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Property, Plant and Equipment - Jointly Owned Utility Plants (Details) - USD ($) $ in Thousands | Dec. 31, 2022 | Dec. 31, 2021
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Big Stone Plant |  |
Jointly Owned Utility Plant Interests [Line Items] |  |
Electric Plant in Service | $ 338,411 | $ 338,699
Construction Work in Progress | 557 | 260
Accumulated Depreciation | (118,044) | (110,604)
Net Plant | $ 220,924 | $ 228,355
Big Stone Plant | OTP |  |
Jointly Owned Utility Plant Interests [Line Items] |  |
Ownership Percentage | 53.90% | 53.90%
Coyote Station |  |
Jointly Owned Utility Plant Interests [Line Items] |  |
Electric Plant in Service | $ 183,461 | $ 182,610
Construction Work in Progress | 2,315 | 1,110
Accumulated Depreciation | (111,666) | (107,894)
Net Plant | $ 74,110 | $ 75,826
Coyote Station | OTP |  |
Jointly Owned Utility Plant Interests [Line Items] |  |
Ownership Percentage | 35.00% | 35.00%
Big Stone South–Ellendale 345 kV line |  |
Jointly Owned Utility Plant Interests [Line Items] |  |
Electric Plant in Service | $ 106,185 | $ 106,194
Construction Work in Progress | 0 | 0
Accumulated Depreciation | (5,587) | (4,052)
Net Plant | $ 100,598 | $ 102,142
Big Stone South–Ellendale 345 kV line | OTP |  |
Jointly Owned Utility Plant Interests [Line Items] |  |
Ownership Percentage | 50.00% | 50.00%
Fargo–Monticello 345 kV line |  |
Jointly Owned Utility Plant Interests [Line Items] |  |
Electric Plant in Service | $ 78,184 | $ 78,184
Construction Work in Progress | 0 | 0
Accumulated Depreciation | (10,095) | (9,069)
Net Plant | $ 68,089 | $ 69,115
Fargo–Monticello 345 kV line | OTP |  |
Jointly Owned Utility Plant Interests [Line Items] |  |
Ownership Percentage | 14.20% | 14.20%
Big Stone South–Brookings 345 kV line |  |
Jointly Owned Utility Plant Interests [Line Items] |  |
Electric Plant in Service | $ 53,041 | $ 52,975
Construction Work in Progress | 0 | 0
Accumulated Depreciation | (4,406) | (3,613)
Net Plant | $ 48,635 | $ 49,362
Big Stone South–Brookings 345 kV line | OTP |  |
Jointly Owned Utility Plant Interests [Line Items] |  |
Ownership Percentage | 50.00% | 50.00%
Brookings–Southeast Twin Cities 345 kV line |  |
Jointly Owned Utility Plant Interests [Line Items] |  |
Electric Plant in Service | $ 26,291 | $ 26,291
Construction Work in Progress | 0 | 0
Accumulated Depreciation | (3,211) | (2,843)
Net Plant | $ 23,080 | $ 23,448
Brookings–Southeast Twin Cities 345 kV line | OTP |  |
Jointly Owned Utility Plant Interests [Line Items] |  |
Ownership Percentage | 4.80% | 4.80%
Bemidji–Grand Rapids 230 kV line |  |
Jointly Owned Utility Plant Interests [Line Items] |  |
Electric Plant in Service | $ 16,331 | $ 16,331
Construction Work in Progress | 0 | 0
Accumulated Depreciation | (3,318) | (2,995)
Net Plant | $ 13,013 | $ 13,336
Bemidji–Grand Rapids 230 kV line | OTP |  |
Jointly Owned Utility Plant Interests [Line Items] |  |
Ownership Percentage | 14.80% | 14.80%

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- Definition The period end amount of construction work in progress, or the deficit in the construction work in progress, at a jointly owned electricity generation plant. + References No definition available. + Details
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- 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 -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 360 -Section S99 -Paragraph 1 -Subparagraph (SAB Topic 10.C) -URI https://asc.fasb.org/extlink&oid=122136288&loc=d3e659983-123033 + Details
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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 -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 360 -Section S99 -Paragraph 1 -Subparagraph (SAB Topic 10.C) -URI https://asc.fasb.org/extlink&oid=122136288&loc=d3e659983-123033 + Details
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