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Benefit Plans (Expected Benefit Payments) (Details)
$ in Millions
Dec. 31, 2016
USD ($)
Defined Benefit Plan Disclosure [Line Items]  
Expected benefit payments, 2017 $ 93.4
Expected benefit payments, 2018 91.7
Expected benefit payments, 2019 93.7
Expected benefit payments, 2020 95.4
Expected benefit payments, 2021 97.5
Expected benefit payments, 2022 - 2026 488.5
Defined Benefit Pension Plans [Member]  
Defined Benefit Plan Disclosure [Line Items]  
Expected benefit payments, 2017 74.8
Expected benefit payments, 2018 73.2
Expected benefit payments, 2019 75.5
Expected benefit payments, 2020 77.6
Expected benefit payments, 2021 79.9
Expected benefit payments, 2022 - 2026 405.9
Other Postretirement Benefits Plans [Member]  
Defined Benefit Plan Disclosure [Line Items]  
Expected benefit payments, 2017 18.6
Expected benefit payments, 2018 18.5
Expected benefit payments, 2019 18.2
Expected benefit payments, 2020 17.8
Expected benefit payments, 2021 17.6
Expected benefit payments, 2022 - 2026 82.6
IPL [Member]  
Defined Benefit Plan Disclosure [Line Items]  
Expected benefit payments, 2017 41.7
Expected benefit payments, 2018 42.7
Expected benefit payments, 2019 42.4
Expected benefit payments, 2020 44.6
Expected benefit payments, 2021 45.1
Expected benefit payments, 2022 - 2026 226.1
IPL [Member] | Defined Benefit Pension Plans [Member]  
Defined Benefit Plan Disclosure [Line Items]  
Expected benefit payments, 2017 34.0
Expected benefit payments, 2018 35.1
Expected benefit payments, 2019 35.0
Expected benefit payments, 2020 37.2
Expected benefit payments, 2021 37.9
Expected benefit payments, 2022 - 2026 192.1
IPL [Member] | Other Postretirement Benefits Plans [Member]  
Defined Benefit Plan Disclosure [Line Items]  
Expected benefit payments, 2017 7.7
Expected benefit payments, 2018 7.6
Expected benefit payments, 2019 7.4
Expected benefit payments, 2020 7.4
Expected benefit payments, 2021 7.2
Expected benefit payments, 2022 - 2026 34.0
WPL [Member]  
Defined Benefit Plan Disclosure [Line Items]  
Expected benefit payments, 2017 38.2
Expected benefit payments, 2018 38.9
Expected benefit payments, 2019 39.6
Expected benefit payments, 2020 39.9
Expected benefit payments, 2021 39.7
Expected benefit payments, 2022 - 2026 199.8
WPL [Member] | Defined Benefit Pension Plans [Member]  
Defined Benefit Plan Disclosure [Line Items]  
Expected benefit payments, 2017 30.2
Expected benefit payments, 2018 30.9
Expected benefit payments, 2019 31.8
Expected benefit payments, 2020 32.5
Expected benefit payments, 2021 32.4
Expected benefit payments, 2022 - 2026 167.1
WPL [Member] | Other Postretirement Benefits Plans [Member]  
Defined Benefit Plan Disclosure [Line Items]  
Expected benefit payments, 2017 8.0
Expected benefit payments, 2018 8.0
Expected benefit payments, 2019 7.8
Expected benefit payments, 2020 7.4
Expected benefit payments, 2021 7.3
Expected benefit payments, 2022 - 2026 $ 32.7