Regulatory assets and liabilities

12 Months Ended

Dec. 31, 2022

Regulatory Assets and Liabilities Disclosure [Abstract]

Regulatory assets and liabilities

Regulatory Assets and Liabilities

The following table summarizes the individual components of unamortized regulatory assets and liabilities as of December 31:

	Estimated Recovery or Refund Period	*	2022		2021
			(In thousands)
Regulatory assets:
Current:
Natural gas costs recoverable through rate adjustments	Up to 1 year		$	141,306	$	86,371
Conservation programs	Up to 1 year		8,544		8,225
Cost recovery mechanisms	Up to 1 year		4,019		4,536
Decoupling	Up to 1 year		1,801		9,131
Other	Up to 1 year		9,422		10,428
			165,092		118,691
Noncurrent:
Pension and postretirement benefits	**		143,349		142,681
Cost recovery mechanisms	Up to 10 years		67,171		44,870
Plant costs/asset retirement obligations	Over plant lives		44,462		63,116
Manufactured gas plant sites remediation	-		26,624		26,053
Plant to be retired	-		21,525		50,070
Taxes recoverable from customers	Over plant lives		12,330		12,339
Long-term debt refinancing costs	Up to 38 years		3,188		3,794
Natural gas costs recoverable through rate adjustments	Up to 2 years		—		5,186
Other	Up to 16 years		11,010		9,742
			329,659		357,851
Total regulatory assets			$	494,751	$	476,542
Regulatory liabilities:
Current:
Electric fuel and purchased power deferral	Up to 1 year		$	4,929	$	—
Conservation programs	Up to 1 year		4,126		12
Taxes refundable to customers	Up to 1 year		3,937		3,841
Refundable fuel & electric costs	Up to 1 year		3,253		713
Natural gas costs refundable through rate adjustments	Up to 1 year		955		6,700
Other	Up to 1 year		9,240		5,037
			26,440		16,303
Noncurrent:
Plant removal and decommissioning costs	Over plant lives		208,650		168,152
Taxes refundable to customers	Over plant lives		203,222		215,421
Cost recovery mechanisms	Up to 19 years		14,025		2,919
Accumulated deferred investment tax credit	Up to 19 years		13,594		12,696
Pension and postretirement benefits	**		7,376		20,434
Other	Up to 15 years		1,587		9,168
			448,454		428,790
Total regulatory liabilities			$	474,894	$	445,093
Net regulatory position			$	19,857	$	31,449

*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.

As of December 31, 2022 and 2021, approximately $242.5 million and $296.6 million, respectively, of regulatory assets were not earning a rate of return but are expected to be recovered from customers in future rates. These assets are largely comprised of the unfunded portion of pension and postretirement benefits, asset retirement obligations, accelerated depreciation on plant retirement and the estimated future cost of manufactured gas plant site remediation.

In the last half of 2021 and in 2022, the Company has experienced higher natural gas costs due to increase in demand outpacing the supply along with the impact of global events. This increase in natural gas costs experienced in certain jurisdictions has been partially offset by the recovery of prior period natural gas costs being recovered over a period longer than the normal one-year period.

In February 2019, the Company announced the retirement of three aging coal-fired electric generating units. The Company accelerated the depreciation related to these facilities in property, plant and equipment and recorded the difference between the accelerated depreciation, in accordance with GAAP, and the depreciation approved for rate-making purposes as regulatory assets. Requests were filed with the NDPSC and SDPUC, and subsequently approved, to offset the savings associated with the cessation of operations of these units with the amortization of the deferred regulatory assets. The Company ceased operations of Lewis & Clark Station in March 2021 and Units 1 and 2 at Heskett Station in February 2022. The Company subsequently reclassified the costs being recovered for these facilities from plant retirement to cost recovery mechanisms in the previous table and began amortizing the associated plant retirement and closure costs in the jurisdictions where requests were filed, as previously discussed. The Company expects to recover the regulatory assets related to the plant retirements in future rates.

If, for any reason, the Company's regulated businesses cease to meet the criteria for application of regulatory accounting for all or part of their operations, the regulatory assets and liabilities relating to those portions ceasing to meet such criteria would be removed from the balance sheet and included in the statement of income or accumulated other comprehensive loss in the period in which the discontinuance of regulatory accounting occurs.