Derivative Instruments and Hedging Activities (Tables)

3 Months Ended

Mar. 31, 2026

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Schedule of Notional Amounts of Outstanding Derivative Positions

The following table presents the outstanding hedged forecasted transactions as of March 31, 2026:

Hedged Transaction

Term

Contracted
Monthly Volumes
of Forecasted
Transactions

Price

Natural gas purchases

Through December 2033

20% to 62%

$2.79 - $6.51 per dekatherm

Tar oil sales

Through December 2027

23% to 90%

$52.00 - $93.80 per barrel

Electricity purchases

Through December 2027

24% to 90%

$30.50 - $58.60 per MWh

Diesel purchases

Through January 2029

9% to 80%

$2.05 - $2.44 per gallon

Schedule of Derivative Instruments in Statement of Financial Position, Fair Value

The fair value and classification of the asset and liability portion of the derivative instruments in the consolidated balance sheets is as follows:


	March 31, 2026				December 31, 2025
Balance Sheet Location	Fair Value of Asset Derivatives		Fair Value of Liability Derivatives		Fair Value of Asset Derivatives		Fair Value of Liability Derivatives
	(In thousands)
Derivatives designated as cash flow hedges:
Commodity derivatives:
Prepayments and other current assets	$	5,031	$	—	$	5,312	$	—
Other investments	1,858		—		1,684		—
Other current liabilities	—		(8,104)		—		(1,319)
Other noncurrent liabilities	—		(1,693)		—		(671)
Total derivatives designated as cash flow hedges	6,889		(9,797)		6,996		(1,990)

Derivatives not designated as cash flow hedges:
Commodity derivatives:
Prepayments and other current assets	12,367		—		34,673		—
Other investments	—		—		1,211		—
Other current liabilities	—		(10,895)		—		(14,763)
Other noncurrent liabilities	—		(13,072)		—		(14,687)
Interest rate derivatives:
Other noncurrent liabilities	—		(19,689)		—		(22,031)
Total derivatives not designated as cash flow hedges	12,367		(43,656)		35,884		(51,481)
	$	19,256	$	(53,453)	$	42,880	$	(53,471)

Derivative Instruments, Gain (Loss)

The following table summarizes Dakota Gas and Dakota Coal gains and losses and financial statement classification of the derivatives designated as cash flow hedges as of March 31, 2026. This does not reflect the expected gains or losses arising from the underlying physical transactions; therefore it is not indicative of the economic gross profit or loss realized when the underlying physical and financial transactions were settled.


	Location of Loss Recognized in Net (Gain) Loss on Cash Flow Hedging Relationships
	March 31, 2026
	Other Operating Revenues		Cost of Products Sold
	(In thousands)
Total amounts of income and expense line items presented on the consolidated statements of operations in which the effects of cash flow hedges are recorded	$	240,425	$	131,746
Loss on cash flow hedges:
Commodity derivatives:
Amount reclassified from accumulated other comprehensive income into net margins and earnings	$	(760)	$	(28)

The following table summarizes Dakota Gas and Dakota Coal gains and losses and financial statement classification of the derivatives designated as cash flow hedges as of March 31, 2025. This does not reflect the expected gains or losses arising from the underlying physical transactions; therefore it is not indicative of the economic gross profit or loss realized when the underlying physical and financial transactions were settled.


	Location of Gain (Loss) Recognized in Net (Gain) Loss on Cash Flow Hedging Relationships
	March 31, 2025
	Other Operating Revenues		Cost of Products Sold
	(In thousands)
Total amounts of income and expense line items presented on the consolidated statements of operations in which the effects of cash flow hedges are recorded	$	222,934	$	123,734
Gain (loss) on cash flow hedges:
Commodity derivatives:
Amount reclassified from accumulated other comprehensive income into net margins and earnings	$	554	$	(73)

The following table summarizes Dakota Gas and Dakota Coal gains and losses and financial statement classification of the derivatives designated as cash flow hedges for the three months ended March 31, 2026 and 2025.


	March 31, 2026		March 31, 2025
	(In thousands)
Decrease in fair value of commodity derivatives	$	(8,703)	$	(1,486)
Recognition of losses (gains) in earnings due to settlements on commodity derivatives	788		(481)
Total other comprehensive loss from hedging	$	(7,915)	$	(1,967)

The following table summarizes the impact of commodity derivatives that do not meet the criteria. This does not reflect the expected gains or losses arising from the underlying physical transactions; therefore it is not indicative of the economic gross profit or loss realized when the underlying physical and financial transactions were settled.


	March 31, 2026		March 31, 2025
Location of Gain on Derivatives Recognized in Net Margin and Earnings	Recognized Gain		Recognized Gain
	(In thousands)
Derivatives not designated as cash flow hedges:
Commodity derivatives:
Other operating revenues	$	19	$	86
Total	$	19	86