FAIR VALUE (Details 2) (Nonregulated Segments, USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Natural gas contracts
Transfers between the levels of the fair value hierarchy
Transfers into Level 1 from Level 3	$ 0	$ 0	$ 0	$ 0
Transfers into Level 2 from Level 3	0.3	0.3	0.3	1.7
Transfers into Level 3 from Level 2	2.5	0.4	4.0	3.2
Transfers into Level 1 from Level 2	0	0	0	0
Transfers into Level 2 from Level 1	0	0	0	0
Transfers into Level 3 from Level 1	0	0	0	0
Electric contracts
Transfers between the levels of the fair value hierarchy
Transfers into Level 1 from Level 3	0	0	0	0
Transfers into Level 2 from Level 3	(0.8)	(1.9)	4.6	(5.8)
Transfers into Level 3 from Level 2	0	1.0	6.2	(7.8)
Transfers into Level 1 from Level 2	0	0	0	0
Transfers into Level 2 from Level 1	0	0	0	0
Transfers into Level 3 from Level 1	$ (0.2)	$ 0	$ (0.2)	$ 0

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The amount of the transfers of assets or liabilities measured on a recurring basis out of Level 1 of the fair value hierarchy into Level 3.

+ References

No definition available.

+ Details

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- Definition

The amount of the transfers of assets or liabilities measured on a recurring basis out of Level 2 of the fair value hierarchy into Level 3.

+ References

No definition available.

+ Details

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- Definition

The amount of the transfers of assets or liabilities measured on a recurring basis out of Level 3 of the fair value hierarchy into Level 1.

+ References

No definition available.

+ Details

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- Definition

The amount of the transfers of assets or liabilities measured on a recurring basis out of Level 3 of the fair value hierarchy into Level 2.

+ References

No definition available.

+ Details

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- Definition

Amount of transfers of liabilities measured on a recurring basis out of Level 1 of the fair value hierarchy into Level 2.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (bb)

-URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258

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- Definition

Amount of transfers of liabilities measured on a recurring basis out of Level 2 of the fair value hierarchy into Level 1.

+ References

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