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Jointly-Owned Facilities and Projects (Tables) | 12 Months Ended
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Dec. 31, 2015
Jointly-Owned Facilities and Projects [Abstract] |
Jointly-Owned Facilities and Projects [Table Text Block] | Minnesota Power’s investments in jointly-owned facilities and projects and the related ownership percentages are as follows:
| Regulated Utility Plant As of December 31 | Plant in Service | Accumulated Depreciation | Construction Work in Progress | % Ownership
| Millions |  |  |  |
| 2015 |  |  |  |
| Boswell Unit 4 |  | $668.2 |  |  | $195.0 |  |  | $6.9 |  | 80
| CapX2020 Projects | 101.1 |  | 3.4 |  | — |  | 9.3 - 14.7
| Total |  | $769.3 |  |  | $198.4 |  |  | $6.9 |  |
| 2014 |  |  |  |
| Boswell Unit 4 |  | $419.1 |  |  | $209.1 |  |  | $168.1 |  | 80
| CapX2020 Projects | 55.5 |  | 1.7 |  | 44.0 |  | 9.3 - 14.7
| Total |  | $474.6 |  |  | $210.8 |  |  | $212.1 |  |

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- Definition Jointly-Owned Facilities and Projects [Abstract] + References No definition available. + Details
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- Definition Tabular disclosure of proportionate interests in jointly owned utility plants. Includes the amount of plants in service, the accumulated provision for depreciation (if available), the amount of plants under construction, and the proportionate share. The amounts presented may be further subdivided to show amounts applicable to plant subcategories (for example, production, transmission, distribution). Includes statements that the amounts represent the utility's share in each joint plant and that it must provide its own financing. Information concerning two or more generating plants on the same site may be combined. States that the utility's share of direct expenses of the joint plants is included in the corresponding operating expenses on its income statement (for example, fuel, maintenance of plant, other operating expense). If the share of direct expenses is charged to purchased power, then disclose the amount so charged and the proportionate amounts charged to specific operating expenses on the records maintained for the joint plants. + 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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