Balance Sheet Components (Tables)

6 Months Ended

Jun. 30, 2023

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, 2023 and December 31, 2022 (dollars in thousands):

	June 30,		December 31,
	2023		2022
Materials and supplies	$	80,569	$	75,766
Emission allowances		14,558		—
Stored natural gas		14,952		26,788
Fuel stock		5,726		5,120
Total	$	115,805	$	107,674

Schedule of Other Current Assets

Other current assets consisted of the following as of June 30, 2023 and December 31, 2022 (dollars in thousands):

	June 30,		December 31,
	2023		2022
Prepayments	$	48,039	$	30,201
Income taxes receivable		23,264		30,740
Derivative assets net of collateral		121		18,198
Collateral posted for derivative instruments after netting with outstanding    derivatives		9,770		66,142
Other		8,687		5,886
Total	$	89,881	$	151,167

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, 2023 and December 31, 2022 (dollars in thousands):

	June 30,		December 31,
	2023		2022
Utility plant in service	$	7,619,473	$	7,561,688
Construction work in progress		175,010		164,147
Total		7,794,483		7,725,835
Less: Accumulated depreciation and amortization		2,245,832		2,281,126
Total	$	5,548,651	$	5,444,709

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, 2023 and December 31, 2022 (dollars in thousands):

	June 30,		December 31,
	2023		2022
Equity investments	$	149,675	$	147,809
Operating lease ROU assets		68,594		68,238
Finance lease ROU assets		38,235		40,056
Non-utility property		30,995		25,401
Notes receivable		18,466		17,954
Long-term prepaid license fees		17,771		17,936
Pension assets		19,137		13,382
Investment in affiliated trust		11,547		11,547
Deferred compensation assets		7,428		7,541
Held for sale		3,259		—
Other		16,701		15,221
Total	$	381,808	$	365,085

Other Current Liabilities

Other current liabilities consisted of the following as of June 30, 2023 and December 31, 2022 (dollars in thousands):

	June 30, 2023		December 31, 2022
Accrued taxes other than income taxes	$	30,838	$	38,568
Derivative liabilities		8,585		26,910
Employee paid time off accruals		33,022		29,279
Accrued interest		27,107		20,863
Deferred wholesale revenue		—		8,481
Pensions and other postretirement benefits		13,255		15,625
Other		35,676		49,689
Total	$	148,483	$	189,415

Schedule of Other Non-Current Liabilities and Deferred Credits

Other non-current liabilities and deferred credits consisted of the following as of June 30, 2023 and December 31, 2022 (dollars in thousands):

	June 30, 2023		December 31, 2022
Operating lease liabilities	$	66,537	$	64,284
Finance lease liabilities		40,795		42,495
Deferred investment tax credits		28,509		28,784
Climate Commitment Act obligations		32,994		—
Asset retirement obligations		15,946		15,783
Derivative liabilities		6,044		7,892
Other		15,912		16,617
Total	$	206,737	$	175,855

Schedule of Regulatory Assets and Liabilities

Regulatory assets and liabilities consisted of the following as of June 30, 2023 and December 31, 2022 (dollars in thousands):

	June 30, 2023				December 31, 2022
	Current		Non-Current		Current		Non-Current
Regulatory Assets
Energy commodity derivatives	$	41,198	$	18,370	$	112,090	$	18,185
Decoupling surcharge		4,105		3,129		6,250		5,449
Deferred natural gas costs		88,897		—		52,091		—
Deferred power costs		29,706		20,527		23,356		24,043
Deferred income taxes		—		240,143		—		240,325
Pension and other postretirement benefit plans		—		132,530		—		135,337
Interest rate swaps		—		182,793		—		185,919
AFUDC above FERC allowed rate		—		50,365		—		51,649
Settlement with Coeur d'Alene Tribe		—		37,251		—		37,809
Advanced meter infrastructure		—		30,863		—		32,381
Utility plant abandoned		—		30,563		—		24,389
Deferred Climate Commitment Act costs		—		32,008		—		—
COVID-19 deferrals		—		9,230		—		9,793
Unamortized debt repurchase costs		—		5,934		—		6,177
Demand side management programs		—		485		—		3,683
Other regulatory assets		—		67,300		—		58,189
Total regulatory assets	$	163,906	$	861,491	$	193,787	$	833,328
Regulatory Liabilities
Income tax related liabilities	$	48,879	$	365,954	$	73,267	$	390,734
Deferred natural gas costs		4,924		—		—		—
Decoupling rebate		13,066		26,798		9,469		20,476
Utility plant retirement costs		—		403,291		—		376,817
Interest rate swaps		—		23,402		—		24,204
COVID-19 deferrals		—		11,069		—		11,874
Other regulatory liabilities		12,224		14,508		12,929		16,732
Total regulatory liabilities	$	79,093	$	845,022	$	95,665	$	840,837