Note 9 - Fair Value Measurements (Tables)

12 Months Ended

Sep. 30, 2022

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, 2022
ASSETS
Gas Utility:
U.S. stock/bond mutual funds	$	19.1	$	—	$	—	$	—		$	19.1
NYMEX/ICE natural gas contracts		57.8		—		—		(57.8	)		—
Gas Marketing:
NYMEX/ICE natural gas contracts		91.8		—		—		(91.8	)		—
Natural gas commodity contracts		56.6		—		—		(4.0	)		52.6
Other:
U.S. stock/bond mutual funds		29.3		—		—		—			29.3
Interest rate swaps		63.6		—		—		—			63.6
Total	$	318.2	$	—	$	—	$	(153.6	)	$	164.6
LIABILITIES
Gas Utility:
NYMEX/ICE natural gas contracts	$	30.7	$	—	$	—	$	(30.7	)	$	—
Gas Marketing:
NYMEX/ICE natural gas contracts		82.3		—		—		(82.3	)		—
Natural gas commodity contracts		65.5		—		—		(4.0	)		61.5
Total	$	178.5	$	—	$	—	$	(117.0	)	$	61.5
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

							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, 2022
ASSETS
U.S. stock/bond mutual funds	$	19.1	$	—	$	—	$	—		$	19.1
NYMEX/ICE natural gas contracts		57.8		—		—		(57.8	)		—
Total	$	76.9	$	—	$	—	$	(57.8	)	$	19.1
LIABILITIES
NYMEX/ICE natural gas contracts	$	30.7	$	—	$	—	$	(30.7	)	$	—
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	)	$	—