Jointly Owned Facilities (Details) $ in Millions	Dec. 31, 2023 USD ($)
Wyodak Plant
Jointly Owned Utility Plant Interests [Line Items]
Ownership Interest	20.00%
Plant in Service	$ 122.3
Construction Work in Progress	0.0
Less Accumulated Depreciation	(73.4)
Plant Net of Accumulated Depreciation	$ 48.9
Transmission Tie
Jointly Owned Utility Plant Interests [Line Items]
Ownership Interest	35.00%
Plant in Service	$ 24.5
Construction Work in Progress	0.3
Less Accumulated Depreciation	(7.8)
Plant Net of Accumulated Depreciation	$ 17.0
Wygen III Generating Facility
Jointly Owned Utility Plant Interests [Line Items]
Ownership Interest	52.00%
Plant in Service	$ 145.3
Construction Work in Progress	0.3
Less Accumulated Depreciation	(32.2)
Plant Net of Accumulated Depreciation	$ 113.4
Wygen I Generating Facility
Jointly Owned Utility Plant Interests [Line Items]
Ownership Interest	76.50%
Plant in Service	$ 116.0
Construction Work in Progress	0.8
Less Accumulated Depreciation	(60.1)
Plant Net of Accumulated Depreciation	$ 56.7

The period end amount owned by the reporting utility of a jointly owned utility plant in service.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 980
-SubTopic 360
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 10.C)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479960/980-360-S99-1

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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- Definition

The total period end amount of plant in service and construction in progress net of accumulated depreciation for the utility's share of jointly owned electricity generation plant.

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- Definition

The period end amount of construction work in progress at a jointly owned electricity generation plant.

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- Definition

The period end amount of accumulated depreciation in a jointly owned electricity generation plant.

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- Definition

The proportionate share of interest (percent) in a jointly owned utility plant.

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