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Acquisitions - Storm Lake I (Details) $ in Millions | Dec. 17, 2014 USD ($) MW | Sep. 30, 2015 USD ($) | Dec. 31, 2014 USD ($)
--- | --- | --- | ---
Liabilities [Abstract] |  |  |  |
Power Purchase Agreements, Non-Current Liability | [1] |  | $ 143.9 | $ 110.7
Power Purchase Agreements, Current Liability | [2] |  | $ 23.8 | $ 19.4
Storm Lake I [Member] |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Date of Acquisition |  | Dec. 17, 2014 |  |
Name of Acquired Entity |  | Storm Lake I |  |
Payments to Acquire Business |  | $ 15.1 |  |
Generating Capacity (MW) | MW |  | 108 |  |
Assets [Abstract] |  |  |  |
Cash and Cash Equivalents |  | $ 0.4 |  |
Other Current Assets |  | 4.7 |  |
Property, Plant and Equipment |  | 47.3 |  |
Other Non-Current Assets | [3] | 11.4 |  |
Total Assets Acquired |  | 63.8 |  |
Liabilities [Abstract] |  |  |  |
Current Liabilities | [4] | 8.2 |  |
Power Purchase Agreements, Non-Current Liability |  | 23.5 |  |
Non-Current Liabilities |  | 17.0 |  |
Total Liabilities Assumed |  | 48.7 |  |
Net Identifiable Assets Acquired |  | 15.1 |  |
Restricted Cash, Non-Current |  | $ 0.4 |  |
Goodwill |  | immaterial |  |
Expected Tax Deductible Amount of Goodwill |  | $ 0.0 |  |
Power Purchase Agreements, Current Liability |  | $ 7.5 |  |
[1] | Power Purchase Agreements were acquired in conjunction with ALLETE Clean Energy’s wind energy facilities acquisitions. (See Note 4. Acquisitions.)
[2] | Power Purchase Agreements were acquired in conjunction with ALLETE Clean Energy’s wind energy facilities acquisitions. (See Note 4. Acquisitions.)
[3] | Included in Other Non-Current Assets was $0.4 million of restricted cash and an immaterial amount of goodwill; for tax purposes, the purchase price allocation resulted in no allocation to goodwill.
[4] | Current Liabilities included $7.5 million related to the current portion of Power Purchase Agreements.

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