JOINTLY OWNED UTILITY FACILITIES (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2011 MW
Weston 4
Share of significant jointly owned electric generating facilities
Ownership (as a percent)	70.00%
WPS's share of rated capacity (in megawatts)	374.5
Utility plant in service	$ 573.3
Accumulated depreciation	78.5
Columbia Energy Center Units 1 and 2
Share of significant jointly owned electric generating facilities
Ownership (as a percent)	31.80%
WPS's share of rated capacity (in megawatts)	335.2
Utility plant in service	167.8
Accumulated depreciation	106.6
Edgewater Unit No. 4
Share of significant jointly owned electric generating facilities
Ownership (as a percent)	31.80%
WPS's share of rated capacity (in megawatts)	105.0
Utility plant in service	39.8
Accumulated depreciation	$ 25.4

The proportionate share of rated capacity in a jointly owned utility plant.

No definition available.

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- Definition

The period end amount owned by the reporting utility of a jointly owned utility plant in service.

+ References

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

-Publisher SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 10

-Section C

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 980

-SubTopic 360

-Section S99

-Paragraph 1

-Subparagraph (SAB TOPIC 10.C)

-URI http://asc.fasb.org/extlink&oid=6500719&loc=d3e659983-123033

+ Details

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- Definition

The period end amount of accumulated depreciation in a jointly owned electricity generation plant.

+ References

+ Details

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- Definition

The proportionate share of interest (percent) in a jointly owned utility plant.

+ References

+ Details

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