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Jointly-Owned Electric Utility Plant (Details) $ in Millions | Dec. 31, 2016 USD ($)
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Jointly Owned Electric Utility Plant [Line Items] |
Electric Plant | $ 1,601.4
Accumulated Provision for Depreciation | 532.4
Construction Work in Progress | 64.8
IPL [Member] |
Jointly Owned Electric Utility Plant [Line Items] |
Electric Plant | 861.8
Accumulated Provision for Depreciation | 289.0
Construction Work in Progress | 13.6
WPL [Member] |
Jointly Owned Electric Utility Plant [Line Items] |
Electric Plant | 739.6
Accumulated Provision for Depreciation | 243.4
Construction Work in Progress | $ 51.2
Ottumwa Unit 1 [Member] | IPL [Member] |
Jointly Owned Electric Utility Plant [Line Items] |
Ownership Interest % | 48.00%
Electric Plant | $ 489.4
Accumulated Provision for Depreciation | 137.3
Construction Work in Progress | $ 11.1
George Neal Unit 4 [Member] | IPL [Member] |
Jointly Owned Electric Utility Plant [Line Items] |
Ownership Interest % | 25.70%
Electric Plant | $ 185.2
Accumulated Provision for Depreciation | 80.8
Construction Work in Progress | $ 1.6
George Neal Unit 3 [Member] | IPL [Member] |
Jointly Owned Electric Utility Plant [Line Items] |
Ownership Interest % | 28.00%
Electric Plant | $ 150.7
Accumulated Provision for Depreciation | 49.1
Construction Work in Progress | $ 0.3
Louisa Unit 1 [Member] | IPL [Member] |
Jointly Owned Electric Utility Plant [Line Items] |
Ownership Interest % | 4.00%
Electric Plant | $ 36.5
Accumulated Provision for Depreciation | 21.8
Construction Work in Progress | $ 0.6
Columbia Units 1-2 [Member] | WPL [Member] |
Jointly Owned Electric Utility Plant [Line Items] |
Ownership Interest % | 46.20%
Electric Plant | $ 640.2
Accumulated Provision for Depreciation | 185.0
Construction Work in Progress | $ 51.0
Edgewater Unit 4 [Member] | WPL [Member] |
Jointly Owned Electric Utility Plant [Line Items] |
Ownership Interest % | 68.20%
Electric Plant | $ 99.4
Accumulated Provision for Depreciation | 58.4
Construction Work in Progress | $ 0.2

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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://www.xbrl.org/2003/role/presentationRef -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=6500719&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://www.xbrl.org/2003/role/presentationRef -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=6500719&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://www.xbrl.org/2003/role/presentationRef -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=6500719&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://www.xbrl.org/2003/role/presentationRef -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=6500719&loc=d3e659983-123033 + Details
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