Property, Plant And Equipment (Tables)

12 Months Ended

Dec. 31, 2024

Property, Plant and Equipment [Abstract]

Schedule of Net Utility Property

Net utility property consisted of the following as of December 31 (dollars in millions):

	2024		2023
Utility plant in service	$	8,180	$	7,799
Construction work in progress		238		180
Total		8,418		7,979
Less: Accumulated depreciation and amortization		2,431		2,279
Total net utility property	$	5,987	$	5,700

Summary of Ratio of Depreciation to Average Depreciable Property and Average Service Lives for Utility Plan in Service

For utility operations, the ratio of depreciation provisions to average depreciable property was as follows for the years ended December 31:

	2024			2023			2022
Avista Utilities		3.45	%		3.52	%		3.50	%
Alaska Electric Light and Power Company		2.80	%		2.78	%		2.78	%

The average service lives for the following broad categories of utility plant in service are (in years):

	Avista Utilities		Alaska Electric Light and Power Company
Electric thermal/other production		27		41
Hydroelectric production		81		42
Electric transmission		44		43
Electric distribution		42		39
Natural gas distribution property		44	N/A
Other shorter-lived general plant		8		18

The gross balances of the major classifications of property, plant and equipment are detailed in the following table as of December 31 (dollars in millions):

	2024		2023
Avista Utilities:
Electric production	$	1,523	$	1,498
Electric transmission		1,105		1,059
Electric distribution		2,580		2,383
Electric construction work-in-progress (CWIP) and other		452		395
Electric total		5,660		5,335
Natural gas underground storage		63		60
Natural gas distribution		1,624		1,539
Natural gas CWIP and other		95		92
Natural gas total		1,782		1,691
Common plant (including CWIP)		760		760
Total Avista Utilities		8,202		7,786
AEL&P:
Electric production		120		119
Electric transmission		23		23
Electric distribution		36		32
Electric CWIP and other		26		9
Electric total		205		183
Common plant		11		10
Total AEL&P		216		193
Total gross utility property		8,418		7,979
Other (1)		6		6
Total	$	8,424	$	7,985

(1)Included in other property and investments-net and other non-current assets on the Consolidated Balance Sheets.