Commitments and Contingencies, Fuel Contracts (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013
Coal
Fuel Contracts [Abstract]
2014	$ 273.8
2015	241.5
2016	143.8
2017	36.7
2018	0
Thereafter	0
Total	695.8
Natural Gas Supply
Fuel Contracts [Abstract]
2014	20.6
2015	0
2016	0
2017	0
2018	0
Thereafter	0
Total	20.6
Natural Gas Storage and Transportation
Fuel Contracts [Abstract]
2014	23.7
2015	22.1
2016	22.1
2017	21.3
2018	15.9
Thereafter	96.1
Total	$ 201.2

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Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing in the fifth fiscal year following the latest fiscal year.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 440

-SubTopic 10

-Section 50

-Paragraph 4

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6394976&loc=d3e25336-109308

+ Details

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- Definition

Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing in the next fiscal year following the latest fiscal year.

+ References

+ Details

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- Definition

Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing in the four fiscal year following the latest fiscal year.

+ References

+ Details

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- Definition

Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing in the second fiscal year following the latest fiscal year.

+ References

+ Details

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- Definition

Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing in the third fiscal year following the latest fiscal year.

+ References

+ Details

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- Definition

Amount of the unrecorded obligation to transfer funds in the future for fixed or minimum amounts or quantities of goods or services at fixed or minimum prices (for example, as in take-or-pay contracts or throughput contracts).

+ References

+ Details

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- Definition

Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing after the fifth fiscal year following the latest fiscal year.

+ References

+ Details

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