Company Quick10K Filing
Alliant Energy
Price54.03 EPS2
Shares240 P/E26
MCap12,986 P/FCF26
Net Debt6,819 EBIT748
TEV19,804 TEV/EBIT26
TTM 2019-09-30, in MM, except price, ratios
10-K 2020-12-31 Filed 2021-02-19
10-Q 2020-09-30 Filed 2020-11-03
10-Q 2020-06-30 Filed 2020-08-10
10-Q 2020-03-31 Filed 2020-05-08
10-Q 2019-09-30 Filed 2019-11-07
10-Q 2019-06-30 Filed 2019-08-02
10-Q 2019-03-31 Filed 2019-05-03
10-K 2018-12-31 Filed 2019-02-22
10-Q 2018-09-30 Filed 2018-11-07
10-Q 2018-06-30 Filed 2018-08-03
10-Q 2018-03-31 Filed 2018-05-03
10-K 2017-12-31 Filed 2018-02-23
10-Q 2017-09-30 Filed 2017-11-03
10-Q 2017-06-30 Filed 2017-08-04
10-Q 2017-03-31 Filed 2017-05-04
10-K 2016-12-31 Filed 2017-02-24
10-Q 2016-09-30 Filed 2016-11-04
10-Q 2016-06-30 Filed 2016-08-02
10-Q 2016-03-31 Filed 2016-05-05
10-K 2015-12-31 Filed 2016-02-24
10-Q 2015-09-30 Filed 2015-11-06
10-Q 2015-06-30 Filed 2015-08-06
10-Q 2015-03-31 Filed 2015-05-01
10-K 2014-12-31 Filed 2015-02-25
10-Q 2014-09-30 Filed 2014-11-07
10-Q 2014-06-30 Filed 2014-08-07
10-Q 2014-03-31 Filed 2014-05-02
10-K 2013-12-31 Filed 2014-02-25
10-Q 2013-09-30 Filed 2013-11-07
10-Q 2013-06-30 Filed 2013-08-02
10-Q 2013-03-31 Filed 2013-05-03
10-K 2012-12-31 Filed 2013-02-26
10-Q 2012-09-30 Filed 2012-11-09
10-Q 2012-06-30 Filed 2012-08-03
10-Q 2012-03-31 Filed 2012-05-04
10-K 2011-12-31 Filed 2012-02-27
10-Q 2011-09-30 Filed 2011-11-03
10-Q 2011-06-30 Filed 2011-08-05
10-Q 2011-03-31 Filed 2011-05-05
10-K 2010-12-31 Filed 2011-02-28
10-Q 2010-06-30 Filed 2010-08-05
10-Q 2010-03-31 Filed 2010-05-05
10-K 2009-12-31 Filed 2010-02-26
8-K 2020-11-17
8-K 2020-11-02
8-K 2020-10-27
8-K 2020-08-18
8-K 2020-08-06
8-K 2020-05-26
8-K 2020-05-21
8-K 2020-05-07
8-K 2020-04-03
8-K 2020-03-30
8-K 2020-03-03
8-K 2020-02-20
8-K 2019-12-12
8-K 2019-11-14
8-K 2019-11-06
8-K 2019-09-19
8-K 2019-08-01
8-K 2019-06-17
8-K 2019-05-16
8-K 2019-05-02
8-K 2019-03-25
8-K 2019-02-21
8-K 2019-02-11
8-K 2018-12-13
8-K 2018-12-13
8-K 2018-12-13
8-K 2018-11-06
8-K 2018-09-19
8-K 2018-08-02
8-K 2018-07-25
8-K 2018-06-06
8-K 2018-05-18
8-K 2018-05-17
8-K 2018-05-02
8-K 2018-04-26
8-K 2018-03-09
8-K 2018-02-22
8-K 2018-01-15

LNT 10K Annual Report

Part I
Item 1. Business
Item 1A. Risk Factors
Item 1B. Unresolved Staff Comments
Item 2. Properties
Item 3. Legal Proceedings
Item 4. Mine Safety Disclosures
Part II
Item 5. Market for Registrants' Common Equity, Related Stockholder Matters and Issuer Purchases of Equity Securities
Item 6. Selected Financial Data
Item 7. Management's Discussion and Analysis of Financial Condition and Results of Operations
Item 7A. Quantitative and Qualitative Disclosures About Market Risk
Item 8. Financial Statements and Supplementary Data
Note 1. Summary of Significant Accounting Policies
Note 1(A) General -
Note 1(E) Property, Plant and Equipment -
Note 1(F) Revenue Recognition -
Note 1(G) Utility Cost Recovery Mechanisms
Note 1(I) Asset Impairments -
Note 1(O) New Accounting Standards -
Note 2. Regulatory Matters
Note 3. Property, Plant and Equipment
Note 4. Jointly - Owned Electric Utility Plant
Note 5. Receivables
Note 5(A) Accounts Receivable - Details for Accounts Receivable Included on The Balance Sheets As of December 31 Were As Follows (In Millions):
Note 6. Investments
Note 7. Common Equity
Note 8. Preferred Stock
Note 9. Debt
Note 9(B) Long - Term Debt - Long - Term Debt, Net As of December 31 Was As Follows (Dollars in Millions):
Note 10. Leases
Note 11. Revenues
Note 12. Income Taxes
Note 13. Benefit Plans
Note 14. Asset Retirement Obligations
Note 15. Derivative Instruments
Note 16. Fair Value Measurements
Note 17. Commitments and Contingencies
Note 17(D) Guarantees and Indemnifications -
Note 18. Segments of Business
Note 19. Related Parties
Item 9. Changes in and Disagreements with Accountants on Accounting and Financial Disclosure
Item 9A. Controls and Procedures
Item 9B. Other Information
Part III
Item 10. Directors, Executive Officers and Corporate Governance
Item 11. Executive Compensation
Item 12. Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters
Item 13. Certain Relationships and Related Transactions, and Director Independence
Item 14. Principal Accounting Fees and Services
Part IV
Item 15. Exhibits, Financial Statement Schedules
Item 16. Form 10 - K Summary
EX-10.14 lnt1231202010-kex1014.htm
EX-21.1 lnt1231202010-kex211.htm
EX-23.1 lnt1231202010-kex231.htm
EX-23.2 lnt1231202010-kex232.htm
EX-23.3 lnt1231202010-kex233.htm
EX-31.1 lnt1231202010-kex311.htm
EX-31.2 lnt1231202010-kex312.htm
EX-31.3 lnt1231202010-kex313.htm
EX-31.4 lnt1231202010-kex314.htm
EX-31.5 lnt1231202010-kex315.htm
EX-31.6 lnt1231202010-kex316.htm
EX-32.1 lnt1231202010-kex321.htm
EX-32.2 lnt1231202010-kex322.htm
EX-32.3 lnt1231202010-kex323.htm

Alliant Energy Earnings 2020-12-31

Balance SheetIncome StatementCash Flow
2016128402012201420172020
Assets, Equity
1.00.80.60.40.20.02012201420172020
Rev, G Profit, Net Income
0.60.30.1-0.2-0.4-0.72012201420172020
Ops, Inv, Fin

lnt-20201231
00003525412020FYfalse000005248500001078320.010.01480,000,000480,000,000249,868,415245,022,800380,542381,23228.7326.241.521.421.342.502.5024,000,00024,000,00013,370,78813,370,7885.005.0018,000,00018,000,00013,236,60113,236,60116203.653.653.253.253.253.253.43.43.43.45.55.55.55.54.14.14.14.13.63.63.63.62.32.36.456.456.456.456.36.36.36.36.256.256.256.254.74.74.74.73.73.73.73.73.53.53.53.54.64.62.252.252.252.253.053.053.053.0533336.256.256.256.256.3756.3756.3756.3757.67.67.67.64.14.14.14.13.653.65123.453.453.753.751.44.254.255.065.061us-gaap:OtherLiabilitiesCurrentus-gaap:OtherLiabilitiesCurrentus-gaap:OtherLiabilitiesNoncurrentus-gaap:OtherLiabilitiesNoncurrent00003525412020-01-012020-12-310000352541lnt:IplMember2020-01-012020-12-310000352541lnt:WplMember2020-01-012020-12-31iso4217:USD00003525412020-06-300000352541lnt:IplMember2020-06-300000352541lnt:WplMember2020-06-30xbrli:shares00003525412021-01-310000352541lnt:IplMember2021-01-310000352541lnt:WplMember2021-01-310000352541us-gaap:FinanceReceivablesMemberlnt:IplMember2020-12-310000352541lnt:WplMember2020-12-3100003525412020-12-3100003525412019-01-012019-12-3100003525412018-01-012018-12-31iso4217:USDxbrli:shares00003525412019-12-3100003525412018-12-3100003525412017-12-310000352541us-gaap:CommonStockMember2017-12-310000352541us-gaap:AdditionalPaidInCapitalMember2017-12-310000352541us-gaap:RetainedEarningsMember2017-12-310000352541us-gaap:AccumulatedOtherComprehensiveIncomeMember2017-12-310000352541us-gaap:DeferredCompensationShareBasedPaymentsMember2017-12-310000352541us-gaap:PreferredStockMember2017-12-310000352541us-gaap:RetainedEarningsMember2018-01-012018-12-310000352541us-gaap:AdditionalPaidInCapitalMember2018-01-012018-12-310000352541us-gaap:DeferredCompensationShareBasedPaymentsMember2018-01-012018-12-310000352541us-gaap:AccumulatedOtherComprehensiveIncomeMember2018-01-012018-12-310000352541us-gaap:CommonStockMember2018-12-310000352541us-gaap:AdditionalPaidInCapitalMember2018-12-310000352541us-gaap:RetainedEarningsMember2018-12-310000352541us-gaap:AccumulatedOtherComprehensiveIncomeMember2018-12-310000352541us-gaap:DeferredCompensationShareBasedPaymentsMember2018-12-310000352541us-gaap:PreferredStockMember2018-12-310000352541us-gaap:RetainedEarningsMember2019-01-012019-12-310000352541us-gaap:AdditionalPaidInCapitalMember2019-01-012019-12-310000352541us-gaap:AccumulatedOtherComprehensiveIncomeMember2019-01-012019-12-310000352541us-gaap:CommonStockMember2019-12-310000352541us-gaap:AdditionalPaidInCapitalMember2019-12-310000352541us-gaap:RetainedEarningsMember2019-12-310000352541us-gaap:AccumulatedOtherComprehensiveIncomeMember2019-12-310000352541us-gaap:DeferredCompensationShareBasedPaymentsMember2019-12-310000352541us-gaap:PreferredStockMember2019-12-310000352541us-gaap:RetainedEarningsMember2020-01-012020-12-310000352541us-gaap:AdditionalPaidInCapitalMember2020-01-012020-12-310000352541us-gaap:DeferredCompensationShareBasedPaymentsMember2020-01-012020-12-310000352541us-gaap:RetainedEarningsMembersrt:CumulativeEffectPeriodOfAdoptionAdjustmentMember2019-12-310000352541srt:CumulativeEffectPeriodOfAdoptionAdjustmentMember2019-12-310000352541us-gaap:AccumulatedOtherComprehensiveIncomeMember2020-01-012020-12-310000352541us-gaap:CommonStockMember2020-12-310000352541us-gaap:AdditionalPaidInCapitalMember2020-12-310000352541us-gaap:RetainedEarningsMember2020-12-310000352541us-gaap:AccumulatedOtherComprehensiveIncomeMember2020-12-310000352541us-gaap:DeferredCompensationShareBasedPaymentsMember2020-12-310000352541us-gaap:PreferredStockMember2020-12-310000352541lnt:IplMember2020-12-310000352541lnt:IplMember2019-01-012019-12-310000352541lnt:IplMember2018-01-012018-12-310000352541lnt:IplMember2019-12-310000352541lnt:IplMember2018-12-310000352541lnt:IplMember2017-12-310000352541us-gaap:CommonStockMemberlnt:IplMember2017-12-310000352541lnt:IplMemberus-gaap:AdditionalPaidInCapitalMember2017-12-310000352541us-gaap:RetainedEarningsMemberlnt:IplMember2017-12-310000352541us-gaap:PreferredStockMemberlnt:IplMember2017-12-310000352541us-gaap:RetainedEarningsMemberlnt:IplMember2018-01-012018-12-310000352541lnt:IplMemberus-gaap:AdditionalPaidInCapitalMember2018-01-012018-12-310000352541us-gaap:CommonStockMemberlnt:IplMember2018-12-310000352541lnt:IplMemberus-gaap:AdditionalPaidInCapitalMember2018-12-310000352541us-gaap:RetainedEarningsMemberlnt:IplMember2018-12-310000352541us-gaap:PreferredStockMemberlnt:IplMember2018-12-310000352541us-gaap:RetainedEarningsMemberlnt:IplMember2019-01-012019-12-310000352541lnt:IplMemberus-gaap:AdditionalPaidInCapitalMember2019-01-012019-12-310000352541us-gaap:CommonStockMemberlnt:IplMember2019-12-310000352541lnt:IplMemberus-gaap:AdditionalPaidInCapitalMember2019-12-310000352541us-gaap:RetainedEarningsMemberlnt:IplMember2019-12-310000352541us-gaap:PreferredStockMemberlnt:IplMember2019-12-310000352541us-gaap:RetainedEarningsMemberlnt:IplMember2020-01-012020-12-310000352541lnt:IplMemberus-gaap:AdditionalPaidInCapitalMember2020-01-012020-12-310000352541us-gaap:CommonStockMemberlnt:IplMember2020-12-310000352541lnt:IplMemberus-gaap:AdditionalPaidInCapitalMember2020-12-310000352541us-gaap:RetainedEarningsMemberlnt:IplMember2020-12-310000352541us-gaap:PreferredStockMemberlnt:IplMember2020-12-310000352541lnt:WplMember2019-01-012019-12-310000352541lnt:WplMember2018-01-012018-12-310000352541lnt:WplMember2019-12-310000352541lnt:WplMember2018-12-310000352541lnt:WplMember2017-12-310000352541us-gaap:CommonStockMemberlnt:WplMember2017-12-310000352541us-gaap:AdditionalPaidInCapitalMemberlnt:WplMember2017-12-310000352541us-gaap:RetainedEarningsMemberlnt:WplMember2017-12-310000352541us-gaap:RetainedEarningsMemberlnt:WplMember2018-01-012018-12-310000352541us-gaap:AdditionalPaidInCapitalMemberlnt:WplMember2018-01-012018-12-310000352541us-gaap:CommonStockMemberlnt:WplMember2018-12-310000352541us-gaap:AdditionalPaidInCapitalMemberlnt:WplMember2018-12-310000352541us-gaap:RetainedEarningsMemberlnt:WplMember2018-12-310000352541us-gaap:RetainedEarningsMemberlnt:WplMember2019-01-012019-12-310000352541us-gaap:AdditionalPaidInCapitalMemberlnt:WplMember2019-01-012019-12-310000352541us-gaap:CommonStockMemberlnt:WplMember2019-12-310000352541us-gaap:AdditionalPaidInCapitalMemberlnt:WplMember2019-12-310000352541us-gaap:RetainedEarningsMemberlnt:WplMember2019-12-310000352541us-gaap:RetainedEarningsMemberlnt:WplMember2020-01-012020-12-310000352541us-gaap:AdditionalPaidInCapitalMemberlnt:WplMember2020-01-012020-12-310000352541us-gaap:CommonStockMemberlnt:WplMember2020-12-310000352541us-gaap:AdditionalPaidInCapitalMemberlnt:WplMember2020-12-310000352541us-gaap:RetainedEarningsMemberlnt:WplMember2020-12-31lnt:customerxbrli:pure0000352541lnt:AlliantEnergyFinanceLLCMember2020-12-31utr:MW0000352541lnt:AlliantEnergyFinanceLLCMember2020-01-012020-12-310000352541lnt:SheboyganFallsEnergyFacilityMember2020-01-012020-12-310000352541lnt:SheboyganFallsEnergyFacilityMember2020-12-310000352541us-gaap:ElectricGenerationEquipmentMemberlnt:IplMember2020-01-012020-12-310000352541us-gaap:ElectricGenerationEquipmentMemberlnt:IplMember2019-01-012019-12-310000352541us-gaap:ElectricGenerationEquipmentMemberlnt:IplMember2018-01-012018-12-310000352541us-gaap:ElectricGenerationEquipmentMemberlnt:WplMember2020-01-012020-12-310000352541us-gaap:ElectricGenerationEquipmentMemberlnt:WplMember2019-01-012019-12-310000352541us-gaap:ElectricGenerationEquipmentMemberlnt:WplMember2018-01-012018-12-310000352541us-gaap:ElectricDistributionMemberlnt:IplMember2020-01-012020-12-310000352541us-gaap:ElectricDistributionMemberlnt:IplMember2019-01-012019-12-310000352541us-gaap:ElectricDistributionMemberlnt:IplMember2018-01-012018-12-310000352541us-gaap:ElectricDistributionMemberlnt:WplMember2020-01-012020-12-310000352541us-gaap:ElectricDistributionMemberlnt:WplMember2019-01-012019-12-310000352541us-gaap:ElectricDistributionMemberlnt:WplMember2018-01-012018-12-310000352541us-gaap:OtherEnergyEquipmentMemberlnt:IplMember2020-01-012020-12-310000352541us-gaap:OtherEnergyEquipmentMemberlnt:IplMember2019-01-012019-12-310000352541us-gaap:OtherEnergyEquipmentMemberlnt:IplMember2018-01-012018-12-310000352541us-gaap:OtherEnergyEquipmentMemberlnt:WplMember2020-01-012020-12-310000352541us-gaap:OtherEnergyEquipmentMemberlnt:WplMember2019-01-012019-12-310000352541us-gaap:OtherEnergyEquipmentMemberlnt:WplMember2018-01-012018-12-310000352541lnt:IplMemberus-gaap:GasTransmissionMember2020-01-012020-12-310000352541lnt:IplMemberus-gaap:GasTransmissionMember2019-01-012019-12-310000352541lnt:IplMemberus-gaap:GasTransmissionMember2018-01-012018-12-310000352541us-gaap:GasTransmissionMemberlnt:WplMember2020-01-012020-12-310000352541us-gaap:GasTransmissionMemberlnt:WplMember2019-01-012019-12-310000352541us-gaap:GasTransmissionMemberlnt:WplMember2018-01-012018-12-310000352541us-gaap:OtherPlantInServiceMemberlnt:IplMember2020-01-012020-12-310000352541us-gaap:OtherPlantInServiceMemberlnt:IplMember2019-01-012019-12-310000352541us-gaap:OtherPlantInServiceMemberlnt:IplMember2018-01-012018-12-310000352541us-gaap:OtherPlantInServiceMemberlnt:WplMember2020-01-012020-12-310000352541us-gaap:OtherPlantInServiceMemberlnt:WplMember2019-01-012019-12-310000352541us-gaap:OtherPlantInServiceMemberlnt:WplMember2018-01-012018-12-310000352541lnt:IplMemberlnt:IPLfercformulawindgenerationMember2020-01-012020-12-310000352541lnt:IplMemberlnt:IPLfercformulawindgenerationMember2019-01-012019-12-310000352541lnt:IplMemberlnt:IPLfercformulawindgenerationMember2018-01-012018-12-310000352541lnt:IplMemberlnt:IplFercFormulaOtherProjectsMember2020-01-012020-12-310000352541lnt:IplMemberlnt:IplFercFormulaOtherProjectsMember2019-01-012019-12-310000352541lnt:IplMemberlnt:IplFercFormulaOtherProjectsMember2018-01-012018-12-310000352541lnt:WplPscwFormulaRetailJurisdictionMemberlnt:WplMember2020-01-012020-12-310000352541lnt:WplPscwFormulaRetailJurisdictionMemberlnt:WplMember2019-01-012019-12-310000352541lnt:WplPscwFormulaRetailJurisdictionMemberlnt:WplMember2018-01-012018-12-310000352541lnt:WplFercFormulaWholesaleJurisdictionMemberlnt:WplMember2020-01-012020-12-310000352541lnt:WplFercFormulaWholesaleJurisdictionMemberlnt:WplMember2019-01-012019-12-310000352541lnt:WplFercFormulaWholesaleJurisdictionMemberlnt:WplMember2018-01-012018-12-310000352541us-gaap:DeferredIncomeTaxChargesMember2020-12-310000352541us-gaap:DeferredIncomeTaxChargesMember2019-12-310000352541lnt:IplMemberus-gaap:DeferredIncomeTaxChargesMember2020-12-310000352541lnt:IplMemberus-gaap:DeferredIncomeTaxChargesMember2019-12-310000352541lnt:WplMemberus-gaap:DeferredIncomeTaxChargesMember2020-12-310000352541lnt:WplMemberus-gaap:DeferredIncomeTaxChargesMember2019-12-310000352541lnt:PensionAndOtherPostretirementBenefitsMember2020-12-310000352541lnt:PensionAndOtherPostretirementBenefitsMember2019-12-310000352541lnt:PensionAndOtherPostretirementBenefitsMemberlnt:IplMember2020-12-310000352541lnt:PensionAndOtherPostretirementBenefitsMemberlnt:IplMember2019-12-310000352541lnt:PensionAndOtherPostretirementBenefitsMemberlnt:WplMember2020-12-310000352541lnt:PensionAndOtherPostretirementBenefitsMemberlnt:WplMember2019-12-310000352541us-gaap:AssetRetirementObligationCostsMember2020-12-310000352541us-gaap:AssetRetirementObligationCostsMember2019-12-310000352541us-gaap:AssetRetirementObligationCostsMemberlnt:IplMember2020-12-310000352541us-gaap:AssetRetirementObligationCostsMemberlnt:IplMember2019-12-310000352541us-gaap:AssetRetirementObligationCostsMemberlnt:WplMember2020-12-310000352541us-gaap:AssetRetirementObligationCostsMemberlnt:WplMember2019-12-310000352541lnt:ElectricGeneratingUnitsRetiredEarlyMemberMember2020-12-310000352541lnt:ElectricGeneratingUnitsRetiredEarlyMemberMember2019-12-310000352541lnt:ElectricGeneratingUnitsRetiredEarlyMemberMemberlnt:IplMember2020-12-310000352541lnt:ElectricGeneratingUnitsRetiredEarlyMemberMemberlnt:IplMember2019-12-310000352541lnt:ElectricGeneratingUnitsRetiredEarlyMemberMemberlnt:WplMember2020-12-310000352541lnt:ElectricGeneratingUnitsRetiredEarlyMemberMemberlnt:WplMember2019-12-310000352541lnt:DAECPPAMember2020-12-310000352541lnt:DAECPPAMember2019-12-310000352541lnt:DAECPPAMemberlnt:IplMember2020-12-310000352541lnt:DAECPPAMemberlnt:IplMember2019-12-310000352541lnt:WesternWisconsinGasDistributionExpansionInvestmentsMember2020-12-310000352541lnt:WesternWisconsinGasDistributionExpansionInvestmentsMember2019-12-310000352541lnt:WesternWisconsinGasDistributionExpansionInvestmentsMemberlnt:WplMember2020-12-310000352541lnt:WesternWisconsinGasDistributionExpansionInvestmentsMemberlnt:WplMember2019-12-310000352541us-gaap:DeferredDerivativeGainLossMember2020-12-310000352541us-gaap:DeferredDerivativeGainLossMember2019-12-310000352541us-gaap:DeferredDerivativeGainLossMemberlnt:IplMember2020-12-310000352541us-gaap:DeferredDerivativeGainLossMemberlnt:IplMember2019-12-310000352541us-gaap:DeferredDerivativeGainLossMemberlnt:WplMember2020-12-310000352541us-gaap:DeferredDerivativeGainLossMemberlnt:WplMember2019-12-310000352541us-gaap:OtherRegulatoryAssetsLiabilitiesMember2020-12-310000352541us-gaap:OtherRegulatoryAssetsLiabilitiesMember2019-12-310000352541lnt:IplMemberus-gaap:OtherRegulatoryAssetsLiabilitiesMember2020-12-310000352541lnt:IplMemberus-gaap:OtherRegulatoryAssetsLiabilitiesMember2019-12-310000352541lnt:WplMemberus-gaap:OtherRegulatoryAssetsLiabilitiesMember2020-12-310000352541lnt:WplMemberus-gaap:OtherRegulatoryAssetsLiabilitiesMember2019-12-310000352541lnt:ElectricGeneratingUnitsRetiredEarlyMemberMemberlnt:SutherlandUnitsOneAndThreeMemberlnt:IplMember2020-12-310000352541lnt:ElectricGeneratingUnitsRetiredEarlyMemberMemberlnt:MLKappMemberlnt:IplMember2020-12-310000352541lnt:ElectricGeneratingUnitsRetiredEarlyMemberMemberlnt:IplMemberlnt:AnalogElectricMetersMember2020-12-310000352541lnt:ElectricGeneratingUnitsRetiredEarlyMemberMemberlnt:EdgewaterUnitThreeAndNelsonDeweyUnitsOneAndTwoMemberlnt:WplMember2020-12-310000352541lnt:ElectricGeneratingUnitsRetiredEarlyMemberMemberlnt:EdgewaterUnit4Memberlnt:WplMember2020-12-310000352541lnt:DAECPPAMember2020-09-012020-09-300000352541lnt:DAECPPAMember2020-01-012020-12-310000352541lnt:TaxRelatedMember2020-12-310000352541lnt:TaxRelatedMember2019-12-310000352541lnt:IplMemberlnt:TaxRelatedMember2020-12-310000352541lnt:IplMemberlnt:TaxRelatedMember2019-12-310000352541lnt:WplMemberlnt:TaxRelatedMember2020-12-310000352541lnt:WplMemberlnt:TaxRelatedMember2019-12-310000352541lnt:CostOfRemovalObligationsMember2020-12-310000352541lnt:CostOfRemovalObligationsMember2019-12-310000352541lnt:CostOfRemovalObligationsMemberlnt:IplMember2020-12-310000352541lnt:CostOfRemovalObligationsMemberlnt:IplMember2019-12-310000352541lnt:CostOfRemovalObligationsMemberlnt:WplMember2020-12-310000352541lnt:CostOfRemovalObligationsMemberlnt:WplMember2019-12-310000352541lnt:IplSElectricTransmissionServiceCostsMember2020-12-310000352541lnt:IplSElectricTransmissionServiceCostsMember2019-12-310000352541lnt:IplMemberlnt:IplSElectricTransmissionServiceCostsMember2020-12-310000352541lnt:IplMemberlnt:IplSElectricTransmissionServiceCostsMember2019-12-310000352541lnt:IplSElectricTransmissionServiceCostsMemberlnt:WplMember2020-12-310000352541lnt:IplSElectricTransmissionServiceCostsMemberlnt:WplMember2019-12-310000352541lnt:WestRiversideLiquidatedDamagesMember2020-12-310000352541lnt:WestRiversideLiquidatedDamagesMember2019-12-310000352541lnt:WestRiversideLiquidatedDamagesMemberlnt:WplMember2020-12-310000352541lnt:WestRiversideLiquidatedDamagesMemberlnt:WplMember2019-12-310000352541us-gaap:DeferredDerivativeGainLossMember2020-12-310000352541us-gaap:DeferredDerivativeGainLossMember2019-12-310000352541lnt:IplMemberus-gaap:DeferredDerivativeGainLossMember2020-12-310000352541lnt:IplMemberus-gaap:DeferredDerivativeGainLossMember2019-12-310000352541lnt:WplMemberus-gaap:DeferredDerivativeGainLossMember2020-12-310000352541lnt:WplMemberus-gaap:DeferredDerivativeGainLossMember2019-12-310000352541us-gaap:OtherRegulatoryAssetsLiabilitiesMember2020-12-310000352541us-gaap:OtherRegulatoryAssetsLiabilitiesMember2019-12-310000352541us-gaap:OtherRegulatoryAssetsLiabilitiesMemberlnt:IplMember2020-12-310000352541us-gaap:OtherRegulatoryAssetsLiabilitiesMemberlnt:IplMember2019-12-310000352541us-gaap:OtherRegulatoryAssetsLiabilitiesMemberlnt:WplMember2020-12-310000352541us-gaap:OtherRegulatoryAssetsLiabilitiesMemberlnt:WplMember2019-12-310000352541lnt:IplMemberlnt:IplSElectricTransmissionServiceCostsMember2020-01-012020-12-310000352541lnt:DerechoWindstormMemberlnt:IplMember2020-08-012020-08-310000352541lnt:DerechoWindstormMemberlnt:IplMembersrt:ScenarioForecastMember2021-12-310000352541lnt:DerechoWindstormMemberlnt:IplMember2020-12-310000352541lnt:IplMemberlnt:TwoThousandTwentyTestPeriodRetailElectricMember2019-01-012019-12-310000352541lnt:IplMemberlnt:TwoThousandTwentyTestPeriodRetailElectricMember2020-01-012020-12-310000352541us-gaap:DeferredIncomeTaxChargesMemberlnt:IplMemberlnt:TwoThousandTwentyTestPeriodRetailElectricMember2020-12-310000352541lnt:IplMemberlnt:TwoThousandTwentyTestPeriodRetailElectricMemberus-gaap:RevenueSubjectToRefundMember2020-12-310000352541lnt:TwoThousandTwentyTestPeriodRetailGasMemberlnt:IplMember2020-01-012020-12-310000352541lnt:IplMemberlnt:TwoThousandSixteenTestYearRetailElectricMember2017-01-012017-12-310000352541lnt:IplMemberlnt:TwoThousandSixteenTestYearRetailElectricMember2018-01-012018-12-310000352541lnt:TwentyNineteenTestPeriodRetailElectricMemberlnt:WplMemberus-gaap:RevenueSubjectToRefundMember2020-01-012020-12-310000352541lnt:WplMemberlnt:TwoThousandTwentyTestPeriodRetailElectricMember2020-01-012020-12-310000352541lnt:ElectricGenerationMember2020-12-310000352541lnt:ElectricGenerationMember2019-12-310000352541lnt:ElectricGenerationMemberlnt:IplMember2020-12-310000352541lnt:ElectricGenerationMemberlnt:IplMember2019-12-310000352541lnt:ElectricGenerationMemberlnt:WplMember2020-12-310000352541lnt:ElectricGenerationMemberlnt:WplMember2019-12-310000352541us-gaap:ElectricDistributionMember2020-12-310000352541us-gaap:ElectricDistributionMember2019-12-310000352541us-gaap:ElectricDistributionMemberlnt:IplMember2020-12-310000352541us-gaap:ElectricDistributionMemberlnt:IplMember2019-12-310000352541us-gaap:ElectricDistributionMemberlnt:WplMember2020-12-310000352541us-gaap:ElectricDistributionMemberlnt:WplMember2019-12-310000352541us-gaap:OtherPlantInServiceMember2020-12-310000352541us-gaap:OtherPlantInServiceMember2019-12-310000352541us-gaap:OtherPlantInServiceMemberlnt:IplMember2020-12-310000352541us-gaap:OtherPlantInServiceMemberlnt:IplMember2019-12-310000352541us-gaap:OtherPlantInServiceMemberlnt:WplMember2020-12-310000352541us-gaap:OtherPlantInServiceMemberlnt:WplMember2019-12-310000352541us-gaap:EquityMember2020-01-012020-12-310000352541us-gaap:EquityMember2019-01-012019-12-310000352541us-gaap:EquityMember2018-01-012018-12-310000352541lnt:IplMemberus-gaap:EquityMember2020-01-012020-12-310000352541lnt:IplMemberus-gaap:EquityMember2019-01-012019-12-310000352541lnt:IplMemberus-gaap:EquityMember2018-01-012018-12-310000352541us-gaap:EquityMemberlnt:WplMember2020-01-012020-12-310000352541us-gaap:EquityMemberlnt:WplMember2019-01-012019-12-310000352541us-gaap:EquityMemberlnt:WplMember2018-01-012018-12-310000352541us-gaap:DebtMember2020-01-012020-12-310000352541us-gaap:DebtMember2019-01-012019-12-310000352541us-gaap:DebtMember2018-01-012018-12-310000352541us-gaap:DebtMemberlnt:IplMember2020-01-012020-12-310000352541us-gaap:DebtMemberlnt:IplMember2019-01-012019-12-310000352541us-gaap:DebtMemberlnt:IplMember2018-01-012018-12-310000352541us-gaap:DebtMemberlnt:WplMember2020-01-012020-12-310000352541us-gaap:DebtMemberlnt:WplMember2019-01-012019-12-310000352541us-gaap:DebtMemberlnt:WplMember2018-01-012018-12-310000352541lnt:SheboyganFallsEnergyFacilityMember2020-01-012020-12-310000352541lnt:CustomerBillingAndInformationSystemMember2020-01-012020-12-310000352541us-gaap:SoftwareAndSoftwareDevelopmentCostsMember2020-01-012020-12-310000352541lnt:CorporateServicesMembersrt:MinimumMember2020-01-012020-12-310000352541srt:MaximumMemberlnt:CorporateServicesMember2020-01-012020-12-310000352541lnt:OttumwaUnit1Memberlnt:IplMember2020-12-310000352541lnt:GeorgeNealUnit4Memberlnt:IplMember2020-12-310000352541lnt:GeorgeNealUnit3Memberlnt:IplMember2020-12-310000352541lnt:IplMemberlnt:LouisaUnit1Member2020-12-310000352541lnt:ColumbiaUnits1And2Memberlnt:WplMember2020-12-310000352541lnt:RiversideEnergyCenterMemberlnt:WplMember2020-12-310000352541lnt:ForwardWindEnergyCenterMemberlnt:WplMember2020-12-310000352541srt:MaximumMember2020-12-310000352541lnt:IplMembersrt:MaximumMember2020-01-012020-12-310000352541lnt:IplMembersrt:MaximumMember2019-01-012019-12-310000352541lnt:IplMembersrt:MaximumMember2018-01-012018-12-310000352541srt:WeightedAverageMemberlnt:IplMember2020-01-012020-12-310000352541srt:WeightedAverageMemberlnt:IplMember2019-01-012019-12-310000352541srt:WeightedAverageMemberlnt:IplMember2018-01-012018-12-310000352541us-gaap:FinanceReceivablesMemberlnt:IplMember2019-12-310000352541lnt:InvestmentInAtcMember2020-12-310000352541lnt:InvestmentInAtcMember2019-12-310000352541lnt:InvestmentInAtcMember2020-01-012020-12-310000352541lnt:InvestmentInAtcMember2019-01-012019-12-310000352541lnt:InvestmentInAtcMember2018-01-012018-12-310000352541lnt:WindInvestmentinOklahomaMember2020-12-310000352541lnt:WindInvestmentinOklahomaMember2019-12-310000352541lnt:WindInvestmentinOklahomaMember2020-01-012020-12-310000352541lnt:WindInvestmentinOklahomaMember2019-01-012019-12-310000352541lnt:WindInvestmentinOklahomaMember2018-01-012018-12-310000352541lnt:OtherEquityMethodInvestmentsMember2020-12-310000352541lnt:OtherEquityMethodInvestmentsMember2019-12-310000352541lnt:OtherEquityMethodInvestmentsMember2020-01-012020-12-310000352541lnt:OtherEquityMethodInvestmentsMember2019-01-012019-12-310000352541lnt:OtherEquityMethodInvestmentsMember2018-01-012018-12-310000352541lnt:TotalsMember2020-12-310000352541lnt:TotalsMember2019-12-310000352541lnt:TotalsMember2020-01-012020-12-310000352541lnt:TotalsMember2019-01-012019-12-310000352541lnt:TotalsMember2018-01-012018-12-310000352541us-gaap:EquityMethodInvestmentNonconsolidatedInvesteeOrGroupOfInvesteesMember2020-01-012020-12-310000352541us-gaap:EquityMethodInvestmentNonconsolidatedInvesteeOrGroupOfInvesteesMember2019-01-012019-12-310000352541us-gaap:EquityMethodInvestmentNonconsolidatedInvesteeOrGroupOfInvesteesMember2018-01-012018-12-310000352541us-gaap:EquityMethodInvestmentNonconsolidatedInvesteeOrGroupOfInvesteesMember2020-12-310000352541us-gaap:EquityMethodInvestmentNonconsolidatedInvesteeOrGroupOfInvesteesMember2019-12-310000352541lnt:AmericanTransmissionCompanyLlcAtcMember2020-12-310000352541lnt:ATCHoldcoLLCMember2020-12-310000352541us-gaap:ForwardContractsMember2020-01-012020-12-310000352541us-gaap:ForwardContractsMember2019-01-012019-12-310000352541us-gaap:ForwardContractsMember2018-01-012018-12-310000352541lnt:AtTheMarketOfferingProgramMember2020-01-012020-12-310000352541lnt:AtTheMarketOfferingProgramMember2019-01-012019-12-310000352541lnt:AtTheMarketOfferingProgramMember2018-01-012018-12-310000352541us-gaap:ForwardContractsMember2019-12-310000352541us-gaap:ForwardContractsMember2020-12-310000352541us-gaap:RedeemablePreferredStockMemberlnt:IplMember2020-12-310000352541lnt:FivePointOnePercentageMemberus-gaap:RedeemablePreferredStockMemberlnt:IplMember2020-01-012020-12-310000352541lnt:FivePointOnePercentageMemberus-gaap:RedeemablePreferredStockMemberlnt:IplMember2019-01-012019-12-310000352541lnt:FivePointOnePercentageMemberus-gaap:RedeemablePreferredStockMemberlnt:IplMember2020-12-310000352541lnt:FivePointOnePercentageMemberus-gaap:RedeemablePreferredStockMemberlnt:IplMember2019-12-31lnt:board_memberlnt:Q0000352541srt:ParentCompanyMember2020-12-310000352541srt:ScenarioForecastMembersrt:ParentCompanyMember2021-12-310000352541lnt:IplMembersrt:ScenarioForecastMember2021-12-310000352541srt:ScenarioForecastMemberlnt:WplMember2021-12-310000352541lnt:ThreePointTwoFivePercentSeniorDebenturesDueTwoThousandTwentyFourMemberDomainlnt:SeniorDebenturesMember2020-12-310000352541lnt:ThreePointTwoFivePercentSeniorDebenturesDueTwoThousandTwentyFourMemberDomainlnt:IplMemberlnt:SeniorDebenturesMember2020-12-310000352541lnt:ThreePointTwoFivePercentSeniorDebenturesDueTwoThousandTwentyFourMemberDomainlnt:SeniorDebenturesMember2019-12-310000352541lnt:ThreePointTwoFivePercentSeniorDebenturesDueTwoThousandTwentyFourMemberDomainlnt:IplMemberlnt:SeniorDebenturesMember2019-12-310000352541lnt:ThreePointFourPercentSeniorDebenturesDueTwoThousandTwentyFiveMemberlnt:SeniorDebenturesMember2020-12-310000352541lnt:ThreePointFourPercentSeniorDebenturesDueTwoThousandTwentyFiveMemberlnt:IplMemberlnt:SeniorDebenturesMember2020-12-310000352541lnt:ThreePointFourPercentSeniorDebenturesDueTwoThousandTwentyFiveMemberlnt:SeniorDebenturesMember2019-12-310000352541lnt:ThreePointFourPercentSeniorDebenturesDueTwoThousandTwentyFiveMemberlnt:IplMemberlnt:SeniorDebenturesMember2019-12-310000352541lnt:SeniorDebenturesMemberlnt:FivePointFivePercentSeniorDebenturesDueTwoThousandTwentyFiveMember2020-12-310000352541lnt:IplMemberlnt:SeniorDebenturesMemberlnt:FivePointFivePercentSeniorDebenturesDueTwoThousandTwentyFiveMember2020-12-310000352541lnt:SeniorDebenturesMemberlnt:FivePointFivePercentSeniorDebenturesDueTwoThousandTwentyFiveMember2019-12-310000352541lnt:IplMemberlnt:SeniorDebenturesMemberlnt:FivePointFivePercentSeniorDebenturesDueTwoThousandTwentyFiveMember2019-12-310000352541lnt:FourPointOneSeniorDebenturesDueTwoThousandTwentyEightMemberlnt:SeniorDebenturesMember2020-12-310000352541lnt:FourPointOneSeniorDebenturesDueTwoThousandTwentyEightMemberlnt:IplMemberlnt:SeniorDebenturesMember2020-12-310000352541lnt:FourPointOneSeniorDebenturesDueTwoThousandTwentyEightMemberlnt:SeniorDebenturesMember2019-12-310000352541lnt:FourPointOneSeniorDebenturesDueTwoThousandTwentyEightMemberlnt:IplMemberlnt:SeniorDebenturesMember2019-12-310000352541lnt:ThreePointSixPercentSeniorDebenturesDueTwoThousandTwentyNineMemberlnt:SeniorDebenturesMember2020-12-310000352541lnt:ThreePointSixPercentSeniorDebenturesDueTwoThousandTwentyNineMemberlnt:IplMemberlnt:SeniorDebenturesMember2020-12-310000352541lnt:ThreePointSixPercentSeniorDebenturesDueTwoThousandTwentyNineMemberlnt:SeniorDebenturesMember2019-12-310000352541lnt:ThreePointSixPercentSeniorDebenturesDueTwoThousandTwentyNineMemberlnt:IplMemberlnt:SeniorDebenturesMember2019-12-310000352541lnt:SeniorDebenturesMemberlnt:TwoPointThreePercentSeniorDebenturesDueTwoThousandThirtyMember2020-12-310000352541lnt:IplMemberlnt:SeniorDebenturesMemberlnt:TwoPointThreePercentSeniorDebenturesDueTwoThousandThirtyMember2020-12-310000352541lnt:SeniorDebenturesMemberlnt:TwoPointThreePercentSeniorDebenturesDueTwoThousandThirtyMember2019-12-310000352541lnt:IplMemberlnt:SeniorDebenturesMemberlnt:TwoPointThreePercentSeniorDebenturesDueTwoThousandThirtyMember2019-12-310000352541lnt:SixPointFourFivePercentSeniorDebenturesDueTwoThousandThirtyThreeMemberlnt:SeniorDebenturesMember2020-12-310000352541lnt:SixPointFourFivePercentSeniorDebenturesDueTwoThousandThirtyThreeMemberlnt:IplMemberlnt:SeniorDebenturesMember2020-12-310000352541lnt:SixPointFourFivePercentSeniorDebenturesDueTwoThousandThirtyThreeMemberlnt:SeniorDebenturesMember2019-12-310000352541lnt:SixPointFourFivePercentSeniorDebenturesDueTwoThousandThirtyThreeMemberlnt:IplMemberlnt:SeniorDebenturesMember2019-12-310000352541lnt:SixPointThreePercentSeniorDebenturesDueTwoThousandThirtyFourMemberlnt:SeniorDebenturesMember2020-12-310000352541lnt:SixPointThreePercentSeniorDebenturesDueTwoThousandThirtyFourMemberlnt:IplMemberlnt:SeniorDebenturesMember2020-12-310000352541lnt:SixPointThreePercentSeniorDebenturesDueTwoThousandThirtyFourMemberlnt:SeniorDebenturesMember2019-12-310000352541lnt:SixPointThreePercentSeniorDebenturesDueTwoThousandThirtyFourMemberlnt:IplMemberlnt:SeniorDebenturesMember2019-12-310000352541lnt:SixPointTwoFivePercentSeniorDebenturesDueTwoThousandThirtyNineMemberlnt:SeniorDebenturesMember2020-12-310000352541lnt:SixPointTwoFivePercentSeniorDebenturesDueTwoThousandThirtyNineMemberlnt:IplMemberlnt:SeniorDebenturesMember2020-12-310000352541lnt:SixPointTwoFivePercentSeniorDebenturesDueTwoThousandThirtyNineMemberlnt:SeniorDebenturesMember2019-12-310000352541lnt:SixPointTwoFivePercentSeniorDebenturesDueTwoThousandThirtyNineMemberlnt:IplMemberlnt:SeniorDebenturesMember2019-12-310000352541lnt:FourPointSevenPercentSeniorDebenturesDueTwoThousandFortyThreeMemberlnt:SeniorDebenturesMember2020-12-310000352541lnt:FourPointSevenPercentSeniorDebenturesDueTwoThousandFortyThreeMemberlnt:IplMemberlnt:SeniorDebenturesMember2020-12-310000352541lnt:FourPointSevenPercentSeniorDebenturesDueTwoThousandFortyThreeMemberlnt:SeniorDebenturesMember2019-12-310000352541lnt:FourPointSevenPercentSeniorDebenturesDueTwoThousandFortyThreeMemberlnt:IplMemberlnt:SeniorDebenturesMember2019-12-310000352541lnt:ThreePointSevenPercentSeniorDebenturesDueTwoThousandFortySixMemberlnt:SeniorDebenturesMember2020-12-310000352541lnt:ThreePointSevenPercentSeniorDebenturesDueTwoThousandFortySixMemberlnt:IplMemberlnt:SeniorDebenturesMember2020-12-310000352541lnt:ThreePointSevenPercentSeniorDebenturesDueTwoThousandFortySixMemberlnt:SeniorDebenturesMember2019-12-310000352541lnt:ThreePointSevenPercentSeniorDebenturesDueTwoThousandFortySixMemberlnt:IplMemberlnt:SeniorDebenturesMember2019-12-310000352541lnt:ThreePointFivePercentSeniorDebenturesDueTwoThousandFortyNineMemberlnt:SeniorDebenturesMember2020-12-310000352541lnt:ThreePointFivePercentSeniorDebenturesDueTwoThousandFortyNineMemberlnt:IplMemberlnt:SeniorDebenturesMember2020-12-310000352541lnt:ThreePointFivePercentSeniorDebenturesDueTwoThousandFortyNineMemberlnt:SeniorDebenturesMember2019-12-310000352541lnt:ThreePointFivePercentSeniorDebenturesDueTwoThousandFortyNineMemberlnt:IplMemberlnt:SeniorDebenturesMember2019-12-310000352541lnt:ThreePointSixFivePercentSeniorDebenturesDueTwoThousandTwentyMemberlnt:SeniorDebenturesMember2020-12-310000352541lnt:ThreePointSixFivePercentSeniorDebenturesDueTwoThousandTwentyMemberlnt:IplMemberlnt:SeniorDebenturesMember2020-12-310000352541lnt:ThreePointSixFivePercentSeniorDebenturesDueTwoThousandTwentyMemberlnt:SeniorDebenturesMember2019-12-310000352541lnt:ThreePointSixFivePercentSeniorDebenturesDueTwoThousandTwentyMemberlnt:IplMemberlnt:SeniorDebenturesMember2019-12-310000352541lnt:SeniorDebenturesMember2020-12-310000352541lnt:IplMemberlnt:SeniorDebenturesMember2020-12-310000352541lnt:SeniorDebenturesMember2019-12-310000352541lnt:IplMemberlnt:SeniorDebenturesMember2019-12-310000352541lnt:DebenturesMemberlnt:TwoPointTwoFivePercentDebentureDueTwoThousandTwentyMember2020-12-310000352541lnt:DebenturesMemberlnt:TwoPointTwoFivePercentDebentureDueTwoThousandTwentyMemberlnt:WplMember2020-12-310000352541lnt:DebenturesMemberlnt:TwoPointTwoFivePercentDebentureDueTwoThousandTwentyMember2019-12-310000352541lnt:DebenturesMemberlnt:TwoPointTwoFivePercentDebentureDueTwoThousandTwentyMemberlnt:WplMember2019-12-310000352541lnt:DebenturesMemberlnt:ThreePointZeroFiveDebentureDueTwoThousandAndTwentySevenMember2020-12-310000352541lnt:DebenturesMemberlnt:ThreePointZeroFiveDebentureDueTwoThousandAndTwentySevenMemberlnt:WplMember2020-12-310000352541lnt:DebenturesMemberlnt:ThreePointZeroFiveDebentureDueTwoThousandAndTwentySevenMember2019-12-310000352541lnt:DebenturesMemberlnt:ThreePointZeroFiveDebentureDueTwoThousandAndTwentySevenMemberlnt:WplMember2019-12-310000352541lnt:DebenturesMemberlnt:ThreePercentDebenturesDueTwoThousandTwentyNineMember2020-12-310000352541lnt:DebenturesMemberlnt:ThreePercentDebenturesDueTwoThousandTwentyNineMemberlnt:WplMember2020-12-310000352541lnt:DebenturesMemberlnt:ThreePercentDebenturesDueTwoThousandTwentyNineMember2019-12-310000352541lnt:DebenturesMemberlnt:ThreePercentDebenturesDueTwoThousandTwentyNineMemberlnt:WplMember2019-12-310000352541lnt:DebenturesMemberlnt:SixPointTwoFivePercentDebentureDueTwoThousandThirtyFourMember2020-12-310000352541lnt:DebenturesMemberlnt:WplMemberlnt:SixPointTwoFivePercentDebentureDueTwoThousandThirtyFourMember2020-12-310000352541lnt:DebenturesMemberlnt:SixPointTwoFivePercentDebentureDueTwoThousandThirtyFourMember2019-12-310000352541lnt:DebenturesMemberlnt:WplMemberlnt:SixPointTwoFivePercentDebentureDueTwoThousandThirtyFourMember2019-12-310000352541lnt:DebenturesMemberlnt:SixPointThreeSevenFivePercentDebentureDueTwoThousandThirtySevenMember2020-12-310000352541lnt:DebenturesMemberlnt:SixPointThreeSevenFivePercentDebentureDueTwoThousandThirtySevenMemberlnt:WplMember2020-12-310000352541lnt:DebenturesMemberlnt:SixPointThreeSevenFivePercentDebentureDueTwoThousandThirtySevenMember2019-12-310000352541lnt:DebenturesMemberlnt:SixPointThreeSevenFivePercentDebentureDueTwoThousandThirtySevenMemberlnt:WplMember2019-12-310000352541lnt:DebenturesMemberlnt:SevenPointSixPercentDebentureDueTwoThousandThirtyEightMember2020-12-310000352541lnt:DebenturesMemberlnt:SevenPointSixPercentDebentureDueTwoThousandThirtyEightMemberlnt:WplMember2020-12-310000352541lnt:DebenturesMemberlnt:SevenPointSixPercentDebentureDueTwoThousandThirtyEightMember2019-12-310000352541lnt:DebenturesMemberlnt:SevenPointSixPercentDebentureDueTwoThousandThirtyEightMemberlnt:WplMember2019-12-310000352541lnt:FourPointOnePercentDebentureDueTwoThousandFortyFourMemberMemberlnt:DebenturesMember2020-12-310000352541lnt:FourPointOnePercentDebentureDueTwoThousandFortyFourMemberMemberlnt:DebenturesMemberlnt:WplMember2020-12-310000352541lnt:FourPointOnePercentDebentureDueTwoThousandFortyFourMemberMemberlnt:DebenturesMember2019-12-310000352541lnt:FourPointOnePercentDebentureDueTwoThousandFortyFourMemberMemberlnt:DebenturesMemberlnt:WplMember2019-12-310000352541lnt:DebenturesMemberlnt:ThreePointSixFivePercentDebenturesDueTwoThousandFiftyMember2020-12-310000352541lnt:DebenturesMemberlnt:ThreePointSixFivePercentDebenturesDueTwoThousandFiftyMemberlnt:WplMember2020-12-310000352541lnt:DebenturesMemberlnt:ThreePointSixFivePercentDebenturesDueTwoThousandFiftyMember2019-12-310000352541lnt:DebenturesMemberlnt:ThreePointSixFivePercentDebenturesDueTwoThousandFiftyMemberlnt:WplMember2019-12-310000352541lnt:DebenturesMemberlnt:FourPointSixPercentDebentureDueTwoThousandTwentyMember2020-12-310000352541lnt:DebenturesMemberlnt:FourPointSixPercentDebentureDueTwoThousandTwentyMemberlnt:WplMember2020-12-310000352541lnt:DebenturesMemberlnt:FourPointSixPercentDebentureDueTwoThousandTwentyMember2019-12-310000352541lnt:DebenturesMemberlnt:FourPointSixPercentDebentureDueTwoThousandTwentyMemberlnt:WplMember2019-12-310000352541lnt:DebenturesMember2020-12-310000352541lnt:DebenturesMemberlnt:WplMember2020-12-310000352541lnt:DebenturesMember2019-12-310000352541lnt:DebenturesMemberlnt:WplMember2019-12-310000352541lnt:TermLoanCreditAgreementThroughMarchTwoThousandTwentyTwoMemberlnt:AlliantEnergyFinanceLLCMemberlnt:TermLoanCreditAgreementMember2020-12-310000352541lnt:TermLoanCreditAgreementThroughMarchTwoThousandTwentyTwoMemberlnt:AlliantEnergyFinanceLLCMemberlnt:TermLoanCreditAgreementMember2019-12-310000352541us-gaap:SeniorNotesMemberlnt:ThreePointFourFivePercentSeniorNotesDueTwoThousandTwentyTwoMemberlnt:CorporateServicesMember2020-12-310000352541us-gaap:SeniorNotesMemberlnt:ThreePointFourFivePercentSeniorNotesDueTwoThousandTwentyTwoMemberlnt:CorporateServicesMember2019-12-310000352541us-gaap:SeniorNotesMemberlnt:AlliantEnergyFinanceLLCMemberlnt:ThreepointsevenfiveseniornotesduetwothousandandtwentythreeMember2020-12-310000352541us-gaap:SeniorNotesMemberlnt:AlliantEnergyFinanceLLCMemberlnt:ThreepointsevenfiveseniornotesduetwothousandandtwentythreeMember2019-12-310000352541us-gaap:SeniorNotesMemberlnt:AlliantEnergyFinanceLLCMemberlnt:OnePointFourPercentSeniorNotesDueTwoThousandTwentySixMember2020-12-310000352541us-gaap:SeniorNotesMemberlnt:AlliantEnergyFinanceLLCMemberlnt:OnePointFourPercentSeniorNotesDueTwoThousandTwentySixMember2019-12-310000352541us-gaap:SeniorNotesMemberlnt:AlliantEnergyFinanceLLCMemberlnt:FourPointTwoFivePercentSeniorNotesDueTwoThousandAndTwentyEightMember2020-12-310000352541us-gaap:SeniorNotesMemberlnt:AlliantEnergyFinanceLLCMemberlnt:FourPointTwoFivePercentSeniorNotesDueTwoThousandAndTwentyEightMember2019-12-310000352541lnt:SheboyganPowerLlcMemberlnt:SeniorSecuredNotesMemberlnt:FivePointZeroSixPercentOtherSeniorNotesDueTwoThousandTwelveToTwoThousandTwentyFourMember2020-12-310000352541lnt:SheboyganPowerLlcMemberlnt:SeniorSecuredNotesMemberlnt:FivePointZeroSixPercentOtherSeniorNotesDueTwoThousandTwelveToTwoThousandTwentyFourMember2019-12-310000352541lnt:AlliantEnergyFinanceLLCMemberlnt:TermLoanCreditAgreementMemberlnt:TermLoanCreditAgreementThroughAprilTwoThousandandTwentyMember2020-12-310000352541lnt:AlliantEnergyFinanceLLCMemberlnt:TermLoanCreditAgreementMemberlnt:TermLoanCreditAgreementThroughAprilTwoThousandandTwentyMember2019-12-310000352541lnt:OnePercentAtDecemberThirtyFirstTwoThousandThirteenOtherLongTermDebtDueTwoThousandFourteenToTwoThousandTwentyFiveMemberlnt:OtherLongTermDebtMiscellaneousMember2020-12-310000352541lnt:OnePercentAtDecemberThirtyFirstTwoThousandThirteenOtherLongTermDebtDueTwoThousandFourteenToTwoThousandTwentyFiveMemberlnt:OtherLongTermDebtMiscellaneousMember2019-12-310000352541lnt:OtherLongTermDebtMember2020-12-310000352541lnt:OtherLongTermDebtMember2019-12-310000352541lnt:CorporateServicesMember2020-12-31lnt:lease_renewal_period_option0000352541lnt:WplMemberlnt:SheboyganFallsEnergyFacilityMember2020-01-012020-12-310000352541lnt:WplMemberlnt:SheboyganFallsEnergyFacilityMember2020-12-310000352541lnt:WplMemberlnt:SheboyganFallsEnergyFacilityMember2019-12-310000352541lnt:WplMemberlnt:SheboyganFallsEnergyFacilityMember2019-01-012019-12-310000352541lnt:ElectricMemberlnt:RetailResidentialMember2020-01-012020-12-310000352541lnt:ElectricMemberlnt:RetailResidentialMember2019-01-012019-12-310000352541lnt:ElectricMemberlnt:RetailResidentialMember2018-01-012018-12-310000352541lnt:ElectricMemberlnt:IplMemberlnt:RetailResidentialMember2020-01-012020-12-310000352541lnt:ElectricMemberlnt:IplMemberlnt:RetailResidentialMember2019-01-012019-12-310000352541lnt:ElectricMemberlnt:IplMemberlnt:RetailResidentialMember2018-01-012018-12-310000352541lnt:ElectricMemberlnt:RetailResidentialMemberlnt:WplMember2020-01-012020-12-310000352541lnt:ElectricMemberlnt:RetailResidentialMemberlnt:WplMember2019-01-012019-12-310000352541lnt:ElectricMemberlnt:RetailResidentialMemberlnt:WplMember2018-01-012018-12-310000352541lnt:ElectricMemberlnt:RetailCommercialMember2020-01-012020-12-310000352541lnt:ElectricMemberlnt:RetailCommercialMember2019-01-012019-12-310000352541lnt:ElectricMemberlnt:RetailCommercialMember2018-01-012018-12-310000352541lnt:ElectricMemberlnt:IplMemberlnt:RetailCommercialMember2020-01-012020-12-310000352541lnt:ElectricMemberlnt:IplMemberlnt:RetailCommercialMember2019-01-012019-12-310000352541lnt:ElectricMemberlnt:IplMemberlnt:RetailCommercialMember2018-01-012018-12-310000352541lnt:ElectricMemberlnt:RetailCommercialMemberlnt:WplMember2020-01-012020-12-310000352541lnt:ElectricMemberlnt:RetailCommercialMemberlnt:WplMember2019-01-012019-12-310000352541lnt:ElectricMemberlnt:RetailCommercialMemberlnt:WplMember2018-01-012018-12-310000352541lnt:ElectricMemberlnt:RetailIndustrialMember2020-01-012020-12-310000352541lnt:ElectricMemberlnt:RetailIndustrialMember2019-01-012019-12-310000352541lnt:ElectricMemberlnt:RetailIndustrialMember2018-01-012018-12-310000352541lnt:ElectricMemberlnt:IplMemberlnt:RetailIndustrialMember2020-01-012020-12-310000352541lnt:ElectricMemberlnt:IplMemberlnt:RetailIndustrialMember2019-01-012019-12-310000352541lnt:ElectricMemberlnt:IplMemberlnt:RetailIndustrialMember2018-01-012018-12-310000352541lnt:ElectricMemberlnt:WplMemberlnt:RetailIndustrialMember2020-01-012020-12-310000352541lnt:ElectricMemberlnt:WplMemberlnt:RetailIndustrialMember2019-01-012019-12-310000352541lnt:ElectricMemberlnt:WplMemberlnt:RetailIndustrialMember2018-01-012018-12-310000352541lnt:ElectricMemberlnt:WholesaleMember2020-01-012020-12-310000352541lnt:ElectricMemberlnt:WholesaleMember2019-01-012019-12-310000352541lnt:ElectricMemberlnt:WholesaleMember2018-01-012018-12-310000352541lnt:ElectricMemberlnt:WholesaleMemberlnt:IplMember2020-01-012020-12-310000352541lnt:ElectricMemberlnt:WholesaleMemberlnt:IplMember2019-01-012019-12-310000352541lnt:ElectricMemberlnt:WholesaleMemberlnt:IplMember2018-01-012018-12-310000352541lnt:ElectricMemberlnt:WholesaleMemberlnt:WplMember2020-01-012020-12-310000352541lnt:ElectricMemberlnt:WholesaleMemberlnt:WplMember2019-01-012019-12-310000352541lnt:ElectricMemberlnt:WholesaleMemberlnt:WplMember2018-01-012018-12-310000352541lnt:ElectricMemberus-gaap:OtherCustomerMember2020-01-012020-12-310000352541lnt:ElectricMemberus-gaap:OtherCustomerMember2019-01-012019-12-310000352541lnt:ElectricMemberus-gaap:OtherCustomerMember2018-01-012018-12-310000352541lnt:ElectricMemberlnt:IplMemberus-gaap:OtherCustomerMember2020-01-012020-12-310000352541lnt:ElectricMemberlnt:IplMemberus-gaap:OtherCustomerMember2019-01-012019-12-310000352541lnt:ElectricMemberlnt:IplMemberus-gaap:OtherCustomerMember2018-01-012018-12-310000352541lnt:ElectricMemberlnt:WplMemberus-gaap:OtherCustomerMember2020-01-012020-12-310000352541lnt:ElectricMemberlnt:WplMemberus-gaap:OtherCustomerMember2019-01-012019-12-310000352541lnt:ElectricMemberlnt:WplMemberus-gaap:OtherCustomerMember2018-01-012018-12-310000352541lnt:ElectricMember2020-01-012020-12-310000352541lnt:ElectricMember2019-01-012019-12-310000352541lnt:ElectricMember2018-01-012018-12-310000352541lnt:ElectricMemberlnt:IplMember2020-01-012020-12-310000352541lnt:ElectricMemberlnt:IplMember2019-01-012019-12-310000352541lnt:ElectricMemberlnt:IplMember2018-01-012018-12-310000352541lnt:ElectricMemberlnt:WplMember2020-01-012020-12-310000352541lnt:ElectricMemberlnt:WplMember2019-01-012019-12-310000352541lnt:ElectricMemberlnt:WplMember2018-01-012018-12-310000352541lnt:RetailResidentialMemberlnt:GasMember2020-01-012020-12-310000352541lnt:RetailResidentialMemberlnt:GasMember2019-01-012019-12-310000352541lnt:RetailResidentialMemberlnt:GasMember2018-01-012018-12-310000352541lnt:IplMemberlnt:RetailResidentialMemberlnt:GasMember2020-01-012020-12-310000352541lnt:IplMemberlnt:RetailResidentialMemberlnt:GasMember2019-01-012019-12-310000352541lnt:IplMemberlnt:RetailResidentialMemberlnt:GasMember2018-01-012018-12-310000352541lnt:RetailResidentialMemberlnt:WplMemberlnt:GasMember2020-01-012020-12-310000352541lnt:RetailResidentialMemberlnt:WplMemberlnt:GasMember2019-01-012019-12-310000352541lnt:RetailResidentialMemberlnt:WplMemberlnt:GasMember2018-01-012018-12-310000352541lnt:RetailCommercialMemberlnt:GasMember2020-01-012020-12-310000352541lnt:RetailCommercialMemberlnt:GasMember2019-01-012019-12-310000352541lnt:RetailCommercialMemberlnt:GasMember2018-01-012018-12-310000352541lnt:IplMemberlnt:RetailCommercialMemberlnt:GasMember2020-01-012020-12-310000352541lnt:IplMemberlnt:RetailCommercialMemberlnt:GasMember2019-01-012019-12-310000352541lnt:IplMemberlnt:RetailCommercialMemberlnt:GasMember2018-01-012018-12-310000352541lnt:RetailCommercialMemberlnt:WplMemberlnt:GasMember2020-01-012020-12-310000352541lnt:RetailCommercialMemberlnt:WplMemberlnt:GasMember2019-01-012019-12-310000352541lnt:RetailCommercialMemberlnt:WplMemberlnt:GasMember2018-01-012018-12-310000352541lnt:GasMemberlnt:RetailIndustrialMember2020-01-012020-12-310000352541lnt:GasMemberlnt:RetailIndustrialMember2019-01-012019-12-310000352541lnt:GasMemberlnt:RetailIndustrialMember2018-01-012018-12-310000352541lnt:IplMemberlnt:GasMemberlnt:RetailIndustrialMember2020-01-012020-12-310000352541lnt:IplMemberlnt:GasMemberlnt:RetailIndustrialMember2019-01-012019-12-310000352541lnt:IplMemberlnt:GasMemberlnt:RetailIndustrialMember2018-01-012018-12-310000352541lnt:WplMemberlnt:GasMemberlnt:RetailIndustrialMember2020-01-012020-12-310000352541lnt:WplMemberlnt:GasMemberlnt:RetailIndustrialMember2019-01-012019-12-310000352541lnt:WplMemberlnt:GasMemberlnt:RetailIndustrialMember2018-01-012018-12-310000352541lnt:GasMemberus-gaap:OtherCustomerMember2020-01-012020-12-310000352541lnt:GasMemberus-gaap:OtherCustomerMember2019-01-012019-12-310000352541lnt:GasMemberus-gaap:OtherCustomerMember2018-01-012018-12-310000352541lnt:IplMemberlnt:GasMemberus-gaap:OtherCustomerMember2020-01-012020-12-310000352541lnt:IplMemberlnt:GasMemberus-gaap:OtherCustomerMember2019-01-012019-12-310000352541lnt:IplMemberlnt:GasMemberus-gaap:OtherCustomerMember2018-01-012018-12-310000352541lnt:WplMemberlnt:GasMemberus-gaap:OtherCustomerMember2020-01-012020-12-310000352541lnt:WplMemberlnt:GasMemberus-gaap:OtherCustomerMember2019-01-012019-12-310000352541lnt:WplMemberlnt:GasMemberus-gaap:OtherCustomerMember2018-01-012018-12-310000352541lnt:GasMember2020-01-012020-12-310000352541lnt:GasMember2019-01-012019-12-310000352541lnt:GasMember2018-01-012018-12-310000352541lnt:IplMemberlnt:GasMember2020-01-012020-12-310000352541lnt:IplMemberlnt:GasMember2019-01-012019-12-310000352541lnt:IplMemberlnt:GasMember2018-01-012018-12-310000352541lnt:WplMemberlnt:GasMember2020-01-012020-12-310000352541lnt:WplMemberlnt:GasMember2019-01-012019-12-310000352541lnt:WplMemberlnt:GasMember2018-01-012018-12-310000352541lnt:SteamMemberlnt:OtherUtilityMember2020-01-012020-12-310000352541lnt:SteamMemberlnt:OtherUtilityMember2019-01-012019-12-310000352541lnt:SteamMemberlnt:OtherUtilityMember2018-01-012018-12-310000352541lnt:SteamMemberlnt:IplMemberlnt:OtherUtilityMember2020-01-012020-12-310000352541lnt:SteamMemberlnt:IplMemberlnt:OtherUtilityMember2019-01-012019-12-310000352541lnt:SteamMemberlnt:IplMemberlnt:OtherUtilityMember2018-01-012018-12-310000352541lnt:OtherUtilityMemberus-gaap:OtherCustomerMember2020-01-012020-12-310000352541lnt:OtherUtilityMemberus-gaap:OtherCustomerMember2019-01-012019-12-310000352541lnt:OtherUtilityMemberus-gaap:OtherCustomerMember2018-01-012018-12-310000352541lnt:IplMemberlnt:OtherUtilityMemberus-gaap:OtherCustomerMember2020-01-012020-12-310000352541lnt:IplMemberlnt:OtherUtilityMemberus-gaap:OtherCustomerMember2019-01-012019-12-310000352541lnt:IplMemberlnt:OtherUtilityMemberus-gaap:OtherCustomerMember2018-01-012018-12-310000352541lnt:WplMemberlnt:OtherUtilityMemberus-gaap:OtherCustomerMember2020-01-012020-12-310000352541lnt:WplMemberlnt:OtherUtilityMemberus-gaap:OtherCustomerMember2019-01-012019-12-310000352541lnt:WplMemberlnt:OtherUtilityMemberus-gaap:OtherCustomerMember2018-01-012018-12-310000352541lnt:OtherUtilityMember2020-01-012020-12-310000352541lnt:OtherUtilityMember2019-01-012019-12-310000352541lnt:OtherUtilityMember2018-01-012018-12-310000352541lnt:IplMemberlnt:OtherUtilityMember2020-01-012020-12-310000352541lnt:IplMemberlnt:OtherUtilityMember2019-01-012019-12-310000352541lnt:IplMemberlnt:OtherUtilityMember2018-01-012018-12-310000352541lnt:WplMemberlnt:OtherUtilityMember2020-01-012020-12-310000352541lnt:WplMemberlnt:OtherUtilityMember2019-01-012019-12-310000352541lnt:WplMemberlnt:OtherUtilityMember2018-01-012018-12-310000352541us-gaap:AllOtherSegmentsMemberus-gaap:OtherCustomerMember2020-01-012020-12-310000352541us-gaap:AllOtherSegmentsMemberus-gaap:OtherCustomerMember2019-01-012019-12-310000352541us-gaap:AllOtherSegmentsMemberus-gaap:OtherCustomerMember2018-01-012018-12-310000352541us-gaap:AllOtherSegmentsMember2020-01-012020-12-310000352541us-gaap:AllOtherSegmentsMember2019-01-012019-12-310000352541us-gaap:AllOtherSegmentsMember2018-01-012018-12-310000352541lnt:IplSTaxBenefitRiderMember2020-01-012020-12-310000352541lnt:IplSTaxBenefitRiderMember2019-01-012019-12-310000352541lnt:IplSTaxBenefitRiderMember2018-01-012018-12-310000352541lnt:IplMemberlnt:IplSTaxBenefitRiderMember2020-01-012020-12-310000352541lnt:IplMemberlnt:IplSTaxBenefitRiderMember2019-01-012019-12-310000352541lnt:IplMemberlnt:IplSTaxBenefitRiderMember2018-01-012018-12-310000352541lnt:TaxBenefitRiderMember2020-01-012020-12-310000352541lnt:TaxBenefitRiderMember2019-01-012019-12-310000352541lnt:TaxBenefitRiderMember2018-01-012018-12-310000352541lnt:IplMemberlnt:TaxBenefitRiderMember2020-01-012020-12-310000352541lnt:IplMemberlnt:TaxBenefitRiderMember2019-01-012019-12-310000352541lnt:IplMemberlnt:TaxBenefitRiderMember2018-01-012018-12-310000352541us-gaap:DomesticCountryMember2020-12-310000352541us-gaap:DomesticCountryMemberlnt:IplMember2020-12-310000352541us-gaap:DomesticCountryMemberlnt:WplMember2020-12-310000352541us-gaap:StateAndLocalJurisdictionMember2020-12-310000352541lnt:IplMemberus-gaap:StateAndLocalJurisdictionMember2020-12-310000352541lnt:WplMemberus-gaap:StateAndLocalJurisdictionMember2020-12-310000352541lnt:IplMemberus-gaap:StateAndLocalJurisdictionMember2020-01-012020-12-310000352541us-gaap:StateAndLocalJurisdictionMember2020-01-012020-12-310000352541lnt:WplMemberus-gaap:StateAndLocalJurisdictionMember2020-01-012020-12-310000352541srt:ScenarioForecastMemberus-gaap:StateAndLocalJurisdictionMember2021-01-012021-12-310000352541lnt:IplMembersrt:ScenarioForecastMemberus-gaap:StateAndLocalJurisdictionMember2021-01-012021-12-310000352541srt:ScenarioForecastMemberlnt:WplMemberus-gaap:StateAndLocalJurisdictionMember2021-01-012021-12-310000352541us-gaap:PensionPlansDefinedBenefitMember2020-12-310000352541us-gaap:PensionPlansDefinedBenefitMember2019-12-310000352541us-gaap:PensionPlansDefinedBenefitMember2018-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember2020-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember2019-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember2018-12-310000352541us-gaap:PensionPlansDefinedBenefitMember2020-01-012020-12-310000352541us-gaap:PensionPlansDefinedBenefitMember2019-01-012019-12-310000352541us-gaap:PensionPlansDefinedBenefitMember2018-01-012018-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember2020-01-012020-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember2019-01-012019-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember2018-01-012018-12-310000352541us-gaap:PensionPlansDefinedBenefitMembersrt:MinimumMember2020-12-310000352541us-gaap:PensionPlansDefinedBenefitMembersrt:MaximumMember2020-12-310000352541us-gaap:PensionPlansDefinedBenefitMembersrt:MinimumMember2019-12-310000352541us-gaap:PensionPlansDefinedBenefitMembersrt:MaximumMember2019-12-310000352541us-gaap:PensionPlansDefinedBenefitMembersrt:MinimumMember2018-12-310000352541us-gaap:PensionPlansDefinedBenefitMembersrt:MaximumMember2018-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:IplMember2020-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:IplMember2019-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:IplMember2018-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberlnt:IplMember2020-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberlnt:IplMember2019-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberlnt:IplMember2018-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:IplMember2020-01-012020-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:IplMember2019-01-012019-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:IplMember2018-01-012018-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberlnt:IplMember2020-01-012020-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberlnt:IplMember2019-01-012019-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberlnt:IplMember2018-01-012018-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:WplMember2020-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:WplMember2019-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:WplMember2018-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberlnt:WplMember2020-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberlnt:WplMember2019-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberlnt:WplMember2018-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:WplMember2020-01-012020-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:WplMember2019-01-012019-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:WplMember2018-01-012018-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberlnt:WplMember2020-01-012020-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberlnt:WplMember2019-01-012019-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberlnt:WplMember2018-01-012018-12-310000352541us-gaap:PensionPlansDefinedBenefitMembersrt:ScenarioForecastMember2021-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:IplMembersrt:ScenarioForecastMember2021-12-310000352541us-gaap:PensionPlansDefinedBenefitMembersrt:ScenarioForecastMemberlnt:WplMember2021-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMembersrt:ScenarioForecastMember2021-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberlnt:IplMembersrt:ScenarioForecastMember2021-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMembersrt:ScenarioForecastMemberlnt:WplMember2021-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberus-gaap:CashAndCashEquivalentsMembersrt:MinimumMember2020-12-310000352541us-gaap:PensionPlansDefinedBenefitMembersrt:MaximumMemberus-gaap:CashAndCashEquivalentsMember2020-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberus-gaap:CashAndCashEquivalentsMember2020-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:DomesticEquitySecuritiesMembersrt:MinimumMember2020-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:DomesticEquitySecuritiesMembersrt:MaximumMember2020-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:DomesticEquitySecuritiesMember2020-12-310000352541lnt:InternationalEquitySecuritiesMemberus-gaap:PensionPlansDefinedBenefitMembersrt:MinimumMember2020-12-310000352541lnt:InternationalEquitySecuritiesMemberus-gaap:PensionPlansDefinedBenefitMembersrt:MaximumMember2020-12-310000352541lnt:InternationalEquitySecuritiesMemberus-gaap:PensionPlansDefinedBenefitMember2020-12-310000352541lnt:GlobalAssetAllocationSecuritiesMemberus-gaap:PensionPlansDefinedBenefitMembersrt:MinimumMember2020-12-310000352541lnt:GlobalAssetAllocationSecuritiesMemberus-gaap:PensionPlansDefinedBenefitMembersrt:MaximumMember2020-12-310000352541lnt:GlobalAssetAllocationSecuritiesMemberus-gaap:PensionPlansDefinedBenefitMember2020-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:RiskParitySecuritiesMembersrt:MinimumMember2020-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:RiskParitySecuritiesMembersrt:MaximumMember2020-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:RiskParitySecuritiesMember2020-12-310000352541us-gaap:FixedIncomeSecuritiesMemberus-gaap:PensionPlansDefinedBenefitMembersrt:MinimumMember2020-12-310000352541us-gaap:FixedIncomeSecuritiesMemberus-gaap:PensionPlansDefinedBenefitMembersrt:MaximumMember2020-12-310000352541us-gaap:FixedIncomeSecuritiesMemberus-gaap:PensionPlansDefinedBenefitMember2020-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberus-gaap:CashAndCashEquivalentsMembersrt:MinimumMember2020-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMembersrt:MaximumMemberus-gaap:CashAndCashEquivalentsMember2020-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberus-gaap:CashAndCashEquivalentsMember2020-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberlnt:DomesticEquitySecuritiesMembersrt:MinimumMember2020-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberlnt:DomesticEquitySecuritiesMembersrt:MaximumMember2020-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberlnt:DomesticEquitySecuritiesMember2020-12-310000352541lnt:InternationalEquitySecuritiesMemberus-gaap:OtherPostretirementBenefitPlansDefinedBenefitMembersrt:MinimumMember2020-12-310000352541lnt:InternationalEquitySecuritiesMemberus-gaap:OtherPostretirementBenefitPlansDefinedBenefitMembersrt:MaximumMember2020-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberlnt:InternationalEquitySecuritiesMember2020-12-310000352541us-gaap:FixedIncomeSecuritiesMemberus-gaap:OtherPostretirementBenefitPlansDefinedBenefitMembersrt:MinimumMember2020-12-310000352541us-gaap:FixedIncomeSecuritiesMemberus-gaap:OtherPostretirementBenefitPlansDefinedBenefitMembersrt:MaximumMember2020-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberus-gaap:FixedIncomeSecuritiesMember2020-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel1Memberus-gaap:CashAndCashEquivalentsMember2020-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel2Memberus-gaap:CashAndCashEquivalentsMember2020-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel3Memberus-gaap:CashAndCashEquivalentsMember2020-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberus-gaap:CashAndCashEquivalentsMember2019-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel1Memberus-gaap:CashAndCashEquivalentsMember2019-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel2Memberus-gaap:CashAndCashEquivalentsMember2019-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel3Memberus-gaap:CashAndCashEquivalentsMember2019-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:DomesticEquitySecuritiesMemberus-gaap:FairValueInputsLevel1Member2020-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:DomesticEquitySecuritiesMemberus-gaap:FairValueInputsLevel2Member2020-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:DomesticEquitySecuritiesMemberus-gaap:FairValueInputsLevel3Member2020-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:DomesticEquitySecuritiesMember2019-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:DomesticEquitySecuritiesMemberus-gaap:FairValueInputsLevel1Member2019-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:DomesticEquitySecuritiesMemberus-gaap:FairValueInputsLevel2Member2019-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:DomesticEquitySecuritiesMemberus-gaap:FairValueInputsLevel3Member2019-12-310000352541lnt:InternationalEquitySecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel1Member2020-12-310000352541lnt:InternationalEquitySecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel2Member2020-12-310000352541lnt:InternationalEquitySecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel3Member2020-12-310000352541lnt:InternationalEquitySecuritiesMemberus-gaap:PensionPlansDefinedBenefitMember2019-12-310000352541lnt:InternationalEquitySecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel1Member2019-12-310000352541lnt:InternationalEquitySecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel2Member2019-12-310000352541lnt:InternationalEquitySecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel3Member2019-12-310000352541lnt:GlobalAssetAllocationSecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel1Member2020-12-310000352541lnt:GlobalAssetAllocationSecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel2Member2020-12-310000352541lnt:GlobalAssetAllocationSecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel3Member2020-12-310000352541lnt:GlobalAssetAllocationSecuritiesMemberus-gaap:PensionPlansDefinedBenefitMember2019-12-310000352541lnt:GlobalAssetAllocationSecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel1Member2019-12-310000352541lnt:GlobalAssetAllocationSecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel2Member2019-12-310000352541lnt:GlobalAssetAllocationSecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel3Member2019-12-310000352541us-gaap:FixedIncomeSecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel1Member2020-12-310000352541us-gaap:FixedIncomeSecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel2Member2020-12-310000352541us-gaap:FixedIncomeSecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel3Member2020-12-310000352541us-gaap:FixedIncomeSecuritiesMemberus-gaap:PensionPlansDefinedBenefitMember2019-12-310000352541us-gaap:FixedIncomeSecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel1Member2019-12-310000352541us-gaap:FixedIncomeSecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel2Member2019-12-310000352541us-gaap:FixedIncomeSecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel3Member2019-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:SubtotalMember2020-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:SubtotalMemberus-gaap:FairValueInputsLevel1Member2020-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:SubtotalMemberus-gaap:FairValueInputsLevel2Member2020-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:SubtotalMemberus-gaap:FairValueInputsLevel3Member2020-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:SubtotalMember2019-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:SubtotalMemberus-gaap:FairValueInputsLevel1Member2019-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:SubtotalMemberus-gaap:FairValueInputsLevel2Member2019-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:SubtotalMemberus-gaap:FairValueInputsLevel3Member2019-12-310000352541lnt:AccruedInvestmentIncomeMemberus-gaap:PensionPlansDefinedBenefitMember2020-12-310000352541lnt:AccruedInvestmentIncomeMemberus-gaap:PensionPlansDefinedBenefitMember2019-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:DefinedBenefitPlanDueToBrokersNetMember2020-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:DefinedBenefitPlanDueToBrokersNetMember2019-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:IplMemberus-gaap:CashAndCashEquivalentsMember2020-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:IplMemberus-gaap:FairValueInputsLevel1Memberus-gaap:CashAndCashEquivalentsMember2020-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:IplMemberus-gaap:FairValueInputsLevel2Memberus-gaap:CashAndCashEquivalentsMember2020-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:IplMemberus-gaap:FairValueInputsLevel3Memberus-gaap:CashAndCashEquivalentsMember2020-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:IplMemberus-gaap:CashAndCashEquivalentsMember2019-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:IplMemberus-gaap:FairValueInputsLevel1Memberus-gaap:CashAndCashEquivalentsMember2019-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:IplMemberus-gaap:FairValueInputsLevel2Memberus-gaap:CashAndCashEquivalentsMember2019-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:IplMemberus-gaap:FairValueInputsLevel3Memberus-gaap:CashAndCashEquivalentsMember2019-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:DomesticEquitySecuritiesMemberlnt:IplMember2020-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:DomesticEquitySecuritiesMemberlnt:IplMemberus-gaap:FairValueInputsLevel1Member2020-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:DomesticEquitySecuritiesMemberlnt:IplMemberus-gaap:FairValueInputsLevel2Member2020-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:DomesticEquitySecuritiesMemberlnt:IplMemberus-gaap:FairValueInputsLevel3Member2020-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:DomesticEquitySecuritiesMemberlnt:IplMember2019-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:DomesticEquitySecuritiesMemberlnt:IplMemberus-gaap:FairValueInputsLevel1Member2019-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:DomesticEquitySecuritiesMemberlnt:IplMemberus-gaap:FairValueInputsLevel2Member2019-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:DomesticEquitySecuritiesMemberlnt:IplMemberus-gaap:FairValueInputsLevel3Member2019-12-310000352541lnt:InternationalEquitySecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberlnt:IplMember2020-12-310000352541lnt:InternationalEquitySecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberlnt:IplMemberus-gaap:FairValueInputsLevel1Member2020-12-310000352541lnt:InternationalEquitySecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberlnt:IplMemberus-gaap:FairValueInputsLevel2Member2020-12-310000352541lnt:InternationalEquitySecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberlnt:IplMemberus-gaap:FairValueInputsLevel3Member2020-12-310000352541lnt:InternationalEquitySecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberlnt:IplMember2019-12-310000352541lnt:InternationalEquitySecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberlnt:IplMemberus-gaap:FairValueInputsLevel1Member2019-12-310000352541lnt:InternationalEquitySecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberlnt:IplMemberus-gaap:FairValueInputsLevel2Member2019-12-310000352541lnt:InternationalEquitySecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberlnt:IplMemberus-gaap:FairValueInputsLevel3Member2019-12-310000352541lnt:GlobalAssetAllocationSecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberlnt:IplMember2020-12-310000352541lnt:GlobalAssetAllocationSecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberlnt:IplMemberus-gaap:FairValueInputsLevel1Member2020-12-310000352541lnt:GlobalAssetAllocationSecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberlnt:IplMemberus-gaap:FairValueInputsLevel2Member2020-12-310000352541lnt:GlobalAssetAllocationSecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberlnt:IplMemberus-gaap:FairValueInputsLevel3Member2020-12-310000352541lnt:GlobalAssetAllocationSecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberlnt:IplMember2019-12-310000352541lnt:GlobalAssetAllocationSecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberlnt:IplMemberus-gaap:FairValueInputsLevel1Member2019-12-310000352541lnt:GlobalAssetAllocationSecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberlnt:IplMemberus-gaap:FairValueInputsLevel2Member2019-12-310000352541lnt:GlobalAssetAllocationSecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberlnt:IplMemberus-gaap:FairValueInputsLevel3Member2019-12-310000352541us-gaap:FixedIncomeSecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberlnt:IplMember2020-12-310000352541us-gaap:FixedIncomeSecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberlnt:IplMemberus-gaap:FairValueInputsLevel1Member2020-12-310000352541us-gaap:FixedIncomeSecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberlnt:IplMemberus-gaap:FairValueInputsLevel2Member2020-12-310000352541us-gaap:FixedIncomeSecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberlnt:IplMemberus-gaap:FairValueInputsLevel3Member2020-12-310000352541us-gaap:FixedIncomeSecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberlnt:IplMember2019-12-310000352541us-gaap:FixedIncomeSecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberlnt:IplMemberus-gaap:FairValueInputsLevel1Member2019-12-310000352541us-gaap:FixedIncomeSecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberlnt:IplMemberus-gaap:FairValueInputsLevel2Member2019-12-310000352541us-gaap:FixedIncomeSecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberlnt:IplMemberus-gaap:FairValueInputsLevel3Member2019-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:SubtotalMemberlnt:IplMember2020-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:SubtotalMemberlnt:IplMemberus-gaap:FairValueInputsLevel1Member2020-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:SubtotalMemberlnt:IplMemberus-gaap:FairValueInputsLevel2Member2020-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:SubtotalMemberlnt:IplMemberus-gaap:FairValueInputsLevel3Member2020-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:SubtotalMemberlnt:IplMember2019-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:SubtotalMemberlnt:IplMemberus-gaap:FairValueInputsLevel1Member2019-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:SubtotalMemberlnt:IplMemberus-gaap:FairValueInputsLevel2Member2019-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:SubtotalMemberlnt:IplMemberus-gaap:FairValueInputsLevel3Member2019-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:WplMemberus-gaap:CashAndCashEquivalentsMember2020-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel1Memberlnt:WplMemberus-gaap:CashAndCashEquivalentsMember2020-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel2Memberlnt:WplMemberus-gaap:CashAndCashEquivalentsMember2020-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel3Memberlnt:WplMemberus-gaap:CashAndCashEquivalentsMember2020-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:WplMemberus-gaap:CashAndCashEquivalentsMember2019-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel1Memberlnt:WplMemberus-gaap:CashAndCashEquivalentsMember2019-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel2Memberlnt:WplMemberus-gaap:CashAndCashEquivalentsMember2019-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel3Memberlnt:WplMemberus-gaap:CashAndCashEquivalentsMember2019-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:DomesticEquitySecuritiesMemberlnt:WplMember2020-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:DomesticEquitySecuritiesMemberus-gaap:FairValueInputsLevel1Memberlnt:WplMember2020-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:DomesticEquitySecuritiesMemberus-gaap:FairValueInputsLevel2Memberlnt:WplMember2020-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:DomesticEquitySecuritiesMemberus-gaap:FairValueInputsLevel3Memberlnt:WplMember2020-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:DomesticEquitySecuritiesMemberlnt:WplMember2019-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:DomesticEquitySecuritiesMemberus-gaap:FairValueInputsLevel1Memberlnt:WplMember2019-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:DomesticEquitySecuritiesMemberus-gaap:FairValueInputsLevel2Memberlnt:WplMember2019-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:DomesticEquitySecuritiesMemberus-gaap:FairValueInputsLevel3Memberlnt:WplMember2019-12-310000352541lnt:InternationalEquitySecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberlnt:WplMember2020-12-310000352541lnt:InternationalEquitySecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel1Memberlnt:WplMember2020-12-310000352541lnt:InternationalEquitySecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel2Memberlnt:WplMember2020-12-310000352541lnt:InternationalEquitySecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel3Memberlnt:WplMember2020-12-310000352541lnt:InternationalEquitySecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberlnt:WplMember2019-12-310000352541lnt:InternationalEquitySecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel1Memberlnt:WplMember2019-12-310000352541lnt:InternationalEquitySecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel2Memberlnt:WplMember2019-12-310000352541lnt:InternationalEquitySecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel3Memberlnt:WplMember2019-12-310000352541lnt:GlobalAssetAllocationSecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberlnt:WplMember2020-12-310000352541lnt:GlobalAssetAllocationSecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel1Memberlnt:WplMember2020-12-310000352541lnt:GlobalAssetAllocationSecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel2Memberlnt:WplMember2020-12-310000352541lnt:GlobalAssetAllocationSecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel3Memberlnt:WplMember2020-12-310000352541lnt:GlobalAssetAllocationSecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberlnt:WplMember2019-12-310000352541lnt:GlobalAssetAllocationSecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel1Memberlnt:WplMember2019-12-310000352541lnt:GlobalAssetAllocationSecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel2Memberlnt:WplMember2019-12-310000352541lnt:GlobalAssetAllocationSecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel3Memberlnt:WplMember2019-12-310000352541us-gaap:FixedIncomeSecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberlnt:WplMember2020-12-310000352541us-gaap:FixedIncomeSecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel1Memberlnt:WplMember2020-12-310000352541us-gaap:FixedIncomeSecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel2Memberlnt:WplMember2020-12-310000352541us-gaap:FixedIncomeSecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel3Memberlnt:WplMember2020-12-310000352541us-gaap:FixedIncomeSecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberlnt:WplMember2019-12-310000352541us-gaap:FixedIncomeSecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel1Memberlnt:WplMember2019-12-310000352541us-gaap:FixedIncomeSecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel2Memberlnt:WplMember2019-12-310000352541us-gaap:FixedIncomeSecuritiesMemberus-gaap:PensionPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel3Memberlnt:WplMember2019-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:SubtotalMemberlnt:WplMember2020-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:SubtotalMemberus-gaap:FairValueInputsLevel1Memberlnt:WplMember2020-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:SubtotalMemberus-gaap:FairValueInputsLevel2Memberlnt:WplMember2020-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:SubtotalMemberus-gaap:FairValueInputsLevel3Memberlnt:WplMember2020-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:SubtotalMemberlnt:WplMember2019-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:SubtotalMemberus-gaap:FairValueInputsLevel1Memberlnt:WplMember2019-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:SubtotalMemberus-gaap:FairValueInputsLevel2Memberlnt:WplMember2019-12-310000352541us-gaap:PensionPlansDefinedBenefitMemberlnt:SubtotalMemberus-gaap:FairValueInputsLevel3Memberlnt:WplMember2019-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel1Memberus-gaap:CashAndCashEquivalentsMember2020-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel2Memberus-gaap:CashAndCashEquivalentsMember2020-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel3Memberus-gaap:CashAndCashEquivalentsMember2020-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberus-gaap:CashAndCashEquivalentsMember2019-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel1Memberus-gaap:CashAndCashEquivalentsMember2019-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel2Memberus-gaap:CashAndCashEquivalentsMember2019-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel3Memberus-gaap:CashAndCashEquivalentsMember2019-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberlnt:DomesticEquitySecuritiesMemberus-gaap:FairValueInputsLevel1Member2020-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberlnt:DomesticEquitySecuritiesMemberus-gaap:FairValueInputsLevel2Member2020-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberlnt:DomesticEquitySecuritiesMemberus-gaap:FairValueInputsLevel3Member2020-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberlnt:DomesticEquitySecuritiesMember2019-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberlnt:DomesticEquitySecuritiesMemberus-gaap:FairValueInputsLevel1Member2019-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberlnt:DomesticEquitySecuritiesMemberus-gaap:FairValueInputsLevel2Member2019-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberlnt:DomesticEquitySecuritiesMemberus-gaap:FairValueInputsLevel3Member2019-12-310000352541lnt:InternationalEquitySecuritiesMemberus-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel1Member2020-12-310000352541lnt:InternationalEquitySecuritiesMemberus-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel2Member2020-12-310000352541lnt:InternationalEquitySecuritiesMemberus-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel3Member2020-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberlnt:InternationalEquitySecuritiesMember2019-12-310000352541lnt:InternationalEquitySecuritiesMemberus-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel1Member2019-12-310000352541lnt:InternationalEquitySecuritiesMemberus-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel2Member2019-12-310000352541lnt:InternationalEquitySecuritiesMemberus-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel3Member2019-12-310000352541us-gaap:FixedIncomeSecuritiesMemberus-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel1Member2020-12-310000352541us-gaap:FixedIncomeSecuritiesMemberus-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel2Member2020-12-310000352541us-gaap:FixedIncomeSecuritiesMemberus-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel3Member2020-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberus-gaap:FixedIncomeSecuritiesMember2019-12-310000352541us-gaap:FixedIncomeSecuritiesMemberus-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel1Member2019-12-310000352541us-gaap:FixedIncomeSecuritiesMemberus-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel2Member2019-12-310000352541us-gaap:FixedIncomeSecuritiesMemberus-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel3Member2019-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel1Member2020-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel2Member2020-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel3Member2020-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel1Member2019-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel2Member2019-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel3Member2019-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberlnt:IplMemberus-gaap:CashAndCashEquivalentsMember2020-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberlnt:IplMemberus-gaap:FairValueInputsLevel1Memberus-gaap:CashAndCashEquivalentsMember2020-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberlnt:IplMemberus-gaap:FairValueInputsLevel2Memberus-gaap:CashAndCashEquivalentsMember2020-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberlnt:IplMemberus-gaap:FairValueInputsLevel3Memberus-gaap:CashAndCashEquivalentsMember2020-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberlnt:IplMemberus-gaap:CashAndCashEquivalentsMember2019-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberlnt:IplMemberus-gaap:FairValueInputsLevel1Memberus-gaap:CashAndCashEquivalentsMember2019-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberlnt:IplMemberus-gaap:FairValueInputsLevel2Memberus-gaap:CashAndCashEquivalentsMember2019-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberlnt:IplMemberus-gaap:FairValueInputsLevel3Memberus-gaap:CashAndCashEquivalentsMember2019-12-310000352541us-gaap:FixedIncomeSecuritiesMemberus-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberlnt:IplMember2020-12-310000352541us-gaap:FixedIncomeSecuritiesMemberus-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberlnt:IplMemberus-gaap:FairValueInputsLevel1Member2020-12-310000352541us-gaap:FixedIncomeSecuritiesMemberus-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberlnt:IplMemberus-gaap:FairValueInputsLevel2Member2020-12-310000352541us-gaap:FixedIncomeSecuritiesMemberus-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberlnt:IplMemberus-gaap:FairValueInputsLevel3Member2020-12-310000352541us-gaap:FixedIncomeSecuritiesMemberus-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberlnt:IplMember2019-12-310000352541us-gaap:FixedIncomeSecuritiesMemberus-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberlnt:IplMemberus-gaap:FairValueInputsLevel1Member2019-12-310000352541us-gaap:FixedIncomeSecuritiesMemberus-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberlnt:IplMemberus-gaap:FairValueInputsLevel2Member2019-12-310000352541us-gaap:FixedIncomeSecuritiesMemberus-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberlnt:IplMemberus-gaap:FairValueInputsLevel3Member2019-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberlnt:IplMemberus-gaap:FairValueInputsLevel1Member2020-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberlnt:IplMemberus-gaap:FairValueInputsLevel2Member2020-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberlnt:IplMemberus-gaap:FairValueInputsLevel3Member2020-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberlnt:IplMemberus-gaap:FairValueInputsLevel1Member2019-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberlnt:IplMemberus-gaap:FairValueInputsLevel2Member2019-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberlnt:IplMemberus-gaap:FairValueInputsLevel3Member2019-12-310000352541us-gaap:FixedIncomeSecuritiesMemberus-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberlnt:WplMember2020-12-310000352541us-gaap:FixedIncomeSecuritiesMemberus-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel1Memberlnt:WplMember2020-12-310000352541us-gaap:FixedIncomeSecuritiesMemberus-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel2Memberlnt:WplMember2020-12-310000352541us-gaap:FixedIncomeSecuritiesMemberus-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel3Memberlnt:WplMember2020-12-310000352541us-gaap:FixedIncomeSecuritiesMemberus-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberlnt:WplMember2019-12-310000352541us-gaap:FixedIncomeSecuritiesMemberus-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel1Memberlnt:WplMember2019-12-310000352541us-gaap:FixedIncomeSecuritiesMemberus-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel2Memberlnt:WplMember2019-12-310000352541us-gaap:FixedIncomeSecuritiesMemberus-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel3Memberlnt:WplMember2019-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel1Memberlnt:WplMember2020-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel2Memberlnt:WplMember2020-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel3Memberlnt:WplMember2020-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel1Memberlnt:WplMember2019-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel2Memberlnt:WplMember2019-12-310000352541us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMemberus-gaap:FairValueInputsLevel3Memberlnt:WplMember2019-12-310000352541us-gaap:OtherPensionPlansPostretirementOrSupplementalPlansDefinedBenefitMemberlnt:IplMember2020-01-012020-12-310000352541us-gaap:OtherPensionPlansPostretirementOrSupplementalPlansDefinedBenefitMemberlnt:WplMember2020-01-012020-12-310000352541us-gaap:OtherPensionPlansPostretirementOrSupplementalPlansDefinedBenefitMember2020-01-012020-12-310000352541lnt:OmnibusIncentivePlanMember2020-12-310000352541srt:MinimumMember2020-01-012020-12-310000352541srt:MaximumMember2020-01-012020-12-310000352541lnt:OmnibusIncentivePlanMember2020-01-012020-12-310000352541us-gaap:PerformanceSharesMember2020-01-012020-12-310000352541us-gaap:PerformanceSharesMembersrt:MinimumMember2020-01-012020-12-310000352541srt:MaximumMemberus-gaap:PerformanceSharesMember2020-01-012020-12-310000352541us-gaap:PerformanceSharesMember2019-12-310000352541us-gaap:PerformanceSharesMember2018-12-310000352541us-gaap:PerformanceSharesMember2019-01-012019-12-310000352541us-gaap:PerformanceSharesMember2020-12-310000352541lnt:PerformanceSharesAndUnitsMember2020-01-012020-12-310000352541lnt:PerformanceSharesLiabilityAwardsMember2019-12-310000352541lnt:PerformanceSharesLiabilityAwardsMember2018-12-310000352541lnt:PerformanceSharesLiabilityAwardsMember2017-12-310000352541lnt:PerformanceUnitsMember2019-12-310000352541lnt:PerformanceUnitsMember2018-12-310000352541lnt:PerformanceUnitsMember2017-12-310000352541lnt:PerformanceSharesLiabilityAwardsMember2020-01-012020-12-310000352541lnt:PerformanceSharesLiabilityAwardsMember2019-01-012019-12-310000352541lnt:PerformanceSharesLiabilityAwardsMember2018-01-012018-12-310000352541lnt:PerformanceUnitsMember2020-01-012020-12-310000352541lnt:PerformanceUnitsMember2019-01-012019-12-310000352541lnt:PerformanceUnitsMember2018-01-012018-12-310000352541lnt:PerformanceSharesLiabilityAwardsMember2020-12-310000352541lnt:PerformanceUnitsMember2020-12-310000352541lnt:PerformanceSharesAndUnitsMembersrt:MinimumMember2020-01-012020-12-310000352541lnt:PerformanceSharesAndUnitsMembersrt:MaximumMember2020-01-012020-12-310000352541lnt:TwoThousandEighteenGrantMemberlnt:PerformanceSharesLiabilityAwardsMember2020-12-310000352541lnt:PerformanceUnitsMemberlnt:TwoThousandEighteenGrantMember2020-12-310000352541lnt:TwoThousandEighteenGrantMemberlnt:PerformanceSharesLiabilityAwardsMember2020-01-012020-12-310000352541lnt:PerformanceUnitsMemberlnt:TwoThousandEighteenGrantMember2020-01-012020-12-310000352541lnt:TwoThousandSeventeenGrantMemberlnt:PerformanceSharesLiabilityAwardsMember2020-01-012020-12-310000352541lnt:TwoThousandSixteenGrantMemberlnt:PerformanceSharesLiabilityAwardsMember2019-01-012019-12-310000352541lnt:TwoThousandFifteenGrantMemberlnt:PerformanceSharesLiabilityAwardsMember2018-01-012018-12-310000352541lnt:PerformanceUnitsMemberlnt:TwoThousandSeventeenGrantMember2020-01-012020-12-310000352541lnt:TwoThousandSixteenGrantMemberlnt:PerformanceUnitsMember2019-01-012019-12-310000352541lnt:PerformanceUnitsMemberlnt:TwoThousandFifteenGrantMember2018-01-012018-12-310000352541us-gaap:RestrictedStockUnitsRSUMember2020-01-012020-12-310000352541us-gaap:RestrictedStockUnitsRSUMember2019-12-310000352541us-gaap:RestrictedStockUnitsRSUMember2018-12-310000352541us-gaap:RestrictedStockUnitsRSUMember2019-01-012019-12-310000352541us-gaap:RestrictedStockUnitsRSUMember2020-12-310000352541lnt:RestrictedStockUnitsLiabilityAwardsMember2020-01-012020-12-310000352541lnt:RestrictedStockUnitLiabilityAwardMember2020-01-012020-12-310000352541lnt:RestrictedStockUnitsLiabilityAwardsMember2019-12-310000352541lnt:RestrictedStockUnitsLiabilityAwardsMember2018-12-310000352541lnt:RestrictedStockUnitsLiabilityAwardsMember2017-12-310000352541lnt:RestrictedStockUnitsLiabilityAwardsMember2019-01-012019-12-310000352541lnt:RestrictedStockUnitsLiabilityAwardsMember2018-01-012018-12-310000352541lnt:RestrictedStockUnitsLiabilityAwardsMember2020-12-310000352541lnt:PerformanceRestrictedStockUnitMember2020-01-012020-12-310000352541lnt:PerformanceRestrictedStockUnitMembersrt:MinimumMember2020-01-012020-12-310000352541lnt:PerformanceRestrictedStockUnitMembersrt:MaximumMember2020-01-012020-12-310000352541lnt:PerformanceRestrictedStockUnitMember2019-12-310000352541lnt:PerformanceRestrictedStockUnitMember2018-12-310000352541lnt:PerformanceRestrictedStockUnitMember2017-12-310000352541lnt:PerformanceRestrictedStockUnitMember2019-01-012019-12-310000352541lnt:PerformanceRestrictedStockUnitMember2018-01-012018-12-310000352541lnt:PerformanceRestrictedStockUnitMember2020-12-31utr:MWh0000352541us-gaap:CommodityMemberlnt:FtrsMwhsMember2020-01-012020-12-31lnt:Dekatherms0000352541srt:NaturalGasPerThousandCubicFeetMemberus-gaap:CommodityMember2020-12-31utr:T0000352541us-gaap:CoalContractMemberus-gaap:CommodityMember2020-01-012020-12-31utr:gal0000352541srt:FuelMemberus-gaap:CommodityMember2020-01-012020-12-310000352541us-gaap:CommodityMemberlnt:IplMemberlnt:FtrsMwhsMember2020-01-012020-12-310000352541srt:NaturalGasPerThousandCubicFeetMemberus-gaap:CommodityMemberlnt:IplMember2020-12-310000352541us-gaap:CoalContractMemberus-gaap:CommodityMemberlnt:IplMember2020-01-012020-12-310000352541srt:FuelMemberus-gaap:CommodityMemberlnt:IplMember2020-01-012020-12-310000352541us-gaap:CommodityMemberlnt:WplMemberlnt:FtrsMwhsMember2020-01-012020-12-310000352541srt:NaturalGasPerThousandCubicFeetMemberus-gaap:CommodityMemberlnt:WplMember2020-12-310000352541us-gaap:CoalContractMemberus-gaap:CommodityMemberlnt:WplMember2020-01-012020-12-310000352541srt:FuelMemberus-gaap:CommodityMemberlnt:WplMember2020-01-012020-12-310000352541us-gaap:CommodityContractMember2020-12-310000352541us-gaap:CommodityContractMember2019-12-310000352541us-gaap:CommodityContractMemberlnt:IplMember2020-12-310000352541us-gaap:CommodityContractMemberlnt:IplMember2019-12-310000352541us-gaap:CommodityContractMemberlnt:WplMember2020-12-310000352541us-gaap:CommodityContractMemberlnt:WplMember2019-12-310000352541us-gaap:CarryingReportedAmountFairValueDisclosureMember2020-12-310000352541us-gaap:FairValueInputsLevel1Member2020-12-310000352541us-gaap:FairValueInputsLevel2Member2020-12-310000352541us-gaap:FairValueInputsLevel3Member2020-12-310000352541us-gaap:CarryingReportedAmountFairValueDisclosureMember2019-12-310000352541us-gaap:FairValueInputsLevel1Member2019-12-310000352541us-gaap:FairValueInputsLevel2Member2019-12-310000352541us-gaap:FairValueInputsLevel3Member2019-12-310000352541us-gaap:CommodityContractMemberus-gaap:CarryingReportedAmountFairValueDisclosureMember2020-12-310000352541us-gaap:CommodityContractMemberus-gaap:FairValueInputsLevel1Member2020-12-310000352541us-gaap:CommodityContractMemberus-gaap:FairValueInputsLevel2Member2020-12-310000352541us-gaap:CommodityContractMemberus-gaap:FairValueInputsLevel3Member2020-12-310000352541us-gaap:CommodityContractMemberus-gaap:CarryingReportedAmountFairValueDisclosureMember2019-12-310000352541us-gaap:CommodityContractMemberus-gaap:FairValueInputsLevel1Member2019-12-310000352541us-gaap:CommodityContractMemberus-gaap:FairValueInputsLevel2Member2019-12-310000352541us-gaap:CommodityContractMemberus-gaap:FairValueInputsLevel3Member2019-12-310000352541lnt:IplMemberus-gaap:CarryingReportedAmountFairValueDisclosureMember2020-12-310000352541lnt:IplMemberus-gaap:FairValueInputsLevel1Member2020-12-310000352541lnt:IplMemberus-gaap:FairValueInputsLevel2Member2020-12-310000352541lnt:IplMemberus-gaap:FairValueInputsLevel3Member2020-12-310000352541lnt:IplMemberus-gaap:CarryingReportedAmountFairValueDisclosureMember2019-12-310000352541lnt:IplMemberus-gaap:FairValueInputsLevel1Member2019-12-310000352541lnt:IplMemberus-gaap:FairValueInputsLevel2Member2019-12-310000352541lnt:IplMemberus-gaap:FairValueInputsLevel3Member2019-12-310000352541us-gaap:CommodityContractMemberlnt:IplMemberus-gaap:CarryingReportedAmountFairValueDisclosureMember2020-12-310000352541us-gaap:CommodityContractMemberlnt:IplMemberus-gaap:FairValueInputsLevel1Member2020-12-310000352541us-gaap:CommodityContractMemberlnt:IplMemberus-gaap:FairValueInputsLevel2Member2020-12-310000352541us-gaap:CommodityContractMemberlnt:IplMemberus-gaap:FairValueInputsLevel3Member2020-12-310000352541us-gaap:CommodityContractMemberlnt:IplMemberus-gaap:CarryingReportedAmountFairValueDisclosureMember2019-12-310000352541us-gaap:CommodityContractMemberlnt:IplMemberus-gaap:FairValueInputsLevel1Member2019-12-310000352541us-gaap:CommodityContractMemberlnt:IplMemberus-gaap:FairValueInputsLevel2Member2019-12-310000352541us-gaap:CommodityContractMemberlnt:IplMemberus-gaap:FairValueInputsLevel3Member2019-12-310000352541us-gaap:CommodityContractMemberus-gaap:CarryingReportedAmountFairValueDisclosureMemberlnt:WplMember2020-12-310000352541us-gaap:CommodityContractMemberus-gaap:FairValueInputsLevel1Memberlnt:WplMember2020-12-310000352541us-gaap:CommodityContractMemberus-gaap:FairValueInputsLevel2Memberlnt:WplMember2020-12-310000352541us-gaap:CommodityContractMemberus-gaap:FairValueInputsLevel3Memberlnt:WplMember2020-12-310000352541us-gaap:CommodityContractMemberus-gaap:CarryingReportedAmountFairValueDisclosureMemberlnt:WplMember2019-12-310000352541us-gaap:CommodityContractMemberus-gaap:FairValueInputsLevel1Memberlnt:WplMember2019-12-310000352541us-gaap:CommodityContractMemberus-gaap:FairValueInputsLevel2Memberlnt:WplMember2019-12-310000352541us-gaap:CommodityContractMemberus-gaap:FairValueInputsLevel3Memberlnt:WplMember2019-12-310000352541us-gaap:CarryingReportedAmountFairValueDisclosureMemberlnt:WplMember2020-12-310000352541us-gaap:FairValueInputsLevel1Memberlnt:WplMember2020-12-310000352541us-gaap:FairValueInputsLevel2Memberlnt:WplMember2020-12-310000352541us-gaap:FairValueInputsLevel3Memberlnt:WplMember2020-12-310000352541us-gaap:CarryingReportedAmountFairValueDisclosureMemberlnt:WplMember2019-12-310000352541us-gaap:FairValueInputsLevel1Memberlnt:WplMember2019-12-310000352541us-gaap:FairValueInputsLevel2Memberlnt:WplMember2019-12-310000352541us-gaap:FairValueInputsLevel3Memberlnt:WplMember2019-12-310000352541us-gaap:CommodityContractMember2019-12-310000352541us-gaap:CommodityContractMember2018-12-310000352541lnt:DeferredProceedsOfReceivablesSoldMember2019-12-310000352541lnt:DeferredProceedsOfReceivablesSoldMember2018-12-310000352541us-gaap:CommodityContractMember2020-01-012020-12-310000352541us-gaap:CommodityContractMember2019-01-012019-12-310000352541lnt:DeferredProceedsOfReceivablesSoldMember2020-01-012020-12-310000352541lnt:DeferredProceedsOfReceivablesSoldMember2019-01-012019-12-310000352541us-gaap:CommodityContractMember2020-12-310000352541lnt:DeferredProceedsOfReceivablesSoldMember2020-12-310000352541lnt:IplMemberus-gaap:CommodityContractMember2019-12-310000352541lnt:IplMemberus-gaap:CommodityContractMember2018-12-310000352541lnt:IplMemberlnt:DeferredProceedsOfReceivablesSoldMember2019-12-310000352541lnt:IplMemberlnt:DeferredProceedsOfReceivablesSoldMember2018-12-310000352541lnt:IplMemberus-gaap:CommodityContractMember2020-01-012020-12-310000352541lnt:IplMemberus-gaap:CommodityContractMember2019-01-012019-12-310000352541lnt:IplMemberlnt:DeferredProceedsOfReceivablesSoldMember2020-01-012020-12-310000352541lnt:IplMemberlnt:DeferredProceedsOfReceivablesSoldMember2019-01-012019-12-310000352541lnt:IplMemberus-gaap:CommodityContractMember2020-12-310000352541lnt:IplMemberlnt:DeferredProceedsOfReceivablesSoldMember2020-12-310000352541lnt:ExcludingFinancialTransmissionRightsMemberus-gaap:CommodityContractMember2020-12-310000352541lnt:FinancialTransmissionRightsMemberus-gaap:CommodityContractMember2020-12-310000352541lnt:ExcludingFinancialTransmissionRightsMemberlnt:IplMemberus-gaap:CommodityContractMember2020-12-310000352541lnt:FinancialTransmissionRightsMemberlnt:IplMemberus-gaap:CommodityContractMember2020-12-310000352541lnt:ExcludingFinancialTransmissionRightsMemberlnt:WplMemberus-gaap:CommodityContractMember2020-12-310000352541lnt:FinancialTransmissionRightsMemberlnt:WplMemberus-gaap:CommodityContractMember2020-12-310000352541lnt:ExcludingFinancialTransmissionRightsMemberus-gaap:CommodityContractMember2019-12-310000352541lnt:FinancialTransmissionRightsMemberus-gaap:CommodityContractMember2019-12-310000352541lnt:ExcludingFinancialTransmissionRightsMemberlnt:IplMemberus-gaap:CommodityContractMember2019-12-310000352541lnt:FinancialTransmissionRightsMemberlnt:IplMemberus-gaap:CommodityContractMember2019-12-310000352541lnt:ExcludingFinancialTransmissionRightsMemberlnt:WplMemberus-gaap:CommodityContractMember2019-12-310000352541lnt:FinancialTransmissionRightsMemberlnt:WplMemberus-gaap:CommodityContractMember2019-12-310000352541lnt:CapitalPurchaseObligationMember2020-01-012020-12-310000352541lnt:CapitalPurchaseObligationMemberlnt:WplMember2020-01-012020-12-310000352541us-gaap:PublicUtilitiesInventoryNaturalGasMember2020-12-310000352541us-gaap:CoalSupplyAgreementsMember2020-12-310000352541lnt:LongTermPurchaseCommitmentsOtherMember2020-12-310000352541lnt:IplMemberus-gaap:PublicUtilitiesInventoryNaturalGasMember2020-12-310000352541lnt:IplMemberus-gaap:CoalSupplyAgreementsMember2020-12-310000352541lnt:IplMemberlnt:LongTermPurchaseCommitmentsOtherMember2020-12-310000352541lnt:WplMemberus-gaap:PublicUtilitiesInventoryNaturalGasMember2020-12-310000352541us-gaap:CoalSupplyAgreementsMemberlnt:WplMember2020-12-310000352541lnt:WplMemberlnt:LongTermPurchaseCommitmentsOtherMember2020-12-310000352541lnt:WhitingPetroleumAffiliateMember2020-01-012020-12-310000352541lnt:WhitingPetroleumAffiliateMember2020-12-310000352541us-gaap:IndemnificationGuaranteeMember2020-12-310000352541us-gaap:IndemnificationGuaranteeMemberlnt:PurchasedPowerMember2020-12-310000352541srt:MinimumMemberus-gaap:NaturalGasProcessingPlantMember2020-01-012020-12-310000352541srt:MaximumMemberus-gaap:NaturalGasProcessingPlantMember2020-01-012020-12-310000352541lnt:IplMembersrt:MinimumMemberus-gaap:NaturalGasProcessingPlantMember2020-01-012020-12-310000352541lnt:IplMembersrt:MaximumMemberus-gaap:NaturalGasProcessingPlantMember2020-01-012020-12-310000352541us-gaap:NaturalGasProcessingPlantMember2020-12-310000352541lnt:IplMemberus-gaap:NaturalGasProcessingPlantMember2020-12-310000352541lnt:FederalEnergyRegulatoryCommissionMember2019-01-012019-12-310000352541lnt:FederalEnergyRegulatoryCommissionMember2017-01-012017-12-310000352541lnt:FederalEnergyRegulatoryCommissionMemberlnt:IplMember2020-01-012020-12-310000352541lnt:FederalEnergyRegulatoryCommissionMemberlnt:WplMember2020-01-012020-12-31lnt:segment0000352541lnt:UtilityBusinessMember2020-01-012020-12-310000352541lnt:UtilityBusinessMember2020-01-012020-12-310000352541us-gaap:UnregulatedOperationMember2020-01-012020-12-310000352541lnt:ElectricMember2020-12-310000352541lnt:GasMember2020-12-310000352541lnt:OtherUtilityMember2020-12-310000352541lnt:UtilityBusinessMember2020-12-310000352541us-gaap:UnregulatedOperationMember2020-12-310000352541lnt:UtilityBusinessMember2019-01-012019-12-310000352541us-gaap:UnregulatedOperationMember2019-01-012019-12-310000352541lnt:ElectricMember2019-12-310000352541lnt:GasMember2019-12-310000352541lnt:OtherUtilityMember2019-12-310000352541lnt:UtilityBusinessMember2019-12-310000352541us-gaap:UnregulatedOperationMember2019-12-310000352541lnt:UtilityBusinessMember2018-01-012018-12-310000352541us-gaap:UnregulatedOperationMember2018-01-012018-12-310000352541lnt:ElectricMember2018-12-310000352541lnt:GasMember2018-12-310000352541lnt:OtherUtilityMember2018-12-310000352541lnt:UtilityBusinessMember2018-12-310000352541us-gaap:UnregulatedOperationMember2018-12-310000352541lnt:IplMemberlnt:UtilityBusinessMember2020-01-012020-12-310000352541lnt:ElectricMemberlnt:IplMember2020-12-310000352541lnt:IplMemberlnt:GasMember2020-12-310000352541lnt:IplMemberlnt:OtherUtilityMember2020-12-310000352541lnt:IplMemberlnt:UtilityBusinessMember2020-12-310000352541lnt:IplMemberlnt:UtilityBusinessMember2019-01-012019-12-310000352541lnt:ElectricMemberlnt:IplMember2019-12-310000352541lnt:IplMemberlnt:GasMember2019-12-310000352541lnt:IplMemberlnt:OtherUtilityMember2019-12-310000352541lnt:IplMemberlnt:UtilityBusinessMember2019-12-310000352541lnt:IplMemberlnt:UtilityBusinessMember2018-01-012018-12-310000352541lnt:ElectricMemberlnt:IplMember2018-12-310000352541lnt:IplMemberlnt:GasMember2018-12-310000352541lnt:IplMemberlnt:OtherUtilityMember2018-12-310000352541lnt:IplMemberlnt:UtilityBusinessMember2018-12-310000352541lnt:WplMemberlnt:UtilityBusinessMember2020-01-012020-12-310000352541lnt:ElectricMemberlnt:WplMember2020-12-310000352541lnt:WplMemberlnt:GasMember2020-12-310000352541lnt:WplMemberlnt:OtherUtilityMember2020-12-310000352541lnt:WplMemberlnt:UtilityBusinessMember2020-12-310000352541lnt:WplMemberlnt:UtilityBusinessMember2019-01-012019-12-310000352541lnt:ElectricMemberlnt:WplMember2019-12-310000352541lnt:WplMemberlnt:GasMember2019-12-310000352541lnt:WplMemberlnt:OtherUtilityMember2019-12-310000352541lnt:WplMemberlnt:UtilityBusinessMember2019-12-310000352541lnt:WplMemberlnt:UtilityBusinessMember2018-01-012018-12-310000352541lnt:ElectricMemberlnt:WplMember2018-12-310000352541lnt:WplMemberlnt:GasMember2018-12-310000352541lnt:WplMemberlnt:OtherUtilityMember2018-12-310000352541lnt:WplMemberlnt:UtilityBusinessMember2018-12-310000352541us-gaap:SubsidiaryOfCommonParentMemberlnt:AdministrativeandGeneralServicesBillingsMemberlnt:IplMemberlnt:CorporateServicesMember2020-01-012020-12-310000352541us-gaap:SubsidiaryOfCommonParentMemberlnt:AdministrativeandGeneralServicesBillingsMemberlnt:IplMemberlnt:CorporateServicesMember2019-01-012019-12-310000352541us-gaap:SubsidiaryOfCommonParentMemberlnt:AdministrativeandGeneralServicesBillingsMemberlnt:IplMemberlnt:CorporateServicesMember2018-01-012018-12-310000352541us-gaap:SubsidiaryOfCommonParentMemberlnt:AdministrativeandGeneralServicesBillingsMemberlnt:WplMemberlnt:CorporateServicesMember2020-01-012020-12-310000352541us-gaap:SubsidiaryOfCommonParentMemberlnt:AdministrativeandGeneralServicesBillingsMemberlnt:WplMemberlnt:CorporateServicesMember2019-01-012019-12-310000352541us-gaap:SubsidiaryOfCommonParentMemberlnt:AdministrativeandGeneralServicesBillingsMemberlnt:WplMemberlnt:CorporateServicesMember2018-01-012018-12-310000352541us-gaap:SubsidiaryOfCommonParentMemberlnt:IplMemberlnt:TransmissionSalesCreditedMemberlnt:CorporateServicesMember2020-01-012020-12-310000352541us-gaap:SubsidiaryOfCommonParentMemberlnt:IplMemberlnt:TransmissionSalesCreditedMemberlnt:CorporateServicesMember2019-01-012019-12-310000352541us-gaap:SubsidiaryOfCommonParentMemberlnt:IplMemberlnt:TransmissionSalesCreditedMemberlnt:CorporateServicesMember2018-01-012018-12-310000352541us-gaap:SubsidiaryOfCommonParentMemberlnt:WplMemberlnt:TransmissionSalesCreditedMemberlnt:CorporateServicesMember2020-01-012020-12-310000352541us-gaap:SubsidiaryOfCommonParentMemberlnt:WplMemberlnt:TransmissionSalesCreditedMemberlnt:CorporateServicesMember2019-01-012019-12-310000352541us-gaap:SubsidiaryOfCommonParentMemberlnt:WplMemberlnt:TransmissionSalesCreditedMemberlnt:CorporateServicesMember2018-01-012018-12-310000352541us-gaap:SubsidiaryOfCommonParentMemberlnt:TransmissionPurchasesBilledMemberlnt:IplMemberlnt:CorporateServicesMember2020-01-012020-12-310000352541us-gaap:SubsidiaryOfCommonParentMemberlnt:TransmissionPurchasesBilledMemberlnt:IplMemberlnt:CorporateServicesMember2019-01-012019-12-310000352541us-gaap:SubsidiaryOfCommonParentMemberlnt:TransmissionPurchasesBilledMemberlnt:IplMemberlnt:CorporateServicesMember2018-01-012018-12-310000352541us-gaap:SubsidiaryOfCommonParentMemberlnt:TransmissionPurchasesBilledMemberlnt:WplMemberlnt:CorporateServicesMember2020-01-012020-12-310000352541us-gaap:SubsidiaryOfCommonParentMemberlnt:TransmissionPurchasesBilledMemberlnt:WplMemberlnt:CorporateServicesMember2019-01-012019-12-310000352541us-gaap:SubsidiaryOfCommonParentMemberlnt:TransmissionPurchasesBilledMemberlnt:WplMemberlnt:CorporateServicesMember2018-01-012018-12-310000352541us-gaap:SubsidiaryOfCommonParentMemberlnt:IplMemberlnt:CorporateServicesMember2020-12-310000352541us-gaap:SubsidiaryOfCommonParentMemberlnt:IplMemberlnt:CorporateServicesMember2019-12-310000352541us-gaap:SubsidiaryOfCommonParentMemberlnt:WplMemberlnt:CorporateServicesMember2020-12-310000352541us-gaap:SubsidiaryOfCommonParentMemberlnt:WplMemberlnt:CorporateServicesMember2019-12-310000352541lnt:AtcBillingsToWplMemberlnt:WplMemberlnt:AmericanTransmissionCompanyLlcAtcMemberus-gaap:EquityMethodInvestmentsMember2020-01-012020-12-310000352541lnt:AtcBillingsToWplMemberlnt:WplMemberlnt:AmericanTransmissionCompanyLlcAtcMemberus-gaap:EquityMethodInvestmentsMember2019-01-012019-12-310000352541lnt:AtcBillingsToWplMemberlnt:WplMemberlnt:AmericanTransmissionCompanyLlcAtcMemberus-gaap:EquityMethodInvestmentsMember2018-01-012018-12-310000352541lnt:WplBillingsToAtcMemberlnt:WplMemberlnt:AmericanTransmissionCompanyLlcAtcMemberus-gaap:EquityMethodInvestmentsMember2020-01-012020-12-310000352541lnt:WplBillingsToAtcMemberlnt:WplMemberlnt:AmericanTransmissionCompanyLlcAtcMemberus-gaap:EquityMethodInvestmentsMember2019-01-012019-12-310000352541lnt:WplBillingsToAtcMemberlnt:WplMemberlnt:AmericanTransmissionCompanyLlcAtcMemberus-gaap:EquityMethodInvestmentsMember2018-01-012018-12-310000352541lnt:WplOwedAtcMemberlnt:WplMember2020-12-310000352541lnt:WplOwedAtcMemberlnt:WplMember2019-12-310000352541srt:ParentCompanyMember2020-01-012020-12-310000352541srt:ParentCompanyMember2019-01-012019-12-310000352541srt:ParentCompanyMember2018-01-012018-12-310000352541srt:ParentCompanyMember2019-12-310000352541srt:ParentCompanyMember2018-12-310000352541srt:ParentCompanyMember2017-12-310000352541us-gaap:AllowanceForCreditLossMember2019-12-310000352541us-gaap:AllowanceForCreditLossMember2020-01-012020-12-310000352541us-gaap:AllowanceForCreditLossMember2020-12-310000352541us-gaap:AllowanceForCreditLossMember2018-12-310000352541us-gaap:AllowanceForCreditLossMember2019-01-012019-12-310000352541us-gaap:AllowanceForCreditLossMember2017-12-310000352541us-gaap:AllowanceForCreditLossMember2018-01-012018-12-310000352541us-gaap:AllowanceForCreditLossMemberlnt:IplMember2019-12-310000352541us-gaap:AllowanceForCreditLossMemberlnt:IplMember2020-01-012020-12-310000352541us-gaap:AllowanceForCreditLossMemberlnt:IplMember2020-12-310000352541us-gaap:AllowanceForCreditLossMemberlnt:IplMember2018-12-310000352541us-gaap:AllowanceForCreditLossMemberlnt:IplMember2019-01-012019-12-310000352541us-gaap:AllowanceForCreditLossMemberlnt:IplMember2017-12-310000352541us-gaap:AllowanceForCreditLossMemberlnt:IplMember2018-01-012018-12-310000352541us-gaap:AllowanceForCreditLossMemberlnt:WplMember2019-12-310000352541us-gaap:AllowanceForCreditLossMemberlnt:WplMember2020-01-012020-12-310000352541us-gaap:AllowanceForCreditLossMemberlnt:WplMember2020-12-310000352541us-gaap:AllowanceForCreditLossMemberlnt:WplMember2018-12-310000352541us-gaap:AllowanceForCreditLossMemberlnt:WplMember2019-01-012019-12-310000352541us-gaap:AllowanceForCreditLossMemberlnt:WplMember2017-12-310000352541us-gaap:AllowanceForCreditLossMemberlnt:WplMember2018-01-012018-12-31
Table of Contents
UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549
FORM 10-K
    ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934
For the fiscal year ended December 31, 2020

or

    TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934
For the transition period from                    to                    

lnt-20201231_g1.jpg
Name of Registrant, State of Incorporation, Address of Principal Executive Offices, Telephone Number, Commission File Number, IRS Employer Identification Number

ALLIANT ENERGY CORPORATION
(a Wisconsin Corporation)
4902 N. Biltmore Lane
Madison, Wisconsin 53718
Telephone (608) 458-3311
Commission File Number - 1-9894
IRS Employer Identification Number - 39-1380265

INTERSTATE POWER & LIGHT COMPANY
(an Iowa corporation)
Alliant Energy Tower
Cedar Rapids, Iowa 52401
Telephone (319) 786-4411
Commission File Number - 1-4117
IRS Employer Identification Number - 42-0331370

WISCONSIN POWER & LIGHT COMPANY
(a Wisconsin corporation)
4902 N. Biltmore Lane
Madison, Wisconsin 53718
Telephone (608) 458-3311
Commission File Number - 0-337
IRS Employer Identification Number - 39-0714890
This combined Form 10-K is separately filed by Alliant Energy Corporation, Interstate Power and Light Company and Wisconsin Power and Light Company. Information contai