v2.4.0.6

Benefit Plans (Expected Benefit Payments) (Details) (USD $) In Millions, unless otherwise specified | Dec. 31, 2012
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Defined Benefit Plan Disclosure [Line Items] |
Expected benefit payments, 2013 | $ 78.5
Expected benefit payments, 2014 | 80.9
Expected benefit payments, 2015 | 84.8
Expected benefit payments, 2016 | 83.0
Expected benefit payments, 2017 | 85.8
Expected benefit payments, 2018 - 2022 | 458.3
Defined Benefit Plans Qualified And Non Qualified Pension Benefits [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Expected benefit payments, 2013 | 61.9
Expected benefit payments, 2014 | 64.7
Expected benefit payments, 2015 | 68.5
Expected benefit payments, 2016 | 66.6
Expected benefit payments, 2017 | 69.2
Expected benefit payments, 2018 - 2022 | 374.1
Other Postretirement Benefits Plans [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Expected benefit payments, 2013 | 16.6
Expected benefit payments, 2014 | 16.2
Expected benefit payments, 2015 | 16.3
Expected benefit payments, 2016 | 16.4
Expected benefit payments, 2017 | 16.6
Expected benefit payments, 2018 - 2022 | 84.2
IPL [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Expected benefit payments, 2013 | 36.5
Expected benefit payments, 2014 | 37.6
Expected benefit payments, 2015 | 39.2
Expected benefit payments, 2016 | 38.1
Expected benefit payments, 2017 | 40.7
Expected benefit payments, 2018 - 2022 | 212.1
IPL [Member] | Defined Benefit Plans Qualified And Non Qualified Pension Benefits [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Expected benefit payments, 2013 | 15.9
Expected benefit payments, 2014 | 16.9
Expected benefit payments, 2015 | 17.9
Expected benefit payments, 2016 | 18.9
Expected benefit payments, 2017 | 20.0
Expected benefit payments, 2018 - 2022 | 116.0
IPL [Member] | Directly Assigned Defined Benefit Pension Benefits [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Expected benefit payments, 2013 | 12.6
Expected benefit payments, 2014 | 13.4
Expected benefit payments, 2015 | 14.1
Expected benefit payments, 2016 | 12.1
Expected benefit payments, 2017 | 13.5
Expected benefit payments, 2018 - 2022 | 60.2
IPL [Member] | Other Postretirement Benefits Plans [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Expected benefit payments, 2013 | 8.0
Expected benefit payments, 2014 | 7.3
Expected benefit payments, 2015 | 7.2
Expected benefit payments, 2016 | 7.1
Expected benefit payments, 2017 | 7.2
Expected benefit payments, 2018 - 2022 | 35.9
WPL [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Expected benefit payments, 2013 | 31.2
Expected benefit payments, 2014 | 31.9
Expected benefit payments, 2015 | 34.2
Expected benefit payments, 2016 | 33.5
Expected benefit payments, 2017 | 34.3
Expected benefit payments, 2018 - 2022 | 186.0
WPL [Member] | Defined Benefit Plans Qualified And Non Qualified Pension Benefits [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Expected benefit payments, 2013 | 14.4
Expected benefit payments, 2014 | 15.2
Expected benefit payments, 2015 | 16.1
Expected benefit payments, 2016 | 17.0
Expected benefit payments, 2017 | 18.0
Expected benefit payments, 2018 - 2022 | 108.7
WPL [Member] | Directly Assigned Defined Benefit Pension Benefits [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Expected benefit payments, 2013 | 10.5
Expected benefit payments, 2014 | 10.2
Expected benefit payments, 2015 | 11.4
Expected benefit payments, 2016 | 9.8
Expected benefit payments, 2017 | 9.5
Expected benefit payments, 2018 - 2022 | 43.0
WPL [Member] | Other Postretirement Benefits Plans [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Expected benefit payments, 2013 | 6.3
Expected benefit payments, 2014 | 6.5
Expected benefit payments, 2015 | 6.7
Expected benefit payments, 2016 | 6.7
Expected benefit payments, 2017 | 6.8
Expected benefit payments, 2018 - 2022 | $ 34.3

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- Definition Amount of benefits expected to be paid in the five fiscal years after the fifth fiscal year following the latest fiscal year from a defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920 + Details
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- Definition Amount of benefits expected to be paid in the next fiscal year following the latest fiscal year from a defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920 + Details
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- Definition Amount of benefits expected to be paid in the fifth fiscal year following the latest fiscal year from a defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920 + Details
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- Definition Amount of benefits expected to be paid in the fourth fiscal year following the latest fiscal year from a defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920 + Details
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- Definition Amount of benefits expected to be paid in the third fiscal year following the latest fiscal year from a defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920 + Details
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- Definition Amount of benefits expected to be paid in the second fiscal year following the latest fiscal year from a defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920 + Details
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