Fair Value Measurements (Tables)

6 Months Ended

Mar. 31, 2022

Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]

Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis

Spire

	Quoted Prices in Active Markets (Level 1)		Significant Observable Inputs (Level 2)		Effects of Netting and Cash Margin Receivables /Payables			Total
As of March 31, 2022
ASSETS
Gas Utility:
U.S. stock/bond mutual funds	$	23.0	$	—	$	—		$	23.0
NYMEX/ICE natural gas contracts		58.9		—		(58.9	)		—
Gas Marketing:
NYMEX/ICE natural gas contracts		—		96.1		(88.4	)		7.7
Natural gas commodity contracts		—		30.8		(1.0	)		29.8
Other:
U.S. stock/bond mutual funds		24.1		—		—			24.1
Interest rate swaps		28.8		—		(7.9	)		20.9
Total	$	134.8	$	126.9	$	(156.2	)	$	105.5
LIABILITIES
Gas Marketing:
NYMEX/ICE natural gas contracts	$	—	$	40.4	$	(40.4	)	$	—
Natural gas commodity contracts		—		106.2		(1.0	)		105.2
Other:
Interest rate swaps		7.9		—		(7.9	)		—
Total	$	7.9	$	146.6	$	(49.3	)	$	105.2

	Quoted Prices in Active Markets (Level 1)		Significant Observable Inputs (Level 2)		Effects of Netting and Cash Margin Receivables /Payables			Total
As of September 30, 2021
ASSETS
Gas Utility:
U.S. stock/bond mutual funds	$	23.8	$	—	$	—		$	23.8
NYMEX/ICE natural gas contracts		104.0		—		(104.0	)		—
Gas Marketing:
NYMEX/ICE natural gas contracts		—		114.7		(93.7	)		21.0
Natural gas commodity contracts		—		35.2		(5.5	)		29.7
Other:
U.S. stock/bond mutual funds		26.2		—		—			26.2
Interest rate swaps		12.6		—		(5.2	)		7.4
Total	$	166.6	$	149.9	$	(208.4	)	$	108.1
LIABILITIES
Gas Utility:
NYMEX/ICE natural gas contracts	$	0.3	$	—	$	(0.3	)	$	—
Gas Marketing:
NYMEX/ICE natural gas contracts		—		62.0		(62.0	)		—
Natural gas commodity contracts		—		96.7		(5.5	)		91.2
Other:
Interest rate swaps		5.7		—		(5.2	)		0.5
Total	$	6.0	$	158.7	$	(73.0	)	$	91.7
As of March 31, 2021
ASSETS
Gas Utility:
U.S. stock/bond mutual funds	$	23.5	$	—	$	—		$	23.5
NYMEX/ICE natural gas contracts		0.4		—		(0.4	)		—
Gasoline and heating oil contracts		0.3		—		(0.3	)		—
Gas Marketing:
NYMEX/ICE natural gas contracts		—		15.1		(12.3	)		2.8
Natural gas commodity contracts		—		9.3		—			9.3
Other:
U.S. stock/bond mutual funds		22.9		—		—			22.9
Interest rate swaps		—		27.9		—			27.9
Total	$	47.1	$	52.3	$	(13.0	)	$	86.4
LIABILITIES
Gas Utility:
NYMEX/ICE natural gas contracts	$	1.8	$	—	$	(1.8	)	$	—
Gas Marketing:
NYMEX/ICE natural gas contracts		—		4.7		(4.7	)		—
Natural gas commodity contracts		—		24.5		—			24.5
Other:
Interest rate swaps		—		21.4		—			21.4
Total	$	1.8	$	50.6	$	(6.5	)	$	45.9

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

Spire Missouri

	Quoted Prices in Active Markets (Level 1)		Significant Observable Inputs (Level 2)		Effects of Netting and Cash Margin Receivables /Payables			Total
As of March 31, 2022
ASSETS
U.S. stock/bond mutual funds	$	23.0	$	—	$	—		$	23.0
NYMEX/ICE natural gas contracts		58.9		—		(58.9	)		—
Total	$	81.9	$	—	$	(58.9	)	$	23.0
As of September 30, 2021
ASSETS
U.S. stock/bond mutual funds	$	23.8	$	—	$	—		$	23.8
NYMEX/ICE natural gas contracts		104.0		—		(104.0	)		—
Total	$	127.8	$	—	$	(104.0	)	$	23.8
LIABILITIES
NYMEX/ICE natural gas contracts	$	0.3	$	—	$	(0.3	)	$	—
As of March 31, 2021
ASSETS
U.S. stock/bond mutual funds	$	23.5	$	—	$	—		$	23.5
NYMEX/ICE natural gas contracts		0.4		—		(0.4	)		—
Gasoline and heating oil contracts		0.3		—		(0.3	)		—
Total	$	24.2	$	—	$	(0.7	)	$	23.5
LIABILITIES
NYMEX/ICE natural gas contracts	$	1.8	$	—	$	(1.8	)	$	—