Jointly-Owned Electric Utility Plant (Details) $ in Millions	Dec. 31, 2023 USD ($)
Jointly Owned Electric Utility Plant [Line Items]
Electric Plant	$ 2,570
Accumulated Provision for Depreciation	952
Construction Work in Progress	33
IPL [Member]
Jointly Owned Electric Utility Plant [Line Items]
Electric Plant	1,053
Accumulated Provision for Depreciation	478
Construction Work in Progress	21
WPL [Member]
Jointly Owned Electric Utility Plant [Line Items]
Electric Plant	1,517
Accumulated Provision for Depreciation	474
Construction Work in Progress	$ 12
Ottumwa Unit 1 [Member] \| IPL [Member]
Jointly Owned Electric Utility Plant [Line Items]
Ownership Interest %	48.00%
Electric Plant	$ 632
Accumulated Provision for Depreciation	264
Construction Work in Progress	$ 7
George Neal Unit 4 [Member] \| IPL [Member]
Jointly Owned Electric Utility Plant [Line Items]
Ownership Interest %	25.70%
Electric Plant	$ 196
Accumulated Provision for Depreciation	107
Construction Work in Progress	$ 6
George Neal Unit 3 [Member] \| IPL [Member]
Jointly Owned Electric Utility Plant [Line Items]
Ownership Interest %	28.00%
Electric Plant	$ 181
Accumulated Provision for Depreciation	85
Construction Work in Progress	$ 8
Louisa Unit 1 [Member] \| IPL [Member]
Jointly Owned Electric Utility Plant [Line Items]
Ownership Interest %	4.00%
Electric Plant	$ 44
Accumulated Provision for Depreciation	22
Construction Work in Progress	$ 0
Columbia Units 1-2 [Member] \| WPL [Member]
Jointly Owned Electric Utility Plant [Line Items]
Ownership Interest %	53.50%
Electric Plant	$ 818
Accumulated Provision for Depreciation	361
Construction Work in Progress	$ 6
West Riverside Energy Center and Solar Facility [Member] \| WPL [Member]
Jointly Owned Electric Utility Plant [Line Items]
Ownership Interest %	73.80%
Electric Plant	$ 581
Accumulated Provision for Depreciation	60
Construction Work in Progress	$ 6
Forward Wind Energy Center [Member] \| WPL [Member]
Jointly Owned Electric Utility Plant [Line Items]
Ownership Interest %	42.60%
Electric Plant	$ 118
Accumulated Provision for Depreciation	53
Construction Work in Progress	$ 0

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
-Topic 980
-SubTopic 360
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 10.C)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479960/980-360-S99-1

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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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