Jointly-Owned Facilities and Assets - Table (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Jointly-Owned Facilities and Assets [Line Items]
Plant in Service	$ 817.3	$ 826.9
Accumulated Depreciation	422.8	393.4
Construction Work in Progress	14.2	2.8
Transmission Assets \| Transmission Assets
Jointly-Owned Facilities and Assets [Line Items]
Plant in Service	101.1	101.0
Accumulated Depreciation	26.1	23.6
Construction Work in Progress	$ 0.0	$ 0.0
Transmission Assets \| Transmission Assets \| Minimum
Jointly-Owned Facilities and Assets [Line Items]
% Ownership	9.30%	9.30%
Transmission Assets \| Transmission Assets \| Maximum
Jointly-Owned Facilities and Assets [Line Items]
% Ownership	14.70%	14.70%
Boswell Unit 4 \| Boswell Unit 4
Jointly-Owned Facilities and Assets [Line Items]
Plant in Service	$ 716.2	$ 725.9
Accumulated Depreciation	396.7	369.8
Construction Work in Progress	$ 14.2	$ 2.8
% Ownership	80.00%	80.00%

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/1943274/2147479070/980-360-S99-1

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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 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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