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Jointly owned facilities (Details) - USD ($) $ in Thousands | Dec. 31, 2021 | Dec. 31, 2020
--- | --- | ---
Jointly owned electricity generation plant | Big Stone Station |  |
Jointly Owned Utility Plant Interests [Line Items] |  |
Proportionate ownership share | 22.70% |
Utility plant in service | $ 157,259 | $ 155,967
Construction work in progress | 571 | 104
Less accumulated depreciation | 47,293 | 45,435
Utility plant in services net | $ 110,537 | 110,636
Jointly owned electricity generation plant | Coyote Station |  |
Jointly Owned Utility Plant Interests [Line Items] |  |
Proportionate ownership share | 25.00% |
Utility plant in service | $ 157,764 | 159,784
Construction work in progress | 784 | 323
Less accumulated depreciation | 109,202 | 108,852
Utility plant in services net | $ 49,346 | 51,255
Jointly owned electricity generation plant | Wygen III |  |
Jointly Owned Utility Plant Interests [Line Items] |  |
Proportionate ownership share | 25.00% |
Utility plant in service | $ 66,357 | 66,101
Construction work in progress | 108 | 232
Less accumulated depreciation | 11,383 | 10,038
Utility plant in services net | $ 55,082 | 56,295
Jointly Owned Electricity Transmission and Distribution System | BSSE |  |
Jointly Owned Utility Plant Interests [Line Items] |  |
Proportionate ownership share | 50.00% |
Utility plant in service | $ 107,424 | 107,442
Construction work in progress | 0 | 0
Less accumulated depreciation | 4,506 | 2,682
Utility plant in services net | $ 102,918 | $ 104,760

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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 http://asc.fasb.org/extlink&oid=122136288&loc=d3e659983-123033 + Details
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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. + References No definition available. + 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 http://asc.fasb.org/extlink&oid=122136288&loc=d3e659983-123033 + Details
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- Definition The period end amount of construction work in progress at a 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 http://asc.fasb.org/extlink&oid=122136288&loc=d3e659983-123033 + Details
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- Definition The period end amount of accumulated depreciation in a 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 http://asc.fasb.org/extlink&oid=122136288&loc=d3e659983-123033 + Details
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- Definition The proportionate share of interest (percent) in a jointly owned utility 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 http://asc.fasb.org/extlink&oid=122136288&loc=d3e659983-123033 + Details
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