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Derivative Instruments (Notional Amounts Of Derivative Instruments) (Details) (Commodity [Member]) | Dec. 31, 2014 MWh
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Electricity (MWhs) [Member] |
Notional Amount of Derivatives [Line Items] |
Notional unit amount of derivatives (in MWhs/Dths/tons) | 8,248,000 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_EnergyAxis = lnt_ElectricityMwhsMember / us-gaap_TradingActivityByTypeAxis = us-gaap_CommodityMember
Electricity (MWhs) [Member] | IPL [Member] |
Notional Amount of Derivatives [Line Items] |
Notional unit amount of derivatives (in MWhs/Dths/tons) | 1,765,000 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_EnergyAxis = lnt_ElectricityMwhsMember / dei_LegalEntityAxis = lnt_IplMember / us-gaap_TradingActivityByTypeAxis = us-gaap_CommodityMember
Electricity (MWhs) [Member] | WPL [Member] |
Notional Amount of Derivatives [Line Items] |
Notional unit amount of derivatives (in MWhs/Dths/tons) | 6,483,000 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_EnergyAxis = lnt_ElectricityMwhsMember / dei_LegalEntityAxis = lnt_WplMember / us-gaap_TradingActivityByTypeAxis = us-gaap_CommodityMember
FTRs (MWhs) [Member] |
Notional Amount of Derivatives [Line Items] |
Notional unit amount of derivatives (in MWhs/Dths/tons) | 9,505,000 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_EnergyAxis = lnt_FtrsMwhsMember / us-gaap_TradingActivityByTypeAxis = us-gaap_CommodityMember
FTRs (MWhs) [Member] | IPL [Member] |
Notional Amount of Derivatives [Line Items] |
Notional unit amount of derivatives (in MWhs/Dths/tons) | 5,503,000 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_EnergyAxis = lnt_FtrsMwhsMember / dei_LegalEntityAxis = lnt_IplMember / us-gaap_TradingActivityByTypeAxis = us-gaap_CommodityMember
FTRs (MWhs) [Member] | WPL [Member] |
Notional Amount of Derivatives [Line Items] |
Notional unit amount of derivatives (in MWhs/Dths/tons) | 4,002,000 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_EnergyAxis = lnt_FtrsMwhsMember / dei_LegalEntityAxis = lnt_WplMember / us-gaap_TradingActivityByTypeAxis = us-gaap_CommodityMember
Natural Gas (Dths) [Member] |
Notional Amount of Derivatives [Line Items] |
Notional unit amount of derivatives (in MWhs/Dths/tons) | 78,304,000 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_EnergyAxis = lnt_NaturalGasDthsMember / us-gaap_TradingActivityByTypeAxis = us-gaap_CommodityMember
Natural Gas (Dths) [Member] | IPL [Member] |
Notional Amount of Derivatives [Line Items] |
Notional unit amount of derivatives (in MWhs/Dths/tons) | 50,919,000 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_EnergyAxis = lnt_NaturalGasDthsMember / dei_LegalEntityAxis = lnt_IplMember / us-gaap_TradingActivityByTypeAxis = us-gaap_CommodityMember
Natural Gas (Dths) [Member] | WPL [Member] |
Notional Amount of Derivatives [Line Items] |
Notional unit amount of derivatives (in MWhs/Dths/tons) | 27,385,000 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_EnergyAxis = lnt_NaturalGasDthsMember / dei_LegalEntityAxis = lnt_WplMember / us-gaap_TradingActivityByTypeAxis = us-gaap_CommodityMember
Coal (tons) [Member] |
Notional Amount of Derivatives [Line Items] |
Notional unit amount of derivatives (in MWhs/Dths/tons) | 5,575,000 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_EnergyAxis = lnt_CoalTonsMember / us-gaap_TradingActivityByTypeAxis = us-gaap_CommodityMember
Coal (tons) [Member] | IPL [Member] |
Notional Amount of Derivatives [Line Items] |
Notional unit amount of derivatives (in MWhs/Dths/tons) | 1,566,000 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_EnergyAxis = lnt_CoalTonsMember / dei_LegalEntityAxis = lnt_IplMember / us-gaap_TradingActivityByTypeAxis = us-gaap_CommodityMember
Coal (tons) [Member] | WPL [Member] |
Notional Amount of Derivatives [Line Items] |
Notional unit amount of derivatives (in MWhs/Dths/tons) | 4,009,000 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_EnergyAxis = lnt_CoalTonsMember / dei_LegalEntityAxis = lnt_WplMember / us-gaap_TradingActivityByTypeAxis = us-gaap_CommodityMember
2015 [Member] | Electricity (MWhs) [Member] |
Notional Amount of Derivatives [Line Items] |
Notional unit amount of derivatives (in MWhs/Dths/tons) | 4,067,000 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_EnergyAxis = lnt_ElectricityMwhsMember / us-gaap_StatementScenarioAxis = lnt_DerivativeNonMonetaryNotionalAmountYearOneMember / us-gaap_TradingActivityByTypeAxis = us-gaap_CommodityMember
2015 [Member] | Electricity (MWhs) [Member] | IPL [Member] |
Notional Amount of Derivatives [Line Items] |
Notional unit amount of derivatives (in MWhs/Dths/tons) | 1,765,000 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_EnergyAxis = lnt_ElectricityMwhsMember / dei_LegalEntityAxis = lnt_IplMember / us-gaap_StatementScenarioAxis = lnt_DerivativeNonMonetaryNotionalAmountYearOneMember / us-gaap_TradingActivityByTypeAxis = us-gaap_CommodityMember
2015 [Member] | Electricity (MWhs) [Member] | WPL [Member] |
Notional Amount of Derivatives [Line Items] |
Notional unit amount of derivatives (in MWhs/Dths/tons) | 2,302,000 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_EnergyAxis = lnt_ElectricityMwhsMember / dei_LegalEntityAxis = lnt_WplMember / us-gaap_StatementScenarioAxis = lnt_DerivativeNonMonetaryNotionalAmountYearOneMember / us-gaap_TradingActivityByTypeAxis = us-gaap_CommodityMember
2015 [Member] | FTRs (MWhs) [Member] |
Notional Amount of Derivatives [Line Items] |
Notional unit amount of derivatives (in MWhs/Dths/tons) | 9,505,000 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_EnergyAxis = lnt_FtrsMwhsMember / us-gaap_StatementScenarioAxis = lnt_DerivativeNonMonetaryNotionalAmountYearOneMember / us-gaap_TradingActivityByTypeAxis = us-gaap_CommodityMember
2015 [Member] | FTRs (MWhs) [Member] | IPL [Member] |
Notional Amount of Derivatives [Line Items] |
Notional unit amount of derivatives (in MWhs/Dths/tons) | 5,503,000 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_EnergyAxis = lnt_FtrsMwhsMember / dei_LegalEntityAxis = lnt_IplMember / us-gaap_StatementScenarioAxis = lnt_DerivativeNonMonetaryNotionalAmountYearOneMember / us-gaap_TradingActivityByTypeAxis = us-gaap_CommodityMember
2015 [Member] | FTRs (MWhs) [Member] | WPL [Member] |
Notional Amount of Derivatives [Line Items] |
Notional unit amount of derivatives (in MWhs/Dths/tons) | 4,002,000 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_EnergyAxis = lnt_FtrsMwhsMember / dei_LegalEntityAxis = lnt_WplMember / us-gaap_StatementScenarioAxis = lnt_DerivativeNonMonetaryNotionalAmountYearOneMember / us-gaap_TradingActivityByTypeAxis = us-gaap_CommodityMember
2015 [Member] | Natural Gas (Dths) [Member] |
Notional Amount of Derivatives [Line Items] |
Notional unit amount of derivatives (in MWhs/Dths/tons) | 56,250,000 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_EnergyAxis = lnt_NaturalGasDthsMember / us-gaap_StatementScenarioAxis = lnt_DerivativeNonMonetaryNotionalAmountYearOneMember / us-gaap_TradingActivityByTypeAxis = us-gaap_CommodityMember
2015 [Member] | Natural Gas (Dths) [Member] | IPL [Member] |
Notional Amount of Derivatives [Line Items] |
Notional unit amount of derivatives (in MWhs/Dths/tons) | 39,727,000 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_EnergyAxis = lnt_NaturalGasDthsMember / dei_LegalEntityAxis = lnt_IplMember / us-gaap_StatementScenarioAxis = lnt_DerivativeNonMonetaryNotionalAmountYearOneMember / us-gaap_TradingActivityByTypeAxis = us-gaap_CommodityMember
2015 [Member] | Natural Gas (Dths) [Member] | WPL [Member] |
Notional Amount of Derivatives [Line Items] |
Notional unit amount of derivatives (in MWhs/Dths/tons) | 16,523,000 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_EnergyAxis = lnt_NaturalGasDthsMember / dei_LegalEntityAxis = lnt_WplMember / us-gaap_StatementScenarioAxis = lnt_DerivativeNonMonetaryNotionalAmountYearOneMember / us-gaap_TradingActivityByTypeAxis = us-gaap_CommodityMember
2015 [Member] | Coal (tons) [Member] |
Notional Amount of Derivatives [Line Items] |
Notional unit amount of derivatives (in MWhs/Dths/tons) | 1,490,000 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_EnergyAxis = lnt_CoalTonsMember / us-gaap_StatementScenarioAxis = lnt_DerivativeNonMonetaryNotionalAmountYearOneMember / us-gaap_TradingActivityByTypeAxis = us-gaap_CommodityMember
2015 [Member] | Coal (tons) [Member] | IPL [Member] |
Notional Amount of Derivatives [Line Items] |
Notional unit amount of derivatives (in MWhs/Dths/tons) | 75,000 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_EnergyAxis = lnt_CoalTonsMember / dei_LegalEntityAxis = lnt_IplMember / us-gaap_StatementScenarioAxis = lnt_DerivativeNonMonetaryNotionalAmountYearOneMember / us-gaap_TradingActivityByTypeAxis = us-gaap_CommodityMember
2015 [Member] | Coal (tons) [Member] | WPL [Member] |
Notional Amount of Derivatives [Line Items] |
Notional unit amount of derivatives (in MWhs/Dths/tons) | 1,415,000 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_EnergyAxis = lnt_CoalTonsMember / dei_LegalEntityAxis = lnt_WplMember / us-gaap_StatementScenarioAxis = lnt_DerivativeNonMonetaryNotionalAmountYearOneMember / us-gaap_TradingActivityByTypeAxis = us-gaap_CommodityMember
2016 [Member] | Electricity (MWhs) [Member] |
Notional Amount of Derivatives [Line Items] |
Notional unit amount of derivatives (in MWhs/Dths/tons) | 1,553,000 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_EnergyAxis = lnt_ElectricityMwhsMember / us-gaap_StatementScenarioAxis = lnt_DerivativeNonMonetaryNotionalAmountYearTwoMember / us-gaap_TradingActivityByTypeAxis = us-gaap_CommodityMember
2016 [Member] | Electricity (MWhs) [Member] | IPL [Member] |
Notional Amount of Derivatives [Line Items] |
Notional unit amount of derivatives (in MWhs/Dths/tons) | 0 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_EnergyAxis = lnt_ElectricityMwhsMember / dei_LegalEntityAxis = lnt_IplMember / us-gaap_StatementScenarioAxis = lnt_DerivativeNonMonetaryNotionalAmountYearTwoMember / us-gaap_TradingActivityByTypeAxis = us-gaap_CommodityMember
2016 [Member] | Electricity (MWhs) [Member] | WPL [Member] |
Notional Amount of Derivatives [Line Items] |
Notional unit amount of derivatives (in MWhs/Dths/tons) | 1,553,000 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_EnergyAxis = lnt_ElectricityMwhsMember / dei_LegalEntityAxis = lnt_WplMember / us-gaap_StatementScenarioAxis = lnt_DerivativeNonMonetaryNotionalAmountYearTwoMember / us-gaap_TradingActivityByTypeAxis = us-gaap_CommodityMember
2016 [Member] | FTRs (MWhs) [Member] |
Notional Amount of Derivatives [Line Items] |
Notional unit amount of derivatives (in MWhs/Dths/tons) | 0 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_EnergyAxis = lnt_FtrsMwhsMember / us-gaap_StatementScenarioAxis = lnt_DerivativeNonMonetaryNotionalAmountYearTwoMember / us-gaap_TradingActivityByTypeAxis = us-gaap_CommodityMember
2016 [Member] | FTRs (MWhs) [Member] | IPL [Member] |
Notional Amount of Derivatives [Line Items] |
Notional unit amount of derivatives (in MWhs/Dths/tons) | 0 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_EnergyAxis = lnt_FtrsMwhsMember / dei_LegalEntityAxis = lnt_IplMember / us-gaap_StatementScenarioAxis = lnt_DerivativeNonMonetaryNotionalAmountYearTwoMember / us-gaap_TradingActivityByTypeAxis = us-gaap_CommodityMember
2016 [Member] | FTRs (MWhs) [Member] | WPL [Member] |
Notional Amount of Derivatives [Line Items] |
Notional unit amount of derivatives (in MWhs/Dths/tons) | 0 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_EnergyAxis = lnt_FtrsMwhsMember / dei_LegalEntityAxis = lnt_WplMember / us-gaap_StatementScenarioAxis = lnt_DerivativeNonMonetaryNotionalAmountYearTwoMember / us-gaap_TradingActivityByTypeAxis = us-gaap_CommodityMember
2016 [Member] | Natural Gas (Dths) [Member] |
Notional Amount of Derivatives [Line Items] |
Notional unit amount of derivatives (in MWhs/Dths/tons) | 20,225,000 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_EnergyAxis = lnt_NaturalGasDthsMember / us-gaap_StatementScenarioAxis = lnt_DerivativeNonMonetaryNotionalAmountYearTwoMember / us-gaap_TradingActivityByTypeAxis = us-gaap_CommodityMember
2016 [Member] | Natural Gas (Dths) [Member] | IPL [Member] |
Notional Amount of Derivatives [Line Items] |
Notional unit amount of derivatives (in MWhs/Dths/tons) | 10,178,000 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_EnergyAxis = lnt_NaturalGasDthsMember / dei_LegalEntityAxis = lnt_IplMember / us-gaap_StatementScenarioAxis = lnt_DerivativeNonMonetaryNotionalAmountYearTwoMember / us-gaap_TradingActivityByTypeAxis = us-gaap_CommodityMember
2016 [Member] | Natural Gas (Dths) [Member] | WPL [Member] |
Notional Amount of Derivatives [Line Items] |
Notional unit amount of derivatives (in MWhs/Dths/tons) | 10,047,000 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_EnergyAxis = lnt_NaturalGasDthsMember / dei_LegalEntityAxis = lnt_WplMember / us-gaap_StatementScenarioAxis = lnt_DerivativeNonMonetaryNotionalAmountYearTwoMember / us-gaap_TradingActivityByTypeAxis = us-gaap_CommodityMember
2016 [Member] | Coal (tons) [Member] |
Notional Amount of Derivatives [Line Items] |
Notional unit amount of derivatives (in MWhs/Dths/tons) | 1,899,000 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_EnergyAxis = lnt_CoalTonsMember / us-gaap_StatementScenarioAxis = lnt_DerivativeNonMonetaryNotionalAmountYearTwoMember / us-gaap_TradingActivityByTypeAxis = us-gaap_CommodityMember
2016 [Member] | Coal (tons) [Member] | IPL [Member] |
Notional Amount of Derivatives [Line Items] |
Notional unit amount of derivatives (in MWhs/Dths/tons) | 830,000 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_EnergyAxis = lnt_CoalTonsMember / dei_LegalEntityAxis = lnt_IplMember / us-gaap_StatementScenarioAxis = lnt_DerivativeNonMonetaryNotionalAmountYearTwoMember / us-gaap_TradingActivityByTypeAxis = us-gaap_CommodityMember
2016 [Member] | Coal (tons) [Member] | WPL [Member] |
Notional Amount of Derivatives [Line Items] |
Notional unit amount of derivatives (in MWhs/Dths/tons) | 1,069,000 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_EnergyAxis = lnt_CoalTonsMember / dei_LegalEntityAxis = lnt_WplMember / us-gaap_StatementScenarioAxis = lnt_DerivativeNonMonetaryNotionalAmountYearTwoMember / us-gaap_TradingActivityByTypeAxis = us-gaap_CommodityMember
2017 [Member] | Electricity (MWhs) [Member] |
Notional Amount of Derivatives [Line Items] |
Notional unit amount of derivatives (in MWhs/Dths/tons) | 1,314,000 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_EnergyAxis = lnt_ElectricityMwhsMember / us-gaap_StatementScenarioAxis = lnt_DerivativeNonMonetaryNotionalAmountYearThreeMember / us-gaap_TradingActivityByTypeAxis = us-gaap_CommodityMember
2017 [Member] | Electricity (MWhs) [Member] | IPL [Member] |
Notional Amount of Derivatives [Line Items] |
Notional unit amount of derivatives (in MWhs/Dths/tons) | 0 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_EnergyAxis = lnt_ElectricityMwhsMember / dei_LegalEntityAxis = lnt_IplMember / us-gaap_StatementScenarioAxis = lnt_DerivativeNonMonetaryNotionalAmountYearThreeMember / us-gaap_TradingActivityByTypeAxis = us-gaap_CommodityMember
2017 [Member] | Electricity (MWhs) [Member] | WPL [Member] |
Notional Amount of Derivatives [Line Items] |
Notional unit amount of derivatives (in MWhs/Dths/tons) | 1,314,000 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_EnergyAxis = lnt_ElectricityMwhsMember / dei_LegalEntityAxis = lnt_WplMember / us-gaap_StatementScenarioAxis = lnt_DerivativeNonMonetaryNotionalAmountYearThreeMember / us-gaap_TradingActivityByTypeAxis = us-gaap_CommodityMember
2017 [Member] | FTRs (MWhs) [Member] |
Notional Amount of Derivatives [Line Items] |
Notional unit amount of derivatives (in MWhs/Dths/tons) | 0 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_EnergyAxis = lnt_FtrsMwhsMember / us-gaap_StatementScenarioAxis = lnt_DerivativeNonMonetaryNotionalAmountYearThreeMember / us-gaap_TradingActivityByTypeAxis = us-gaap_CommodityMember
2017 [Member] | FTRs (MWhs) [Member] | IPL [Member] |
Notional Amount of Derivatives [Line Items] |
Notional unit amount of derivatives (in MWhs/Dths/tons) | 0 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_EnergyAxis = lnt_FtrsMwhsMember / dei_LegalEntityAxis = lnt_IplMember / us-gaap_StatementScenarioAxis = lnt_DerivativeNonMonetaryNotionalAmountYearThreeMember / us-gaap_TradingActivityByTypeAxis = us-gaap_CommodityMember
2017 [Member] | FTRs (MWhs) [Member] | WPL [Member] |
Notional Amount of Derivatives [Line Items] |
Notional unit amount of derivatives (in MWhs/Dths/tons) | 0 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_EnergyAxis = lnt_FtrsMwhsMember / dei_LegalEntityAxis = lnt_WplMember / us-gaap_StatementScenarioAxis = lnt_DerivativeNonMonetaryNotionalAmountYearThreeMember / us-gaap_TradingActivityByTypeAxis = us-gaap_CommodityMember
2017 [Member] | Natural Gas (Dths) [Member] |
Notional Amount of Derivatives [Line Items] |
Notional unit amount of derivatives (in MWhs/Dths/tons) | 1,829,000 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_EnergyAxis = lnt_NaturalGasDthsMember / us-gaap_StatementScenarioAxis = lnt_DerivativeNonMonetaryNotionalAmountYearThreeMember / us-gaap_TradingActivityByTypeAxis = us-gaap_CommodityMember
2017 [Member] | Natural Gas (Dths) [Member] | IPL [Member] |
Notional Amount of Derivatives [Line Items] |
Notional unit amount of derivatives (in MWhs/Dths/tons) | 1,014,000 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_EnergyAxis = lnt_NaturalGasDthsMember / dei_LegalEntityAxis = lnt_IplMember / us-gaap_StatementScenarioAxis = lnt_DerivativeNonMonetaryNotionalAmountYearThreeMember / us-gaap_TradingActivityByTypeAxis = us-gaap_CommodityMember
2017 [Member] | Natural Gas (Dths) [Member] | WPL [Member] |
Notional Amount of Derivatives [Line Items] |
Notional unit amount of derivatives (in MWhs/Dths/tons) | 815,000 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_EnergyAxis = lnt_NaturalGasDthsMember / dei_LegalEntityAxis = lnt_WplMember / us-gaap_StatementScenarioAxis = lnt_DerivativeNonMonetaryNotionalAmountYearThreeMember / us-gaap_TradingActivityByTypeAxis = us-gaap_CommodityMember
2017 [Member] | Coal (tons) [Member] |
Notional Amount of Derivatives [Line Items] |
Notional unit amount of derivatives (in MWhs/Dths/tons) | 1,073,000 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_EnergyAxis = lnt_CoalTonsMember / us-gaap_StatementScenarioAxis = lnt_DerivativeNonMonetaryNotionalAmountYearThreeMember / us-gaap_TradingActivityByTypeAxis = us-gaap_CommodityMember
2017 [Member] | Coal (tons) [Member] | IPL [Member] |
Notional Amount of Derivatives [Line Items] |
Notional unit amount of derivatives (in MWhs/Dths/tons) | 274,000 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_EnergyAxis = lnt_CoalTonsMember / dei_LegalEntityAxis = lnt_IplMember / us-gaap_StatementScenarioAxis = lnt_DerivativeNonMonetaryNotionalAmountYearThreeMember / us-gaap_TradingActivityByTypeAxis = us-gaap_CommodityMember
2017 [Member] | Coal (tons) [Member] | WPL [Member] |
Notional Amount of Derivatives [Line Items] |
Notional unit amount of derivatives (in MWhs/Dths/tons) | 799,000 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_EnergyAxis = lnt_CoalTonsMember / dei_LegalEntityAxis = lnt_WplMember / us-gaap_StatementScenarioAxis = lnt_DerivativeNonMonetaryNotionalAmountYearThreeMember / us-gaap_TradingActivityByTypeAxis = us-gaap_CommodityMember
2018 [Member] | Electricity (MWhs) [Member] |
Notional Amount of Derivatives [Line Items] |
Notional unit amount of derivatives (in MWhs/Dths/tons) | 1,314,000 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_EnergyAxis = lnt_ElectricityMwhsMember / us-gaap_StatementScenarioAxis = lnt_DerivativeNonMonetaryNotionalAmountYearFourMember / us-gaap_TradingActivityByTypeAxis = us-gaap_CommodityMember
2018 [Member] | Electricity (MWhs) [Member] | IPL [Member] |
Notional Amount of Derivatives [Line Items] |
Notional unit amount of derivatives (in MWhs/Dths/tons) | 0 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_EnergyAxis = lnt_ElectricityMwhsMember / dei_LegalEntityAxis = lnt_IplMember / us-gaap_StatementScenarioAxis = lnt_DerivativeNonMonetaryNotionalAmountYearFourMember / us-gaap_TradingActivityByTypeAxis = us-gaap_CommodityMember
2018 [Member] | Electricity (MWhs) [Member] | WPL [Member] |
Notional Amount of Derivatives [Line Items] |
Notional unit amount of derivatives (in MWhs/Dths/tons) | 1,314,000 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_EnergyAxis = lnt_ElectricityMwhsMember / dei_LegalEntityAxis = lnt_WplMember / us-gaap_StatementScenarioAxis = lnt_DerivativeNonMonetaryNotionalAmountYearFourMember / us-gaap_TradingActivityByTypeAxis = us-gaap_CommodityMember
2018 [Member] | FTRs (MWhs) [Member] |
Notional Amount of Derivatives [Line Items] |
Notional unit amount of derivatives (in MWhs/Dths/tons) | 0 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_EnergyAxis = lnt_FtrsMwhsMember / us-gaap_StatementScenarioAxis = lnt_DerivativeNonMonetaryNotionalAmountYearFourMember / us-gaap_TradingActivityByTypeAxis = us-gaap_CommodityMember
2018 [Member] | FTRs (MWhs) [Member] | IPL [Member] |
Notional Amount of Derivatives [Line Items] |
Notional unit amount of derivatives (in MWhs/Dths/tons) | 0 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_EnergyAxis = lnt_FtrsMwhsMember / dei_LegalEntityAxis = lnt_IplMember / us-gaap_StatementScenarioAxis = lnt_DerivativeNonMonetaryNotionalAmountYearFourMember / us-gaap_TradingActivityByTypeAxis = us-gaap_CommodityMember
2018 [Member] | FTRs (MWhs) [Member] | WPL [Member] |
Notional Amount of Derivatives [Line Items] |
Notional unit amount of derivatives (in MWhs/Dths/tons) | 0 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_EnergyAxis = lnt_FtrsMwhsMember / dei_LegalEntityAxis = lnt_WplMember / us-gaap_StatementScenarioAxis = lnt_DerivativeNonMonetaryNotionalAmountYearFourMember / us-gaap_TradingActivityByTypeAxis = us-gaap_CommodityMember
2018 [Member] | Natural Gas (Dths) [Member] |
Notional Amount of Derivatives [Line Items] |
Notional unit amount of derivatives (in MWhs/Dths/tons) | 0 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_EnergyAxis = lnt_NaturalGasDthsMember / us-gaap_StatementScenarioAxis = lnt_DerivativeNonMonetaryNotionalAmountYearFourMember / us-gaap_TradingActivityByTypeAxis = us-gaap_CommodityMember
2018 [Member] | Natural Gas (Dths) [Member] | IPL [Member] |
Notional Amount of Derivatives [Line Items] |
Notional unit amount of derivatives (in MWhs/Dths/tons) | 0 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_EnergyAxis = lnt_NaturalGasDthsMember / dei_LegalEntityAxis = lnt_IplMember / us-gaap_StatementScenarioAxis = lnt_DerivativeNonMonetaryNotionalAmountYearFourMember / us-gaap_TradingActivityByTypeAxis = us-gaap_CommodityMember
2018 [Member] | Natural Gas (Dths) [Member] | WPL [Member] |
Notional Amount of Derivatives [Line Items] |
Notional unit amount of derivatives (in MWhs/Dths/tons) | 0 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_EnergyAxis = lnt_NaturalGasDthsMember / dei_LegalEntityAxis = lnt_WplMember / us-gaap_StatementScenarioAxis = lnt_DerivativeNonMonetaryNotionalAmountYearFourMember / us-gaap_TradingActivityByTypeAxis = us-gaap_CommodityMember
2018 [Member] | Coal (tons) [Member] |
Notional Amount of Derivatives [Line Items] |
Notional unit amount of derivatives (in MWhs/Dths/tons) | 1,113,000 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_EnergyAxis = lnt_CoalTonsMember / us-gaap_StatementScenarioAxis = lnt_DerivativeNonMonetaryNotionalAmountYearFourMember / us-gaap_TradingActivityByTypeAxis = us-gaap_CommodityMember
2018 [Member] | Coal (tons) [Member] | IPL [Member] |
Notional Amount of Derivatives [Line Items] |
Notional unit amount of derivatives (in MWhs/Dths/tons) | 387,000 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_EnergyAxis = lnt_CoalTonsMember / dei_LegalEntityAxis = lnt_IplMember / us-gaap_StatementScenarioAxis = lnt_DerivativeNonMonetaryNotionalAmountYearFourMember / us-gaap_TradingActivityByTypeAxis = us-gaap_CommodityMember
2018 [Member] | Coal (tons) [Member] | WPL [Member] |
Notional Amount of Derivatives [Line Items] |
Notional unit amount of derivatives (in MWhs/Dths/tons) | 726,000 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_EnergyAxis = lnt_CoalTonsMember / dei_LegalEntityAxis = lnt_WplMember / us-gaap_StatementScenarioAxis = lnt_DerivativeNonMonetaryNotionalAmountYearFourMember / us-gaap_TradingActivityByTypeAxis = us-gaap_CommodityMember

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- Definition Aggregate notional amount of derivative expressed in nonmonetary units. For example, the number of barrels specified in a fuel oil forward purchase contract. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Article 12 -Section 13 -Sentence Column B + Details
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