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Jointly-Owned Electric Facility (Details) (USD $) In Millions, unless otherwise specified | 12 Months Ended
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Dec. 31, 2011 MW
Jointly Owned Electric Facility [Line Items] |
Plant in Service | $ 418.8
Accumulated Depreciation | 177.4
Construction Work in Progress | 24.7
Boswell Unit 4 [Member] |
Jointly Owned Electric Facility [Line Items] |
Plant in Service | 406.9
Accumulated Depreciation | 177.4
Construction Work in Progress | 8.8
% Ownership | 80.00%
Coal-fired generating unit capacity | 585
Jointly-Owned Electric Facility Percentage Not Owned | 20.00%
CapX2020 [Member] |
Jointly Owned Electric Facility [Line Items] |
Plant in Service | 11.9
Accumulated Depreciation | 0
Construction Work in Progress | $ 15.9
% Ownership Range | 9.3 - 14.7

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- Definition Represents MW capacity for coal-fired generating unit near Center, ND. + References No definition available. + Details
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- Definition Jointly-Owned Electric Facility Percentage Not Owned + References No definition available. + Details
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- Definition Jointly Owned Utility Plant, Proportionate Ownership Share Range + 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://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 10 -Section C Reference 2: http://www.xbrl.org/2003/role/presentationRef -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=6500719&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://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 10 -Section C Reference 2: http://www.xbrl.org/2003/role/presentationRef -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=6500719&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://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 10 -Section C Reference 2: http://www.xbrl.org/2003/role/presentationRef -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=6500719&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://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 10 -Section C Reference 2: http://www.xbrl.org/2003/role/presentationRef -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=6500719&loc=d3e659983-123033 + Details
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