Summary Of Significant Accounting Policies (Carrying Value Of Assets Purchased) (Details) (Riverside Energy Center [Member], WPL [Member], USD $) In Millions, unless otherwise specified	Dec. 31, 2012
Riverside Energy Center [Member] \| WPL [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Electric plant in service	$ 512.7
Accumulated depreciation	(121.4)
Current assets	4.2
Other assets	8.0
Carrying value of assets purchased	$ 403.5

Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets

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- Definition

Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Noncurrent Assets

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No definition available.

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- Definition

Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Public Utilities, Plant In Service, Accumulated Depreciation

+ References

No definition available.

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- Definition

Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Public Utilities, Plant In Service, Gross

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No definition available.

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- Definition

Net amount recognized for aggregate assets, including goodwill, in excess of or less than the aggregate liabilities assumed (also referred to as net assets acquired). This amount may also be viewed as incremental amount of equity that the consolidated entity (including the portion attributable to a noncontrolling interest) will recognize as a result of the business combination.

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No definition available.

+ Details

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