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Jointly-Owned Electric Utility Plant (Details) $ in Millions | Dec. 31, 2019 USD ($)
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Jointly Owned Electric Utility Plant [Line Items] |
Electric Plant | $ 1,864.1
Accumulated Provision for Depreciation | 670.7
Construction Work in Progress | 673.7
IPL [Member] |
Jointly Owned Electric Utility Plant [Line Items] |
Electric Plant | 966.9
Accumulated Provision for Depreciation | 362.4
Construction Work in Progress | 20.7
WPL [Member] |
Jointly Owned Electric Utility Plant [Line Items] |
Electric Plant | 897.2
Accumulated Provision for Depreciation | 308.3
Construction Work in Progress | $ 653.0
Ottumwa Unit 1 [Member] | IPL [Member] |
Jointly Owned Electric Utility Plant [Line Items] |
Ownership Interest % | 48.00%
Electric Plant | $ 571.5
Accumulated Provision for Depreciation | 180.8
Construction Work in Progress | $ 18.8
George Neal Unit 4 [Member] | IPL [Member] |
Jointly Owned Electric Utility Plant [Line Items] |
Ownership Interest % | 25.70%
Electric Plant | $ 191.8
Accumulated Provision for Depreciation | 93.5
Construction Work in Progress | $ 0.8
George Neal Unit 3 [Member] | IPL [Member] |
Jointly Owned Electric Utility Plant [Line Items] |
Ownership Interest % | 28.00%
Electric Plant | $ 163.7
Accumulated Provision for Depreciation | 63.2
Construction Work in Progress | $ 0.9
Louisa Unit 1 [Member] | IPL [Member] |
Jointly Owned Electric Utility Plant [Line Items] |
Ownership Interest % | 4.00%
Electric Plant | $ 39.9
Accumulated Provision for Depreciation | 24.9
Construction Work in Progress | $ 0.2
Columbia Units 1-2 [Member] | WPL [Member] |
Jointly Owned Electric Utility Plant [Line Items] |
Ownership Interest % | 53.30%
Electric Plant | $ 777.0
Accumulated Provision for Depreciation | 264.7
Construction Work in Progress | $ 5.5
Forward Wind Energy Center (FWEC) [Member] | WPL [Member] |
Jointly Owned Electric Utility Plant [Line Items] |
Ownership Interest % | 42.60%
Electric Plant | $ 120.2
Accumulated Provision for Depreciation | 43.6
Construction Work in Progress | $ 0.0
West Riverside [Member] | WPL [Member] |
Jointly Owned Electric Utility Plant [Line Items] |
Ownership Interest % | 91.80%
Electric Plant | $ 0.0
Accumulated Provision for Depreciation | 0.0
Construction Work in Progress | $ 647.5

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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 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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