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v2.4.1.9

Condensed Consolidated Balance Sheets (USD $) In Millions, unless otherwise specified | Mar. 31, 2015 | Dec. 31, 2014
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Current assets: |  |
Cash and cash equivalents | $ 97.6 us-gaap_CashAndCashEquivalentsAtCarryingValue | $ 56.9 us-gaap_CashAndCashEquivalentsAtCarryingValue
Accounts receivable, less allowance for doubtful accounts | 361.6 us-gaap_AccountsReceivableNetCurrent | 427.3 us-gaap_AccountsReceivableNetCurrent
Production fuel, at weighted average cost | 67.6 us-gaap_EnergyRelatedInventoryOtherFossilFuel | 83.8 us-gaap_EnergyRelatedInventoryOtherFossilFuel
Materials and supplies, at weighted average cost | 81.5 us-gaap_InventoryRawMaterialsAndSupplies | 72.9 us-gaap_InventoryRawMaterialsAndSupplies
Gas stored underground, at weighted average cost | 18.3 us-gaap_EnergyRelatedInventoryGasStoredUnderground | 67.1 us-gaap_EnergyRelatedInventoryGasStoredUnderground
Regulatory assets | 59.0 us-gaap_RegulatoryAssetsCurrent | 68.1 us-gaap_RegulatoryAssetsCurrent
Other | 227.6 us-gaap_OtherAssetsCurrent | 267.0 us-gaap_OtherAssetsCurrent
Total current assets | 913.2 us-gaap_AssetsCurrent | 1,043.1 us-gaap_AssetsCurrent
Property, plant and equipment, net | 9,050.0 us-gaap_PropertyPlantAndEquipmentNet | 8,938.4 us-gaap_PropertyPlantAndEquipmentNet
Investments: |  |
Investment in American Transmission Company LLC | 288.5 lnt_InvestmentsBusinessLine1 | 286.5 lnt_InvestmentsBusinessLine1
Other | 55.4 lnt_OtherLongTermInvestmentsAndMarketableSecurities | 58.4 lnt_OtherLongTermInvestmentsAndMarketableSecurities
Total investments | 343.9 us-gaap_LongTermInvestments | 344.9 us-gaap_LongTermInvestments
Other assets: |  |
Regulatory assets | 1,731.3 us-gaap_RegulatoryAssetsNoncurrent | 1,715.6 us-gaap_RegulatoryAssetsNoncurrent
Deferred charges and other | 41.2 us-gaap_OtherAssetsNoncurrent | 43.9 us-gaap_OtherAssetsNoncurrent
Total other assets | 1,772.5 lnt_DeferredChargesRegulatoryAssetsAndOtherAssetsNoncurrent | 1,759.5 lnt_DeferredChargesRegulatoryAssetsAndOtherAssetsNoncurrent
Total assets | 12,079.6 us-gaap_Assets | 12,085.9 us-gaap_Assets
Current liabilities: |  |
Current maturities of long-term debt | 183.0 us-gaap_LongTermDebtCurrent | 183.0 us-gaap_LongTermDebtCurrent
Commercial paper | 41.5 us-gaap_CommercialPaper | 141.3 us-gaap_CommercialPaper
Accounts payable | 356.9 us-gaap_AccountsPayableCurrent | 427.9 us-gaap_AccountsPayableCurrent
Regulatory liabilities | 209.4 us-gaap_RegulatoryLiabilityCurrent | 200.1 us-gaap_RegulatoryLiabilityCurrent
Other | 232.3 us-gaap_OtherLiabilitiesCurrent | 262.4 us-gaap_OtherLiabilitiesCurrent
Total current liabilities | 1,023.1 us-gaap_LiabilitiesCurrent | 1,214.7 us-gaap_LiabilitiesCurrent
Long-term debt, net (excluding current portion) | 3,606.7 us-gaap_LongTermDebtNoncurrent | 3,606.7 us-gaap_LongTermDebtNoncurrent
Other liabilities: |  |
Deferred income tax liabilities | 2,366.9 us-gaap_DeferredTaxLiabilitiesNoncurrent | 2,321.1 us-gaap_DeferredTaxLiabilitiesNoncurrent
Regulatory liabilities | 606.7 us-gaap_RegulatoryLiabilityNoncurrent | 621.1 us-gaap_RegulatoryLiabilityNoncurrent
Pension and other benefit obligations | 417.7 us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent | 421.7 us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent
Other | 259.7 us-gaap_OtherLiabilitiesNoncurrent | 260.1 us-gaap_OtherLiabilitiesNoncurrent
Total other liabilities | 3,651.0 us-gaap_DeferredCreditsAndOtherLiabilities | 3,624.0 us-gaap_DeferredCreditsAndOtherLiabilities
Commitments and contingencies (Note 13) |  |
Common equity: |  |
Common stock | 1.1 us-gaap_CommonStockValue | 1.1 us-gaap_CommonStockValue
Additional paid-in capital | 1,631.6 us-gaap_AdditionalPaidInCapitalCommonStock | 1,509.1 us-gaap_AdditionalPaidInCapitalCommonStock
Retained earnings | 1,973.9 us-gaap_RetainedEarningsAccumulatedDeficit | 1,938.0 us-gaap_RetainedEarningsAccumulatedDeficit
Accumulated other comprehensive loss | (0.6)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax | (0.6)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax
Shares in deferred compensation trust - 232,550 and 238,935 shares at a weighted average cost of $38.27 and $37.45 per share | (8.9)us-gaap_CommonStockHeldInTrust | (8.9)us-gaap_CommonStockHeldInTrust
Total common equity | 3,597.1 us-gaap_StockholdersEquity | 3,438.7 us-gaap_StockholdersEquity
Cumulative preferred stock of Interstate Power and Light Company | 200.0 us-gaap_MinorityInterestPreferredStockAmount | 200.0 us-gaap_MinorityInterestPreferredStockAmount
Noncontrolling interest | 1.7 us-gaap_OtherMinorityInterests | 1.8 us-gaap_OtherMinorityInterests
Total equity | 3,798.8 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest | 3,640.5 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
Total liabilities and equity | 12,079.6 us-gaap_LiabilitiesAndStockholdersEquity | 12,085.9 us-gaap_LiabilitiesAndStockholdersEquity
IPL [Member] |  |
Current assets: |  |
Cash and cash equivalents | 2.6 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = lnt_IplMember | 5.3 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = lnt_IplMember
Accounts receivable, less allowance for doubtful accounts | 158.8 us-gaap_AccountsReceivableNetCurrent / dei_LegalEntityAxis = lnt_IplMember | 216.7 us-gaap_AccountsReceivableNetCurrent / dei_LegalEntityAxis = lnt_IplMember
Production fuel, at weighted average cost | 36.2 us-gaap_EnergyRelatedInventoryOtherFossilFuel / dei_LegalEntityAxis = lnt_IplMember | 52.7 us-gaap_EnergyRelatedInventoryOtherFossilFuel / dei_LegalEntityAxis = lnt_IplMember
Materials and supplies, at weighted average cost | 48.1 us-gaap_InventoryRawMaterialsAndSupplies / dei_LegalEntityAxis = lnt_IplMember | 42.0 us-gaap_InventoryRawMaterialsAndSupplies / dei_LegalEntityAxis = lnt_IplMember
Gas stored underground, at weighted average cost | 5.2 us-gaap_EnergyRelatedInventoryGasStoredUnderground / dei_LegalEntityAxis = lnt_IplMember | 30.8 us-gaap_EnergyRelatedInventoryGasStoredUnderground / dei_LegalEntityAxis = lnt_IplMember
Regulatory assets | 31.1 us-gaap_RegulatoryAssetsCurrent / dei_LegalEntityAxis = lnt_IplMember | 38.7 us-gaap_RegulatoryAssetsCurrent / dei_LegalEntityAxis = lnt_IplMember
Other | 136.5 us-gaap_OtherAssetsCurrent / dei_LegalEntityAxis = lnt_IplMember | 169.9 us-gaap_OtherAssetsCurrent / dei_LegalEntityAxis = lnt_IplMember
Total current assets | 418.5 us-gaap_AssetsCurrent / dei_LegalEntityAxis = lnt_IplMember | 556.1 us-gaap_AssetsCurrent / dei_LegalEntityAxis = lnt_IplMember
Property, plant and equipment, net | 4,631.4 us-gaap_PropertyPlantAndEquipmentNet / dei_LegalEntityAxis = lnt_IplMember | 4,554.7 us-gaap_PropertyPlantAndEquipmentNet / dei_LegalEntityAxis = lnt_IplMember
Investments: |  |
Total investments | 19.1 us-gaap_LongTermInvestments / dei_LegalEntityAxis = lnt_IplMember | 19.1 us-gaap_LongTermInvestments / dei_LegalEntityAxis = lnt_IplMember
Other assets: |  |
Regulatory assets | 1,332.6 us-gaap_RegulatoryAssetsNoncurrent / dei_LegalEntityAxis = lnt_IplMember | 1,319.2 us-gaap_RegulatoryAssetsNoncurrent / dei_LegalEntityAxis = lnt_IplMember
Deferred charges and other | 12.9 us-gaap_OtherAssetsNoncurrent / dei_LegalEntityAxis = lnt_IplMember | 12.7 us-gaap_OtherAssetsNoncurrent / dei_LegalEntityAxis = lnt_IplMember
Total other assets | 1,345.5 lnt_DeferredChargesRegulatoryAssetsAndOtherAssetsNoncurrent / dei_LegalEntityAxis = lnt_IplMember | 1,331.9 lnt_DeferredChargesRegulatoryAssetsAndOtherAssetsNoncurrent / dei_LegalEntityAxis = lnt_IplMember
Total assets | 6,414.5 us-gaap_Assets / dei_LegalEntityAxis = lnt_IplMember | 6,461.8 us-gaap_Assets / dei_LegalEntityAxis = lnt_IplMember
Current liabilities: |  |
Current maturities of long-term debt | 150.0 us-gaap_LongTermDebtCurrent / dei_LegalEntityAxis = lnt_IplMember | 150.0 us-gaap_LongTermDebtCurrent / dei_LegalEntityAxis = lnt_IplMember
Commercial paper | 0 us-gaap_CommercialPaper / dei_LegalEntityAxis = lnt_IplMember |
Accounts payable | 199.6 us-gaap_AccountsPayableCurrent / dei_LegalEntityAxis = lnt_IplMember | 259.6 us-gaap_AccountsPayableCurrent / dei_LegalEntityAxis = lnt_IplMember
Accounts payable to associated companies | 34.4 lnt_AccountsPayableToAssociatedCompanies / dei_LegalEntityAxis = lnt_IplMember | 31.3 lnt_AccountsPayableToAssociatedCompanies / dei_LegalEntityAxis = lnt_IplMember
Regulatory liabilities | 137.5 us-gaap_RegulatoryLiabilityCurrent / dei_LegalEntityAxis = lnt_IplMember | 129.7 us-gaap_RegulatoryLiabilityCurrent / dei_LegalEntityAxis = lnt_IplMember
Other | 122.7 us-gaap_OtherLiabilitiesCurrent / dei_LegalEntityAxis = lnt_IplMember | 135.3 us-gaap_OtherLiabilitiesCurrent / dei_LegalEntityAxis = lnt_IplMember
Total current liabilities | 644.2 us-gaap_LiabilitiesCurrent / dei_LegalEntityAxis = lnt_IplMember | 705.9 us-gaap_LiabilitiesCurrent / dei_LegalEntityAxis = lnt_IplMember
Long-term debt, net (excluding current portion) | 1,618.8 us-gaap_LongTermDebtNoncurrent / dei_LegalEntityAxis = lnt_IplMember | 1,618.7 us-gaap_LongTermDebtNoncurrent / dei_LegalEntityAxis = lnt_IplMember
Other liabilities: |  |
Deferred income tax liabilities | 1,370.4 us-gaap_DeferredTaxLiabilitiesNoncurrent / dei_LegalEntityAxis = lnt_IplMember | 1,341.4 us-gaap_DeferredTaxLiabilitiesNoncurrent / dei_LegalEntityAxis = lnt_IplMember
Regulatory liabilities | 434.6 us-gaap_RegulatoryLiabilityNoncurrent / dei_LegalEntityAxis = lnt_IplMember | 453.8 us-gaap_RegulatoryLiabilityNoncurrent / dei_LegalEntityAxis = lnt_IplMember
Pension and other benefit obligations | 142.1 us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent / dei_LegalEntityAxis = lnt_IplMember | 142.4 us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent / dei_LegalEntityAxis = lnt_IplMember
Other | 177.5 us-gaap_OtherLiabilitiesNoncurrent / dei_LegalEntityAxis = lnt_IplMember | 185.5 us-gaap_OtherLiabilitiesNoncurrent / dei_LegalEntityAxis = lnt_IplMember
Total other liabilities | 2,124.6 us-gaap_DeferredCreditsAndOtherLiabilities / dei_LegalEntityAxis = lnt_IplMember | 2,123.1 us-gaap_DeferredCreditsAndOtherLiabilities / dei_LegalEntityAxis = lnt_IplMember
Commitments and contingencies (Note 13) |  |
Common equity: |  |
Common stock | 33.4 us-gaap_CommonStockValue / dei_LegalEntityAxis = lnt_IplMember | 33.4 us-gaap_CommonStockValue / dei_LegalEntityAxis = lnt_IplMember
Additional paid-in capital | 1,242.8 us-gaap_AdditionalPaidInCapitalCommonStock / dei_LegalEntityAxis = lnt_IplMember | 1,242.8 us-gaap_AdditionalPaidInCapitalCommonStock / dei_LegalEntityAxis = lnt_IplMember
Retained earnings | 550.7 us-gaap_RetainedEarningsAccumulatedDeficit / dei_LegalEntityAxis = lnt_IplMember | 537.9 us-gaap_RetainedEarningsAccumulatedDeficit / dei_LegalEntityAxis = lnt_IplMember
Total common equity | 1,826.9 us-gaap_StockholdersEquity / dei_LegalEntityAxis = lnt_IplMember | 1,814.1 us-gaap_StockholdersEquity / dei_LegalEntityAxis = lnt_IplMember
Cumulative preferred stock of Interstate Power and Light Company | 200.0 us-gaap_MinorityInterestPreferredStockAmount / dei_LegalEntityAxis = lnt_IplMember | 200.0 us-gaap_MinorityInterestPreferredStockAmount / dei_LegalEntityAxis = lnt_IplMember
Total equity | 2,026.9 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = lnt_IplMember | 2,014.1 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = lnt_IplMember
Total liabilities and equity | 6,414.5 us-gaap_LiabilitiesAndStockholdersEquity / dei_LegalEntityAxis = lnt_IplMember | 6,461.8 us-gaap_LiabilitiesAndStockholdersEquity / dei_LegalEntityAxis = lnt_IplMember
WPL [Member] |  |
Current assets: |  |
Cash and cash equivalents | 90.9 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = lnt_WplMember | 46.7 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = lnt_WplMember
Accounts receivable, less allowance for doubtful accounts | 188.4 us-gaap_AccountsReceivableNetCurrent / dei_LegalEntityAxis = lnt_WplMember | 185.8 us-gaap_AccountsReceivableNetCurrent / dei_LegalEntityAxis = lnt_WplMember
Production fuel, at weighted average cost | 31.4 us-gaap_EnergyRelatedInventoryOtherFossilFuel / dei_LegalEntityAxis = lnt_WplMember | 31.1 us-gaap_EnergyRelatedInventoryOtherFossilFuel / dei_LegalEntityAxis = lnt_WplMember
Materials and supplies, at weighted average cost | 31.5 us-gaap_InventoryRawMaterialsAndSupplies / dei_LegalEntityAxis = lnt_WplMember | 29.2 us-gaap_InventoryRawMaterialsAndSupplies / dei_LegalEntityAxis = lnt_WplMember
Gas stored underground, at weighted average cost | 13.1 us-gaap_EnergyRelatedInventoryGasStoredUnderground / dei_LegalEntityAxis = lnt_WplMember | 36.3 us-gaap_EnergyRelatedInventoryGasStoredUnderground / dei_LegalEntityAxis = lnt_WplMember
Regulatory assets | 27.9 us-gaap_RegulatoryAssetsCurrent / dei_LegalEntityAxis = lnt_WplMember | 29.4 us-gaap_RegulatoryAssetsCurrent / dei_LegalEntityAxis = lnt_WplMember
Other | 83.2 us-gaap_OtherAssetsCurrent / dei_LegalEntityAxis = lnt_WplMember | 98.7 us-gaap_OtherAssetsCurrent / dei_LegalEntityAxis = lnt_WplMember
Total current assets | 466.4 us-gaap_AssetsCurrent / dei_LegalEntityAxis = lnt_WplMember | 457.2 us-gaap_AssetsCurrent / dei_LegalEntityAxis = lnt_WplMember
Property, plant and equipment, net | 3,966.7 us-gaap_PropertyPlantAndEquipmentNet / dei_LegalEntityAxis = lnt_WplMember | 3,938.9 us-gaap_PropertyPlantAndEquipmentNet / dei_LegalEntityAxis = lnt_WplMember
Investments: |  |
Investment in American Transmission Company LLC | 288.5 lnt_InvestmentsBusinessLine1 / dei_LegalEntityAxis = lnt_WplMember | 286.5 lnt_InvestmentsBusinessLine1 / dei_LegalEntityAxis = lnt_WplMember
Other | 18.7 lnt_OtherLongTermInvestmentsAndMarketableSecurities / dei_LegalEntityAxis = lnt_WplMember | 19.5 lnt_OtherLongTermInvestmentsAndMarketableSecurities / dei_LegalEntityAxis = lnt_WplMember
Total investments | 307.2 us-gaap_LongTermInvestments / dei_LegalEntityAxis = lnt_WplMember | 306.0 us-gaap_LongTermInvestments / dei_LegalEntityAxis = lnt_WplMember
Other assets: |  |
Regulatory assets | 398.7 us-gaap_RegulatoryAssetsNoncurrent / dei_LegalEntityAxis = lnt_WplMember | 396.4 us-gaap_RegulatoryAssetsNoncurrent / dei_LegalEntityAxis = lnt_WplMember
Deferred charges and other | 27.9 us-gaap_OtherAssetsNoncurrent / dei_LegalEntityAxis = lnt_WplMember | 29.7 us-gaap_OtherAssetsNoncurrent / dei_LegalEntityAxis = lnt_WplMember
Total other assets | 426.6 lnt_DeferredChargesRegulatoryAssetsAndOtherAssetsNoncurrent / dei_LegalEntityAxis = lnt_WplMember | 426.1 lnt_DeferredChargesRegulatoryAssetsAndOtherAssetsNoncurrent / dei_LegalEntityAxis = lnt_WplMember
Total assets | 5,166.9 us-gaap_Assets / dei_LegalEntityAxis = lnt_WplMember | 5,128.2 us-gaap_Assets / dei_LegalEntityAxis = lnt_WplMember
Current liabilities: |  |
Current maturities of long-term debt | 30.6 us-gaap_LongTermDebtCurrent / dei_LegalEntityAxis = lnt_WplMember | 30.6 us-gaap_LongTermDebtCurrent / dei_LegalEntityAxis = lnt_WplMember
Commercial paper | 0 us-gaap_CommercialPaper / dei_LegalEntityAxis = lnt_WplMember |
Accounts payable | 107.7 us-gaap_AccountsPayableCurrent / dei_LegalEntityAxis = lnt_WplMember | 112.9 us-gaap_AccountsPayableCurrent / dei_LegalEntityAxis = lnt_WplMember
Accounts payable to associated companies | 21.3 lnt_AccountsPayableToAssociatedCompanies / dei_LegalEntityAxis = lnt_WplMember | 25.5 lnt_AccountsPayableToAssociatedCompanies / dei_LegalEntityAxis = lnt_WplMember
Regulatory liabilities | 71.9 us-gaap_RegulatoryLiabilityCurrent / dei_LegalEntityAxis = lnt_WplMember | 70.4 us-gaap_RegulatoryLiabilityCurrent / dei_LegalEntityAxis = lnt_WplMember
Other | 82.7 us-gaap_OtherLiabilitiesCurrent / dei_LegalEntityAxis = lnt_WplMember | 70.9 us-gaap_OtherLiabilitiesCurrent / dei_LegalEntityAxis = lnt_WplMember
Total current liabilities | 314.2 us-gaap_LiabilitiesCurrent / dei_LegalEntityAxis = lnt_WplMember | 310.3 us-gaap_LiabilitiesCurrent / dei_LegalEntityAxis = lnt_WplMember
Long-term debt, net (excluding current portion) | 1,543.4 us-gaap_LongTermDebtNoncurrent / dei_LegalEntityAxis = lnt_WplMember | 1,543.3 us-gaap_LongTermDebtNoncurrent / dei_LegalEntityAxis = lnt_WplMember
Other liabilities: |  |
Deferred income tax liabilities | 984.4 us-gaap_DeferredTaxLiabilitiesNoncurrent / dei_LegalEntityAxis = lnt_WplMember | 970.0 us-gaap_DeferredTaxLiabilitiesNoncurrent / dei_LegalEntityAxis = lnt_WplMember
Regulatory liabilities | 172.1 us-gaap_RegulatoryLiabilityNoncurrent / dei_LegalEntityAxis = lnt_WplMember | 167.3 us-gaap_RegulatoryLiabilityNoncurrent / dei_LegalEntityAxis = lnt_WplMember
Capital lease obligations - Sheboygan Falls Energy Facility | 88.0 us-gaap_CapitalLeaseObligationsNoncurrent / dei_LegalEntityAxis = lnt_WplMember | 89.4 us-gaap_CapitalLeaseObligationsNoncurrent / dei_LegalEntityAxis = lnt_WplMember
Pension and other benefit obligations | 179.7 us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent / dei_LegalEntityAxis = lnt_WplMember | 180.4 us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent / dei_LegalEntityAxis = lnt_WplMember
Other | 159.5 us-gaap_OtherLiabilitiesNoncurrent / dei_LegalEntityAxis = lnt_WplMember | 155.2 us-gaap_OtherLiabilitiesNoncurrent / dei_LegalEntityAxis = lnt_WplMember
Total other liabilities | 1,583.7 us-gaap_DeferredCreditsAndOtherLiabilities / dei_LegalEntityAxis = lnt_WplMember | 1,562.3 us-gaap_DeferredCreditsAndOtherLiabilities / dei_LegalEntityAxis = lnt_WplMember
Common equity: |  |
Common stock | 66.2 us-gaap_CommonStockValue / dei_LegalEntityAxis = lnt_WplMember | 66.2 us-gaap_CommonStockValue / dei_LegalEntityAxis = lnt_WplMember
Additional paid-in capital | 959.0 us-gaap_AdditionalPaidInCapitalCommonStock / dei_LegalEntityAxis = lnt_WplMember | 959.0 us-gaap_AdditionalPaidInCapitalCommonStock / dei_LegalEntityAxis = lnt_WplMember
Retained earnings | 691.4 us-gaap_RetainedEarningsAccumulatedDeficit / dei_LegalEntityAxis = lnt_WplMember | 678.6 us-gaap_RetainedEarningsAccumulatedDeficit / dei_LegalEntityAxis = lnt_WplMember
Total common equity | 1,716.6 us-gaap_StockholdersEquity / dei_LegalEntityAxis = lnt_WplMember | 1,703.8 us-gaap_StockholdersEquity / dei_LegalEntityAxis = lnt_WplMember
Noncontrolling interest | 9.0 us-gaap_OtherMinorityInterests / dei_LegalEntityAxis = lnt_WplMember | 8.5 us-gaap_OtherMinorityInterests / dei_LegalEntityAxis = lnt_WplMember
Total equity | 1,725.6 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = lnt_WplMember | 1,712.3 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = lnt_WplMember
Total liabilities and equity | $ 5,166.9 us-gaap_LiabilitiesAndStockholdersEquity / dei_LegalEntityAxis = lnt_WplMember | $ 5,128.2 us-gaap_LiabilitiesAndStockholdersEquity / dei_LegalEntityAxis = lnt_WplMember

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- Definition This represents the noncurrent liability for underfunded plans recognized in the balance sheet that is associated with the defined benefit pension plans and other postretirement defined benefit plans. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.24) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e2417-114920 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e2410-114920 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=21915240&loc=d3e1703-114919 + Details
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