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Schedule II | 12 Months Ended
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Dec. 31, 2012
Schedule II [Abstract] |
Valuation and Qualifying Accounts and Reserves [Text Block] | Schedule II ALLETE Valuation and Qualifying Accounts and Reserves
| Balance at Beginning of Period | Additions | Deductions from Reserves (a) | Balance at End of Period
| Charged to Income | Other Charges
Millions |  |  |  |  |
Reserve Deducted from Related Assets |  |  |  |  |
Reserve For Uncollectible Accounts |  |  |  |  |
2010 Trade Accounts Receivable |  | $0.9 |  |  | $1.1 |  | — |  |  | $1.1 |  |  | $0.9 |
Finance Receivables – Long-Term |  | $0.4 |  |  | $0.8 |  | — |  |  | $0.4 |  |  | $0.8 |
2011 Trade Accounts Receivable |  | $0.9 |  |  | $1.3 |  | — |  |  | $1.3 |  |  | $0.9 |
Finance Receivables – Long-Term |  | $0.8 |  |  | $0.1 |  | — |  |  | $0.3 |  |  | $0.6 |
2012 Trade Accounts Receivable |  | $0.9 |  |  | $1.0 |  | — |  |  | $0.9 |  |  | $1.0 |
Finance Receivables – Long-Term |  | $0.6 |  | — |  | — |  | — |  |  | $0.6 |
Deferred Asset Valuation Allowance |  |  |  |  |
2010 Deferred Tax Assets |  | $0.3 |  | $0.2 | — |  | — |  |  | $0.5 |
2011 Deferred Tax Assets |  | $0.5 |  | $(0.1) | — |  | — |  |  | $0.4 |
2012 Deferred Tax Assets |  | $0.4 |  |  | $2.0 |  | — |  | — |  |  | $2.4 |
(a) | Includes uncollectible accounts written off.

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- Definition The entire disclosure for any allowance and reserve accounts (their beginning and ending balances, as well as a reconciliation by type of activity during the period). Alternatively, disclosure of the required information may be within the footnotes to the financial statements or a supplemental schedule to the financial statements. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 09 -Article 12 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=6881521&loc=d3e24092-122690 + Details
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