Regulatory Assets and Liabilities (Tables)

12 Months Ended

Dec. 31, 2023

Regulatory Assets and Liabilities Disclosure [Abstract]

Schedule of Regulatory Assets and Liabilities [Table Text Block]

	December 31,
	2023		2022
	(Thousands)
Current regulatory assets:
Fuel recovery	$	19	$	11,871
Levelized depreciation	2,035		1,694
Total current regulatory assets	2,054		13,565
Long-term regulatory assets:
Levelized depreciation	9,519		11,601
Grossed-up deferred taxes on equity funds used during construction	3,969		4,350
Washington State Carbon and Greenhouse Gas Tax	22,308		—
Total long-term regulatory assets	35,796		15,951
Total regulatory assets	$	37,850	$	29,516
Current regulatory liabilities:
Customer tax refund	$	—	$	125,506
Deferred federal taxes - liability	18,643		18,643
Deferred state taxes - liability	1,094		1,094
Fuel recovery	1,637		—
Total current regulatory liabilities	21,374		145,243
Long-term regulatory liabilities:
Deferred federal taxes - liability	169,240		187,883
Postretirement benefits	42,415		42,207
Asset retirement obligations, net	30,685		30,590
Deferred state taxes - liability	9,932		11,026
Total long-term regulatory liabilities	252,272		271,706
Total regulatory liabilities	$	273,646	$	416,949