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Jointly Owned Facilities (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Jointly Owned Electricity Generation Plant | Big Stone Station
Jointly Owned Utility Plant Interests [Line Items]
Proportionate ownership share	22.70%
Utility plant in service	$ 155,302	$ 159,437
CWIP	318	197
Less accumulated depreciation	55,327	52,264
Utility plant in services net	$ 100,293	107,370
Jointly Owned Electricity Generation Plant | Coyote Station
Jointly Owned Utility Plant Interests [Line Items]
Proportionate ownership share	25.00%
Utility plant in service	$ 160,343	160,208
CWIP	755	159
Less accumulated depreciation	115,133	113,187
Utility plant in services net	$ 45,965	47,180
Jointly Owned Electricity Generation Plant | Wygen III
Jointly Owned Utility Plant Interests [Line Items]
Proportionate ownership share	25.00%
Utility plant in service	$ 67,851	66,852
CWIP	97	127
Less accumulated depreciation	15,340	13,728
Utility plant in services net	$ 52,608	53,251
Jointly Owned Electricity Transmission and Distribution System | BSSE
Jointly Owned Utility Plant Interests [Line Items]
Proportionate ownership share	50.00%
Utility plant in service	$ 111,043	107,260
CWIP	0	0
Less accumulated depreciation	10,359	8,111
Utility plant in services net	$ 100,684	99,149
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
CWIP	6,112	1,372
Less accumulated depreciation	0	0
Utility plant in services net	$ 6,112	$ 1,372

X

- Definition

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

+ References

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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- 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

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 980
-SubTopic 360
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-Section S99
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- Definition

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

+ References

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-Section S99
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- Definition

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

+ References

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-Section S99
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- Definition

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

+ References

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-SubTopic 360
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