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Jointly-Owned Electric Utility Plant (Details) $ in Millions | Dec. 31, 2020 USD ($)
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Jointly Owned Electric Utility Plant [Line Items] |
Electric Plant | $ 2,574
Accumulated Provision for Depreciation | 727
Construction Work in Progress | 41
IPL [Member] |
Jointly Owned Electric Utility Plant [Line Items] |
Electric Plant | 982
Accumulated Provision for Depreciation | 380
Construction Work in Progress | 24
WPL [Member] |
Jointly Owned Electric Utility Plant [Line Items] |
Electric Plant | 1,592
Accumulated Provision for Depreciation | 347
Construction Work in Progress | $ 17
Ottumwa Unit 1 [Member] | IPL [Member] |
Jointly Owned Electric Utility Plant [Line Items] |
Ownership Interest % | 48.00%
Electric Plant | $ 580
Accumulated Provision for Depreciation | 195
Construction Work in Progress | $ 22
George Neal Unit 4 [Member] | IPL [Member] |
Jointly Owned Electric Utility Plant [Line Items] |
Ownership Interest % | 25.70%
Electric Plant | $ 192
Accumulated Provision for Depreciation | 96
Construction Work in Progress | $ 2
George Neal Unit 3 [Member] | IPL [Member] |
Jointly Owned Electric Utility Plant [Line Items] |
Ownership Interest % | 28.00%
Electric Plant | $ 171
Accumulated Provision for Depreciation | 67
Construction Work in Progress | $ 0
Louisa Unit 1 [Member] | IPL [Member] |
Jointly Owned Electric Utility Plant [Line Items] |
Ownership Interest % | 4.00%
Electric Plant | $ 39
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 | $ 786
Accumulated Provision for Depreciation | 289
Construction Work in Progress | $ 4
West Riverside [Member] | WPL [Member] |
Jointly Owned Electric Utility Plant [Line Items] |
Ownership Interest % | 91.80%
Electric Plant | $ 686
Accumulated Provision for Depreciation | 12
Construction Work in Progress | $ 13
Forward Wind Energy Center [Member] | WPL [Member] |
Jointly Owned Electric Utility Plant [Line Items] |
Ownership Interest % | 42.60%
Electric Plant | $ 120
Accumulated Provision for Depreciation | 46
Construction Work in Progress | $ 0

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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://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 + Details
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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. + Details
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- Definition The period end amount of construction work in progress at a jointly owned electricity generation plant. + References 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 + Details
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- Definition The period end amount of accumulated depreciation in a jointly owned electricity generation plant. + References 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 + Details
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- Definition The proportionate share of interest (percent) in a jointly owned utility plant. + References 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 + Details
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