Property, Plant and Equipment (Narrative) (Details)	Sep. 30, 2023
WPL [Member] \| West Riverside Energy Center [Member]
Property, Plant and Equipment [Line Items]
Ownership interest, percent	73.80%

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

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

Name:	us-gaap_JointlyOwnedUtilityPlantProportionateOwnershipShare
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant