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Jointly-Owned Facilities and Projects (Details) $ in Millions | Dec. 31, 2015 USD ($) MW | Dec. 31, 2014 USD ($)
--- | --- | ---
Jointly-Owned Facilities and Projects [Line Items] |  |
Plant in Service | $ 769.3 | $ 474.6
Accumulated Depreciation | 198.4 | 210.8
Construction Work in Progress | $ 6.9 | 212.1
CapX2020 Projects [Member] |  |
Jointly-Owned Facilities and Projects [Line Items] |  |
Number of Projects | 3 |
Completed Project - Prior Years [Member] | CapX2020 Projects [Member] |  |
Jointly-Owned Facilities and Projects [Line Items] |  |
Number of Projects | 2 |
Transmission [Member] | CapX2020 Projects [Member] |  |
Jointly-Owned Facilities and Projects [Line Items] |  |
Plant in Service | $ 101.1 | 55.5
Accumulated Depreciation | 3.4 | 1.7
Construction Work in Progress | $ 0.0 | $ 44.0
Transmission [Member] | CapX2020 Projects [Member] | Minimum [Member] |  |
Jointly-Owned Facilities and Projects [Line Items] |  |
% Ownership | 9.30% | 9.30%
Transmission [Member] | CapX2020 Projects [Member] | Maximum [Member] |  |
Jointly-Owned Facilities and Projects [Line Items] |  |
% Ownership | 14.70% | 14.70%
Transmission [Member] | Completed Project - Current Year [Member] | CapX2020 Projects [Member] |  |
Jointly-Owned Facilities and Projects [Line Items] |  |
Number of Projects | 1 |
Transmission [Member] | Completed Project - Prior Years [Member] | CapX2020 Projects [Member] |  |
Jointly-Owned Facilities and Projects [Line Items] |  |
Number of Projects | 2 |
Boswell Unit 4 [Member] | Generation [Member] |  |
Jointly-Owned Facilities and Projects [Line Items] |  |
% Ownership | 80.00% | 80.00%
Generating Capacity (MW) | MW | 585 |
% Not Owned | 20.00% |
Plant in Service | $ 668.2 | $ 419.1
Accumulated Depreciation | 195.0 | 209.1
Construction Work in Progress | $ 6.9 | $ 168.1

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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 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 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 10 -Section C + Details
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