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Commitments, Guarantees and Contingencies - North Dakota Wind Development (Details) (USD $) In Millions, unless otherwise specified | Sep. 30, 2012 | Dec. 31, 2011
--- | --- | ---
North Dakota Wind Development [Line Items] |  |
Capital Cost Spent to Date | $ 45.7 | $ 27.8
Bison 1 Wind Project [Member] |  |
North Dakota Wind Development [Line Items] |  |
Transmission Line Length (Miles) | 22 |
Transmission Line Capacity (kV) | 230 |
Generating Unit Capacity (MW) | 82 |
Total Project Cost | 174.3 |
Bison 2 Wind Project [Member] |  |
North Dakota Wind Development [Line Items] |  |
Generating Unit Capacity (MW) | 105 |
Expected Capital Cost | 160.0 |
Capital Cost Spent to Date | 129.2 |
Bison 3 Wind Project [Member] |  |
North Dakota Wind Development [Line Items] |  |
Generating Unit Capacity (MW) | 105 |
Expected Capital Cost | 160.0 |
Capital Cost Spent to Date | $ 131.0 |
DC Transmission Line from Square Butte [Member] |  |
North Dakota Wind Development [Line Items] |  |
Transmission Line Length (Miles) | 465 |
Transmission Line Capacity (kV) | 250 |

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- Details
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- Definition Length of a transmission line in miles. + References No definition available. + Details
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