Note 9 - Fair Value Measurements (Tables)

12 Months Ended

Sep. 30, 2024

Notes Tables

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

							Effects of
	Quoted						Netting
	Prices		Significant		Significant		and Cash
	in Active		Observable		Unobservable		Margin
	Markets		Inputs		Inputs		Receivables
	(Level 1)		(Level 2)		(Level 3)		/Payables			Total
As of September 30, 2024
ASSETS
Gas Utility:
U.S. stock/bond mutual funds	$	24.3	$	—	$	—	$	—		$	24.3
NYMEX/ICE natural gas contracts		3.4		—		—		(3.4	)		—
Gas Marketing:
NYMEX/ICE natural gas contracts		7.0		—		—		(7.0	)		—
Natural gas commodity contracts		—		46.0		—		(3.5	)		42.5
Other:
U.S. stock/bond mutual funds		17.9		—		—		—			17.9
U.S. bonds		21.9		—		—					21.9
Global Bonds		5.9		—		—		—			5.9
Interest rate swaps		—		0.8		—		—			0.8
Total	$	80.4	$	46.8	$	—	$	(13.9	)	$	113.3
LIABILITIES
Gas Utility:
NYMEX/ICE natural gas contracts	$	13.6	$	—	$	—	$	(3.8	)	$	9.8
Gas Marketing:
NYMEX/ICE natural gas contracts		17.7		—		—		(17.7	)		—
Natural gas commodity contracts		—		24.5		—		(3.5	)		21.0
Other:
Interest rate swaps		—		1.5		—		—			1.5
Total	$	31.3	$	26.0	$	—	$	(25.0	)	$	32.3
As of September 30, 2023
ASSETS
Gas Utility:
U.S. stock/bond mutual funds	$	20.4	$	—	$	—	$	—		$	20.4
Gasoline and heating oil contracts		—		0.1		—		(0.1	)		—
NYMEX/ICE natural gas contracts		6.3		—		—		(6.3	)		—
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		7.5		—		—		—			7.5
U.S. bonds		28.7		—		—					28.7
Global Bonds		1.4		—		—		—			1.4
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

							Effects of
	Quoted						Netting
	Prices		Significant		Significant		and Cash
	in Active		Observable		Unobservable		Margin
	Markets		Inputs		Inputs		Receivables
	(Level 1)		(Level 2)		(Level 3)		/Payables			Total
As of September 30, 2024
ASSETS
U.S. stock/bond mutual funds	$	24.3	$	—	$	—	$	—		$	24.3
NYMEX/ICE natural gas contracts		3.4		—		—		(3.4	)		—
Total	$	27.7	$	—	$	—	$	(3.4	)	$	24.3
LIABILITIES
NYMEX/ICE natural gas contracts	$	13.6	$	—	$	—	$	(3.8	)	$	9.8
As of September 30, 2023
ASSETS
U.S. stock/bond mutual funds	$	20.4	$	—	$	—	$	—		$	20.4
Gasoline and heating oil contracts		—		0.1		—		(0.1	)		—
NYMEX/ICE natural gas contracts		6.3		—		—		(6.3	)		—
Total	$	26.7	$	0.1	$	—	$	(6.4	)	$	20.4
LIABILITIES
NYMEX/ICE natural gas contracts	$	50.8	$	—	$	—	$	(44.0	)	$	6.8