Joint Ownership of Transmission Facilities (Details) $ in Thousands	Dec. 31, 2015 USD ($)
Jointly Owned Utility Plant [Abstract]
Plant in service	$ 154,394
Accumulated depreciation	6,863
Construction work in progress	20,527
CapX2020 Transmission \| Electric Transmission
Jointly Owned Utility Plant [Abstract]
Plant in service	154,394
Accumulated depreciation	6,863
Construction work in progress	$ 1,633
Ownership % (in hundredths)	80.00%
La Crosse, Wis. to Madison, Wis. \| Electric Transmission
Jointly Owned Utility Plant [Abstract]
Plant in service	$ 0
Accumulated depreciation	0
Construction work in progress	$ 18,894
Ownership % (in hundredths)	37.00%

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

Reference 1: 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

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 10
-Section C

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- Definition

The period end amount of construction work in progress at a jointly owned electricity generation plant.

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- Definition

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

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- Definition

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

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