Property Plant and Equipment Joint Ownership (Details) $ in Millions	Dec. 31, 2020 USD ($)
Jointly Owned Utility Plant Interests [Line Items]
Plant in Service	$ 357
Accumulated Depreciation	35
CWIP	0
Jointly Owned Electricity Generation Plant [Member] \| La Crosse, Wis. to Madison, Wis.
Jointly Owned Utility Plant Interests [Line Items]
Plant in Service	188
Accumulated Depreciation	12
CWIP	$ 0
Percent Owned	37.00%
Jointly Owned Electricity Generation Plant [Member] \| CapX2020 Transmission
Jointly Owned Utility Plant Interests [Line Items]
Plant in Service	$ 169
Accumulated Depreciation	23
CWIP	$ 0
Percent Owned	80.00%

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

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-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=115995737&loc=d3e659983-123033

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

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

+ References

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- Definition

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

+ References

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- Definition

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

+ References

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