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Jointly owned facilities | 12 Months Ended
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Dec. 31, 2012
Regulated Operations [Abstract] |
Jointly owned facilities | Jointly Owned Facilities The consolidated financial statements include the Company's 22.7 percent, 25.0 percent and 25.0 percent ownership interests in the assets, liabilities and expenses of the Big Stone Station, Coyote Station and Wygen III, respectively. Each owner of the stations is responsible for financing its investment in the jointly owned facilities. The Company's share of the stations operating expenses was reflected in the appropriate categories of operating expenses (fuel, operation and maintenance, and taxes, other than income) in the Consolidated Statements of Income. At December 31, the Company's share of the cost of utility plant in service and related accumulated depreciation for the stations was as follows:
| 2012 |  | 2011 |
| (In thousands)
Big Stone Station: |  |
Utility plant in service | $ | 63,146 |  | $ | 63,715 |
Less accumulated depreciation | 40,859 |  | 42,475 |
| $ | 22,287 |  | $ | 21,240 |
Coyote Station: |  |  |  |
Utility plant in service | $ | 135,073 |  | $ | 131,719 |
Less accumulated depreciation | 87,524 |  | 86,788 |
| $ | 47,549 |  | $ | 44,931 |
Wygen III: |  |  |  |
Utility plant in service | $ | 63,462 |  | $ | 63,300 |
Less accumulated depreciation | 3,368 |  | 2,106 |
| $ | 60,094 |  | $ | 61,194 |

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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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