Jointly Owned Facilities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Jointly Owned Electricity Generation Plant \| Big Stone Station
Jointly Owned Utility Plant Interests [Line Items]
Proportionate ownership share	22.70%
Utility plant in service	$ 159,437	$ 157,699
Construction work in progress	197	231
Less accumulated depreciation	52,264	48,590
Utility plant in services net	$ 107,370	109,340
Jointly Owned Electricity Generation Plant \| Coyote Station
Jointly Owned Utility Plant Interests [Line Items]
Proportionate ownership share	25.00%
Utility plant in service	$ 160,208	158,274
Construction work in progress	159	1,807
Less accumulated depreciation	113,187	111,203
Utility plant in services net	$ 47,180	48,878
Jointly Owned Electricity Generation Plant \| Wygen III
Jointly Owned Utility Plant Interests [Line Items]
Proportionate ownership share	25.00%
Utility plant in service	$ 66,852	66,238
Construction work in progress	127	273
Less accumulated depreciation	13,728	12,477
Utility plant in services net	$ 53,251	54,034
Jointly Owned Electricity Transmission and Distribution System \| BSSE
Jointly Owned Utility Plant Interests [Line Items]
Proportionate ownership share	50.00%
Utility plant in service	$ 107,260	107,260
Construction work in progress	0	0
Less accumulated depreciation	8,111	6,182
Utility plant in services net	$ 99,149	101,078
Jointly Owned Electricity Transmission and Distribution System \| JETx
Jointly Owned Utility Plant Interests [Line Items]
Proportionate ownership share	50.00%
Utility plant in service	$ 0	0
Construction work in progress	1,372	0
Less accumulated depreciation	0	0
Utility plant in services net	$ 1,372	$ 0

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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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.

+ References

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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.

+ References

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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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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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