Note 10 - Derivative Instruments and Hedging Activities (Tables)

12 Months Ended

Sep. 30, 2022

Notes Tables

Schedule of Derivative Instruments [Table Text Block]

	September 30, 2022				September 30, 2021
Gas Marketing	Notional (MMBtu millions)		Maximum Term (Months)		Notional (MMBtu millions)		Maximum Term (Months)
Natural gas futures purchased		76.3		54		103.3		51
Natural gas options purchased, net		3.7		12		7.1		15
Natural gas basis swaps purchased		61.7		39		101.7		27
Gas Utility
Natural gas futures purchased		13.0		12		52.8		12

	September 30, 2022				September 30, 2021
	Notional (MMBtu millions)		Maximum Term (Months)		Notional (MMBtu millions)		Maximum Term (Months)
Natural gas futures purchased		13.0		12		52.8		12

Derivative Instruments, Gain (Loss) [Table Text Block]

Effect of Derivative Instruments on the Consolidated Statements of Income and Comprehensive Income
	Location of Gain (Loss)
	Recorded in Income	2022			2021			2020
Derivatives in Cash Flow Hedging Relationships
Effective portion of gain (loss) recognized in OCI on derivatives:
Interest rate swaps		$	56.7		$	61.2		$	(8.9	)
Effective portion of (loss) gain reclassified from AOCI to income:
Interest rate swaps	Interest Expense	$	(1.2	)	$	(1.3	)	$	(3.2	)
Derivatives Not Designated as Hedging Instruments*
Gain (Loss) recognized in income on derivatives:
Natural gas commodity contracts	Operating Expenses: Natural Gas	$	52.6		$	54.1		$	9.2
NYMEX / ICE natural gas contracts	Operating Expenses: Natural Gas		43.3			(77.5	)		(11.8	)
Total		$	95.9		$	(23.4	)	$	(2.6	)

Schedule of Derivative Instruments in Statement of Financial Position, Fair Value [Table Text Block]

Fair Value of Derivative Instruments in the Consolidated Balance Sheets
	Derivative Assets*			Derivative Liabilities*
September 30, 2022	Balance Sheet Location	Fair Value		Balance Sheet Location	Fair Value
Derivatives designated as hedging instruments
Other: Interest rate swaps	Current Assets: Other	$	63.6	Current Liabilities: Other	$	—
Subtotal			63.6			—
Derivatives not designated as hedging instruments
Gas Utility:
Natural gas contracts	Current Assets: Other		57.8	Current Liabilities: Other		30.7
Gas Marketing:
NYMEX / ICE natural gas contracts	Current Assets: Other		79.2	Current Liabilities – Other		71.5
	Deferred Charges and Other Assets: Other	12.7		Deferred Credits and Other Liabilities: Other		10.8
Natural gas commodity	Current Assets: Other		53.4	Current Liabilities – Other		55.1
	Deferred Charges and Other Assets: Other		3.1	Deferred Credits and Other Liabilities: Other		10.4
Subtotal			206.2			178.5
Total derivatives		$	269.8		$	178.5
September 30, 2021
Derivatives designated as hedging instruments
Other: Interest rate swaps	Current Assets: Other	$	12.6	Current Liabilities: Other	$	5.7
Subtotal			12.6			5.7
Derivatives not designated as hedging instruments
Gas Utility:
Natural gas contracts	Current Assets: Other		104.0	Current Liabilities: Other		0.3
Gas Marketing:
NYMEX / ICE natural gas contracts	Current Assets: Other	93.9		Current Liabilities – Other		50.1
	Deferred Charges and Other Assets: Other		20.8	Deferred Credits and Other Liabilities: Other		11.9
Natural gas commodity	Current Assets: Other		34.1	Current Liabilities – Other		82.5
	Deferred Charges and Other Assets: Other		1.1	Deferred Credits and Other Liabilities: Other		14.2
Subtotal			253.9			159.0
Total derivatives		$	266.5		$	164.7

Fair Value of Derivative Instruments in the Balance Sheets
	Derivative Assets*			Derivative Liabilities*
September 30, 2022	Balance Sheet Location	Fair Value		Balance Sheet Location	Fair Value
Derivatives not designated as hedging instruments
Natural gas contracts	Current Assets: Other	$	57.8	Current Liabilities: Other	$	30.7
September 30, 2021
Derivatives not designated as hedging instruments
Natural gas contracts	Current Assets: Other	$	104.0	Current Liabilities: Other	$	0.3

Derivative Instrument Reconciliation [Table Text Block]

	2022			2021
Fair value of derivative assets presented above	$	269.8		$	266.5
Fair value of cash margin receivable offset with derivatives		(36.6	)		(135.4	)
Netting of assets and liabilities with the same counterparty		(117.0	)		(73.0	)
Total	$	116.2		$	58.1
Derivative Instrument Assets, per Consolidated Balance Sheets:
Current Assets: Other	$	113.1		$	57.0
Deferred Charges and Other Assets: Other		3.1			1.1
Total	$	116.2		$	58.1
Fair value of derivative liabilities presented above	$	178.5		$	164.7
Netting of assets and liabilities with the same counterparty		(117.0	)		(73.0	)
Total	$	61.5		$	91.7
Derivative Instrument Liabilities, per Consolidated Balance Sheets:
Current Liabilities: Other	$	51.1		$	77.5
Deferred Credits and Other Liabilities: Other		10.4			14.2
Total	$	61.5		$	91.7

	2022			2021
Fair value of derivative assets presented above	$	57.8		$	104.0
Fair value of cash margin (payable) receivable offset with derivatives		(27.1	)		(103.7	)
Netting of assets and liabilities with the same counterparty		(30.7	)		(0.3	)
Total	$	—		$	—
Fair value of derivative liabilities presented above	$	30.7		$	0.3
Netting of assets and liabilities with the same counterparty		(30.7	)		(0.3	)
Total	$	—		$	—