Balance Sheet Components (Tables)

6 Months Ended

Jun. 30, 2024

Balance Sheet Related Disclosures [Abstract]

Schedule of Inventory

Inventories of materials and supplies, emission allowances, fuel stock and stored natural gas are recorded at average cost and consisted of the following as of June 30, 2024 and December 31, 2023 (dollars in thousands):

	June 30,		December 31,
	2024		2023
Materials and supplies	$	92,446	$	81,651
Emission allowances		64,925		56,097
Stored natural gas		10,937		16,272
Fuel stock		7,280		5,964
Total	$	175,588	$	159,984

Schedule of Other Current Assets

Other current assets consisted of the following as of June 30, 2024 and December 31, 2023 (dollars in thousands):

	June 30,		December 31,
	2024		2023
Prepayments	$	52,276	$	52,752
Income taxes receivable		7,991		29,234
Derivative assets net of collateral		4,462		11,821
Other		11,988		9,977
Total	$	76,717	$	103,784

Schedule of Net Utility Property Recorded at Original Cost Net of Accumulated Depreciation

Net utility property, which is recorded at original cost, net of accumulated depreciation, consisted of the following as of June 30, 2024 and December 31, 2023 (dollars in thousands):

	June 30,		December 31,
	2024		2023
Utility plant in service	$	7,946,547	$	7,799,481
Construction work in progress		222,560		179,527
Total		8,169,107		7,979,008
Less: Accumulated depreciation and amortization		2,341,964		2,278,952
Total	$	5,827,143	$	5,700,056

Other Property and Investments-Net and Other Non-Current Assets

Other property and investments-net and other non-current assets consisted of the following as of June 30, 2024 and December 31, 2023 (dollars in thousands):

	June 30,		December 31,
	2024		2023
Equity investments	$	157,369	$	153,350
Operating lease ROU assets		66,864		67,585
Finance lease ROU assets		34,593		36,414
Non-utility property		33,508		33,813
Notes receivable		15,578		15,287
Long-term prepaid license fees		21,356		19,448
Pension asset		41,625		32,997
Investment in affiliated trust		11,547		11,547
Deferred compensation assets		8,551		7,794
Other		17,583		15,750
Total	$	408,574	$	393,985

Other Current Liabilities

Other current liabilities consisted of the following as of June 30, 2024 and December 31, 2023 (dollars in thousands):

	June 30, 2024		December 31, 2023
Accrued taxes other than income taxes	$	28,572	$	31,928
Derivative liabilities net of collateral		23,764		17,217
Employee paid time off accruals		35,110		32,072
Accrued interest		24,080		23,539
Climate Commitment Act obligations		—		19,081
Pensions and other postretirement benefits		11,130		14,082
Other		44,105		54,017
Total	$	166,761	$	191,936

Schedule of Other Non-Current Liabilities and Deferred Credits

Other non-current liabilities and deferred credits consisted of the following as of June 30, 2024 and December 31, 2023 (dollars in thousands):

	June 30, 2024		December 31, 2023
Operating lease liabilities	$	64,851	$	63,559
Finance lease liabilities		37,313		39,095
Deferred investment tax credits		27,833		28,233
Climate Commitment Act obligations		65,046		26,026
Asset retirement obligations		18,210		18,058
Derivative liabilities net of collateral		8,665		17,902
Other		19,902		17,357
Total	$	241,820	$	210,230

Schedule of Regulatory Assets and Liabilities

Regulatory assets and liabilities consisted of the following as of June 30, 2024 and December 31, 2023 (dollars in thousands):

	June 30, 2024				December 31, 2023
	Current		Non-Current		Current		Non-Current
Regulatory Assets
Energy commodity derivatives	$	41,242	$	10,362	$	51,419	$	17,720
Deferred Climate Commitment Act costs		39,558		20,530		—		46,022
Deferred power costs		17,859		12,895		29,190		20,654
Wildfire resiliency		10,487		12,490		—		23,737
Decoupling surcharge		8,133		8,218		4,638		5,469
Deferred natural gas costs		9,452		—		60,667		—
Deferred income taxes		—		247,393		—		244,303
Pension and other postretirement benefit plans		—		112,730		—		117,658
Interest rate swaps		—		175,820		—		179,489
AFUDC above FERC allowed rate		—		48,727		—		49,985
Settlement with Coeur d'Alene Tribe		—		36,134		—		36,692
Advanced meter infrastructure		—		27,827		—		29,345
Utility plant abandoned		—		36,878		—		38,274
Colstrip excess depreciation		—		22,347		—		19,429
COVID-19 deferrals		—		11,945		—		12,142
Demand side management programs		—		16,068		—		10,033
Other regulatory assets		3,658		44,403		413		43,216
Total regulatory assets	$	130,389	$	844,767	$	146,327	$	894,168
Regulatory Liabilities
Other income tax related liabilities	$	14,753	$	54,559	$	25,129	$	56,582
Excess deferred income taxes		14,230		286,185		14,510		293,029
Deferred Climate Commitment Act revenues		34,670		9,435		—		37,231
Deferred power costs		250		2,463		—		4,000
Deferred natural gas costs		10,469		—		9,296		—
Decoupling rebate		9,648		2,869		18,680		6,344
Utility plant retirement costs		—		432,227		—		417,027
Interest rate swaps		—		24,405		—		23,752
COVID-19 deferrals		—		10,787		—		10,172
Other regulatory liabilities		10,365		6,131		8,392		8,529
Total regulatory liabilities	$	94,385	$	829,061	$	76,007	$	856,666