Regulatory assets and liabilities (Tables)

3 Months Ended

Mar. 31, 2023

Regulatory Assets and Liabilities Disclosure [Abstract]

Regulatory Assets

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

	Estimated Recovery or Refund Period as of March 31, 2023	*	March 31, 2023		March 31, 2022		December 31, 2022
			(In thousands)
Regulatory assets:
Current:
Natural gas costs recoverable through rate adjustments	Up to 1 year		$	198,166	$	66,132	$	141,306
Conservation programs	Up to 1 year		8,599		7,567		8,544
Cost recovery mechanisms	Up to 1 year		3,954		3,432		4,019
Other	Up to 1 year		5,599		11,947		11,223
			216,318		89,078		165,092
Noncurrent:
Pension and postretirement benefits	**		143,349		142,681		143,349
Cost recovery mechanisms	Up to 10 years		65,732		67,989		67,171
Plant costs/asset retirement obligations	Over plant lives		44,131		63,325		44,462
Manufactured gas plant site remediation	-		26,605		26,089		26,624
Environmental compliance programs	-		21,942		—		—
Plant to be retired	-		21,072		29,452		21,525
Taxes recoverable from customers	Over plant lives		12,198		12,492		12,330
Long-term debt refinancing costs	Up to 37 years		3,041		3,636		3,188
Other	Up to 16 years		11,430		13,564		11,010
			349,500		359,228		329,659
Total regulatory assets			$	565,818	$	448,306	$	494,751
Regulatory liabilities:
Current:
Electric fuel and purchased power deferral	Up to 1 year		9,630		—		4,929
Natural gas costs refundable through rate adjustments	Up to 1 year		6,331		13,107		955
Conservation programs	Up to 1 year		3,834		144		4,126
Cost recovery mechanisms	Up to 1 year		2,926		2,550		1,977
Taxes refundable to customers	Up to 1 year		1,513		3,470		3,937
Refundable fuel and electric costs	Up to 1 year		1,179		316		3,253
Other	Up to 1 year		18,982		11,599		7,263
			44,395		31,186		26,440
Noncurrent:
Plant removal and decommissioning costs	Over plant lives		214,467		171,485		208,650
Taxes refundable to customers	Over plant lives		200,879		212,472		203,222
Cost recovery mechanisms	Up to 19 years		16,313		9,508		14,025
Accumulated deferred investment tax credit	Up to 19 years		13,996		13,352		13,594
Pension and postretirement benefits	**		7,376		20,434		7,376
Other	Up to 15 years		1,638		6,377		1,587
			454,669		433,628		448,454
Total regulatory liabilities			$	499,064	$	464,814	$	474,894
Net regulatory position			$	66,754	$	(16,508)	$	19,857

*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.

Regulatory Liabilities

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

	Estimated Recovery or Refund Period as of March 31, 2023	*	March 31, 2023		March 31, 2022		December 31, 2022
			(In thousands)
Regulatory assets:
Current:
Natural gas costs recoverable through rate adjustments	Up to 1 year		$	198,166	$	66,132	$	141,306
Conservation programs	Up to 1 year		8,599		7,567		8,544
Cost recovery mechanisms	Up to 1 year		3,954		3,432		4,019
Other	Up to 1 year		5,599		11,947		11,223
			216,318		89,078		165,092
Noncurrent:
Pension and postretirement benefits	**		143,349		142,681		143,349
Cost recovery mechanisms	Up to 10 years		65,732		67,989		67,171
Plant costs/asset retirement obligations	Over plant lives		44,131		63,325		44,462
Manufactured gas plant site remediation	-		26,605		26,089		26,624
Environmental compliance programs	-		21,942		—		—
Plant to be retired	-		21,072		29,452		21,525
Taxes recoverable from customers	Over plant lives		12,198		12,492		12,330
Long-term debt refinancing costs	Up to 37 years		3,041		3,636		3,188
Other	Up to 16 years		11,430		13,564		11,010
			349,500		359,228		329,659
Total regulatory assets			$	565,818	$	448,306	$	494,751
Regulatory liabilities:
Current:
Electric fuel and purchased power deferral	Up to 1 year		9,630		—		4,929
Natural gas costs refundable through rate adjustments	Up to 1 year		6,331		13,107		955
Conservation programs	Up to 1 year		3,834		144		4,126
Cost recovery mechanisms	Up to 1 year		2,926		2,550		1,977
Taxes refundable to customers	Up to 1 year		1,513		3,470		3,937
Refundable fuel and electric costs	Up to 1 year		1,179		316		3,253
Other	Up to 1 year		18,982		11,599		7,263
			44,395		31,186		26,440
Noncurrent:
Plant removal and decommissioning costs	Over plant lives		214,467		171,485		208,650
Taxes refundable to customers	Over plant lives		200,879		212,472		203,222
Cost recovery mechanisms	Up to 19 years		16,313		9,508		14,025
Accumulated deferred investment tax credit	Up to 19 years		13,996		13,352		13,594
Pension and postretirement benefits	**		7,376		20,434		7,376
Other	Up to 15 years		1,638		6,377		1,587
			454,669		433,628		448,454
Total regulatory liabilities			$	499,064	$	464,814	$	474,894
Net regulatory position			$	66,754	$	(16,508)	$	19,857

*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.