5)	(0.5)
Net cash provided by financing activities	(18.2)	(16.3)
Net Increase (Decrease) in Cash, Cash Equivalents, and Restricted Cash	0.1	0.1
Cash, Cash Equivalents, and Restricted Cash at Beginning of Period	0	0
Cash and Cash Equivalents at End of Period	0.1	0.1
Supplemental disclosure of cash paid for:
Interest, net of amounts capitalized	(9.5)	(8.7)
Income taxes	$ 0	$ 0

Summary of Significant Accounti

Summary of Significant Accounting Policies	6 Months Ended
	Mar. 31, 2020
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” or the “Missouri Utilities”) and Spire Alabama Inc. (“Spire Alabama”). Spire Missouri and Spire Alabama are wholly owned subsidiaries of Spire. Spire Missouri, Spire Alabama and the subsidiaries of Spire EnergySouth Inc. (“Spire EnergySouth”) are collectively referred to as the “Utilities.” The subsidiaries of Spire EnergySouth are Spire Gulf Inc. and Spire Mississippi Inc. 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 (consisting of only normal recurring 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’s, Spire Missouri’s and Spire Alabama’s combined Annual Report on Form 10-K for the fiscal year ended September 30, 2019. 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 two reportable segments: Gas Utility and Gas Marketing. 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: the Missouri Utilities, serving St. Louis and eastern Missouri (“Spire Missouri East”) and Kansas City and western Missouri (“Spire Missouri West”); Spire Alabama, serving central and northern Alabama; and the subsidiaries of Spire EnergySouth, serving southern Alabama and south-central Mississippi. The Gas Marketing segment includes Spire’s primary gas-related business, Spire Marketing Inc. (“Spire Marketing”), which provides non-regulated natural gas services, primarily in the central and southern United States (U.S.). The activities of other subsidiaries are reported as Other and are described in Note 9 , Information by Operating Segment. Spire Missouri and Spire Alabama each have a single reportable segment. Nearly all the Company’s earnings are derived from its Gas Utility segment. Due to the seasonal nature of the Utilities’ business and the 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. 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 Financial Accounting Standards Board (FASB) Accounting Standards Codification (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. Under GAAP, revenues and expenses associated with trading activities are presented on a net basis in Gas Marketing operating revenues (or expenses, if negative) in the Condensed Consolidated Statements of Income. This net presentation has no effect on operating income or net income. REGULATED OPERATIONS – The Utilities account for their regulated operations in accordance with FASB 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 4 , Regulatory Matters. TRANSACTIONS WITH AFFILIATES – Transactions between affiliates of the Company have been eliminated from the consolidated financial statements of Spire. Spire Missouri and Spire Alabama borrowed funds from the Company and incurred related interest, as reflected in their separate financial statements, and they participated in normal intercompany shared services transactions. In addition, Spire Missouri’s other transactions with affiliates are presented in the table below: Three Months Ended March 31, Six Months Ended March 31, 2020 2019 2020 2019 Purchases of natural gas from Spire Marketing Inc. $ 13.3 $ 29.2 $ 32.8 $ 69.0 Transportation services received from Spire STL Pipeline LLC 7.9 — 11.8 — Sales of natural gas to Spire Marketing Inc. — — — 1.4 Transportation services received from Spire NGL Inc. 0.2 0.2 0.5 0.5 In the three and six months ended March 31, 2020, Spire Alabama had purchases of natural gas from Spire Marketing totaling $1.0 and $4.3, respectively. ACCRUED CAPITAL EXPENDITURES – Accrued capital expenditures, shown in the following table, are excluded from capital expenditures in the statements of cash flows until paid. March 31, September 30, March 31, 2020 2019 2019 Spire $ 51.4 $ 80.6 $ 63.6 Spire Missouri 21.5 40.1 19.0 Spire Alabama 17.6 11.9 12.1 NEW ACCOUNTING PRONOUNCEMENTS – Spire, Spire Missouri and Spire Alabama adopted Accounting Standards Update (ASU) No. 2016-02, Leases , along with related ASU Nos. 2018-01, 2018-10, 2018-11, 2018-20 and 2019-01 (collectively, “ASC 842”) using a modified retrospective transition method for leases existing at, or entered into after, October 1, 2019. Under the selected transition method, comparative periods in the financial statements are presented under ASC 840 (previous lease accounting guidance). ASC 842 requires lessees to recognize a right-of-use asset and lease liability for almost all lease contracts based on the present value of lease payments. It provides new guidelines for identifying and classifying a lease, and classification affects the pattern and income statement line item for the related expense. The Company and its subsidiaries elected a package of three practical expedients permitted by the standard, allowing them not to reassess existing contracts for (1) whether it is or contains a lease, (2) lease classification and (3) initial direct costs. They also elected to use the benefit of hindsight in determining both the lease term and impairments associated with any existing leases, which resulted in lease terms that best represent management’s expectations with respect to use of the underlying asset but did not result in recognition of any impairment. Finally, they elected not to assess whether existing land easements are leases under ASC 842. The adoption of ASC 842 impacted the balance sheets through recognition of right-of-use assets and lease liabilities for operating leases but did not result in a cumulative effect adjustment or significant impacts to income or cash flows. For other lease policy elections and disclosures about leases, see Note 11 , Leases. Spire, Spire Missouri and Spire Alabama adopted the guidance in ASU No. 2017-12, Derivatives and Hedging: Targeted Improvements to Accounting for Hedging Activities In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments – Credit Losses: Measurement of Credit Losses on Financial Instruments

Revenue

Revenue	6 Months Ended
	Mar. 31, 2020
Revenue From Contract With Customer [Abstract]
Revenue	2. REVENUE The following tables show revenue disaggregated by source and customer type. Three Months Ended March 31, Six Months Ended March 31, 2020 2019 2020 2019 Spire Gas Utility: Residential $ 471.9 $ 551.3 $ 840.3 $ 944.9 Commercial & industrial 156.8 185.9 279.3 316.2 Transportation 32.5 31.3 63.5 60.8 Off-system & other incentive 9.3 11.5 18.7 26.4 Other customer revenue 3.2 10.9 5.6 23.6 Total revenue from contracts with customers 673.7 790.9 1,207.4 1,371.9 Changes in accrued revenue under alternative revenue programs 5.3 (14.1 ) 2.3 (19.9 ) Total Gas Utility operating revenues 679.0 776.8 1,209.7 1,352.0 Gas Marketing: Revenue from contracts with retail customers 33.3 25.5 65.6 51.3 Revenue from wholesale derivative contracts — — — — Total Gas Marketing operating revenues 33.3 25.5 65.6 51.3 Other 14.7 4.3 25.8 9.7 Total before eliminations 727.0 806.6 1,301.1 1,413.0 Intersegment eliminations (see Note 9, Information by Operating Segment) (11.5 ) (3.1 ) (18.7 ) (7.5 ) Total Operating Revenues $ 715.5 $ 803.5 $ 1,282.4 $ 1,405.5 Spire Missouri Residential $ 331.1 $ 410.9 $ 607.0 $ 713.0 Commercial & industrial 99.2 129.2 180.0 218.3 Transportation 9.7 9.9 18.7 18.9 Off-system & other incentive 9.3 11.5 18.7 26.4 Other customer revenue 0.9 4.2 1.4 6.8 Total revenue from contracts with customers 450.2 565.7 825.8 983.4 Changes in accrued revenue under alternative revenue programs 7.3 (9.1 ) 5.7 (13.6 ) Total Operating Revenues $ 457.5 $ 556.6 $ 831.5 $ 969.8 Spire Alabama Residential $ 120.5 $ 116.9 $ 194.8 $ 192.3 Commercial & industrial 46.2 44.1 77.5 75.5 Transportation 19.9 18.8 39.5 37.0 Other customer revenue 1.7 5.3 3.3 14.9 Total revenue from contracts with customers 188.3 185.1 315.1 319.7 Changes in accrued revenue under alternative revenue programs (2.8 ) (4.7 ) (3.4 ) (5.8 ) Total Operating Revenues $ 185.5 $ 180.4 $ 311.7 $ 313.9 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 March 31, Six Months Ended March 31, 2020 2019 2020 2019 Spire $ 37.9 $ 43.5 $ 62.5 $ 69.4 Spire Missouri 26.2 32.1 43.4 50.6 Spire Alabama 9.9 9.6 16.1 15.9

Earnings Per Common Share

Earnings Per Common Share	6 Months Ended
	Mar. 31, 2020
Earnings Per Share [Abstract]
Earnings Per Common Share	3. EARNINGS PER COMMON SHARE Three Months Ended March 31, Six Months Ended March 31, 2020 2019 2020 2019 Basic Earnings Per Common Share: Net Income $ 133.6 $ 154.6 $ 200.6 $ 221.9 Less: Provision for preferred dividends 3.7 — 7.4 — Income allocated to participating securities 0.2 0.3 0.3 0.5 Income Available to Common Shareholders $ 129.7 $ 154.3 $ 192.9 $ 221.4 Weighted Average Common Shares Outstanding (in millions) 51.0 50.6 51.0 50.6 Basic Earnings Per Common Share $ 2.55 $ 3.05 $ 3.78 $ 4.37 Diluted Earnings Per Common Share: Net Income $ 133.6 $ 154.6 $ 200.6 $ 221.9 Less: Provision for preferred dividends 3.7 — 7.4 — Income allocated to participating securities 0.2 0.3 0.3 0.5 Income Available to Common Shareholders $ 129.7 $ 154.3 $ 192.9 $ 221.4 Weighted Average Common Shares Outstanding (in millions) 51.0 50.6 51.0 50.6 Dilutive Effect of Restricted Stock and Restricted Stock Units (in millions)* 0.1 0.2 0.1 0.2 Weighted Average Diluted Common Shares (in millions) 51.1 50.8 51.1 50.8 Diluted Earnings Per Common Share $ 2.54 $ 3.04 $ 3.77 $ 4.36 * Calculation excludes certain outstanding common shares (shown in millions by period at the right) attributable to stock units subject to performance or market conditions and restricted stock, which could have a dilutive effect in the future 0.1 0.3 0.1 0.3

Regulatory Matters

Regulatory Matters	6 Months Ended
	Mar. 31, 2020
Regulated Operations [Abstract]
Regulatory Matters	4. REGULATORY 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 March 31, September 30, March 31, Spire 2020 2019 2019 Regulatory Assets: Current: Pension and postretirement benefit costs $ 30.1 $ 30.1 $ 30.2 Unamortized purchased gas adjustments 10.4 18.2 19.3 Other 27.5 30.3 25.8 Total Current Regulatory Assets 68.0 78.6 75.3 Noncurrent: Pension and postretirement benefit costs 415.6 416.6 345.8 Cost of removal 154.3 150.9 134.6 Future income taxes due from customers 113.5 108.8 102.2 Energy efficiency 37.7 35.0 32.0 Unamortized purchased gas adjustments — 9.1 — Other 49.6 47.2 45.3 Total Noncurrent Regulatory Assets 770.7 767.6 659.9 Total Regulatory Assets $ 838.7 $ 846.2 $ 735.2 Regulatory Liabilities: Current: Pension and postretirement benefit costs $ 5.8 $ 5.8 $ 5.8 Unamortized purchased gas adjustments 8.0 26.2 3.4 Other 18.0 28.8 26.1 Total Current Regulatory Liabilities 31.8 60.8 35.3 Noncurrent: Deferred taxes due to customers 174.2 179.8 155.7 Pension and postretirement benefit costs 152.5 142.3 115.3 Accrued cost of removal 31.7 41.6 53.7 Unamortized purchased gas adjustments 82.6 — 75.7 Other 31.3 35.3 30.9 Total Noncurrent Regulatory Liabilities 472.3 399.0 431.3 Total Regulatory Liabilities $ 504.1 $ 459.8 $ 466.6 March 31, September 30, March 31, Spire Missouri 2020 2019 2019 Regulatory Assets: Current: Pension and postretirement benefit costs $ 21.9 $ 21.9 $ 21.9 Unamortized purchased gas adjustments — — 0.6 Other 7.5 7.5 7.5 Total Current Regulatory Assets 29.4 29.4 30.0 Noncurrent: Future income taxes due from customers 106.8 102.9 99.0 Pension and postretirement benefit costs 337.5 333.3 277.9 Energy efficiency 37.7 35.0 32.0 Unamortized purchased gas adjustments — 9.1 — Other 30.1 27.2 24.7 Total Noncurrent Regulatory Assets 512.1 507.5 433.6 Total Regulatory Assets $ 541.5 $ 536.9 $ 463.6 Regulatory Liabilities: Current: Pension and postretirement benefit costs $ 3.6 $ 3.6 $ 3.6 Unamortized purchased gas adjustments 7.1 25.4 2.7 Other 13.6 23.3 17.9 Total Current Regulatory Liabilities 24.3 52.3 24.2 Noncurrent: Deferred taxes due to customers 156.8 162.5 138.3 Pension and postretirement benefit costs 130.7 119.1 79.4 Accrued cost of removal 4.8 15.7 26.8 Unamortized purchased gas adjustments 82.6 — 75.7 Other 25.5 29.2 24.9 Total Noncurrent Regulatory Liabilities 400.4 326.5 345.1 Total Regulatory Liabilities $ 424.7 $ 378.8 $ 369.3 March 31, September 30, March 31, Spire Alabama 2020 2019 2019 Regulatory Assets: Current: Pension and postretirement benefit costs $ 7.2 $ 7.3 $ 7.3 Unamortized purchased gas adjustments 10.4 17.7 18.0 Other 5.7 8.9 5.1 Total Current Regulatory Assets 23.3 33.9 30.4 Noncurrent: Pension and postretirement benefit costs 72.6 77.2 61.1 Cost of removal 154.3 150.9 134.6 Other 3.2 3.1 3.2 Total Noncurrent Regulatory Assets 230.1 231.2 198.9 Total Regulatory Assets $ 253.4 $ 265.1 $ 229.3 Regulatory Liabilities: Current: Pension and postretirement benefit costs $ 2.2 $ 2.2 $ 2.2 Other 0.2 1.2 3.9 Total Current Regulatory Liabilities 2.4 3.4 6.1 Noncurrent: Pension and postretirement benefit costs 17.8 19.1 26.5 Other 3.8 3.9 4.0 Total Noncurrent Regulatory Liabilities 21.6 23.0 30.5 Total Regulatory Liabilities $ 24.0 $ 26.4 $ 36.6 A portion of the Company’s and Spire Missouri’s regulatory assets are not earning a return, as shown in the table below: March 31, September 30, March 31, 2020 2019 2019 Spire Pension and postretirement benefit costs $ 226.2 $ 211.1 $ 144.7 Future income taxes due from customers 113.5 108.8 102.2 Other 13.7 14.3 14.8 Total Regulatory Assets Not Earning a Return $ 353.4 $ 334.2 $ 261.7 Spire Missouri Pension and postretirement benefit costs $ 226.2 $ 211.1 $ 144.7 Future income taxes due from customers 106.8 102.9 99.0 Other 13.7 14.3 14.8 Total Regulatory Assets Not Earning a Return $ 346.7 $ 328.3 $ 258.5 Like all the Company’s regulatory assets, these regulatory assets are expected to be recovered 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 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. Spire Alabama does not have any regulatory assets that are not earning a return. Spire Missouri On March 7, 2018, the MoPSC issued its order in two general rate cases (docketed as GR-2017-0215 and GR-2017-0216), approving new tariffs that became effective on April 19, 2018. Certain provisions of the order allow less future recovery of certain deferred or capitalized costs than estimated based upon previous rate proceedings, and management determined that the related regulatory assets should be written down or off in connection with the preparation of the financial statements for the second quarter of 2018. The charges totaled $38.4 for the year ended September 30, 2018 and are included primarily in operation and maintenance expense on the statements of income and in other cash flows from operating activities on the statements of cash flows. The after-tax reduction to net income and earnings per share was $23.6 and $0.49, respectively. On April 25, 2018, Spire Missouri filed an appeal of the MoPSC’s order related to the disallowance of certain pension costs incurred prior to 1997 ($28.8), real estate sold in 2014 ($1.8), and rate case expenses ($0.9) to Missouri’s Southern District Court of Appeals. On March 15, 2019, the appeal was denied by the Southern District Court of Appeals, and Spire Missouri requested review by the Missouri Supreme Court, which agreed to take the case. Oral arguments were made before the Missouri Supreme Court on January 29, 2020. The case is awaiting a decision. The charges related to the long-standing pension and real estate assets, totaling $30.6, were excluded in the determination of 2018 net economic earnings. Spire Missouri filed Infrastructure System Replacement Surcharge (ISRS) applications which were approved by the MoPSC and the costs associated therewith were included in new tariffs that went into effect from our last general rate cases on April 19, 2018. Since the Company’s last rate cases, ISRS filings became effective on October 8, 2018, May 25, 2019 and November 16, 2019, bringing total authorized future annualized ISRS revenues for Spire Missouri to $29.2. On February 3, 2020, Spire Missouri filed new ISRS applications with the MoPSC. Spire, MoPSC Staff, and the Office of Public Counsel (OPC) have entered into a Unanimous Stipulation and Agreement to resolve the February 2020 ISRS filings by increasing annualized ISRS revenue by $11.1. A portion of that revenue, representing replacement of bare steel facilities to which cathodic protection was later added, is subject to a potential refund based on the Court of Appeals’ decision on the ISRS eligibility of such materials for replacement in the appeal of the July 2019 ISRS case, discussed below. The MoPSC has not yet approved the Unanimous Stipulation and Agreement but has suspended the procedural schedule in the case in light of the parties’ filed agreement. Spire Missouri expects the MoPSC to issue a final order regarding the Unanimous Stipulation and Agreement no later than May 23, 2020. As reported last year, on November 19, 2019, the Missouri Western District Court of Appeals issued rulings (“ISRS rulings”) that determined certain capital investments in 2016 through 2018 were not eligible for recovery under the ISRS. The ISRS rulings upheld appeals by the OPC that contested recovery of portions of Spire Missouri’s ISRS and overturned the three prior MoPSC decisions. On January 2, 2020, Spire Missouri submitted Applications for Transfer to the Missouri Supreme Court. The MoPSC also submitted Applications for Transfer to the Missouri Supreme Court that advanced similar positions as Spire Missouri. On March 17, 2020, the Missouri Supreme Court denied the Applications for Transfer of all three ISRS rulings, and they have been remanded to the MoPSC to determine the appropriate refund, if any, that may be required. Spire Missouri is participating in the remand proceedings. The MoPSC must issue its decisions regarding the appropriate amount of refunds, if any, by July 16, 2020. Spire Missouri has recorded an estimate of the maximum impact of the ISRS rulings based on its interpretation of the rulings and evidence available. As of September 30, 2019, Spire Missouri recorded an estimated $12.2 regulatory liability for this matter by reducing revenue for fiscal year 2019. There were two components of this provision. The first related to a $4.2 refund ordered by the ISRS rulings for amounts collected prior to the last rate case, after which recoveries of related authorized revenues became part of base rates that went into effect in April 2018. The second component related to an estimate of $8.0 for revenues associated with the June 2018 ISRS filing that was approved by the MoPSC effective October 8, 2018. During the first six months of fiscal 2020, additional provisions totaling $4.2 were recorded to the regulatory liability for ISRS revenues related to customer billings recorded during this period under the June 2018 ISRS filing, along with a $0.6 provision for interest due on the entirety of the ISRS revenues in dispute if refunded. The after-tax impact of the six-month period provisions reduced net income by $3.7, which is excluded for the net economic earnings financial measure. Additional ISRS revenues are currently under appeal related to the January 2019 ISRS filings with annual authorized revenue of $12.4, as approved by the MoPSC effective May 25, 2019, and the July 2019 ISRS filings with annual authorized revenue totaling $8.8, which was approved by the MoPSC effective November 16, 2019. Those cases are in various stages of briefing, and no decisions have yet been rendered by the Missouri Western District Court of Appeals. In future periods, Spire Missouri will evaluate the need for any additional adjustment to the provisions based upon new information and further developments. In January 2020, legislation was introduced in both the Missouri House and Senate to clarify language in the statute governing ISRS mechanism. Specifically, the bills seek to ensure that we can continue to upgrade our infrastructure, enhance its safety and reliability, and secure timely recovery of costs incurred. Senate Bill 618 was passed by the Missouri Senate, with amendments, passed required House committees and is awaiting House floor debate. House Bill 1992 was passed by the Utilities Committee of the Missouri House and is on the House calendar. Our government affairs team continues to evaluate other avenues to achieve final passage of the initiative. Spire Alabama As part of their annual updates for RSE, on November 25, 2019, Spire Alabama and Spire Gulf filed an increase for rate year 2020 of $5.9 and $1.6, respectively, which became effective December 1, 2019. In addition, Spire Alabama was granted authority to begin an off-system sales and capacity release sharing program similar to the program currently in place at Spire Missouri. Spire Alabama filed a Gas Supply Adjustment (GSA) rate decrease effective February 1, 2020, of approximately $13.9 (on an annual basis) primarily attributable to lower natural gas prices and results of the recently approved off-system sale and capacity release share program. On March 24, 2020, the APSC approved an application for up to $150.0 of long-term debt financing for Spire Alabama. Other On November 21, 2019, the Federal Energy Regulatory Commission (FERC) issued an Order on Rehearing of its August 3, 2018 order issuing a certificate of public convenience and necessity to Spire STL Pipeline LLC. In the Order on Rehearing, the FERC dismissed or denied the outstanding requests for rehearing filed by several parties, dismissed the request for stay filed by one party and noted the withdrawal of the request for rehearing by another party. On January 21, 2020, two of the rehearing parties timely filed petitions for review of the FERC’s orders with the Court of Appeals for the District of Columbia Circuit. Spire and Spire Missouri have intervened in this matter.

Financing Arrangements and Long

Financing Arrangements and Long-term Debt	6 Months Ended
	Mar. 31, 2020
Debt Disclosure [Abstract]
Financing Arrangements and Long-term Debt	5. FINANCING ARRANGEMENTS AND LONG-TERM DEBT Spire, Spire Missouri and Spire Alabama have a syndicated revolving credit facility pursuant to a loan agreement with 11 banks, expiring October 31, 2023. The loan agreement has an aggregate credit commitment of $975.0, including sublimits of $300.0 for Spire, $475.0 for Spire Missouri, and $200.0 for Spire Alabama. These sublimits may be reallocated from time to time among the three borrowers within the $975.0 aggregate commitment, with commitments fees applied for each borrower relative to its credit rating. Spire 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 March 31, 2020, total debt was 54% of total capitalization for the consolidated Company, 45% for Spire Missouri, and 34% for Spire Alabama. Spire has a commercial paper program (“CP Program”) pursuant to which Spire 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 $975.0. The notes may have maturities of up to 365 days from date of issue. On March 26, 2020, Spire entered into a new loan agreement with two banks providing for a term loan of $150.0, which was immediately fully funded and matures on March 25, 2021, subject to optional prepayment by Spire. The term loan bears interest at the LIBOR Rate (as defined in the loan agreement) plus 0.85% per annum. Proceeds were used for working capital and general corporate purposes. Information about Spire’s consolidated short-term borrowings and about Spire Missouri’s and Spire Alabama’s borrowings from Spire is presented in the following table. As of March 31, 2020, $91.7 of Spire’s short-term borrowings were used to support lending to the Utilities. Spire (Parent Only) Spire Missouri Spire Alabama Spire Credit Term CP Credit Spire Credit Spire Consol- Facility Loan Program Facility Note Facility Note idated Six Months Ended March 31, 2020 Weighted average borrowings outstanding $ 0.2 $ 5.7 $ 615.6 $ 12.0 $ 283.9 $ 2.9 $ 97.4 $ 636.4 Lowest borrowings outstanding — — 175.5 — 39.6 — 18.5 436.1 Highest borrowings outstanding 23.1 150.0 856.6 185.1 429.5 50.0 161.3 856.6 Weighted average interest rate 1.9 % 2.1 % 2.1 % 1.8 % 2.1 % 1.8 % 2.1 % 2.1 % As of March 31, 2020 Borrowings outstanding $ — $ 150.0 $ 175.5 $ 185.1 $ 39.6 $ 50.0 $ 33.0 $ 560.6 Weighted average interest rate n/a 2.1 % 1.8 % 1.8 % 1.9 % 1.9 % 1.9 % 1.9 % As of September 30, 2019 Borrowings outstanding $ — $ — $ 743.2 $ — $ 386.4 $ — $ 128.7 $ 743.2 Weighted average interest rate n/a n/a 2.3 % n/a 2.3 % n/a 2.3 % 2.3 % As of March 31, 2019 Borrowings outstanding $ — $ — $ 512.0 $ — $ 232.9 $ — $ 73.7 $ 512.0 Weighted average interest rate n/a n/a 2.8 % n/a 2.8 % n/a 2.8 % 2.8 % The long-term debt agreements of Spire, Spire Missouri and Spire Alabama contain customary covenants and default provisions. As of March 31, 2020, there were no events of default under these covenants. Interest expense shown on Spire’s consolidated statements of income and Spire Missouri’s statements of comprehensive income is net of the capitalized interest amounts shown in the following table. Three Months Ended March 31, Six Months Ended March 31, 2020 2019 2020 2019 Spire $ 1.4 $ 1.4 $ 3.6 $ 2.6 Spire Missouri 0.3 0.4 0.6 0.9 Spire Alabama 0.4 — 1.0 — On November 12, 2019, Spire Missouri issued and sold to certain institutional purchasers in a private placement $275.0 of 2.84% first mortgage bonds due November 15, 2029. Interest is payable semi-annually. The bonds are secured by a mortgage and deed of trust and rank equal in right to payment with all Spire Missouri’s other first mortgage bonds. Spire Missouri used the proceeds to repay its $100.0 floating-rate note and for other general corporate purposes. On December 2, 2019, Spire Alabama issued and sold to certain institutional investors in a private placement $100.0 of 2.88% Series 2019B Senior Notes due December 1, 2029. Interest is payable semi-annually. The notes are senior unsecured obligations of Spire Alabama and rank equal in right to payment with all its other senior unsecured indebtedness. Spire Alabama used the proceeds to repay short-term debt and for general corporate purposes. On December 23, 2019, Spire STL Pipeline issued and sold notes to certain institutional investors in a $135.0 private placement. Interest is payable semi-annually at 2.95%, and principal repayment is scheduled annually in accordance with a 15-year amortization schedule with an average life of 9.2 years. Proceeds were used to repay short-term debt.

Fair Value of Financial Instrum

Fair Value of Financial Instruments	6 Months Ended
	Mar. 31, 2020
Fair Value Disclosures [Abstract]
Fair Value of Financial Instruments	6. FAIR VALUE OF FINANCIAL INSTRUMENTS The carrying amounts of cash and cash equivalents 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 7 , 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 March 31, 2020, September 30, 2019, and March 31, 2019. Classification of Estimated Fair Value Carrying Amount Fair Value Quoted Prices in Active Markets (Level 1) Significant Observable Inputs (Level 2) Spire As of March 31, 2020 Cash and cash equivalents $ 108.4 $ 108.4 $ 108.4 $ — Notes payable 560.6 560.6 — 560.6 Long-term debt, including current portion 2,490.2 2,671.0 — 2,671.0 As of September 30, 2019 Cash and cash equivalents $ 5.8 $ 5.8 $ 5.8 $ — Notes payable 743.2 743.2 — 743.2 Long-term debt, including current portion 2,122.6 2,373.4 — 2,373.4 As of March 31, 2019 Cash and cash equivalents $ 11.1 $ 11.1 $ 11.1 $ — Notes payable 512.0 512.0 — 512.0 Long-term debt, including current portion 2,256.9 2,319.9 — 2,319.9 Spire Missouri As of March 31, 2020 Cash and cash equivalents $ 5.1 $ 5.1 $ 5.1 $ — Notes payable 185.1 185.1 — 185.1 Notes payable – associated companies 39.6 39.6 — 39.6 Long-term debt 1,098.7 1,231.2 — 1,231.2 As of September 30, 2019 Cash and cash equivalents $ 2.6 $ 2.6 $ 2.6 $ — Notes payable – 386.4 386.4 — 386.4 Long-term debt 925.0 1,065.2 — 1,065.2 As of March 31, 2019 Cash and cash equivalents $ 6.9 $ 6.9 $ 6.9 $ — Notes payable – 232.9 232.9 — 232.9 Long-term debt, including current portion 974.7 1,036.9 — 1,036.9 Spire Alabama As of March 31, 2020 Cash and cash equivalents $ 0.1 $ 0.1 $ 0.1 $ — Notes payable 50.0 50.0 — 50.0 Notes payable – 33.0 33.0 — 33.0 Long-term debt 471.7 535.1 — 535.1 As of September 30, 2019 Notes payable – $ 128.7 $ 128.7 $ — $ 128.7 Long-term debt, including current portion 412.2 474.8 — 474.8 As of March 31, 2019 Cash and cash equivalents $ 0.1 $ 0.1 $ 0.1 $ — Notes payable – 73.7 73.7 — 73.7 Long-term debt, including current portion 412.1 423.8 — 423.8

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Mar. 31, 2020
Fair Value Disclosures [Abstract]
Fair Value Measurements	7. FAIR VALUE MEASUREMENTS The information presented below 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 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). Derivative instruments classified in Level 2 include physical commodity derivatives that are valued using broker or dealer quotation services 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 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. The Level 3 balances as of March 31, 2020, September 30, 2019, and March 31, 2019, consisted of gas commodity contracts. The Company’s and the Utilities’ 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 are included in “Other Investments” on the Company’s balance sheets and in “Other Property and Investments” on Spire Missouri’s balance sheets. 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. Spire Quoted Prices in Active Markets (Level 1) Significant Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Effects of Netting and Cash Margin Receivables /Payables Total As of March 31, 2020 ASSETS Gas Utility: U.S. stock/bond mutual funds $ 18.1 $ — $ — $ — $ 18.1 NYMEX/ICE natural gas contracts 0.1 — — (0.1 ) — Gas Marketing: NYMEX/ICE natural gas contracts 0.2 6.8 — (7.0 ) — Natural gas commodity contracts — 17.5 — (4.8 ) 12.7 Other: U.S. stock/bond mutual funds 17.6 — — — 17.6 Total $ 36.0 $ 24.3 $ — $ (11.9 ) $ 48.4 LIABILITIES Gas Utility: NYMEX/ICE natural gas contracts $ 12.2 $ — $ — $ (12.2 ) $ — Gasoline and heating oil contracts 0.4 — — (0.4 ) — Gas Marketing: NYMEX/ICE natural gas contracts 0.5 8.4 — (8.9 ) — Natural gas commodity contracts — 27.7 1.1 (4.8 ) 24.0 Other: Interest rate swaps — 66.9 — — 66.9 Total $ 13.1 $ 103.0 $ 1.1 $ (26.3 ) $ 90.9 Quoted Prices in Active Markets (Level 1) Significant Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Effects of Netting and Cash Margin Receivables /Payables Total As of September 30, 2019 ASSETS Gas Utility: U.S. stock/bond mutual funds $ 20.5 $ — $ — $ — $ 20.5 Gas Marketing: NYMEX/ICE natural gas contracts 0.9 6.5 — (6.9 ) 0.5 Natural gas commodity contracts — 16.8 — (2.5 ) 14.3 Other: U.S. stock/bond mutual funds 15.5 — — — 15.5 Total $ 36.9 $ 23.3 $ — $ (9.4 ) $ 50.8 LIABILITIES Gas Utility: NYMEX/ICE natural gas contracts $ 12.3 $ — $ — $ (12.3 ) $ — Gas Marketing: NYMEX/ICE natural gas contracts 0.4 8.5 — (8.9 ) — Natural gas commodity contracts — 13.8 0.1 (2.5 ) 11.4 Other: Interest rate swaps — 43.4 — — 43.4 Total $ 12.7 $ 65.7 $ 0.1 $ (23.7 ) $ 54.8 As of March 31, 2019 ASSETS Gas Utility: U.S. stock/bond mutual funds $ 19.7 $ — $ — $ — $ 19.7 NYMEX/ICE natural gas contracts 2.5 — — (2.5 ) — Gas Marketing: NYMEX/ICE natural gas contracts 0.2 7.1 — (4.3 ) 3.0 Natural gas commodity contracts — 30.4 — (3.4 ) 27.0 Other: U.S. stock/bond mutual funds 11.9 — — — 11.9 Total $ 34.3 $ 37.5 $ — $ (10.2 ) $ 61.6 LIABILITIES Gas Marketing: NYMEX/ICE natural gas contracts $ 0.4 $ 4.1 $ — $ (4.5 ) $ — Natural gas commodity contracts — 18.9 0.2 (3.5 ) 15.6 Other: Interest rate swaps — 15.2 — — 15.2 Total $ 0.4 $ 38.2 $ 0.2 $ (8.0 ) $ 30.8 Spire Missouri Quoted Prices in Active Markets (Level 1) Significant Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Effects of Netting and Cash Margin Receivables /Payables Total As of March 31, 2020 ASSETS U.S. stock/bond mutual funds $ 18.1 $ — $ — $ — $ 18.1 NYMEX/ICE natural gas contracts 0.1 — — (0.1 ) — Total $ 18.2 $ — $ — $ (0.1 ) $ 18.1 LIABILITIES NYMEX/ICE natural gas contracts $ 12.2 $ — $ — $ (12.2 ) $ — Gasoline and heating oil contracts 0.4 — — (0.4 ) — Total $ 12.6 $ — $ — $ (12.6 ) $ — As of September 30, 2019 ASSETS U.S. stock/bond mutual funds $ 20.5 $ — $ — $ — $ 20.5 LIABILITIES NYMEX/ICE natural gas contracts $ 12.3 $ — $ — $ (12.3 ) $ — As of March 31, 2019 ASSETS U.S. stock/bond mutual funds $ 19.7 $ — $ — $ — $ 19.7 NYMEX/ICE natural gas contracts 2.5 — — (2.5 ) — Total $ 22.2 $ — $ — $ (2.5 ) $ 19.7 Spire Alabama Spire Alabama occasionally utilizes a gasoline derivative program to stabilize the cost of fuel used in operations but had no outstanding derivative contracts as of March 31, 2020, September 30, 2019 and March 31, 2019.

Pension Plans and Other Postret

Pension Plans and Other Postretirement Benefits	6 Months Ended
	Mar. 31, 2020
Defined Contribution Pension And Other Postretirement Plans Disclosure [Abstract]
Pension Plans and Other Postretirement Benefits	8. PENSION PLANS AND OTHER POSTRETIREMENT BENEFITS Pension Plans Spire and the Utilities maintain pension plans for their employees. The Missouri Utilities have non-contributory, defined benefit, trusteed forms of pension plans covering the majority of their employees. Plan assets consist primarily of corporate and U.S. government obligations and a growth segment consisting of exposure to equity markets, commodities, real estate and inflation-indexed securities, achieved through derivative instruments. Spire Alabama has non-contributory, defined benefit, trusteed forms of pension plans covering the majority of its 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 included the following components: Three Months Ended March 31, Six Months Ended March 31, 2020 2019 2020 2019 Spire Service cost – benefits earned during the period $ 5.6 $ 4.9 $ 11.1 $ 9.7 Interest cost on projected benefit obligation* 5.8 7.0 11.7 14.1 Expected return on plan assets* (9.0 ) (8.9 ) (18.2 ) (18.0 ) Amortization of prior service credit* (0.6 ) (0.3 ) (1.2 ) (0.6 ) Amortization of actuarial loss* 3.9 2.3 7.6 4.6 Loss on lump-sum settlements* 21.0 — 21.0 — Subtotal 26.7 5.0 32.0 9.8 Regulatory adjustment (11.3 ) 9.8 (1.7 ) 19.7 Net pension cost $ 15.4 $ 14.8 $ 30.3 $ 29.5 Spire Missouri Service cost – benefits earned during the period $ 3.9 $ 3.1 $ 7.7 $ 6.2 Interest cost on projected benefit obligation* 4.0 4.9 8.2 9.9 Expected return on plan assets* (6.3 ) (6.3 ) (12.9 ) (12.7 ) Amortization of prior service cost* 0.1 0.2 0.1 0.4 Amortization of actuarial loss* 3.1 2.2 6.0 4.3 Loss on lump-sum settlements* 21.0 — 21.0 — Subtotal 25.8 4.1 30.1 8.1 Regulatory adjustment (13.2 ) 7.9 (5.5 ) 15.9 Net pension cost $ 12.6 $ 12.0 $ 24.6 $ 24.0 Spire Alabama Service cost – benefits earned during the period $ 1.5 $ 1.6 $ 3.0 $ 3.1 Interest cost on projected benefit obligation* 1.3 1.5 2.5 3.0 Expected return on plan assets* (1.8 ) (1.8 ) (3.5 ) (3.6 ) Amortization of prior service credit* (0.6 ) (0.5 ) (1.2 ) (0.9 ) Amortization of actuarial loss* 0.8 0.2 1.6 0.4 Subtotal 1.2 1.0 2.4 2.0 Regulatory adjustment 1.7 1.7 3.4 3.4 Net pension cost $ 2.9 $ 2.7 $ 5.8 $ 5.4 * Denotes pension expense line items that are recorded below the operating income line in the income statements, in the line item “Other Income (Expense), Net.” Pursuant to the provisions of the Missouri Utilities’ 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 In the quarter ended March 31, 2020, two Spire Missouri plans met the criteria for settlement recognition. The lump-sum payments recognized as settlements for the remeasurement were $59.1. The lump-sum settlement resulted in a loss of $21.0. For the remeasurements, the discount rates for the Missouri plans were updated to 2.85% from 3.2% at September 30, 2019. For the three and six months ended March 31, 2019 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 2020 contributions to Spire Missouri’s pension plans through March 31, 2020 were $10.9 to the qualified trusts and none to non-qualified plans. There were $6.6 of fiscal 2020 contributions to the Spire Alabama pension plans through March 31, 2020. Contributions to the qualified trusts of the Missouri Utilities’ pension plans for the remainder of fiscal 2020 are anticipated to be $18.1. Contributions to Spire Alabama’s pension plans for the remainder of fiscal 2020 are anticipated to be $6.5. 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, the Spire Missouri West 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. Net periodic postretirement benefit costs consisted of the following components: Three Months Ended March 31, Six Months Ended March 31, 2020 2019 2020 2019 Spire Service cost – benefits earned during the period $ 1.5 $ 1.8 $ 2.9 $ 3.7 Interest cost on accumulated postretirement benefit obligation* 1.5 2.1 3.1 4.4 Expected return on plan assets* (4.1 ) (3.9 ) (8.2 ) (8.0 ) Amortization of prior service credit* (0.1 ) (0.1 ) (0.3 ) (0.1 ) Amortization of actuarial gain* (0.5 ) (0.2 ) (1.0 ) (0.3 ) Subtotal (1.7 ) (0.3 ) (3.5 ) (0.3 ) Regulatory adjustment 4.0 2.6 8.0 5.0 Net postretirement benefit cost $ 2.3 $ 2.3 $ 4.5 $ 4.7 Spire Missouri Service cost – benefits earned during the period $ 1.3 $ 1.7 $ 2.6 $ 3.4 Interest cost on accumulated postretirement benefit obligation* 1.1 1.7 2.3 3.4 Expected return on plan assets* (2.9 ) (2.7 ) (5.7 ) (5.5 ) Amortization of prior service (credit) cost* — — (0.1 ) 0.1 Amortization of actuarial gain* (0.5 ) (0.2 ) (1.0 ) (0.3 ) Subtotal (1.0 ) 0.5 (1.9 ) 1.1 Regulatory adjustment 4.5 3.0 8.9 5.9 Net postretirement benefit cost $ 3.5 $ 3.5 $ 7.0 $ 7.0 Spire Alabama Service cost – benefits earned during the period $ 0.1 $ 0.1 $ 0.2 $ 0.2 Interest cost on accumulated postretirement benefit obligation* 0.4 0.4 0.7 0.9 Expected return on plan assets* (1.2 ) (1.2 ) (2.4 ) (2.4 ) Amortization of prior service credit* (0.1 ) (0.1 ) (0.2 ) (0.2 ) Subtotal (0.8 ) (0.8 ) (1.7 ) (1.5 ) Regulatory adjustment (0.5 ) (0.4 ) (0.9 ) (0.9 ) Net postretirement benefit income $ (1.3 ) $ (1.2 ) $ (2.6 ) $ (2.4 ) * Denotes other postretirement expense line items that are recorded below the operating income line in the income statements, in the line item “Other Income (Expense), Net.” 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

Information by Operating Segmen

Information by Operating Segment	6 Months Ended
	Mar. 31, 2020
Segment Reporting [Abstract]
Information by Operating Segment	9. INFORMATION BY OPERATING SEGMENT The Company has two reportable segments: Gas Utility and Gas Marketing. 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. Other components of the Company’s consolidated information include: • unallocated corporate items, including certain debt and associated interest costs; • Spire STL Pipeline, a subsidiary of Spire which has constructed and, as of November 2019, operates a 65-mile FERC-regulated pipeline to deliver natural gas into eastern Missouri; • Spire Storage, a subsidiary of Spire providing physical natural gas storage services; and • Spire’s subsidiaries engaged in the operation of a propane pipeline, the compression of natural gas, and risk management, among other activities. 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 and Spire Alabama, sales of natural gas from Spire Missouri to Spire Marketing, propane transportation services provided by Spire NGL Inc. to Spire Missouri, and propane storage services provided by Spire Missouri to Spire NGL Inc. Management evaluates the performance of the operating segments based on the computation of net economic earnings. Net economic 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 other non-recurring or unusual items such as certain regulatory, legislative, or GAAP standard-setting actions. In fiscal 2020, this includes provisions for the ISRS rulings discussed in Note 4 , Regulatory Matters. Gas Utility Gas Marketing Other Eliminations Consolidated Three Months Ended March 31, 2020 Operating Revenues: Revenues from external customers $ 679.1 $ 33.3 $ 3.1 $ — $ 715.5 Intersegment revenues (0.1 ) — 11.6 (11.5 ) — Total Operating Revenues 679.0 33.3 14.7 (11.5 ) 715.5 Operating Expenses: Gas Utility Natural and propane gas 271.6 — — (22.6 ) 249.0 Operation and maintenance 95.8 — — (2.7 ) 93.1 Depreciation and amortization 47.0 — — — 47.0 Taxes, other than income taxes 51.7 — — — 51.7 Total Gas Utility Operating Expenses 466.1 — — (25.3 ) 440.8 Gas Marketing and Other — 37.7 12.7 13.8 64.2 Total Operating Expenses 466.1 37.7 12.7 (11.5 ) 505.0 Operating Income $ 212.9 $ (4.4 ) $ 2.0 $ — $ 210.5 Net Economic Earnings (Loss) $ 144.3 $ 5.1 $ (5.4 ) $ — $ 144.0 Gas Utility Gas Marketing Other Eliminations Consolidated Three Months Ended March 31, 2019 Operating Revenues: Revenues from external customers $ 776.7 $ 25.4 $ 1.4 $ — $ 803.5 Intersegment revenues 0.1 0.1 2.9 (3.1 ) — Total Operating Revenues 776.8 25.5 4.3 (3.1 ) 803.5 Operating Expenses: Gas Utility Natural and propane gas 366.7 — — (29.3 ) 337.4 Operation and maintenance 112.0 — — (2.5 ) 109.5 Depreciation and amortization 44.4 — — — 44.4 Taxes, other than income taxes 57.4 — — — 57.4 Total Gas Utility Operating Expenses 580.5 — — (31.8 ) 548.7 Gas Marketing and Other — 8.7 7.9 28.7 45.3 Total Operating Expenses 580.5 8.7 7.9 (3.1 ) 594.0 Operating Income (Loss) $ 196.3 $ 16.8 $ (3.6 ) $ — $ 209.5 Net Economic Earnings (Loss) $ 146.7 $ 6.2 $ (5.0 ) $ — $ 147.9 Gas Utility Gas Marketing Other Eliminations Consolidated Six Months Ended March 31, 2020 Operating Revenues: Revenues from external customers $ 1,209.7 $ 65.6 $ 7.1 $ — $ 1,282.4 Intersegment revenues — — 18.7 (18.7 ) — Total Operating Revenues 1,209.7 65.6 25.8 (18.7 ) 1,282.4 Operating Expenses: Gas Utility Natural and propane gas 513.1 — — (49.5 ) 463.6 Operation and maintenance 204.4 — — (5.3 ) 199.1 Depreciation and amortization 93.4 — — — 93.4 Taxes, other than income taxes 89.6 — — — 89.6 Total Gas Utility Operating Expenses 900.5 — — (54.8 ) 845.7 Gas Marketing and Other — 65.6 22.2 36.1 123.9 Total Operating Expenses 900.5 65.6 22.2 (18.7 ) 969.6 Operating Income (Loss) $ 309.2 $ — $ 3.6 $ — $ 312.8 Net Economic Earnings (Loss) $ 213.4 $ 11.2 $ (8.8 ) $ — $ 215.8 Gas Utility Gas Marketing Other Eliminations Consolidated Six Months Ended March 31, 2019 Operating Revenues: Revenues from external customers $ 1,350.5 $ 51.2 $ 3.8 $ — $ 1,405.5 Intersegment revenues 1.5 0.1 5.9 (7.5 ) — Total Operating Revenues 1,352.0 51.3 9.7 (7.5 ) 1,405.5 Operating Expenses: Gas Utility Natural and propane gas 658.5 — — (69.4 ) 589.1 Operation and maintenance 216.9 — — (4.9 ) 212.0 Depreciation and amortization 88.1 — — — 88.1 Taxes, other than income taxes 96.6 — — — 96.6 Total Gas Utility Operating Expenses 1,060.1 — — (74.3 ) 985.8 Gas Marketing and Other — 22.0 16.3 66.8 105.1 Total Operating Expenses 1,060.1 22.0 16.3 (7.5 ) 1,090.9 Operating Income (Loss) $ 291.9 $ 29.3 $ (6.6 ) $ — $ 314.6 Net Economic Earnings (Loss) $ 213.1 $ 14.5 $ (13.8 ) $ — $ 213.8 The Company’s total assets by segment were as follows: March 31, September 30, March 31, 2020 2019 2019 Total Assets: Gas Utility $ 6,311.6 $ 6,094.6 $ 5,850.1 Gas Marketing 159.3 212.3 366.7 Other 2,214.7 2,692.7 2,396.8 Eliminations (667.6 ) (1,380.4 ) (1,340.0 ) Total Assets $ 8,018.0 $ 7,619.2 $ 7,273.6 The following table reconciles the Company’s net economic earnings to net income. Three Months Ended March 31, Six Months Ended March 31, 2020 2019 2020 2019 Net Income $ 133.6 $ 154.6 $ 200.6 $ 221.9 Adjustments, pre-tax: Provision for ISRS rulings 2.2 — 4.8 — Unrealized loss (gain) on energy-related derivatives 11.6 (9.1 ) 15.3 (11.3 ) Acquisition, divestiture and restructuring activities — — — 0.4 Income tax effect of adjustments (3.4 ) 2.4 (4.9 ) 2.8 Net Economic Earnings $ 144.0 $ 147.9 $ 215.8 $ 213.8

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Mar. 31, 2020
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	10. COMMITMENTS AND CONTINGENCIES Commitments The Company and the Utilities have entered into contracts with various counterparties, expiring on dates through 2032, for the storage, transportation, and supply of natural gas. Minimum payments required under the contracts in place at March 31, 2020, are estimated at $1,558.7, $760.3, and $189.2 for the Company, 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. 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 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. 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. 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 (MDNR) Brownfields/Voluntary Cleanup Program (BVCP). The third site is the result of a relatively new claim assertion by the United States Environmental Protection Agency (EPA). In conjunction with redevelopment of one of the sites, 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 letter from the MDNR. 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 amount paid by Spire Missouri did not materially impact the financial condition, results of operations, or cash flows of the Company. Spire Missouri has not owned the second site for many years. In a letter dated June 29, 2011, the Attorney General for the State of Missouri informed Spire Missouri that the MDNR had completed an investigation of the site. The Attorney General requested that Spire Missouri participate in the follow up investigations of the site. In a letter dated January 10, 2012, Spire Missouri stated that it would participate in future environmental response activities at the site in conjunction with other PRPs that are willing to contribute to such efforts in a meaningful and equitable fashion. Accordingly, Spire Missouri entered into a cost sharing agreement for remedial investigation with other PRPs. To date, MDNR has not approved the agreement, so remedial investigation has not yet occurred. 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 in the northern portion of the City on which Spire Missouri operated a MGP. Spire Missouri has not owned or operated the site (also known as Station “B”) for over 70 years. Spire Missouri and the site owner have met with the EPA and reviewed its assertions. Both Spire Missouri and the site owner have 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, Spire Missouri requested more information from the EPA, some of which would also be utilized to identify other former owners and operators of the site that could be added as PRPs. To date, Spire Missouri has not 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, in an effort 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 seven 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 North, Kansas City Coal Gas Station A South, and Independence MGP #2. Source removal has been conducted at all of the owned sites since 2003 with the exception of Joplin. On September 15, 2016, a request was made with the MDNR for a restrictive covenant use limitation with respect to Joplin. Remediation efforts at the seven sites are at various stages of completion, ranging from groundwater monitoring and sampling following source removal activities to the aforementioned request in respect to Joplin. As part of its participation in the BVCP, Spire Missouri communicates regularly with the MDNR with respect to its remediation efforts and monitoring activities at these sites. On May 11, 2015, MDNR approved the next phase of investigation at the Kansas City Station A North and Railroad areas. To date, costs incurred for all Missouri Utilities’ MGP sites for investigation, remediation and monitoring these sites 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 may incur could be materially higher or lower depending upon several factors, including whether remediation actions 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 2013, Spire Missouri retained an outside consultant to conduct probabilistic cost modeling of 19 former MGP sites owned or operated by Spire Missouri. The purpose of this analysis was to develop an estimated range of probabilistic future liability for each site. That analysis, completed in August 2014, provided a range of demonstrated possible future expenditures to investigate, monitor and remediate all 19 MGP sites. Spire Missouri has recorded its best estimate of the probable expenditures that relate to these matters. The amount is not material. Spire Missouri 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 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. Spire Alabama does not foresee a probable or reasonably estimable loss associated with these sites. 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. 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. Spire In addition to those discussed above for Spire Missouri and Spire Alabama, Spire is aware of the following contingent matter. In February 2018, the Company was made aware of a complaint filed with the U.S. Department of Housing and Urban Development (HUD) by the South Alabama Center for Fair Housing and the National Community Reinvestment Coalition. The complaint alleges that the Company discriminated against unspecified residents of Eight Mile, Alabama, on the basis of race in violation of the Fair Housing Act by failing to adequately address the odorant release that occurred in 2008. The Company believes there is no basis for the complaint, HUD has no jurisdiction in the matter, and there will be no material impact on its future financial condition or results of operations.

Leases

Leases	6 Months Ended
	Mar. 31, 2020
Leases [Abstract]
Leases	11. LEASES The lease agreement covering the Company’s primary office space in St. Louis extends through February 2035, with an option to renew for an additional five years. Spire Alabama currently has leased office space in two buildings in Birmingham; one lease expires in 2020 and the other extends through January 2024. The lease agreement covering Spire Marketing and Spire Storage office space in Houston extends through December 2028, with options to terminate three years earlier or to renew for an additional five years. The renewal options in the St. Louis and Houston leases are reasonably certain to be exercised and are included in the lease term used to determine the right-of use assets and lease liabilities. The Company and its subsidiaries have other relatively minor rental arrangements for real estate and equipment with remaining terms of up to eleven years. Operating lease cost, cash flow and noncash information for the three and six months ended March 31, 2020 are shown in the following tables. Three Months Ended March 31, 2020 Spire Spire Missouri Spire Alabama Operating lease cost, including amounts capitalized $ 2.4 $ 0.1 $ 1.1 Cash flow and noncash information about operating leases: Operating cash flows representing cash paid for amounts included in the measurement of lease liabilities 2.2 0.1 0.9 Right-of-use assets obtained in exchange for lease liabilities — — — Six Months Ended March 31, 2020 Spire Spire Missouri Spire Alabama Operating lease cost, including amounts capitalized $ 4.8 $ 0.3 $ 2.1 Cash flow and noncash information about operating leases: Operating cash flows representing cash paid for amounts included in the measurement of lease liabilities 4.5 0.3 1.9 Right-of-use assets obtained in exchange for lease liabilities 71.1 2.1 10.0 The following table shows balance sheet and weighted-average information about operating leases as of March 31, 2020. Balance sheet classification Spire Spire Missouri Spire Alabama Right-of-use assets Deferred Charges and Other Assets: Other $ 67.7 $ 1.9 $ 8.0 Lease liabilities, current Current Liabilities, Other 6.9 0.3 2.3 Lease liabilities, noncurrent Deferred Credits and Other Liabilities: Other 60.6 1.5 5.6 Weighted-average remaining lease term 16.1 years 5.8 years 3.7 years Weighted-average discount rate 4.1 % 2.5 % 2.2 % Following is a maturity analysis by fiscal year for operating lease liabilities as of March 31, 2020. Spire Spire Missouri Spire Alabama Remainder of 2020 $ 3.4 $ 0.1 $ 1.2 2021 7.2 0.4 2.1 2022 7.2 0.4 2.1 2023 7.2 0.3 2.1 2024 5.8 0.3 0.7 2025 5.1 0.3 — Thereafter 58.4 0.2 — Total undiscounted lease payments 94.3 2.0 8.2 Less present value discount (26.8 ) (0.2 ) (0.3 ) Total current and noncurrent lease liabilities $ 67.5 $ 1.8 $ 7.9 As of September 30, 2019, the annual minimum rental commitments for operating leases (under ASC 840) were as follows. 2020 2021 2022 2023 2024 Later Total Spire $ 8.2 $ 7.0 $ 6.8 $ 6.1 $ 4.8 $ 36.5 $ 69.4 Spire Missouri 0.5 0.2 — — — — 0.7 Spire Alabama 2.9 2.1 2.1 2.1 0.7 — 9.9 There are no significant finance leases, short-term leases, subleases, variable lease payments, residual value guarantees, restrictions or covenants pertaining to leases. The Company elected, for all asset classes, not to recognize right-of-use assets and lease liabilities for short-term leases. Instead, the lease payments are recognized in profit or loss on a straight-line basis over the lease term and variable lease payments are recognized in the period in which the obligation for those payments is incurred. The Company elected, for all asset classes, not to separate nonlease components from lease components and instead to account for each separate lease component and the nonlease components associated with that lease component as a single lease component. The discount rate used for all the leases is the applicable incremental borrowing rate, which is the rate of interest that a lessee would have to pay to borrow on a collateralized basis over a similar term an amount equal to the lease payments in a similar economic environment. For a subsidiary lessee, the rate applicable to the subsidiary is used unless the lease terms are influenced by parent credit.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Mar. 31, 2020
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” or the “Missouri Utilities”) and Spire Alabama Inc. (“Spire Alabama”). Spire Missouri and Spire Alabama are wholly owned subsidiaries of Spire. Spire Missouri, Spire Alabama and the subsidiaries of Spire EnergySouth Inc. (“Spire EnergySouth”) are collectively referred to as the “Utilities.” The subsidiaries of Spire EnergySouth are Spire Gulf Inc. and Spire Mississippi Inc. 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 (consisting of only normal recurring 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’s, Spire Missouri’s and Spire Alabama’s combined Annual Report on Form 10-K for the fiscal year ended September 30, 2019. 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.
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 Financial Accounting Standards Board (FASB) Accounting Standards Codification (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. Under GAAP, revenues and expenses associated with trading activities are presented on a net basis in Gas Marketing operating revenues (or expenses, if negative) in the Condensed Consolidated Statements of Income. This net presentation has no effect on operating income or net income.
Regulated Operations	REGULATED OPERATIONS – The Utilities account for their regulated operations in accordance with FASB 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 4 , Regulatory Matters.
Transactions with Affiliates	TRANSACTIONS WITH AFFILIATES – Transactions between affiliates of the Company have been eliminated from the consolidated financial statements of Spire. Spire Missouri and Spire Alabama borrowed funds from the Company and incurred related interest, as reflected in their separate financial statements, and they participated in normal intercompany shared services transactions. In addition, Spire Missouri’s other transactions with affiliates are presented in the table below: Three Months Ended March 31, Six Months Ended March 31, 2020 2019 2020 2019 Purchases of natural gas from Spire Marketing Inc. $ 13.3 $ 29.2 $ 32.8 $ 69.0 Transportation services received from Spire STL Pipeline LLC 7.9 — 11.8 — Sales of natural gas to Spire Marketing Inc. — — — 1.4 Transportation services received from Spire NGL Inc. 0.2 0.2 0.5 0.5 In the three and six months ended March 31, 2020, Spire Alabama had purchases of natural gas from Spire Marketing totaling $1.0 and $4.3, respectively.
Accrued 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. March 31, September 30, March 31, 2020 2019 2019 Spire $ 51.4 $ 80.6 $ 63.6 Spire Missouri 21.5 40.1 19.0 Spire Alabama 17.6 11.9 12.1
New Accounting Pronouncements	NEW ACCOUNTING PRONOUNCEMENTS – Spire, Spire Missouri and Spire Alabama adopted Accounting Standards Update (ASU) No. 2016-02, Leases , along with related ASU Nos. 2018-01, 2018-10, 2018-11, 2018-20 and 2019-01 (collectively, “ASC 842”) using a modified retrospective transition method for leases existing at, or entered into after, October 1, 2019. Under the selected transition method, comparative periods in the financial statements are presented under ASC 840 (previous lease accounting guidance). ASC 842 requires lessees to recognize a right-of-use asset and lease liability for almost all lease contracts based on the present value of lease payments. It provides new guidelines for identifying and classifying a lease, and classification affects the pattern and income statement line item for the related expense. The Company and its subsidiaries elected a package of three practical expedients permitted by the standard, allowing them not to reassess existing contracts for (1) whether it is or contains a lease, (2) lease classification and (3) initial direct costs. They also elected to use the benefit of hindsight in determining both the lease term and impairments associated with any existing leases, which resulted in lease terms that best represent management’s expectations with respect to use of the underlying asset but did not result in recognition of any impairment. Finally, they elected not to assess whether existing land easements are leases under ASC 842. The adoption of ASC 842 impacted the balance sheets through recognition of right-of-use assets and lease liabilities for operating leases but did not result in a cumulative effect adjustment or significant impacts to income or cash flows. For other lease policy elections and disclosures about leases, see Note 11 , Leases. Spire, Spire Missouri and Spire Alabama adopted the guidance in ASU No. 2017-12, Derivatives and Hedging: Targeted Improvements to Accounting for Hedging Activities In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments – Credit Losses: Measurement of Credit Losses on Financial Instruments

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	6 Months Ended
	Mar. 31, 2020
Accounting Policies [Abstract]
Schedule of Inter-Company Transactions	In addition, Spire Missouri’s other transactions with affiliates are presented in the table below Three Months Ended March 31, Six Months Ended March 31, 2020 2019 2020 2019 Purchases of natural gas from Spire Marketing Inc. $ 13.3 $ 29.2 $ 32.8 $ 69.0 Transportation services received from Spire STL Pipeline LLC 7.9 — 11.8 — Sales of natural gas to Spire Marketing Inc. — — — 1.4 Transportation services received from Spire NGL Inc. 0.2 0.2 0.5 0.5
Schedule of Capital Expenditures Excluded from Statement of Cash Flow	Accrued capital expenditures, shown in the following table, are excluded from capital expenditures in the statements of cash flows until paid. March 31, September 30, March 31, 2020 2019 2019 Spire $ 51.4 $ 80.6 $ 63.6 Spire Missouri 21.5 40.1 19.0 Spire Alabama 17.6 11.9 12.1

Revenue (Tables)

Revenue (Tables)	6 Months Ended
	Mar. 31, 2020
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 March 31, Six Months Ended March 31, 2020 2019 2020 2019 Spire Gas Utility: Residential $ 471.9 $ 551.3 $ 840.3 $ 944.9 Commercial & industrial 156.8 185.9 279.3 316.2 Transportation 32.5 31.3 63.5 60.8 Off-system & other incentive 9.3 11.5 18.7 26.4 Other customer revenue 3.2 10.9 5.6 23.6 Total revenue from contracts with customers 673.7 790.9 1,207.4 1,371.9 Changes in accrued revenue under alternative revenue programs 5.3 (14.1 ) 2.3 (19.9 ) Total Gas Utility operating revenues 679.0 776.8 1,209.7 1,352.0 Gas Marketing: Revenue from contracts with retail customers 33.3 25.5 65.6 51.3 Revenue from wholesale derivative contracts — — — — Total Gas Marketing operating revenues 33.3 25.5 65.6 51.3 Other 14.7 4.3 25.8 9.7 Total before eliminations 727.0 806.6 1,301.1 1,413.0 Intersegment eliminations (see Note 9, Information by Operating Segment) (11.5 ) (3.1 ) (18.7 ) (7.5 ) Total Operating Revenues $ 715.5 $ 803.5 $ 1,282.4 $ 1,405.5 Spire Missouri Residential $ 331.1 $ 410.9 $ 607.0 $ 713.0 Commercial & industrial 99.2 129.2 180.0 218.3 Transportation 9.7 9.9 18.7 18.9 Off-system & other incentive 9.3 11.5 18.7 26.4 Other customer revenue 0.9 4.2 1.4 6.8 Total revenue from contracts with customers 450.2 565.7 825.8 983.4 Changes in accrued revenue under alternative revenue programs 7.3 (9.1 ) 5.7 (13.6 ) Total Operating Revenues $ 457.5 $ 556.6 $ 831.5 $ 969.8 Spire Alabama Residential $ 120.5 $ 116.9 $ 194.8 $ 192.3 Commercial & industrial 46.2 44.1 77.5 75.5 Transportation 19.9 18.8 39.5 37.0 Other customer revenue 1.7 5.3 3.3 14.9 Total revenue from contracts with customers 188.3 185.1 315.1 319.7 Changes in accrued revenue under alternative revenue programs (2.8 ) (4.7 ) (3.4 ) (5.8 ) Total Operating Revenues $ 185.5 $ 180.4 $ 311.7 $ 313.9
Schedule of Gross Receipts Taxes	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 March 31, Six Months Ended March 31, 2020 2019 2020 2019 Spire $ 37.9 $ 43.5 $ 62.5 $ 69.4 Spire Missouri 26.2 32.1 43.4 50.6 Spire Alabama 9.9 9.6 16.1 15.9

Earnings Per Common Share (Tabl

Earnings Per Common Share (Tables)	6 Months Ended
	Mar. 31, 2020
Earnings Per Share [Abstract]
Schedule of Basic and Diluted Earnings Per Share	Three Months Ended March 31, Six Months Ended March 31, 2020 2019 2020 2019 Basic Earnings Per Common Share: Net Income $ 133.6 $ 154.6 $ 200.6 $ 221.9 Less: Provision for preferred dividends 3.7 — 7.4 — Income allocated to participating securities 0.2 0.3 0.3 0.5 Income Available to Common Shareholders $ 129.7 $ 154.3 $ 192.9 $ 221.4 Weighted Average Common Shares Outstanding (in millions) 51.0 50.6 51.0 50.6 Basic Earnings Per Common Share $ 2.55 $ 3.05 $ 3.78 $ 4.37 Diluted Earnings Per Common Share: Net Income $ 133.6 $ 154.6 $ 200.6 $ 221.9 Less: Provision for preferred dividends 3.7 — 7.4 — Income allocated to participating securities 0.2 0.3 0.3 0.5 Income Available to Common Shareholders $ 129.7 $ 154.3 $ 192.9 $ 221.4 Weighted Average Common Shares Outstanding (in millions) 51.0 50.6 51.0 50.6 Dilutive Effect of Restricted Stock and Restricted Stock Units (in millions)* 0.1 0.2 0.1 0.2 Weighted Average Diluted Common Shares (in millions) 51.1 50.8 51.1 50.8 Diluted Earnings Per Common Share $ 2.54 $ 3.04 $ 3.77 $ 4.36 * Calculation excludes certain outstanding common shares (shown in millions by period at the right) attributable to stock units subject to performance or market conditions and restricted stock, which could have a dilutive effect in the future 0.1 0.3 0.1 0.3

Regulatory Matters (Tables)

Regulatory Matters (Tables)	6 Months Ended
	Mar. 31, 2020
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 March 31, 2020, September 30, 2019, and March 31, 2019. March 31, September 30, March 31, Spire 2020 2019 2019 Regulatory Assets: Current: Pension and postretirement benefit costs $ 30.1 $ 30.1 $ 30.2 Unamortized purchased gas adjustments 10.4 18.2 19.3 Other 27.5 30.3 25.8 Total Current Regulatory Assets 68.0 78.6 75.3 Noncurrent: Pension and postretirement benefit costs 415.6 416.6 345.8 Cost of removal 154.3 150.9 134.6 Future income taxes due from customers 113.5 108.8 102.2 Energy efficiency 37.7 35.0 32.0 Unamortized purchased gas adjustments — 9.1 — Other 49.6 47.2 45.3 Total Noncurrent Regulatory Assets 770.7 767.6 659.9 Total Regulatory Assets $ 838.7 $ 846.2 $ 735.2 Regulatory Liabilities: Current: Pension and postretirement benefit costs $ 5.8 $ 5.8 $ 5.8 Unamortized purchased gas adjustments 8.0 26.2 3.4 Other 18.0 28.8 26.1 Total Current Regulatory Liabilities 31.8 60.8 35.3 Noncurrent: Deferred taxes due to customers 174.2 179.8 155.7 Pension and postretirement benefit costs 152.5 142.3 115.3 Accrued cost of removal 31.7 41.6 53.7 Unamortized purchased gas adjustments 82.6 — 75.7 Other 31.3 35.3 30.9 Total Noncurrent Regulatory Liabilities 472.3 399.0 431.3 Total Regulatory Liabilities $ 504.1 $ 459.8 $ 466.6 March 31, September 30, March 31, Spire Missouri 2020 2019 2019 Regulatory Assets: Current: Pension and postretirement benefit costs $ 21.9 $ 21.9 $ 21.9 Unamortized purchased gas adjustments — — 0.6 Other 7.5 7.5 7.5 Total Current Regulatory Assets 29.4 29.4 30.0 Noncurrent: Future income taxes due from customers 106.8 102.9 99.0 Pension and postretirement benefit costs 337.5 333.3 277.9 Energy efficiency 37.7 35.0 32.0 Unamortized purchased gas adjustments — 9.1 — Other 30.1 27.2 24.7 Total Noncurrent Regulatory Assets 512.1 507.5 433.6 Total Regulatory Assets $ 541.5 $ 536.9 $ 463.6 Regulatory Liabilities: Current: Pension and postretirement benefit costs $ 3.6 $ 3.6 $ 3.6 Unamortized purchased gas adjustments 7.1 25.4 2.7 Other 13.6 23.3 17.9 Total Current Regulatory Liabilities 24.3 52.3 24.2 Noncurrent: Deferred taxes due to customers 156.8 162.5 138.3 Pension and postretirement benefit costs 130.7 119.1 79.4 Accrued cost of removal 4.8 15.7 26.8 Unamortized purchased gas adjustments 82.6 — 75.7 Other 25.5 29.2 24.9 Total Noncurrent Regulatory Liabilities 400.4 326.5 345.1 Total Regulatory Liabilities $ 424.7 $ 378.8 $ 369.3 March 31, September 30, March 31, Spire Alabama 2020 2019 2019 Regulatory Assets: Current: Pension and postretirement benefit costs $ 7.2 $ 7.3 $ 7.3 Unamortized purchased gas adjustments 10.4 17.7 18.0 Other 5.7 8.9 5.1 Total Current Regulatory Assets 23.3 33.9 30.4 Noncurrent: Pension and postretirement benefit costs 72.6 77.2 61.1 Cost of removal 154.3 150.9 134.6 Other 3.2 3.1 3.2 Total Noncurrent Regulatory Assets 230.1 231.2 198.9 Total Regulatory Assets $ 253.4 $ 265.1 $ 229.3 Regulatory Liabilities: Current: Pension and postretirement benefit costs $ 2.2 $ 2.2 $ 2.2 Other 0.2 1.2 3.9 Total Current Regulatory Liabilities 2.4 3.4 6.1 Noncurrent: Pension and postretirement benefit costs 17.8 19.1 26.5 Other 3.8 3.9 4.0 Total Noncurrent Regulatory Liabilities 21.6 23.0 30.5 Total Regulatory Liabilities $ 24.0 $ 26.4 $ 36.6
Schedule of Regulatory Assets Not Earning a Return	A portion of the Company’s and Spire Missouri’s regulatory assets are not earning a return, as shown in the table below: March 31, September 30, March 31, 2020 2019 2019 Spire Pension and postretirement benefit costs $ 226.2 $ 211.1 $ 144.7 Future income taxes due from customers 113.5 108.8 102.2 Other 13.7 14.3 14.8 Total Regulatory Assets Not Earning a Return $ 353.4 $ 334.2 $ 261.7 Spire Missouri Pension and postretirement benefit costs $ 226.2 $ 211.1 $ 144.7 Future income taxes due from customers 106.8 102.9 99.0 Other 13.7 14.3 14.8 Total Regulatory Assets Not Earning a Return $ 346.7 $ 328.3 $ 258.5

Financing Arrangements and Lo_2

Financing Arrangements and Long-term Debt (Tables)	6 Months Ended
	Mar. 31, 2020
Debt Disclosure [Abstract]
Schedule of Spire Missouri and Alabama Short-term Borrowings	Information about Spire’s consolidated short-term borrowings and about Spire Missouri’s and Spire Alabama’s borrowings from Spire is presented in the following table. As of March 31, 2020, $91.7 of Spire’s short-term borrowings were used to support lending to the Utilities. Spire (Parent Only) Spire Missouri Spire Alabama Spire Credit Term CP Credit Spire Credit Spire Consol- Facility Loan Program Facility Note Facility Note idated Six Months Ended March 31, 2020 Weighted average borrowings outstanding $ 0.2 $ 5.7 $ 615.6 $ 12.0 $ 283.9 $ 2.9 $ 97.4 $ 636.4 Lowest borrowings outstanding — — 175.5 — 39.6 — 18.5 436.1 Highest borrowings outstanding 23.1 150.0 856.6 185.1 429.5 50.0 161.3 856.6 Weighted average interest rate 1.9 % 2.1 % 2.1 % 1.8 % 2.1 % 1.8 % 2.1 % 2.1 % As of March 31, 2020 Borrowings outstanding $ — $ 150.0 $ 175.5 $ 185.1 $ 39.6 $ 50.0 $ 33.0 $ 560.6 Weighted average interest rate n/a 2.1 % 1.8 % 1.8 % 1.9 % 1.9 % 1.9 % 1.9 % As of September 30, 2019 Borrowings outstanding $ — $ — $ 743.2 $ — $ 386.4 $ — $ 128.7 $ 743.2 Weighted average interest rate n/a n/a 2.3 % n/a 2.3 % n/a 2.3 % 2.3 % As of March 31, 2019 Borrowings outstanding $ — $ — $ 512.0 $ — $ 232.9 $ — $ 73.7 $ 512.0 Weighted average interest rate n/a n/a 2.8 % n/a 2.8 % n/a 2.8 % 2.8 %
Summary Capitalized Interest	Interest expense shown on Spire’s consolidated statements of income and Spire Missouri’s statements of comprehensive income is net of the capitalized interest amounts shown in the following table. Three Months Ended March 31, Six Months Ended March 31, 2020 2019 2020 2019 Spire $ 1.4 $ 1.4 $ 3.6 $ 2.6 Spire Missouri 0.3 0.4 0.6 0.9 Spire Alabama 0.4 — 1.0 —

Fair Value of Financial Instr_2

Fair Value of Financial Instruments (Tables)	6 Months Ended
	Mar. 31, 2020
Fair Value Disclosures [Abstract]
Summary of Financial Instruments 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 March 31, 2020, September 30, 2019, and March 31, 2019. Classification of Estimated Fair Value Carrying Amount Fair Value Quoted Prices in Active Markets (Level 1) Significant Observable Inputs (Level 2) Spire As of March 31, 2020 Cash and cash equivalents $ 108.4 $ 108.4 $ 108.4 $ — Notes payable 560.6 560.6 — 560.6 Long-term debt, including current portion 2,490.2 2,671.0 — 2,671.0 As of September 30, 2019 Cash and cash equivalents $ 5.8 $ 5.8 $ 5.8 $ — Notes payable 743.2 743.2 — 743.2 Long-term debt, including current portion 2,122.6 2,373.4 — 2,373.4 As of March 31, 2019 Cash and cash equivalents $ 11.1 $ 11.1 $ 11.1 $ — Notes payable 512.0 512.0 — 512.0 Long-term debt, including current portion 2,256.9 2,319.9 — 2,319.9 Spire Missouri As of March 31, 2020 Cash and cash equivalents $ 5.1 $ 5.1 $ 5.1 $ — Notes payable 185.1 185.1 — 185.1 Notes payable – associated companies 39.6 39.6 — 39.6 Long-term debt 1,098.7 1,231.2 — 1,231.2 As of September 30, 2019 Cash and cash equivalents $ 2.6 $ 2.6 $ 2.6 $ — Notes payable – 386.4 386.4 — 386.4 Long-term debt 925.0 1,065.2 — 1,065.2 As of March 31, 2019 Cash and cash equivalents $ 6.9 $ 6.9 $ 6.9 $ — Notes payable – 232.9 232.9 — 232.9 Long-term debt, including current portion 974.7 1,036.9 — 1,036.9 Spire Alabama As of March 31, 2020 Cash and cash equivalents $ 0.1 $ 0.1 $ 0.1 $ — Notes payable 50.0 50.0 — 50.0 Notes payable – 33.0 33.0 — 33.0 Long-term debt 471.7 535.1 — 535.1 As of September 30, 2019 Notes payable – $ 128.7 $ 128.7 $ — $ 128.7 Long-term debt, including current portion 412.2 474.8 — 474.8 As of March 31, 2019 Cash and cash equivalents $ 0.1 $ 0.1 $ 0.1 $ — Notes payable – 73.7 73.7 — 73.7 Long-term debt, including current portion 412.1 423.8 — 423.8

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Mar. 31, 2020
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Schedule of Fair Value Assets and Liabilities Measured on Recurring Basis	The information presented below 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 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). Derivative instruments classified in Level 2 include physical commodity derivatives that are valued using broker or dealer quotation services 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 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. The Level 3 balances as of March 31, 2020, September 30, 2019, and March 31, 2019, consisted of gas commodity contracts. The Company’s and the Utilities’ 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 are included in “Other Investments” on the Company’s balance sheets and in “Other Property and Investments” on Spire Missouri’s balance sheets. 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. Spire Quoted Prices in Active Markets (Level 1) Significant Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Effects of Netting and Cash Margin Receivables /Payables Total As of March 31, 2020 ASSETS Gas Utility: U.S. stock/bond mutual funds $ 18.1 $ — $ — $ — $ 18.1 NYMEX/ICE natural gas contracts 0.1 — — (0.1 ) — Gas Marketing: NYMEX/ICE natural gas contracts 0.2 6.8 — (7.0 ) — Natural gas commodity contracts — 17.5 — (4.8 ) 12.7 Other: U.S. stock/bond mutual funds 17.6 — — — 17.6 Total $ 36.0 $ 24.3 $ — $ (11.9 ) $ 48.4 LIABILITIES Gas Utility: NYMEX/ICE natural gas contracts $ 12.2 $ — $ — $ (12.2 ) $ — Gasoline and heating oil contracts 0.4 — — (0.4 ) — Gas Marketing: NYMEX/ICE natural gas contracts 0.5 8.4 — (8.9 ) — Natural gas commodity contracts — 27.7 1.1 (4.8 ) 24.0 Other: Interest rate swaps — 66.9 — — 66.9 Total $ 13.1 $ 103.0 $ 1.1 $ (26.3 ) $ 90.9 Quoted Prices in Active Markets (Level 1) Significant Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Effects of Netting and Cash Margin Receivables /Payables Total As of September 30, 2019 ASSETS Gas Utility: U.S. stock/bond mutual funds $ 20.5 $ — $ — $ — $ 20.5 Gas Marketing: NYMEX/ICE natural gas contracts 0.9 6.5 — (6.9 ) 0.5 Natural gas commodity contracts — 16.8 — (2.5 ) 14.3 Other: U.S. stock/bond mutual funds 15.5 — — — 15.5 Total $ 36.9 $ 23.3 $ — $ (9.4 ) $ 50.8 LIABILITIES Gas Utility: NYMEX/ICE natural gas contracts $ 12.3 $ — $ — $ (12.3 ) $ — Gas Marketing: NYMEX/ICE natural gas contracts 0.4 8.5 — (8.9 ) — Natural gas commodity contracts — 13.8 0.1 (2.5 ) 11.4 Other: Interest rate swaps — 43.4 — — 43.4 Total $ 12.7 $ 65.7 $ 0.1 $ (23.7 ) $ 54.8 As of March 31, 2019 ASSETS Gas Utility: U.S. stock/bond mutual funds $ 19.7 $ — $ — $ — $ 19.7 NYMEX/ICE natural gas contracts 2.5 — — (2.5 ) — Gas Marketing: NYMEX/ICE natural gas contracts 0.2 7.1 — (4.3 ) 3.0 Natural gas commodity contracts — 30.4 — (3.4 ) 27.0 Other: U.S. stock/bond mutual funds 11.9 — — — 11.9 Total $ 34.3 $ 37.5 $ — $ (10.2 ) $ 61.6 LIABILITIES Gas Marketing: NYMEX/ICE natural gas contracts $ 0.4 $ 4.1 $ — $ (4.5 ) $ — Natural gas commodity contracts — 18.9 0.2 (3.5 ) 15.6 Other: Interest rate swaps — 15.2 — — 15.2 Total $ 0.4 $ 38.2 $ 0.2 $ (8.0 ) $ 30.8
Spire Missouri
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Schedule of Fair Value Assets and Liabilities Measured on Recurring Basis	Quoted Prices in Active Markets (Level 1) Significant Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Effects of Netting and Cash Margin Receivables /Payables Total As of March 31, 2020 ASSETS U.S. stock/bond mutual funds $ 18.1 $ — $ — $ — $ 18.1 NYMEX/ICE natural gas contracts 0.1 — — (0.1 ) — Total $ 18.2 $ — $ — $ (0.1 ) $ 18.1 LIABILITIES NYMEX/ICE natural gas contracts $ 12.2 $ — $ — $ (12.2 ) $ — Gasoline and heating oil contracts 0.4 — — (0.4 ) — Total $ 12.6 $ — $ — $ (12.6 ) $ — As of September 30, 2019 ASSETS U.S. stock/bond mutual funds $ 20.5 $ — $ — $ — $ 20.5 LIABILITIES NYMEX/ICE natural gas contracts $ 12.3 $ — $ — $ (12.3 ) $ — As of March 31, 2019 ASSETS U.S. stock/bond mutual funds $ 19.7 $ — $ — $ — $ 19.7 NYMEX/ICE natural gas contracts 2.5 — — (2.5 ) — Total $ 22.2 $ — $ — $ (2.5 ) $ 19.7

Pension Plans and Other Postr_2

Pension Plans and Other Postretirement Benefits (Tables)	6 Months Ended
	Mar. 31, 2020
Pension Plans
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Net periodic cost	The net periodic pension cost included the following components: Three Months Ended March 31, Six Months Ended March 31, 2020 2019 2020 2019 Spire Service cost – benefits earned during the period $ 5.6 $ 4.9 $ 11.1 $ 9.7 Interest cost on projected benefit obligation* 5.8 7.0 11.7 14.1 Expected return on plan assets* (9.0 ) (8.9 ) (18.2 ) (18.0 ) Amortization of prior service credit* (0.6 ) (0.3 ) (1.2 ) (0.6 ) Amortization of actuarial loss* 3.9 2.3 7.6 4.6 Loss on lump-sum settlements* 21.0 — 21.0 — Subtotal 26.7 5.0 32.0 9.8 Regulatory adjustment (11.3 ) 9.8 (1.7 ) 19.7 Net pension cost $ 15.4 $ 14.8 $ 30.3 $ 29.5 Spire Missouri Service cost – benefits earned during the period $ 3.9 $ 3.1 $ 7.7 $ 6.2 Interest cost on projected benefit obligation* 4.0 4.9 8.2 9.9 Expected return on plan assets* (6.3 ) (6.3 ) (12.9 ) (12.7 ) Amortization of prior service cost* 0.1 0.2 0.1 0.4 Amortization of actuarial loss* 3.1 2.2 6.0 4.3 Loss on lump-sum settlements* 21.0 — 21.0 — Subtotal 25.8 4.1 30.1 8.1 Regulatory adjustment (13.2 ) 7.9 (5.5 ) 15.9 Net pension cost $ 12.6 $ 12.0 $ 24.6 $ 24.0 Spire Alabama Service cost – benefits earned during the period $ 1.5 $ 1.6 $ 3.0 $ 3.1 Interest cost on projected benefit obligation* 1.3 1.5 2.5 3.0 Expected return on plan assets* (1.8 ) (1.8 ) (3.5 ) (3.6 ) Amortization of prior service credit* (0.6 ) (0.5 ) (1.2 ) (0.9 ) Amortization of actuarial loss* 0.8 0.2 1.6 0.4 Subtotal 1.2 1.0 2.4 2.0 Regulatory adjustment 1.7 1.7 3.4 3.4 Net pension cost $ 2.9 $ 2.7 $ 5.8 $ 5.4 * Denotes pension expense line items that are recorded below the operating income line in the income statements, in the line item “Other Income (Expense), Net.”
Other Postretirement Plans
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Net periodic cost	Net periodic postretirement benefit costs consisted of the following components: Three Months Ended March 31, Six Months Ended March 31, 2020 2019 2020 2019 Spire Service cost – benefits earned during the period $ 1.5 $ 1.8 $ 2.9 $ 3.7 Interest cost on accumulated postretirement benefit obligation* 1.5 2.1 3.1 4.4 Expected return on plan assets* (4.1 ) (3.9 ) (8.2 ) (8.0 ) Amortization of prior service credit* (0.1 ) (0.1 ) (0.3 ) (0.1 ) Amortization of actuarial gain* (0.5 ) (0.2 ) (1.0 ) (0.3 ) Subtotal (1.7 ) (0.3 ) (3.5 ) (0.3 ) Regulatory adjustment 4.0 2.6 8.0 5.0 Net postretirement benefit cost $ 2.3 $ 2.3 $ 4.5 $ 4.7 Spire Missouri Service cost – benefits earned during the period $ 1.3 $ 1.7 $ 2.6 $ 3.4 Interest cost on accumulated postretirement benefit obligation* 1.1 1.7 2.3 3.4 Expected return on plan assets* (2.9 ) (2.7 ) (5.7 ) (5.5 ) Amortization of prior service (credit) cost* — — (0.1 ) 0.1 Amortization of actuarial gain* (0.5 ) (0.2 ) (1.0 ) (0.3 ) Subtotal (1.0 ) 0.5 (1.9 ) 1.1 Regulatory adjustment 4.5 3.0 8.9 5.9 Net postretirement benefit cost $ 3.5 $ 3.5 $ 7.0 $ 7.0 Spire Alabama Service cost – benefits earned during the period $ 0.1 $ 0.1 $ 0.2 $ 0.2 Interest cost on accumulated postretirement benefit obligation* 0.4 0.4 0.7 0.9 Expected return on plan assets* (1.2 ) (1.2 ) (2.4 ) (2.4 ) Amortization of prior service credit* (0.1 ) (0.1 ) (0.2 ) (0.2 ) Subtotal (0.8 ) (0.8 ) (1.7 ) (1.5 ) Regulatory adjustment (0.5 ) (0.4 ) (0.9 ) (0.9 ) Net postretirement benefit income $ (1.3 ) $ (1.2 ) $ (2.6 ) $ (2.4 ) * Denotes other postretirement expense line items that are recorded below the operating income line in the income statements, in the line item “Other Income (Expense), Net.”

Information by Operating Segm_2

Information by Operating Segment (Tables)	6 Months Ended
	Mar. 31, 2020
Segment Reporting [Abstract]
Schedule of Operating Segment Information	Gas Utility Gas Marketing Other Eliminations Consolidated Three Months Ended March 31, 2020 Operating Revenues: Revenues from external customers $ 679.1 $ 33.3 $ 3.1 $ — $ 715.5 Intersegment revenues (0.1 ) — 11.6 (11.5 ) — Total Operating Revenues 679.0 33.3 14.7 (11.5 ) 715.5 Operating Expenses: Gas Utility Natural and propane gas 271.6 — — (22.6 ) 249.0 Operation and maintenance 95.8 — — (2.7 ) 93.1 Depreciation and amortization 47.0 — — — 47.0 Taxes, other than income taxes 51.7 — — — 51.7 Total Gas Utility Operating Expenses 466.1 — — (25.3 ) 440.8 Gas Marketing and Other — 37.7 12.7 13.8 64.2 Total Operating Expenses 466.1 37.7 12.7 (11.5 ) 505.0 Operating Income $ 212.9 $ (4.4 ) $ 2.0 $ — $ 210.5 Net Economic Earnings (Loss) $ 144.3 $ 5.1 $ (5.4 ) $ — $ 144.0 Gas Utility Gas Marketing Other Eliminations Consolidated Three Months Ended March 31, 2019 Operating Revenues: Revenues from external customers $ 776.7 $ 25.4 $ 1.4 $ — $ 803.5 Intersegment revenues 0.1 0.1 2.9 (3.1 ) — Total Operating Revenues 776.8 25.5 4.3 (3.1 ) 803.5 Operating Expenses: Gas Utility Natural and propane gas 366.7 — — (29.3 ) 337.4 Operation and maintenance 112.0 — — (2.5 ) 109.5 Depreciation and amortization 44.4 — — — 44.4 Taxes, other than income taxes 57.4 — — — 57.4 Total Gas Utility Operating Expenses 580.5 — — (31.8 ) 548.7 Gas Marketing and Other — 8.7 7.9 28.7 45.3 Total Operating Expenses 580.5 8.7 7.9 (3.1 ) 594.0 Operating Income (Loss) $ 196.3 $ 16.8 $ (3.6 ) $ — $ 209.5 Net Economic Earnings (Loss) $ 146.7 $ 6.2 $ (5.0 ) $ — $ 147.9 Gas Utility Gas Marketing Other Eliminations Consolidated Six Months Ended March 31, 2020 Operating Revenues: Revenues from external customers $ 1,209.7 $ 65.6 $ 7.1 $ — $ 1,282.4 Intersegment revenues — — 18.7 (18.7 ) — Total Operating Revenues 1,209.7 65.6 25.8 (18.7 ) 1,282.4 Operating Expenses: Gas Utility Natural and propane gas 513.1 — — (49.5 ) 463.6 Operation and maintenance 204.4 — — (5.3 ) 199.1 Depreciation and amortization 93.4 — — — 93.4 Taxes, other than income taxes 89.6 — — — 89.6 Total Gas Utility Operating Expenses 900.5 — — (54.8 ) 845.7 Gas Marketing and Other — 65.6 22.2 36.1 123.9 Total Operating Expenses 900.5 65.6 22.2 (18.7 ) 969.6 Operating Income (Loss) $ 309.2 $ — $ 3.6 $ — $ 312.8 Net Economic Earnings (Loss) $ 213.4 $ 11.2 $ (8.8 ) $ — $ 215.8 Gas Utility Gas Marketing Other Eliminations Consolidated Six Months Ended March 31, 2019 Operating Revenues: Revenues from external customers $ 1,350.5 $ 51.2 $ 3.8 $ — $ 1,405.5 Intersegment revenues 1.5 0.1 5.9 (7.5 ) — Total Operating Revenues 1,352.0 51.3 9.7 (7.5 ) 1,405.5 Operating Expenses: Gas Utility Natural and propane gas 658.5 — — (69.4 ) 589.1 Operation and maintenance 216.9 — — (4.9 ) 212.0 Depreciation and amortization 88.1 — — — 88.1 Taxes, other than income taxes 96.6 — — — 96.6 Total Gas Utility Operating Expenses 1,060.1 — — (74.3 ) 985.8 Gas Marketing and Other — 22.0 16.3 66.8 105.1 Total Operating Expenses 1,060.1 22.0 16.3 (7.5 ) 1,090.9 Operating Income (Loss) $ 291.9 $ 29.3 $ (6.6 ) $ — $ 314.6 Net Economic Earnings (Loss) $ 213.1 $ 14.5 $ (13.8 ) $ — $ 213.8 The Company’s total assets by segment were as follows: March 31, September 30, March 31, 2020 2019 2019 Total Assets: Gas Utility $ 6,311.6 $ 6,094.6 $ 5,850.1 Gas Marketing 159.3 212.3 366.7 Other 2,214.7 2,692.7 2,396.8 Eliminations (667.6 ) (1,380.4 ) (1,340.0 ) Total Assets $ 8,018.0 $ 7,619.2 $ 7,273.6
Schedule of Reconciliation of Consolidated Net Economic Earnings to Consolidated Net Income	The following table reconciles the Company’s net economic earnings to net income. Three Months Ended March 31, Six Months Ended March 31, 2020 2019 2020 2019 Net Income $ 133.6 $ 154.6 $ 200.6 $ 221.9 Adjustments, pre-tax: Provision for ISRS rulings 2.2 — 4.8 — Unrealized loss (gain) on energy-related derivatives 11.6 (9.1 ) 15.3 (11.3 ) Acquisition, divestiture and restructuring activities — — — 0.4 Income tax effect of adjustments (3.4 ) 2.4 (4.9 ) 2.8 Net Economic Earnings $ 144.0 $ 147.9 $ 215.8 $ 213.8

Leases (Tables)

Leases (Tables)	6 Months Ended
	Mar. 31, 2020
Leases [Abstract]
Operating Lease Cost Cash Flow and Noncash Information	Operating lease cost, cash flow and noncash information for the three and six months ended March 31, 2020 are shown in the following tables. Three Months Ended March 31, 2020 Spire Spire Missouri Spire Alabama Operating lease cost, including amounts capitalized $ 2.4 $ 0.1 $ 1.1 Cash flow and noncash information about operating leases: Operating cash flows representing cash paid for amounts included in the measurement of lease liabilities 2.2 0.1 0.9 Right-of-use assets obtained in exchange for lease liabilities — — — Six Months Ended March 31, 2020 Spire Spire Missouri Spire Alabama Operating lease cost, including amounts capitalized $ 4.8 $ 0.3 $ 2.1 Cash flow and noncash information about operating leases: Operating cash flows representing cash paid for amounts included in the measurement of lease liabilities 4.5 0.3 1.9 Right-of-use assets obtained in exchange for lease liabilities 71.1 2.1 10.0
Summary of Balance Sheet and Weighted-Average Information about Operating Leases	The following table shows balance sheet and weighted-average information about operating leases as of March 31, 2020. Balance sheet classification Spire Spire Missouri Spire Alabama Right-of-use assets Deferred Charges and Other Assets: Other $ 67.7 $ 1.9 $ 8.0 Lease liabilities, current Current Liabilities, Other 6.9 0.3 2.3 Lease liabilities, noncurrent Deferred Credits and Other Liabilities: Other 60.6 1.5 5.6 Weighted-average remaining lease term 16.1 years 5.8 years 3.7 years Weighted-average discount rate 4.1 % 2.5 % 2.2 %
Schedule of Maturity Analysis for Operating Lease Liabilities	Following is a maturity analysis by fiscal year for operating lease liabilities as of March 31, 2020. Spire Spire Missouri Spire Alabama Remainder of 2020 $ 3.4 $ 0.1 $ 1.2 2021 7.2 0.4 2.1 2022 7.2 0.4 2.1 2023 7.2 0.3 2.1 2024 5.8 0.3 0.7 2025 5.1 0.3 — Thereafter 58.4 0.2 — Total undiscounted lease payments 94.3 2.0 8.2 Less present value discount (26.8 ) (0.2 ) (0.3 ) Total current and noncurrent lease liabilities $ 67.5 $ 1.8 $ 7.9
Schedule of Annual Minimum Rental Commitments for Operating Leases	As of September 30, 2019, the annual minimum rental commitments for operating leases (under ASC 840) were as follows. 2020 2021 2022 2023 2024 Later Total Spire $ 8.2 $ 7.0 $ 6.8 $ 6.1 $ 4.8 $ 36.5 $ 69.4 Spire Missouri 0.5 0.2 — — — — 0.7 Spire Alabama 2.9 2.1 2.1 2.1 0.7 — 9.9

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Additional Information (Details) $ in Millions	3 Months Ended	6 Months Ended
	Mar. 31, 2020USD ($)	Mar. 31, 2020USD ($)	Mar. 31, 2020reporting_unit	Mar. 31, 2020operating-segment
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Number of reportable segments			2	2
Affiliated Entity | Spire Marketing | Spire Alabama | Regulated Operation
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Purchases of natural gas from related party	$ 1	$ 4.3

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Schedule of Inter-Company Transactions (Details) - Affiliated Entity - Spire Missouri - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Spire Marketing Inc | Regulated Operation
Related Party Transaction [Line Items]
Purchases of natural gas from Spire Marketing Inc.	$ 13.3	$ 29.2	$ 32.8	$ 69
Sales of natural gas to Spire Marketing Inc.				1.4
Spire STL Pipeline LLC | Unregulated Operation
Related Party Transaction [Line Items]
Transportation services received from	7.9		11.8
Spire NGL Inc. | Unregulated Operation
Related Party Transaction [Line Items]
Transportation services received from	$ 0.2	$ 0.2	$ 0.5	$ 0.5

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Accrued Capital Expenditures (Details) - USD ($) $ in Millions	6 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Sep. 30, 2019
Schedule Of Accrued Capital Expenditures Excluded From Statement Of Cash Flow [Line Items]
Accruals for capital expenditures	$ 51.4	$ 63.6	$ 80.6
Spire Missouri
Schedule Of Accrued Capital Expenditures Excluded From Statement Of Cash Flow [Line Items]
Accruals for capital expenditures	21.5	19	40.1
Spire Alabama
Schedule Of Accrued Capital Expenditures Excluded From Statement Of Cash Flow [Line Items]
Accruals for capital expenditures	$ 17.6	$ 12.1	$ 11.9

Revenue - Schedule of Revenue D

Revenue - Schedule of Revenue Disaggregated by Source and Customer Type (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Disaggregation Of Revenue [Line Items]
Total operating revenues	$ 679.1	$ 776.7	$ 1,209.7	$ 1,350.5
Total operating revenues	36.4	26.8	72.7	55
Total operating revenues	715.5	803.5	1,282.4	1,405.5
Intersegment Eliminations
Disaggregation Of Revenue [Line Items]
Total operating revenues	(11.5)	(3.1)	(18.7)	(7.5)
Gas Utility
Disaggregation Of Revenue [Line Items]
Total operating revenues	679.1	776.7	1,209.7	1,350.5
Gas Utility | Operating Segments
Disaggregation Of Revenue [Line Items]
Total operating revenues	679	776.8	1,209.7	1,352
Gas Utility | Intersegment Eliminations
Disaggregation Of Revenue [Line Items]
Total operating revenues	(0.1)	0.1	0	1.5
Gas Marketing
Disaggregation Of Revenue [Line Items]
Total operating revenues	33.3	25.4	65.6	51.2
Gas Marketing | Operating Segments
Disaggregation Of Revenue [Line Items]
Total operating revenues	33.3	25.5	65.6	51.3
Gas Marketing | Intersegment Eliminations
Disaggregation Of Revenue [Line Items]
Total operating revenues	0	0.1	0	0.1
Spire
Disaggregation Of Revenue [Line Items]
Total operating revenues	715.5	803.5	1,282.4	1,405.5
Spire | Operating Segments
Disaggregation Of Revenue [Line Items]
Total operating revenues	727	806.6	1,301.1	1,413
Spire | Intersegment Eliminations
Disaggregation Of Revenue [Line Items]
Total operating revenues	(11.5)	(3.1)	(18.7)	(7.5)
Spire | Gas Utility | Operating Segments
Disaggregation Of Revenue [Line Items]
Total operating revenues	673.7	790.9	1,207.4	1,371.9
Changes in accrued revenue under alternative revenue programs	5.3	(14.1)	2.3	(19.9)
Total operating revenues	679	776.8	1,209.7	1,352
Spire | Gas Utility | Operating Segments | Residential
Disaggregation Of Revenue [Line Items]
Total operating revenues	471.9	551.3	840.3	944.9
Spire | Gas Utility | Operating Segments | Commercial & Industrial
Disaggregation Of Revenue [Line Items]
Total operating revenues	156.8	185.9	279.3	316.2
Spire | Gas Utility | Operating Segments | Transportation
Disaggregation Of Revenue [Line Items]
Total operating revenues	32.5	31.3	63.5	60.8
Spire | Gas Utility | Operating Segments | Off-system & Other Incentive
Disaggregation Of Revenue [Line Items]
Total operating revenues	9.3	11.5	18.7	26.4
Spire | Gas Utility | Operating Segments | Other Customer Revenue
Disaggregation Of Revenue [Line Items]
Total operating revenues	3.2	10.9	5.6	23.6
Spire | Gas Marketing | Operating Segments
Disaggregation Of Revenue [Line Items]
Total operating revenues	33.3	25.5	65.6	51.3
Spire | Gas Marketing | Operating Segments | Revenue From Contracts With Retail Customers
Disaggregation Of Revenue [Line Items]
Total operating revenues	33.3	25.5	65.6	51.3
Spire | Other | Operating Segments
Disaggregation Of Revenue [Line Items]
Total operating revenues	$ 14.7	$ 4.3	$ 25.8	$ 9.7

Revenue - Schedule of Operating

Revenue - Schedule of Operating Revenue Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Disaggregation Of Revenue [Line Items]
Total Operating Revenues	$ 715.5	$ 803.5	$ 1,282.4	$ 1,405.5
Spire Missouri
Disaggregation Of Revenue [Line Items]
Total operating revenues	450.2	565.7	825.8	983.4
Changes in accrued revenue under alternative revenue programs	7.3	(9.1)	5.7	(13.6)
Total Operating Revenues	457.5	556.6	831.5	969.8
Spire Missouri | Residential
Disaggregation Of Revenue [Line Items]
Total operating revenues	331.1	410.9	607	713
Spire Missouri | Commercial & Industrial
Disaggregation Of Revenue [Line Items]
Total operating revenues	99.2	129.2	180	218.3
Spire Missouri | Transportation
Disaggregation Of Revenue [Line Items]
Total operating revenues	9.7	9.9	18.7	18.9
Spire Missouri | Off-system & Other Incentive
Disaggregation Of Revenue [Line Items]
Total operating revenues	9.3	11.5	18.7	26.4
Spire Missouri | Other Customer Revenue
Disaggregation Of Revenue [Line Items]
Total operating revenues	0.9	4.2	1.4	6.8
Spire Alabama
Disaggregation Of Revenue [Line Items]
Total operating revenues	188.3	185.1	315.1	319.7
Changes in accrued revenue under alternative revenue programs	(2.8)	(4.7)	(3.4)	(5.8)
Total Operating Revenues	185.5	180.4	311.7	313.9
Spire Alabama | Residential
Disaggregation Of Revenue [Line Items]
Total operating revenues	120.5	116.9	194.8	192.3
Spire Alabama | Commercial & Industrial
Disaggregation Of Revenue [Line Items]
Total operating revenues	46.2	44.1	77.5	75.5
Spire Alabama | Transportation
Disaggregation Of Revenue [Line Items]
Total operating revenues	19.9	18.8	39.5	37
Spire Alabama | Other Customer Revenue
Disaggregation Of Revenue [Line Items]
Total operating revenues	$ 1.7	$ 5.3	$ 3.3	$ 14.9

Revenue - Schedule of Gross Rec

Revenue - Schedule of Gross Receipts Taxes (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Scheduleof Gross Receipts Taxes [Line Items]
Gross receipts taxes recorded in regulated gas distribution operating revenues	$ 37.9	$ 43.5	$ 62.5	$ 69.4
Spire Missouri
Scheduleof Gross Receipts Taxes [Line Items]
Gross receipts taxes recorded in regulated gas distribution operating revenues	26.2	32.1	43.4	50.6
Spire Alabama
Scheduleof Gross Receipts Taxes [Line Items]
Gross receipts taxes recorded in regulated gas distribution operating revenues	$ 9.9	$ 9.6	$ 16.1	$ 15.9

Earnings Per Common Share - Sch

Earnings Per Common Share - Schedule of Basic and Diluted Earnings Per Common Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Basic Earnings Per Common Share:
Net Income	$ 133.6	$ 154.6	$ 200.6	$ 221.9
Less: Provision for preferred dividends	3.7		7.4
Income allocated to participating securities	0.2	0.3	0.3	0.5
Net Income Available to Common Shareholders	$ 129.7	$ 154.3	$ 192.9	$ 221.4
Weighted Average Common Shares Outstanding (in millions)	51	50.6	51	50.6
Basic Earnings Per Common Share	$ 2.55	$ 3.05	$ 3.78	$ 4.37
Diluted Earnings Per Common Share:
Net Income	$ 133.6	$ 154.6	$ 200.6	$ 221.9
Less: Provision for preferred dividends	3.7		7.4
Income allocated to participating securities	0.2	0.3	0.3	0.5
Income Available to Common Shareholders	$ 129.7	$ 154.3	$ 192.9	$ 221.4
Weighted Average Common Shares Outstanding (in millions)	51	50.6	51	50.6
Dilutive Effect of Restricted Stock and Restricted Stock Units (in millions)	0.1	0.2	0.1	0.2
Weighted Average Diluted Common Shares (in millions)	51.1	50.8	51.1	50.8
Diluted Earnings Per Common Share	$ 2.54	$ 3.04	$ 3.77	$ 4.36

Earnings Per Common Share - S_2

Earnings Per Common Share - Schedule of Basic and Diluted Earnings Per Common Share (Parenthetical) (Details) - shares shares in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Restricted Stock and Restricted Stock Units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Outstanding common shares excluded from calculation of diluted EPS (in shares)	0.1	0.3	0.1	0.3

Regulatory Matters - Schedule o

Regulatory Matters - Schedule of Regulatory Assets and Liabilities, Reflected in Balance Sheets (Details) - USD ($) $ in Millions	Mar. 31, 2020	Sep. 30, 2019	Mar. 31, 2019
Regulatory Asset And Liabilities [Line Items]
Regulatory assets, current	$ 68	$ 78.6	$ 75.3
Regulatory assets, non current	770.7	767.6	659.9
Total Regulatory Assets	838.7	846.2	735.2
Regulatory liabilities, current	31.8	60.8	35.3
Regulatory liabilities, non current	472.3	399	431.3
Total Regulatory Liabilities	504.1	459.8	466.6
Spire Missouri
Regulatory Asset And Liabilities [Line Items]
Regulatory assets, current	29.4	29.4	30
Regulatory assets, non current	512.1	507.5	433.6
Total Regulatory Assets	541.5	536.9	463.6
Regulatory liabilities, current	24.3	52.3	24.2
Regulatory liabilities, non current	400.4	326.5	345.1
Total Regulatory Liabilities	424.7	378.8	369.3
Spire Alabama
Regulatory Asset And Liabilities [Line Items]
Regulatory assets, current	23.3	33.9	30.4
Regulatory assets, non current	230.1	231.2	198.9
Total Regulatory Assets	253.4	265.1	229.3
Regulatory liabilities, current	2.4	3.4	6.1
Regulatory liabilities, non current	21.6	23	30.5
Total Regulatory Liabilities	24	26.4	36.6
Pension and Other Postretirement Benefits
Regulatory Asset And Liabilities [Line Items]
Regulatory assets, current	30.1	30.1	30.2
Regulatory assets, non current	415.6	416.6	345.8
Pension and Other Postretirement Benefits | Spire Missouri
Regulatory Asset And Liabilities [Line Items]
Regulatory assets, current	21.9	21.9	21.9
Regulatory assets, non current	337.5	333.3	277.9
Pension and Other Postretirement Benefits | Spire Alabama
Regulatory Asset And Liabilities [Line Items]
Regulatory assets, current	7.2	7.3	7.3
Regulatory assets, non current	72.6	77.2	61.1
Unamortized Purchased Gas Adjustments
Regulatory Asset And Liabilities [Line Items]
Regulatory assets, current	10.4	18.2	19.3
Regulatory assets, non current	0	9.1	0
Unamortized Purchased Gas Adjustments | Spire Missouri
Regulatory Asset And Liabilities [Line Items]
Regulatory assets, current	0	0	0.6
Regulatory assets, non current	0	9.1	0
Unamortized Purchased Gas Adjustments | Spire Alabama
Regulatory Asset And Liabilities [Line Items]
Regulatory assets, current	10.4	17.7	18
Other
Regulatory Asset And Liabilities [Line Items]
Regulatory assets, current	27.5	30.3	25.8
Regulatory assets, non current	49.6	47.2	45.3
Other | Spire Missouri
Regulatory Asset And Liabilities [Line Items]
Regulatory assets, current	7.5	7.5	7.5
Regulatory assets, non current	30.1	27.2	24.7
Other | Spire Alabama
Regulatory Asset And Liabilities [Line Items]
Regulatory assets, current	5.7	8.9	5.1
Regulatory assets, non current	3.2	3.1	3.2
Future Income Taxes Due from Customers
Regulatory Asset And Liabilities [Line Items]
Regulatory assets, non current	113.5	108.8	102.2
Future Income Taxes Due from Customers | Spire Missouri
Regulatory Asset And Liabilities [Line Items]
Regulatory assets, non current	106.8	102.9	99
Accrued Cost of Removal
Regulatory Asset And Liabilities [Line Items]
Regulatory assets, non current	154.3	150.9	134.6
Accrued Cost of Removal | Spire Alabama
Regulatory Asset And Liabilities [Line Items]
Regulatory assets, non current	154.3	150.9	134.6
Energy Efficiency
Regulatory Asset And Liabilities [Line Items]
Regulatory assets, non current	37.7	35	32
Energy Efficiency | Spire Missouri
Regulatory Asset And Liabilities [Line Items]
Regulatory assets, non current	37.7	35	32
Pension and Other Postretirement Benefits
Regulatory Asset And Liabilities [Line Items]
Regulatory liabilities, current	5.8	5.8	5.8
Regulatory liabilities, non current	152.5	142.3	115.3
Pension and Other Postretirement Benefits | Spire Missouri
Regulatory Asset And Liabilities [Line Items]
Regulatory liabilities, current	3.6	3.6	3.6
Regulatory liabilities, non current	130.7	119.1	79.4
Pension and Other Postretirement Benefits | Spire Alabama
Regulatory Asset And Liabilities [Line Items]
Regulatory liabilities, current	2.2	2.2	2.2
Regulatory liabilities, non current	17.8	19.1	26.5
Unamortized Purchased Gas Adjustments
Regulatory Asset And Liabilities [Line Items]
Regulatory liabilities, current	8	26.2	3.4
Regulatory liabilities, non current	82.6	0	75.7
Unamortized Purchased Gas Adjustments | Spire Missouri
Regulatory Asset And Liabilities [Line Items]
Regulatory liabilities, current	7.1	25.4	2.7
Regulatory liabilities, non current	82.6	0	75.7
Other
Regulatory Asset And Liabilities [Line Items]
Regulatory liabilities, current	18	28.8	26.1
Regulatory liabilities, non current	31.3	35.3	30.9
Other | Spire Missouri
Regulatory Asset And Liabilities [Line Items]
Regulatory liabilities, current	13.6	23.3	17.9
Regulatory liabilities, non current	25.5	29.2	24.9
Other | Spire Alabama
Regulatory Asset And Liabilities [Line Items]
Regulatory liabilities, current	0.2	1.2	3.9
Regulatory liabilities, non current	3.8	3.9	4
Deferred Taxes Due to Customers
Regulatory Asset And Liabilities [Line Items]
Regulatory liabilities, non current	174.2	179.8	155.7
Deferred Taxes Due to Customers | Spire Missouri
Regulatory Asset And Liabilities [Line Items]
Regulatory liabilities, non current	156.8	162.5	138.3
Accrued Cost of Removal
Regulatory Asset And Liabilities [Line Items]
Regulatory liabilities, non current	31.7	41.6	53.7
Accrued Cost of Removal | Spire Missouri
Regulatory Asset And Liabilities [Line Items]
Regulatory liabilities, non current	$ 4.8	$ 15.7	$ 26.8

Regulatory Matters - Schedule_2

Regulatory Matters - Schedule of Regulatory Assets Not Earning a Return (Details) - USD ($) $ in Millions	Mar. 31, 2020	Sep. 30, 2019	Mar. 31, 2019
Regulatory Assets [Line Items]
Total Regulatory Assets Not Earning a Return	$ 353.4	$ 334.2	$ 261.7
Pension and Other Postretirement Benefits
Regulatory Assets [Line Items]
Total Regulatory Assets Not Earning a Return	226.2	211.1	144.7
Future Income Taxes Due from Customers
Regulatory Assets [Line Items]
Total Regulatory Assets Not Earning a Return	113.5	108.8	102.2
Other
Regulatory Assets [Line Items]
Total Regulatory Assets Not Earning a Return	13.7	14.3	14.8
Spire Missouri
Regulatory Assets [Line Items]
Total Regulatory Assets Not Earning a Return	346.7	328.3	258.5
Spire Missouri | Pension and Other Postretirement Benefits
Regulatory Assets [Line Items]
Total Regulatory Assets Not Earning a Return	226.2	211.1	144.7
Spire Missouri | Future Income Taxes Due from Customers
Regulatory Assets [Line Items]
Total Regulatory Assets Not Earning a Return	106.8	102.9	99
Spire Missouri | Other
Regulatory Assets [Line Items]
Total Regulatory Assets Not Earning a Return	$ 13.7	$ 14.3	$ 14.8

Regulatory Matters - Additional

Regulatory Matters - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions

Feb. 03, 2020

Nov. 16, 2019

May 25, 2019

Mar. 15, 2019

Oct. 08, 2018

Apr. 25, 2018

Mar. 07, 2018

Dec. 31, 2019

Apr. 30, 2018

Mar. 31, 2020

Sep. 30, 2018

Mar. 24, 2020

Sep. 30, 2019

Public Utilities, General Disclosures [Line Items]

Remaining recovery period for certain regulatory assets for which no return on investment during recovery period is provided (in years)

20 years

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

15 years

APSC | Spire Alabama

Public Utilities, General Disclosures [Line Items]

Requested rate increase

$ 5.9

Gas supply adjustment decrease on annual basis

$ 13.9

Regulatory preferred stock and debt securities issuance, amount authorized

$ 150

GPSC | Spire Gulf

Public Utilities, General Disclosures [Line Items]

Requested rate increase

$ 1.6

Infrastructure System Replacement Surcharge | Spire Missouri

Public Utilities, General Disclosures [Line Items]

Estimated regulatory liabilities

$ 12.2

Refund ordered amounts collected prior to last rate case

$ 4.2

Infrastructure System Replacement Surcharge | MoPSC

Public Utilities, General Disclosures [Line Items]

Regulatory costs

$ 38.4

After-tax rate reduction to net income

$ 23.6

After-tax rate reduction to earnings per share

$ 0.49

Approved rate increase (decrease), costs from buildings sold in 2014 excluded from rate base

$ (1.8)

Rate case expenses

(0.9)

Infrastructure System Replacement Surcharge | MoPSC | Spire Missouri

Public Utilities, General Disclosures [Line Items]

Approved rate authorized future annualized revenue

29.2

Approved estimate revenue

$ 8

Additional provision for regulatory liability

4.2

Provision for interest

0.6

After-tax impact on loss contingency provision reducing net income

$ (3.7)

Annual authorized revenue

$ 8.8

$ 12.4

Infrastructure System Replacement Surcharge | Spire, MoPSC and OPC | Spire Missouri

Public Utilities, General Disclosures [Line Items]

Approved rate authorized future annualized revenue

$ 11.1

Pension Cost | Infrastructure System Replacement Surcharge | MoPSC

Public Utilities, General Disclosures [Line Items]

Regulatory costs

$ 30.6

Regulatory assets recovery

$ (28.8)

Financing Arrangements and Lo_3

Financing Arrangements and Long-term Debt - Additional Information (Details)	Mar. 26, 2020USD ($)bank	Dec. 23, 2019USD ($)	Dec. 02, 2019USD ($)	Nov. 12, 2019USD ($)	Mar. 31, 2020USD ($)	Dec. 14, 2016bank
Line of Credit Facility [Line Items]
Long-term Debt					$ 975,000,000
Private Placement | Spire STL Pipeline LLC
Line of Credit Facility [Line Items]
Debt term		9 years 2 months 12 days
Long-term debt		$ 135,000,000
Stated interest rate		2.95%
Debt instrument, payment terms					Interest is payable semi-annually at 2.95%, and principal repayment is scheduled annually in accordance with a 15-year amortization schedule with an average life of 9.2 years.
Debt instrument, amortization period		15 years
Liabilities | Lender Concentration Risk
Line of Credit Facility [Line Items]
Line of credit facility, number of banks in agreement | bank						11
Spire
Line of Credit Facility [Line Items]
Term loan bear interest rate per annum					2.10%
Short-term borrowings used to support lending to Utilities					$ 91,700,000
Spire | Term Loan
Line of Credit Facility [Line Items]
Line of credit facility, number of banks in agreement | bank	2
Long-term Debt	$ 150,000,000
Debt instrument, maturity date	Mar. 25, 2021
Team loan interest rate description					The term loan bears interest at the LIBOR Rate (as defined in the loan agreement) plus 0.85% per annum.
Term loan bear interest rate per annum					2.10%
Spire | Term Loan | LIBOR
Line of Credit Facility [Line Items]
Term loan bear interest rate per annum	0.85%
Spire Missouri | 2.84% Series, due November 15, 2029
Line of Credit Facility [Line Items]
Debt instrument, maturity date				Nov. 15, 2029
Long-term debt				$ 275,000,000
Stated interest rate				2.84%
Spire Missouri | Floating-Rate Note
Line of Credit Facility [Line Items]
Repayment of long-term debt				$ 100,000,000
Spire Alabama | Senior Notes | Series 2019B Senior Notes due 2029 | Private Placement
Line of Credit Facility [Line Items]
Debt instrument, maturity date			Dec. 1, 2029
Long-term debt			$ 100,000,000
Stated interest rate			2.88%
Debt instrument, payment terms					Interest is payable semi-annually.
Revolving Credit Facility Borrowings
Line of Credit Facility [Line Items]
Line of credit facility borrowing capacity					$ 975,000,000
Minimum required ratio of earnings before interest, taxes, depreciation, and amortization (EBITDA) times interest expense as required by the line of credit covenant					70.00%
Debt to total capitalization ratio					0.54
Revolving Credit Facility Borrowings | Spire
Line of Credit Facility [Line Items]
Line of credit facility borrowing capacity					$ 300,000,000
Term loan bear interest rate per annum					1.90%
Revolving Credit Facility Borrowings | Spire Missouri
Line of Credit Facility [Line Items]
Line of credit facility borrowing capacity					$ 475,000,000
Debt to total capitalization ratio					0.45
Term loan bear interest rate per annum					1.80%
Revolving Credit Facility Borrowings | Spire Alabama
Line of Credit Facility [Line Items]
Line of credit facility borrowing capacity					$ 200,000,000
Debt to total capitalization ratio					0.34
Term loan bear interest rate per annum					1.80%
Commercial Paper Notes
Line of Credit Facility [Line Items]
Line of credit facility borrowing capacity					$ 975,000,000
Debt term					365 days
Commercial Paper Notes | Spire
Line of Credit Facility [Line Items]
Term loan bear interest rate per annum					2.10%

Financing Arrangements and Lo_4

Financing Arrangements and Long-term Debt - Schedule of Spire Missouri and Alabama Short-term Borrowings (Details) - USD ($) $ in Millions	6 Months Ended
	Mar. 31, 2020	Sep. 30, 2019	Mar. 31, 2019
Spire Alabama | Spire Note
Short-term Debt [Line Items]
Weighted average borrowings outstanding	$ 97.4
Lowest borrowings outstanding	18.5
Highest borrowings outstanding	$ 161.3
Weighted average interest rate	2.10%
Borrowings outstanding	$ 33	$ 128.7	$ 73.7
Weighted average interest rate	1.90%	2.30%	2.80%
Spire Alabama | Revolving Credit Facility Borrowings
Short-term Debt [Line Items]
Weighted average borrowings outstanding	$ 2.9
Highest borrowings outstanding	$ 50
Weighted average interest rate	1.80%
Borrowings outstanding	$ 50
Weighted average interest rate	1.90%
Spire Missouri | Spire Note
Short-term Debt [Line Items]
Weighted average borrowings outstanding	$ 283.9
Lowest borrowings outstanding	39.6
Highest borrowings outstanding	$ 429.5
Weighted average interest rate	2.10%
Borrowings outstanding	$ 39.6	$ 386.4	$ 232.9
Weighted average interest rate	1.90%	2.30%	2.80%
Spire Missouri | Revolving Credit Facility Borrowings
Short-term Debt [Line Items]
Weighted average borrowings outstanding	$ 12
Highest borrowings outstanding	$ 185.1
Weighted average interest rate	1.80%
Borrowings outstanding	$ 185.1
Weighted average interest rate	1.80%
Spire
Short-term Debt [Line Items]
Weighted average borrowings outstanding	$ 636.4
Lowest borrowings outstanding	436.1
Highest borrowings outstanding	$ 856.6
Weighted average interest rate	2.10%
Borrowings outstanding	$ 560.6	$ 743.2	$ 512
Weighted average interest rate	1.90%	2.30%	2.80%
Spire | Term Loan
Short-term Debt [Line Items]
Weighted average borrowings outstanding	$ 5.7
Highest borrowings outstanding	$ 150
Weighted average interest rate	2.10%
Borrowings outstanding	$ 150
Weighted average interest rate	2.10%
Spire | Revolving Credit Facility Borrowings
Short-term Debt [Line Items]
Weighted average borrowings outstanding	$ 0.2
Highest borrowings outstanding	$ 23.1
Weighted average interest rate	1.90%
Spire | Commercial Paper Notes
Short-term Debt [Line Items]
Weighted average borrowings outstanding	$ 615.6
Lowest borrowings outstanding	175.5
Highest borrowings outstanding	$ 856.6
Weighted average interest rate	2.10%
Borrowings outstanding	$ 175.5	$ 743.2	$ 512
Weighted average interest rate	1.80%	2.30%	2.80%

Financing Arrangements and Lo_5

Financing Arrangements and Long-term Debt - Summary of Net of Capitalized Interest (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Spire Missouri
Line of Credit Facility [Line Items]
Interest expense, net	$ 0.3	$ 0.4	$ 0.6	$ 0.9
Spire Alabama
Line of Credit Facility [Line Items]
Interest expense, net	0.4		1
Spire
Line of Credit Facility [Line Items]
Interest expense, net	$ 1.4	$ 1.4	$ 3.6	$ 2.6

Fair Value of Financial Instr_3

Fair Value of Financial Instruments - Summary of Financial Instruments Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Millions	Mar. 31, 2020	Sep. 30, 2019	Mar. 31, 2019
Quoted Prices in Active Markets (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	$ 108.4	$ 5.8	$ 11.1
Quoted Prices in Active Markets (Level 1) | Spire Missouri
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	5.1	2.6	6.9
Quoted Prices in Active Markets (Level 1) | Spire Alabama
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	0.1		0.1
Significant Observable Inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes payable	560.6	743.2	512
Long-term debt, including current portion	2,671	2,373.4	2,319.9
Significant Observable Inputs (Level 2) | Spire Missouri
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes payable	185.1
Notes payable – associated companies	39.6	386.4	232.9
Long-term debt, including current portion	1,231.2	1,065.2	1,036.9
Significant Observable Inputs (Level 2) | Spire Alabama
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes payable	50		73.7
Notes payable – associated companies	33	128.7
Long-term debt, including current portion	535.1	474.8	423.8
Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	108.4	5.8	11.1
Notes payable	560.6	743.2	512
Long-term debt, including current portion	2,490.2	2,122.6	2,256.9
Carrying Amount | Spire Missouri
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	5.1	2.6	6.9
Notes payable	185.1
Notes payable – associated companies	39.6	386.4	232.9
Long-term debt, including current portion	1,098.7	925	974.7
Carrying Amount | Spire Alabama
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	0.1		0.1
Notes payable	50		73.7
Notes payable – associated companies	33	128.7
Long-term debt, including current portion	471.7	412.2	412.1
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	108.4	5.8	11.1
Notes payable	560.6	743.2	512
Long-term debt, including current portion	2,671	2,373.4	2,319.9
Fair Value | Spire Missouri
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	5.1	2.6	6.9
Notes payable	185.1
Notes payable – associated companies	39.6	386.4	232.9
Long-term debt, including current portion	1,231.2	1,065.2	1,036.9
Fair Value | Spire Alabama
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	0.1		0.1
Notes payable	50		73.7
Notes payable – associated companies	33	128.7
Long-term debt, including current portion	$ 535.1	$ 474.8	$ 423.8

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Fair Value Assets and Liabilities Measured on Recurring Basis (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Millions	Mar. 31, 2020	Sep. 30, 2019	Mar. 31, 2019
ASSETS
Effects of netting and cash margin receivables/payables	$ (11.9)	$ (9.4)	$ (10.2)
Derivative asset after the effects of netting	48.4	50.8	61.6
LIABILITIES
Effects of netting and cash margin receivables/payables	(26.3)	(23.7)	(8)
Derivative liability after the effects of netting	90.9	54.8	30.8
Spire Missouri
ASSETS
Effects of netting and cash margin receivables/payables	(0.1)		(2.5)
Derivative asset after the effects of netting	18.1		19.7
LIABILITIES
Effects of netting and cash margin receivables/payables	(12.6)
Derivative liability after the effects of netting	0
U.S. stock/bond mutual funds | Spire Missouri
ASSETS
Effects of netting and cash margin receivables/payables	0	0	0
Derivative asset after the effects of netting	18.1	20.5	19.7
NYMEX/ICE natural gas contracts | Spire Missouri
ASSETS
Effects of netting and cash margin receivables/payables	(0.1)		(2.5)
Derivative asset after the effects of netting	0		0
LIABILITIES
Effects of netting and cash margin receivables/payables	(12.2)	(12.3)
Derivative liability after the effects of netting	0	0
Gasoline and heating oil contracts | Spire Missouri
LIABILITIES
Effects of netting and cash margin receivables/payables	(0.4)
Derivative liability after the effects of netting	0
Other | U.S. stock/bond mutual funds
ASSETS
Effects of netting and cash margin receivables/payables	0	0	0
Derivative asset after the effects of netting	17.6	15.5	11.9
Other | Interest rate swaps
LIABILITIES
Effects of netting and cash margin receivables/payables	0	0	0
Derivative liability after the effects of netting	66.9	43.4	15.2
Gas Utility | Operating Segments | U.S. stock/bond mutual funds
ASSETS
Effects of netting and cash margin receivables/payables	0	0	0
Derivative asset after the effects of netting	18.1	20.5	19.7
Gas Utility | Operating Segments | NYMEX/ICE natural gas contracts
ASSETS
Effects of netting and cash margin receivables/payables	(0.1)		(2.5)
Derivative asset after the effects of netting	0		0
LIABILITIES
Effects of netting and cash margin receivables/payables	(12.2)	(12.3)
Derivative liability after the effects of netting	0	0
Gas Utility | Operating Segments | Gasoline and heating oil contracts
LIABILITIES
Effects of netting and cash margin receivables/payables	(0.4)
Derivative liability after the effects of netting	0
Gas Marketing | Operating Segments | NYMEX/ICE natural gas contracts
ASSETS
Effects of netting and cash margin receivables/payables	(7)	(6.9)	(4.3)
Derivative asset after the effects of netting	0	0.5	3
LIABILITIES
Effects of netting and cash margin receivables/payables	(8.9)	(8.9)	(4.5)
Derivative liability after the effects of netting	0	0	0
Gas Marketing | Operating Segments | Natural gas commodity contracts
ASSETS
Effects of netting and cash margin receivables/payables	(4.8)	(2.5)	(3.4)
Derivative asset after the effects of netting	12.7	14.3	27
LIABILITIES
Effects of netting and cash margin receivables/payables	(4.8)	(2.5)	(3.5)
Derivative liability after the effects of netting	24	11.4	15.6
Quoted Prices in Active Markets (Level 1)
ASSETS
Derivative asset before effects of netting	36	36.9	34.3
LIABILITIES
Derivative liability before effects of netting	13.1	12.7	0.4
Quoted Prices in Active Markets (Level 1) | Spire Missouri
ASSETS
Derivative asset before effects of netting	18.2		22.2
LIABILITIES
Derivative liability before effects of netting	12.6
Quoted Prices in Active Markets (Level 1) | U.S. stock/bond mutual funds | Spire Missouri
ASSETS
Derivative asset before effects of netting	18.1	20.5	19.7
Quoted Prices in Active Markets (Level 1) | NYMEX/ICE natural gas contracts | Spire Missouri
ASSETS
Derivative asset before effects of netting	0.1		2.5
LIABILITIES
Derivative liability before effects of netting	12.2	12.3
Quoted Prices in Active Markets (Level 1) | Gasoline and heating oil contracts | Spire Missouri
LIABILITIES
Derivative liability before effects of netting	0.4
Quoted Prices in Active Markets (Level 1) | Other | U.S. stock/bond mutual funds
ASSETS
Derivative asset before effects of netting	17.6	15.5	11.9
Quoted Prices in Active Markets (Level 1) | Other | Interest rate swaps
LIABILITIES
Derivative liability before effects of netting	0	0	0
Quoted Prices in Active Markets (Level 1) | Gas Utility | Operating Segments | U.S. stock/bond mutual funds
ASSETS
Derivative asset before effects of netting	18.1	20.5	19.7
Quoted Prices in Active Markets (Level 1) | Gas Utility | Operating Segments | NYMEX/ICE natural gas contracts
ASSETS
Derivative asset before effects of netting	0.1		2.5
LIABILITIES
Derivative liability before effects of netting	12.2	12.3
Quoted Prices in Active Markets (Level 1) | Gas Utility | Operating Segments | Gasoline and heating oil contracts
LIABILITIES
Derivative liability before effects of netting	0.4
Quoted Prices in Active Markets (Level 1) | Gas Marketing | Operating Segments | NYMEX/ICE natural gas contracts
ASSETS
Derivative asset before effects of netting	0.2	0.9	0.2
LIABILITIES
Derivative liability before effects of netting	0.5	0.4	0.4
Quoted Prices in Active Markets (Level 1) | Gas Marketing | Operating Segments | Natural gas commodity contracts
ASSETS
Derivative asset before effects of netting	0	0	0
LIABILITIES
Derivative liability before effects of netting	0	0	0
Significant Observable Inputs (Level 2)
ASSETS
Derivative asset before effects of netting	24.3	23.3	37.5
LIABILITIES
Derivative liability before effects of netting	103	65.7	38.2
Significant Observable Inputs (Level 2) | Spire Missouri
ASSETS
Derivative asset before effects of netting	0		0
LIABILITIES
Derivative liability before effects of netting	0
Significant Observable Inputs (Level 2) | U.S. stock/bond mutual funds | Spire Missouri
ASSETS
Derivative asset before effects of netting	0	0	0
Significant Observable Inputs (Level 2) | NYMEX/ICE natural gas contracts | Spire Missouri
ASSETS
Derivative asset before effects of netting	0		0
LIABILITIES
Derivative liability before effects of netting	0	0
Significant Observable Inputs (Level 2) | Gasoline and heating oil contracts | Spire Missouri
LIABILITIES
Derivative liability before effects of netting	0
Significant Observable Inputs (Level 2) | Other | U.S. stock/bond mutual funds
ASSETS
Derivative asset before effects of netting	0	0	0
Significant Observable Inputs (Level 2) | Other | Interest rate swaps
LIABILITIES
Derivative liability before effects of netting	66.9	43.4	15.2
Significant Observable Inputs (Level 2) | Gas Utility | Operating Segments | U.S. stock/bond mutual funds
ASSETS
Derivative asset before effects of netting	0	0	0
Significant Observable Inputs (Level 2) | Gas Utility | Operating Segments | NYMEX/ICE natural gas contracts
ASSETS
Derivative asset before effects of netting	0		0
LIABILITIES
Derivative liability before effects of netting	0	0
Significant Observable Inputs (Level 2) | Gas Utility | Operating Segments | Gasoline and heating oil contracts
LIABILITIES
Derivative liability before effects of netting	0
Significant Observable Inputs (Level 2) | Gas Marketing | Operating Segments | NYMEX/ICE natural gas contracts
ASSETS
Derivative asset before effects of netting	6.8	6.5	7.1
LIABILITIES
Derivative liability before effects of netting	8.4	8.5	4.1
Significant Observable Inputs (Level 2) | Gas Marketing | Operating Segments | Natural gas commodity contracts
ASSETS
Derivative asset before effects of netting	17.5	16.8	30.4
LIABILITIES
Derivative liability before effects of netting	27.7	13.8	18.9
Significant Unobservable Inputs (Level 3)
ASSETS
Derivative asset before effects of netting	0	0	0
LIABILITIES
Derivative liability before effects of netting	1.1	0.1	0.2
Significant Unobservable Inputs (Level 3) | Spire Missouri
ASSETS
Derivative asset before effects of netting	0		0
LIABILITIES
Derivative liability before effects of netting	0
Significant Unobservable Inputs (Level 3) | U.S. stock/bond mutual funds | Spire Missouri
ASSETS
Derivative asset before effects of netting	0	0	0
Significant Unobservable Inputs (Level 3) | NYMEX/ICE natural gas contracts | Spire Missouri
ASSETS
Derivative asset before effects of netting	0		0
LIABILITIES
Derivative liability before effects of netting	0	0
Significant Unobservable Inputs (Level 3) | Gasoline and heating oil contracts | Spire Missouri
LIABILITIES
Derivative liability before effects of netting	0
Significant Unobservable Inputs (Level 3) | Other | U.S. stock/bond mutual funds
ASSETS
Derivative asset before effects of netting	0	0	0
Significant Unobservable Inputs (Level 3) | Other | Interest rate swaps
LIABILITIES
Derivative liability before effects of netting	0	0	0
Significant Unobservable Inputs (Level 3) | Gas Utility | Operating Segments | U.S. stock/bond mutual funds
ASSETS
Derivative asset before effects of netting	0	0	0
Significant Unobservable Inputs (Level 3) | Gas Utility | Operating Segments | NYMEX/ICE natural gas contracts
ASSETS
Derivative asset before effects of netting	0		0
LIABILITIES
Derivative liability before effects of netting	0	0
Significant Unobservable Inputs (Level 3) | Gas Utility | Operating Segments | Gasoline and heating oil contracts
LIABILITIES
Derivative liability before effects of netting	0
Significant Unobservable Inputs (Level 3) | Gas Marketing | Operating Segments | NYMEX/ICE natural gas contracts
ASSETS
Derivative asset before effects of netting	0	0	0
LIABILITIES
Derivative liability before effects of netting	0	0	0
Significant Unobservable Inputs (Level 3) | Gas Marketing | Operating Segments | Natural gas commodity contracts
ASSETS
Derivative asset before effects of netting	0	0	0
LIABILITIES
Derivative liability before effects of netting	$ 1.1	$ 0.1	$ 0.2

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Details) - USD ($)	Mar. 31, 2020	Sep. 30, 2019	Mar. 31, 2019
Spire Alabama
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Outstanding derivative contracts	$ 0	$ 0	$ 0

Pension Plans and Other Postr_3

Pension Plans and Other Postretirement Benefits - Schedule of Net Periodic Cost (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Pension Plans
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost – benefits earned during the period	$ 5.6	$ 4.9	$ 11.1	$ 9.7
Interest cost on projected benefit obligation	5.8	7	11.7	14.1
Expected return on plan assets	(9)	(8.9)	(18.2)	(18)
Amortization of prior service (credit) cost	(0.6)	(0.3)	(1.2)	(0.6)
Amortization of actuarial (gain) loss	3.9	2.3	7.6	4.6
Loss on lump-sum settlements	21		21
Subtotal	26.7	5	32	9.8
Regulatory adjustment	(11.3)	9.8	(1.7)	19.7
Net pension cost	15.4	14.8	30.3	29.5
Other Postretirement Plans
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost – benefits earned during the period	1.5	1.8	2.9	3.7
Interest cost on projected benefit obligation	1.5	2.1	3.1	4.4
Expected return on plan assets	(4.1)	(3.9)	(8.2)	(8)
Amortization of prior service (credit) cost	(0.1)	(0.1)	(0.3)	(0.1)
Amortization of actuarial (gain) loss	(0.5)	(0.2)	(1)	(0.3)
Subtotal	(1.7)	(0.3)	(3.5)	(0.3)
Regulatory adjustment	4	2.6	8	5
Net pension cost	2.3	2.3	4.5	4.7
Spire Missouri | Pension Plans
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost – benefits earned during the period	3.9	3.1	7.7	6.2
Interest cost on projected benefit obligation	4	4.9	8.2	9.9
Expected return on plan assets	(6.3)	(6.3)	(12.9)	(12.7)
Amortization of prior service (credit) cost	0.1	0.2	0.1	0.4
Amortization of actuarial (gain) loss	3.1	2.2	6	4.3
Loss on lump-sum settlements	21		21
Subtotal	25.8	4.1	30.1	8.1
Regulatory adjustment	(13.2)	7.9	(5.5)	15.9
Net pension cost	12.6	12	24.6	24
Spire Missouri | Other Postretirement Plans
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost – benefits earned during the period	1.3	1.7	2.6	3.4
Interest cost on projected benefit obligation	1.1	1.7	2.3	3.4
Expected return on plan assets	(2.9)	(2.7)	(5.7)	(5.5)
Amortization of prior service (credit) cost			(0.1)	0.1
Amortization of actuarial (gain) loss	(0.5)	(0.2)	(1)	(0.3)
Subtotal	(1)	0.5	(1.9)	1.1
Regulatory adjustment	4.5	3	8.9	5.9
Net pension cost	3.5	3.5	7	7
Spire Alabama | Pension Plans
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost – benefits earned during the period	1.5	1.6	3	3.1
Interest cost on projected benefit obligation	1.3	1.5	2.5	3
Expected return on plan assets	(1.8)	(1.8)	(3.5)	(3.6)
Amortization of prior service (credit) cost	(0.6)	(0.5)	(1.2)	(0.9)
Amortization of actuarial (gain) loss	0.8	0.2	1.6	0.4
Subtotal	1.2	1	2.4	2
Regulatory adjustment	1.7	1.7	3.4	3.4
Net pension cost	2.9	2.7	5.8	5.4
Spire Alabama | Other Postretirement Plans
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost – benefits earned during the period	0.1	0.1	0.2	0.2
Interest cost on projected benefit obligation	0.4	0.4	0.7	0.9
Expected return on plan assets	(1.2)	(1.2)	(2.4)	(2.4)
Amortization of prior service (credit) cost	(0.1)	(0.1)	(0.2)	(0.2)
Subtotal	(0.8)	(0.8)	(1.7)	(1.5)
Regulatory adjustment	(0.5)	(0.4)	(0.9)	(0.9)
Net pension cost	$ (1.3)	$ (1.2)	$ (2.6)	$ (2.4)

Pension Plans and Other Postr_4

Pension Plans and Other Postretirement Benefits - Additional Information (Details) - USD ($)	6 Months Ended
	Mar. 31, 2020	Sep. 30, 2019
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Medical insurance available until age is reached after early retirement	65 years
Other Postretirement Benefits Plan
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Settlement benefits paid	$ 59,100,000
Settlement loss	21,000,000
Employer contributions	$ 6,600,000
Other Postretirement Benefits Plan | Spire Missouri
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rates	2.85%	3.20%
Anticipated contributions to pension plans for qualified trust	$ 18,100,000
Other Postretirement Benefits Plan | Spire Missouri | Qualified Plan
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Employer contributions	10,900,000
Other Postretirement Benefits Plan | Spire Missouri | Nonqualified Plan
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Employer contributions	0
Other Postretirement Benefits Plan | Spire Alabama
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Anticipated contributions to pension plans for qualified trust	6,500,000
Other Postretirement Benefits Plan | Spire Missouri
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Employer contributions	0
Anticipated contributions to pension plans for qualified trust	0
Other Postretirement Benefits Plan | Spire Alabama
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Employer contributions	0
Anticipated contributions to pension plans for qualified trust	$ 0

Information by Operating Segm_3

Information by Operating Segment - Additional Information (Details) - 6 months ended Mar. 31, 2020	reporting_unit	operating-segment
Segment Reporting [Abstract]
Number of reportable segments	2	2

Information by Operating Segm_4

Information by Operating Segment - Schedule of Operating Segment Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019	Sep. 30, 2019
Operating Segment Information [Abstract]
Total Operating Revenues	$ 715.5	$ 803.5	$ 1,282.4	$ 1,405.5
Gas Utility
Natural and propane gas	249	337.4	463.6	589.1
Operation and maintenance	93.1	109.5	199.1	212
Depreciation and amortization	47	44.4	93.4	88.1
Taxes, other than income taxes	51.7	57.4	89.6	96.6
Total Gas Utility Operating Expenses	440.8	548.7	845.7	985.8
Gas Marketing and other	64.2	45.3	123.9	105.1
Total Operating Expenses	505	594	969.6	1,090.9
Operating Income	210.5	209.5	312.8	314.6
Net Economic Earnings (Loss)	144	147.9	215.8	213.8
Total Assets	8,018	7,273.6	8,018	7,273.6	$ 7,619.2
Eliminations
Operating Segment Information [Abstract]
Total Operating Revenues	(11.5)	(3.1)	(18.7)	(7.5)
Gas Utility
Natural and propane gas	(22.6)	(29.3)	(49.5)	(69.4)
Operation and maintenance	(2.7)	(2.5)	(5.3)	(4.9)
Depreciation and amortization	0	0	0	0
Taxes, other than income taxes	0	0	0	0
Total Gas Utility Operating Expenses	(25.3)	(31.8)	(54.8)	(74.3)
Gas Marketing and other	13.8	28.7	36.1	66.8
Total Operating Expenses	(11.5)	(3.1)	(18.7)	(7.5)
Operating Income	0	0	0	0
Net Economic Earnings (Loss)	0	0	0	0
Total Assets	(667.6)	(1,340)	(667.6)	(1,340)	(1,380.4)
Gas Utility
Operating Segment Information [Abstract]
Total Operating Revenues	679.1	776.7	1,209.7	1,350.5
Gas Utility | Eliminations
Operating Segment Information [Abstract]
Total Operating Revenues	(0.1)	0.1	0	1.5
Gas Utility | Operating Segments
Operating Segment Information [Abstract]
Total Operating Revenues	679	776.8	1,209.7	1,352
Gas Utility
Natural and propane gas	271.6	366.7	513.1	658.5
Operation and maintenance	95.8	112	204.4	216.9
Depreciation and amortization	47	44.4	93.4	88.1
Taxes, other than income taxes	51.7	57.4	89.6	96.6
Total Gas Utility Operating Expenses	466.1	580.5	900.5	1,060.1
Gas Marketing and other	0	0	0	0
Total Operating Expenses	466.1	580.5	900.5	1,060.1
Operating Income	212.9	196.3	309.2	291.9
Net Economic Earnings (Loss)	144.3	146.7	213.4	213.1
Total Assets	6,311.6	5,850.1	6,311.6	5,850.1	6,094.6
Gas Marketing
Operating Segment Information [Abstract]
Total Operating Revenues	33.3	25.4	65.6	51.2
Gas Marketing | Eliminations
Operating Segment Information [Abstract]
Total Operating Revenues	0	0.1	0	0.1
Gas Marketing | Operating Segments
Operating Segment Information [Abstract]
Total Operating Revenues	33.3	25.5	65.6	51.3
Gas Utility
Natural and propane gas	0	0	0	0
Operation and maintenance	0	0	0	0
Depreciation and amortization	0	0	0	0
Taxes, other than income taxes	0	0	0	0
Total Gas Utility Operating Expenses	0	0	0	0
Gas Marketing and other	37.7	8.7	65.6	22
Total Operating Expenses	37.7	8.7	65.6	22
Operating Income	(4.4)	16.8	0	29.3
Net Economic Earnings (Loss)	5.1	6.2	11.2	14.5
Total Assets	159.3	366.7	159.3	366.7	212.3
Corporate, Non-Segment
Operating Segment Information [Abstract]
Total Operating Revenues	3.1	1.4	7.1	3.8
Corporate, Non-Segment | Eliminations
Operating Segment Information [Abstract]
Total Operating Revenues	11.6	2.9	18.7	5.9
Corporate, Non-Segment | Operating Segments
Operating Segment Information [Abstract]
Total Operating Revenues	14.7	4.3	25.8	9.7
Gas Utility
Natural and propane gas	0	0	0	0
Operation and maintenance	0	0	0	0
Depreciation and amortization	0	0	0	0
Taxes, other than income taxes	0	0	0	0
Total Gas Utility Operating Expenses	0	0	0	0
Gas Marketing and other	12.7	7.9	22.2	16.3
Total Operating Expenses	12.7	7.9	22.2	16.3
Operating Income	2	(3.6)	3.6	(6.6)
Net Economic Earnings (Loss)	(5.4)	(5)	(8.8)	(13.8)
Total Assets	$ 2,214.7	$ 2,396.8	$ 2,214.7	$ 2,396.8	$ 2,692.7

Information by Operating Segm_5

Information by Operating Segment - Reconciliation of Consolidated Net Economic Earnings to Consolidated Net Income (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Segment Reporting [Abstract]
Net Income	$ 133.6	$ 154.6	$ 200.6	$ 221.9
Provision for ISRS rulings	2.2	0	4.8	0
Unrealized loss (gain) on energy-related derivatives	11.6	(9.1)	15.3	(11.3)
Acquisition, divestiture and restructuring activities	0	0	0	0.4
Income tax effect of adjustments	(3.4)	2.4	(4.9)	2.8
Net Economic Earnings	$ 144	$ 147.9	$ 215.8	$ 213.8

Commitments and Contingencies -

Commitments and Contingencies - Additional Information - Commitments (Details) $ in Millions	6 Months Ended
	Mar. 31, 2020USD ($)
Long-term Purchase Commitment [Line Items]
Minimum total payments required for natural gas contracts	$ 1,558.7
Spire Missouri
Long-term Purchase Commitment [Line Items]
Minimum total payments required for natural gas contracts	760.3
Spire Alabama
Long-term Purchase Commitment [Line Items]
Minimum total payments required for natural gas contracts	$ 189.2

Commitments and Contingencies_2

Commitments and Contingencies - Additional Information - Contingencies (Details) - site	Mar. 31, 2020	Sep. 30, 2013
Spire Missouri East
Site Contingency [Line Items]
Number of former manufactured gas plant (MGP) sites in Missouri	3
Number of sites enrolled in Brownfields/Voluntary clean up program	2
Spire Missouri East | Previous Ownership
Site Contingency [Line Items]
Number of former manufactured gas plant (MGP)		19
Spire Missouri West | Previous Ownership
Site Contingency [Line Items]
Number of former manufactured gas plant (MGP)	7
Spire Alabama
Site Contingency [Line Items]
Number of former manufactured gas plant (MGP)	9
Number of former manufactured gas distribution	5
Spire Alabama | Current Ownership
Site Contingency [Line Items]
Number of former manufactured gas plant (MGP)	4
Number of former manufactured gas distribution	1

Leases - Additional Information

Leases - Additional Information (Details)	6 Months Ended
	Mar. 31, 2020officespace
Lessee Lease Description [Line Items]
Operating lease, existence of option to extend	true
Operating lease, option to extend	The lease agreement covering Spire Marketing and Spire Storage office space in Houston extends through December 2028, with options to terminate three years earlier or to renew for an additional five years
Operating lease extend period	2028-12
Operating lease, renewal term	5 years
Operating lease, existence of option to terminate	true
Operating lease, existence of option to terminate period	with options to terminate three years
Spire Missouri
Lessee Lease Description [Line Items]
Operating lease, existence of option to extend	true
Operating lease, option to extend	The lease agreement covering the Company’s primary office space in St. Louis extends through February 2035, with an option to renew for an additional five years
Operating lease extend period	2035-02
Operating lease, renewal term	5 years
Spire Alabama
Lessee Lease Description [Line Items]
Operating lease, existence of option to extend	true
Operating lease, option to extend	Spire Alabama currently has leased office space in two buildings in Birmingham; one lease expires in 2020 and the other extends through January 2024.
Operating lease extend period	2024-01
Number of office space	2
Lease expiration period	2020

Leases - Operating Lease Cost C

Leases - Operating Lease Cost Cash Flow and Noncash Information (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Mar. 31, 2020	Mar. 31, 2020
Lessee Lease Description [Line Items]
Operating lease cost, including amounts capitalized	$ 2.4	$ 4.8
Cash flow and noncash information about operating leases:
Operating cash flows representing cash paid for amounts included in the measurement of lease liabilities	2.2	4.5
Right-of-use assets obtained in exchange for lease liabilities		71.1
Spire Missouri Inc
Lessee Lease Description [Line Items]
Operating lease cost, including amounts capitalized	0.1	0.3
Cash flow and noncash information about operating leases:
Operating cash flows representing cash paid for amounts included in the measurement of lease liabilities	0.1	0.3
Right-of-use assets obtained in exchange for lease liabilities		2.1
Spire Alabama
Lessee Lease Description [Line Items]
Operating lease cost, including amounts capitalized	1.1	2.1
Cash flow and noncash information about operating leases:
Operating cash flows representing cash paid for amounts included in the measurement of lease liabilities	$ 0.9	1.9
Right-of-use assets obtained in exchange for lease liabilities		$ 10

Leases - Summary of Balance She

Leases - Summary of Balance Sheet and Weighted-Average Information about Operating Leases (Details) $ in Millions	Mar. 31, 2020USD ($)
Lessee Lease Description [Line Items]
Right-of-use assets	$ 67.7
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	us-gaap:OtherAssetsNoncurrent
Lease liabilities, current	$ 6.9
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesCurrent
Lease liabilities, noncurrent	$ 60.6
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesNoncurrent
Weighted-average remaining lease term	16 years 1 month 6 days
Weighted-average discount rate	4.10%
Spire Missouri Inc
Lessee Lease Description [Line Items]
Right-of-use assets	$ 1.9
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	us-gaap:OtherAssetsNoncurrent
Lease liabilities, current	$ 0.3
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesCurrent
Lease liabilities, noncurrent	$ 1.5
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesNoncurrent
Weighted-average remaining lease term	5 years 9 months 18 days
Weighted-average discount rate	2.50%
Spire Alabama
Lessee Lease Description [Line Items]
Right-of-use assets	$ 8
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	us-gaap:OtherAssetsNoncurrent
Lease liabilities, current	$ 2.3
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesCurrent
Lease liabilities, noncurrent	$ 5.6
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesNoncurrent
Weighted-average remaining lease term	3 years 8 months 12 days
Weighted-average discount rate	2.20%

Leases - Schedule of Maturity A

Leases - Schedule of Maturity Analysis for Operating Lease Liabilities (Details) $ in Millions	Mar. 31, 2020USD ($)
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
Remainder of 2020	$ 3.4
2021	7.2
2022	7.2
2023	7.2
2024	5.8
2025	5.1
Thereafter	58.4
Total undiscounted lease payments	94.3
Less present value discount	(26.8)
Total current and noncurrent lease liabilities	67.5
Spire Missouri Inc
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
Remainder of 2020	0.1
2021	0.4
2022	0.4
2023	0.3
2024	0.3
2025	0.3
Thereafter	0.2
Total undiscounted lease payments	2
Less present value discount	(0.2)
Total current and noncurrent lease liabilities	1.8
Spire Alabama
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
Remainder of 2020	1.2
2021	2.1
2022	2.1
2023	2.1
2024	0.7
Total undiscounted lease payments	8.2
Less present value discount	(0.3)
Total current and noncurrent lease liabilities	$ 7.9

Leases - Schedule of Annual Min

Leases - Schedule of Annual Minimum Rental Commitments for Operating Leases (Details) $ in Millions	Sep. 30, 2019USD ($)
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2020	$ 8.2
2021	7
2022	6.8
2023	6.1
2024	4.8
Later	36.5
Total	69.4
Spire Missouri Inc
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2020	0.5
2021	0.2
Total	0.7
Spire Alabama
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2020	2.9
2021	2.1
2022	2.1
2023	2.1
2024	0.7
Total	$ 9.9