Note 8 - Fair Value Measurements (Tables)

6 Months Ended

Mar. 31, 2024

Notes Tables

Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block]

	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, 2024
ASSETS
Gas Utility:
U.S. stock/bond mutual funds	$	22.6	$	—	$	—		$	22.6
NYMEX/ICE natural gas contracts		3.7		—		(3.7	)		—
Gasoline and heating oil contracts		—		0.1		(0.1	)		—
Gas Marketing:
NYMEX/ICE natural gas contracts		8.6		—		(8.6	)		—
Natural gas commodity contracts		—		62.2		(2.6	)		59.6
Other:
U.S. stock/bond mutual funds		16.6		—		—			16.6
U.S. bonds		17.1		—		—			17.1
Global bonds		1.4		—		—			1.4
Interest rate swaps		—		29.0		—			29.0
Total	$	70.0	$	91.3	$	(15.0	)	$	146.3
LIABILITIES
Gas Utility:
NYMEX/ICE natural gas contracts	$	35.7	$	—	$	(35.7	)	$	—
Gas Marketing:
NYMEX/ICE natural gas contracts		30.7		—		(30.7	)		—
Natural gas commodity contracts		—		25.3		(2.6	)		22.7
Total	$	66.4	$	25.3	$	(69.0	)	$	22.7

	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, 2023
ASSETS
Gas Utility:
U.S. stock/bond mutual funds	$	20.4	$	—	$	—		$	20.4
NYMEX/ICE natural gas contracts		6.3		—		(6.3	)		—
Gasoline and heating oil contracts		—		0.1		(0.1	)		—
Gas Marketing:
NYMEX/ICE natural gas contracts		10.1		—		(10.1	)		—
Natural gas commodity contracts		—		36.7		(3.6	)		33.1
Other:
U.S. stock/bond mutual funds		37.6		—		—			37.6
Interest rate swaps		—		44.2		—			44.2
Total	$	74.4	$	81.0	$	(20.1	)	$	135.3
LIABILITIES
Gas Utility:
NYMEX/ICE natural gas contracts	$	50.8	$	—	$	(44.0	)	$	6.8
Gas Marketing:
NYMEX/ICE natural gas contracts		21.8		—		(21.8	)		—
Natural gas commodity contracts		—		27.6		(3.6	)		24.0
Total	$	72.6	$	27.6	$	(69.4	)	$	30.8
As of March 31, 2023
ASSETS
Gas Utility:
U.S. stock/bond mutual funds	$	20.7	$	—	$	—		$	20.7
NYMEX/ICE natural gas contracts		0.1		—		(0.1	)		—
Gas Marketing:
NYMEX/ICE natural gas contracts		31.9		—		(31.9	)		—
Natural gas commodity contracts *		—		39.2		(1.3	)		37.9
Other:
U.S. stock/bond mutual funds		29.2		—		—			29.2
Interest rate swaps *		—		16.5		—			16.5
Total	$	81.9	$	55.7	$	(33.3	)	$	104.3
LIABILITIES
Gas Utility:
NYMEX/ICE natural gas contracts	$	62.7	$	—	$	(62.7	)	$	—
Gasoline and heating oil contracts		0.5		—		(0.5	)		—
Gas Marketing:
NYMEX/ICE natural gas contracts		48.1		—		(48.1	)		—
Natural gas commodity contracts *		—		32.4		(1.3	)		31.1
Other:
Interest rate swaps *		—		2.2		—			2.2
Total	$	111.3	$	34.6	$	(112.6	)	$	33.3

	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, 2024
ASSETS
U.S. stock/bond mutual funds	$	22.6	$	—	$	—		$	22.6
NYMEX/ICE natural gas contracts		3.7		—		(3.7	)		—
Gasoline and heating oil contracts		—		0.1		(0.1	)		—
Total	$	26.3	$	0.1	$	(3.8	)	$	22.6
LIABILITIES
NYMEX/ICE natural gas contracts	$	35.7	$	—	$	(35.7	)	$	—
As of September 30, 2023
ASSETS
U.S. stock/bond mutual funds	$	20.4	$	—	$	—		$	20.4
NYMEX/ICE natural gas contracts		6.3		—		(6.3	)		—
Gasoline and heating oil contracts		—		0.1		(0.1	)		—
Total	$	26.7	$	0.1	$	(6.4	)	$	20.4
LIABILITIES
NYMEX/ICE natural gas contracts	$	50.8	$	—	$	(44.0	)	$	6.8
As of March 31, 2023
ASSETS
U.S. stock/bond mutual funds	$	20.7	$	—	$	—		$	20.7
NYMEX/ICE natural gas contracts		0.1		—		(0.1	)		—
Total	$	20.8	$	—	$	(0.1	)	$	20.7
LIABILITIES
NYMEX/ICE natural gas contracts	$	62.7	$	—	$	(62.7	)	$	—
Gasoline and heating oil contracts		0.5		—		(0.5	)		—
Total	$	63.2	$	—	$	(63.2	)	$	—