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Select Balance Sheet Information - Schedule of Property, Plant and Equipment (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, net of accumulated depreciation	$ 2,289,491	$ 2,212,717
Electric Plant
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	3,046,027	2,958,311
Less Accumulated Depreciation and Amortization	876,330	859,988
Property, Plant and Equipment, net of accumulated depreciation	2,169,697	2,098,323
Nonelectric Property, Plant and Equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	318,388	309,098
Less Accumulated Depreciation and Amortization	198,594	194,704
Property, Plant and Equipment, net of accumulated depreciation	119,794	114,394
Electric Plant in Service | Electric Plant
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	2,917,699	2,844,379
Construction Work in Progress | Electric Plant
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	128,328	113,932
Construction Work in Progress | Nonelectric Property, Plant and Equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	22,840	15,170
Nonelectric Property, Plant and Equipment in Service | Nonelectric Property, Plant and Equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 295,548	$ 293,928

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- Definition

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

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