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Investment in ATC (Tables) | 9 Months Ended
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Sep. 30, 2012
Investment in ATC [Abstract] |
ALLETE's Investment in ATC [Table Text Block] |
ALLETE’s Investment in ATC |
Millions |
Equity Investment Balance as of December 31, 2011 |  | $98.9 |
Cash Investments | 3.9 |
Equity in ATC Earnings | 14.3 |
Distributed ATC Earnings | (11.6 | )
Equity Investment Balance as of September 30, 2012 |  | $105.5 |
ATC Summarized Financial Data [Table Text Block] | ATC’s summarized financial data for the quarters and nine months ended September 30, 2012 and 2011, is as follows:
| Quarter Ended |  | Nine Months Ended
ATC Summarized Financial Data | September 30, |  | September 30,
Income Statement Data | 2012 |  | 2011 |  | 2012 |  | 2011
Millions |  |  |  |  |  |  |
Revenue | $150.3 |  | $142.8 |  |  | $450.1 |  |  |  | $420.6 |
Operating Expense | 68.8 |  | 66.4 |  | 210.1 |  |  | 192.5 |
Other Expense | 21.0 |  | 19.7 |  | 62.1 |  |  | 61.6 |
Net Income |  | $60.5 |  |  | $56.7 |  |  | $177.9 |  |  |  | $166.5 |
ALLETE’s Equity in Net Income | $4.9 |  | $4.7 |  |  | $14.3 |  |  |  | $13.7 |

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- Definition Tabular disclosure of equity method investments in common stock. The disclosure may include: (a) the name of each investee or group of investments for which combined disclosure is appropriate, (2) the percentage ownership of common stock, (3) the difference, if any, between the carrying amount of an investment and the value of the underlying equity in the net assets and the accounting treatment of difference, if any, and (4) the aggregate value of each identified investment based on its quoted market price, if available. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6382943&loc=d3e33918-111571 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Principles Board Opinion (APB) -Number 18 -Paragraph 20 -Subparagraph a, b -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. + Details
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