Regulatory assets and liabilities (Tables)

3 Months Ended

Mar. 31, 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 March 31, 2025	*	March 31, 2025		March 31, 2024		December 31, 2024
			(In thousands)
Regulatory assets:
Current:
Environmental compliance programs	Up to 1 year		$	56,441	$	7,443	$	76,964
Natural gas costs recoverable through rate adjustments	Up to 1 year		51,321		110,481		91,091
Conservation programs	Up to 1 year		16,902		13,735		19,123
Electric fuel and purchased power deferral	Up to 1 year		7,109		17,061		9,662
Cost recovery mechanisms	Up to 1 year		4,806		6,454		5,114
Decoupling mechanisms	Up to 1 year		4,769		1,046		6,767
Other	Up to 1 year		1,993		2,394		6,715
			143,341		158,614		215,436
Noncurrent:
Pension and postretirement benefits	**		142,065		142,511		142,064
Cost recovery mechanisms	Up to 24 years		72,764		84,546		76,542
Plant costs/asset retirement obligations	Over plant lives		46,920		45,702		47,042
Manufactured gas plant site remediation	-		27,443		25,851		27,964
Taxes recoverable from customers	Over plant lives		12,228		12,331		12,221
Covid-19 deferred costs	Up to 3 years		3,926		3,087		4,167
Long-term debt refinancing costs	Up to 36 years		1,865		2,453		2,011
Natural gas costs recoverable through rate adjustments	-		—		25,915		—
Electric fuel and purchased power deferral	-		—		15,612		4,349
Environmental compliance programs	-		—		50,372		—
Other	Up to 14 years		4,797		6,053		5,990
			312,008		414,433		322,350
Total regulatory assets			$	455,349	$	573,047	$	537,786
Regulatory liabilities:
Current:
Environmental compliance programs	Up to 1 year		$	65,680	$	—	$	72,387
Natural gas costs refundable through rate adjustments	Up to 1 year		46,744		54,282		45,427
Demand charges	Up to 1 year		10,000		8,645		—
Provision for rate refund	Up to 1 year		3,833		6,517		3,677
Margin sharing	Up to 1 year		3,562		2,869		4,156
Conservation programs	Up to 1 year		2,782		3,576		2,082
Taxes refundable to customers	Up to 1 year		2,087		1,991		2,163
Cost recovery mechanisms	Up to 1 year		716		5,642		1,720
Other	Up to 1 year		4,761		6,593		5,555
			140,165		90,115		137,167
Noncurrent:
Plant removal and decommissioning costs	Over plant lives		221,349		220,519		217,603
Taxes refundable to customers	Over plant lives		182,742		190,850		185,402
Cost recovery mechanisms	Up to 17 years		33,373		24,269		30,354
Accumulated deferred investment tax credit	Over plant lives		19,301		16,129		18,788
Pension and postretirement benefits	**		4,862		6,044		4,862
Environmental compliance programs	-		—		63,746		—
Other	Up to 13 years		2,252		1,927		2,161
			463,879		523,484		459,170
Total regulatory liabilities			$	604,044	$	613,599	$	596,337
Net regulatory position			$	(148,695)	$	(40,552)	$	(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 March 31, 2025	*	March 31, 2025		March 31, 2024		December 31, 2024
			(In thousands)
Regulatory assets:
Current:
Environmental compliance programs	Up to 1 year		$	56,441	$	7,443	$	76,964
Natural gas costs recoverable through rate adjustments	Up to 1 year		51,321		110,481		91,091
Conservation programs	Up to 1 year		16,902		13,735		19,123
Electric fuel and purchased power deferral	Up to 1 year		7,109		17,061		9,662
Cost recovery mechanisms	Up to 1 year		4,806		6,454		5,114
Decoupling mechanisms	Up to 1 year		4,769		1,046		6,767
Other	Up to 1 year		1,993		2,394		6,715
			143,341		158,614		215,436
Noncurrent:
Pension and postretirement benefits	**		142,065		142,511		142,064
Cost recovery mechanisms	Up to 24 years		72,764		84,546		76,542
Plant costs/asset retirement obligations	Over plant lives		46,920		45,702		47,042
Manufactured gas plant site remediation	-		27,443		25,851		27,964
Taxes recoverable from customers	Over plant lives		12,228		12,331		12,221
Covid-19 deferred costs	Up to 3 years		3,926		3,087		4,167
Long-term debt refinancing costs	Up to 36 years		1,865		2,453		2,011
Natural gas costs recoverable through rate adjustments	-		—		25,915		—
Electric fuel and purchased power deferral	-		—		15,612		4,349
Environmental compliance programs	-		—		50,372		—
Other	Up to 14 years		4,797		6,053		5,990
			312,008		414,433		322,350
Total regulatory assets			$	455,349	$	573,047	$	537,786
Regulatory liabilities:
Current:
Environmental compliance programs	Up to 1 year		$	65,680	$	—	$	72,387
Natural gas costs refundable through rate adjustments	Up to 1 year		46,744		54,282		45,427
Demand charges	Up to 1 year		10,000		8,645		—
Provision for rate refund	Up to 1 year		3,833		6,517		3,677
Margin sharing	Up to 1 year		3,562		2,869		4,156
Conservation programs	Up to 1 year		2,782		3,576		2,082
Taxes refundable to customers	Up to 1 year		2,087		1,991		2,163
Cost recovery mechanisms	Up to 1 year		716		5,642		1,720
Other	Up to 1 year		4,761		6,593		5,555
			140,165		90,115		137,167
Noncurrent:
Plant removal and decommissioning costs	Over plant lives		221,349		220,519		217,603
Taxes refundable to customers	Over plant lives		182,742		190,850		185,402
Cost recovery mechanisms	Up to 17 years		33,373		24,269		30,354
Accumulated deferred investment tax credit	Over plant lives		19,301		16,129		18,788
Pension and postretirement benefits	**		4,862		6,044		4,862
Environmental compliance programs	-		—		63,746		—
Other	Up to 13 years		2,252		1,927		2,161
			463,879		523,484		459,170
Total regulatory liabilities			$	604,044	$	613,599	$	596,337
Net regulatory position			$	(148,695)	$	(40,552)	$	(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.