Fair Value Measurements (Tables)

9 Months Ended

Jun. 30, 2021

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)		Significant Unobservable Inputs (Level 3)		Effects of Netting and Cash Margin Receivables /Payables			Total
As of June 30, 2021
ASSETS
Gas Utility:
U.S. stock/bond mutual funds	$	24.3	$	—	$	—	$	—		$	24.3
NYMEX/ICE natural gas contracts		25.3		—		—		(25.3	)		—
Gas Marketing:
NYMEX/ICE natural gas contracts		—		47.5		—		(47.5	)		—
Natural gas commodity contracts		—		20.2		—		—			20.2
Other:
U.S. stock/bond mutual funds		21.5		—		—		—			21.5
Interest rate swaps		—		9.0		—		(5.5	)		3.5
Total	$	71.1	$	76.7	$	—	$	(78.3	)	$	69.5
LIABILITIES
Gas Marketing:
NYMEX/ICE natural gas contracts	$	—	$	18.8	$	—	$	(16.0	)	$	2.8
Natural gas commodity contracts		—		57.8		—		—			57.8
Other:
Interest rate swaps		—		6.7		—		(5.5	)		1.2
Total	$	—	$	83.3	$	—	$	(21.5	)	$	61.8

	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, 2020
ASSETS
Gas Utility:
U.S. stock/bond mutual funds	$	21.9	$	—	$	—	$	—		$	21.9
NYMEX/ICE natural gas contracts		6.3		—		—		(6.3	)		—
Gasoline and heating oil contracts		0.3		—		—		(0.3	)		—
Gas Marketing:
NYMEX/ICE natural gas contracts		—		27.7		—		(25.4	)		2.3
Natural gas commodity contracts		—		14.5		0.4		—			14.9
Other:
U.S. stock/bond mutual funds		18.6		—		—		—			18.6
Total	$	47.1	$	42.2	$	0.4	$	(32.0	)	$	57.7
LIABILITIES
Gas Utility:
NYMEX/ICE natural gas contracts	$	0.9	$	—	$	—	$	(0.9	)	$	—
Gas Marketing:
NYMEX/ICE natural gas contracts		0.7		21.4		—		(22.1	)		—
Natural gas commodity contracts		—		22.3		—		—			22.3
Other:
Interest rate swaps		—		54.2		—		—			54.2
Total	$	1.6	$	97.9	$	—	$	(23.0	)	$	76.5
As of June 30, 2020
ASSETS
Gas Utility:
U.S. stock/bond mutual funds	$	20.8	$	—	$	—	$	—		$	20.8
NYMEX/ICE natural gas contracts		1.8		—		—		(1.8	)		—
Gasoline and heating oil contracts		0.3		—		—		(0.3	)		—
Gas Marketing:
NYMEX/ICE natural gas contracts		—		20.1		—		(16.4	)		3.7
Natural gas commodity contracts		—		17.5		1.0		(6.4	)		12.1
Other:
U.S. stock/bond mutual funds		19.2		—		—		—			19.2
Total	$	42.1	$	37.6	$	1.0	$	(24.9	)	$	55.8
LIABILITIES
Gas Utility:
NYMEX/ICE natural gas contracts	$	7.2	$	—	$	—	$	(7.2	)	$	—
Gas Marketing:
NYMEX/ICE natural gas contracts		0.3		16.1		—		(16.4	)		—
Natural gas commodity contracts		—		16.7		—		(6.4	)		10.3
Other:
Interest rate swaps		—		66.1		—		—			66.1
Total	$	7.5	$	98.9	$	—	$	(30.0	)	$	76.4

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)		Significant Unobservable Inputs (Level 3)		Effects of Netting and Cash Margin Receivables /Payables			Total
As of June 30, 2021
ASSETS
U.S. stock/bond mutual funds	$	24.3	$	—	$	—	$	—		$	24.3
NYMEX/ICE natural gas contracts		25.3		—		—		(25.3	)		—
Total	$	49.6	$	—	$	—	$	(25.3	)	$	24.3
As of September 30, 2020
ASSETS
U.S. stock/bond mutual funds	$	21.9	$	—	$	—	$	—		$	21.9
NYMEX/ICE natural gas contracts		6.3		—		—		(6.3	)		—
Gasoline and heating oil contracts		0.3		—		—		(0.3	)		—
Total	$	28.5	$	—	$	—	$	(6.6	)	$	21.9
LIABILITIES
NYMEX/ICE natural gas contracts	$	0.9	$	—	$	—	$	(0.9	)	$	—
As of June 30, 2020
ASSETS
U.S. stock/bond mutual funds	$	20.8	$	—	$	—	$	—		$	20.8
NYMEX/ICE natural gas contracts		1.8		—		—		(1.8	)		—
Gasoline and heating oil contracts		0.3		—		—		(0.3	)		—
Total	$	22.9	$	—	$	—	$	(2.1	)	$	20.8
LIABILITIES
NYMEX/ICE natural gas contracts	$	7.2	$	—	$	—	$	(7.2	)	$	—