Regulatory assets and liabilities (Tables)

9 Months Ended

Sep. 30, 2025

Regulatory Assets and Liabilities Disclosure [Abstract]

The following table summarizes the individual components of unamortized regulatory assets and liabilities:


	Estimated Recovery or Refund Period as of September 30, 2025	*	September 30, 2025		September 30, 2024		December 31, 2024
			(In thousands)
Regulatory assets:
Current:
Environmental compliance programs	Up to 1 year		$	69,646	$	80,198	$	76,964
Natural gas costs recoverable through rate adjustments	Up to 1 year		34,325		111,946		91,091
Conservation programs	Up to 1 year		27,405		19,059		19,123
Demand cost deferral	Up to 1 year		15,287		13,898		5,237
Decoupling mechanisms	Up to 1 year		9,716		4,795		6,767
Electric fuel and purchased power deferral	Up to 1 year		9,644		4,497		9,662
Cost recovery mechanisms	Up to 1 year		8,606		4,332		5,114
Other	Up to 1 year		4,520		2,283		1,478
			179,149		241,008		215,436
Noncurrent:
Pension and postretirement benefits	**		142,064		142,511		142,064
Cost recovery mechanisms	Up to 24 years		68,314		82,907		76,542
Plant costs/asset retirement obligations	Over plant lives		46,334		45,249		47,042
Manufactured gas plant site remediation	-		27,147		25,789		27,964
Taxes recoverable from customers	Over plant lives		12,257		12,316		12,221
Covid-19 deferred costs	Up to 3 years		3,863		3,857		4,167
Long-term debt refinancing costs	Up to 36 years		1,571		2,159		2,011
Natural gas costs recoverable through rate adjustments	-		—		11,707		—
Electric fuel and purchased power deferral	-		—		8,335		4,349
Environmental compliance programs	-		—		2,858		—
Other	Up to 14 years		4,340		5,890		5,990
			305,890		343,578		322,350
Total regulatory assets			$	485,039	$	584,586	$	537,786
Regulatory liabilities:
Current:
Environmental compliance programs	Up to 1 year		$	84,884	$	77,392	$	72,387
Natural gas costs refundable through rate adjustments	Up to 1 year		43,373		54,197		45,427
Provision for rate refund	Up to 1 year		4,358		8,868		3,677
Margin sharing	Up to 1 year		3,831		3,945		4,156
Taxes refundable to customers	Up to 1 year		2,325		2,195		2,163
Conservation programs	Up to 1 year		1,108		2,662		2,082
Cost recovery mechanisms	Up to 1 year		154		2,634		1,720
Other	Up to 1 year		3,789		5,175		5,555
			143,822		157,068		137,167
Noncurrent:
Plant removal and decommissioning costs	Over plant lives		228,982		224,839		217,603
Taxes refundable to customers	Over plant lives		177,469		184,715		185,402
Cost recovery mechanisms	Up to 17 years		38,426		28,397		30,354
Accumulated deferred investment tax credit	Over plant lives		21,615		17,679		18,788
Pension and postretirement benefits	**		4,862		6,043		4,862
Other	Up to 13 years		2,458		2,117		2,161
			473,812		463,790		459,170
Total regulatory liabilities			$	617,634	$	620,858	$	596,337
Net regulatory position			$	(132,595)	$	(36,272)	$	(58,551)

*Estimated recovery or refund period for amounts currently being recovered or refunded in rates to customers.

** Recovered as expense is incurred or cash contributions are made.

Schedule of Regulatory Liabilities

The following table summarizes the individual components of unamortized regulatory assets and liabilities:


	Estimated Recovery or Refund Period as of September 30, 2025	*	September 30, 2025		September 30, 2024		December 31, 2024
			(In thousands)
Regulatory assets:
Current:
Environmental compliance programs	Up to 1 year		$	69,646	$	80,198	$	76,964
Natural gas costs recoverable through rate adjustments	Up to 1 year		34,325		111,946		91,091
Conservation programs	Up to 1 year		27,405		19,059		19,123
Demand cost deferral	Up to 1 year		15,287		13,898		5,237
Decoupling mechanisms	Up to 1 year		9,716		4,795		6,767
Electric fuel and purchased power deferral	Up to 1 year		9,644		4,497		9,662
Cost recovery mechanisms	Up to 1 year		8,606		4,332		5,114
Other	Up to 1 year		4,520		2,283		1,478
			179,149		241,008		215,436
Noncurrent:
Pension and postretirement benefits	**		142,064		142,511		142,064
Cost recovery mechanisms	Up to 24 years		68,314		82,907		76,542
Plant costs/asset retirement obligations	Over plant lives		46,334		45,249		47,042
Manufactured gas plant site remediation	-		27,147		25,789		27,964
Taxes recoverable from customers	Over plant lives		12,257		12,316		12,221
Covid-19 deferred costs	Up to 3 years		3,863		3,857		4,167
Long-term debt refinancing costs	Up to 36 years		1,571		2,159		2,011
Natural gas costs recoverable through rate adjustments	-		—		11,707		—
Electric fuel and purchased power deferral	-		—		8,335		4,349
Environmental compliance programs	-		—		2,858		—
Other	Up to 14 years		4,340		5,890		5,990
			305,890		343,578		322,350
Total regulatory assets			$	485,039	$	584,586	$	537,786
Regulatory liabilities:
Current:
Environmental compliance programs	Up to 1 year		$	84,884	$	77,392	$	72,387
Natural gas costs refundable through rate adjustments	Up to 1 year		43,373		54,197		45,427
Provision for rate refund	Up to 1 year		4,358		8,868		3,677
Margin sharing	Up to 1 year		3,831		3,945		4,156
Taxes refundable to customers	Up to 1 year		2,325		2,195		2,163
Conservation programs	Up to 1 year		1,108		2,662		2,082
Cost recovery mechanisms	Up to 1 year		154		2,634		1,720
Other	Up to 1 year		3,789		5,175		5,555
			143,822		157,068		137,167
Noncurrent:
Plant removal and decommissioning costs	Over plant lives		228,982		224,839		217,603
Taxes refundable to customers	Over plant lives		177,469		184,715		185,402
Cost recovery mechanisms	Up to 17 years		38,426		28,397		30,354
Accumulated deferred investment tax credit	Over plant lives		21,615		17,679		18,788
Pension and postretirement benefits	**		4,862		6,043		4,862
Other	Up to 13 years		2,458		2,117		2,161
			473,812		463,790		459,170
Total regulatory liabilities			$	617,634	$	620,858	$	596,337
Net regulatory position			$	(132,595)	$	(36,272)	$	(58,551)

*Estimated recovery or refund period for amounts currently being recovered or refunded in rates to customers.

** Recovered as expense is incurred or cash contributions are made.