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Short-Term and Long-Term Debt Short-Term and Long-Term Debt (Tables) | 9 Months Ended
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Sep. 30, 2016
Debt Disclosure [Abstract] |
Schedule of Short-Term and Long-Term Debt [Table Text Block] | The following tables present ALLETE’s short-term and long-term debt as of September 30, 2016 and December 31, 2015.
September 30, 2016 | Principal |  |  | Unamortized Debt Issuance Costs |  | Total |
Millions |  |  |  |  |
Short-Term Debt (a) |  | $187.2 |  |  | $(0.6) |  |  | $186.6 |
Long-Term Debt | 1,369.7 |  |  | (10.8) |  | 1,358.9 |
Total Debt |  | $1,556.9 |  |  | $(11.4) |  |  | $1,545.5 |
(a) | Consisted of long-term debt due within one year.
December 31, 2015 | Principal |  |  | Unamortized Debt Issuance Costs |  | Total |
Millions |  |  |  |  |
Short-Term Debt (a) |  | $37.9 |  |  | $(0.6) |  |  | $37.3 |
Long-Term Debt | 1,568.7 |  |  | (12.0) |  | 1,556.7 |
Total Debt |  | $1,606.6 |  |  | $(12.6) |  |  | $1,594.0 |
(a) | Consisted of long-term debt due within one year and notes payable.

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- Definition Tabular disclosure of information pertaining to short-term and long-debt instruments or arrangements, including but not limited to identification of terms, features, collateral requirements and other information necessary to a fair presentation. + References No definition available. + Details
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