XML 168 R95.htm IDEA: XBRL DOCUMENT
v2.4.1.9

Leases (Schedule Of Lease Expenses Included In Consolidated Statements Of Income) (Details) (WPL [Member], Sheboygan Falls Energy Facility [Member], USD $) In Millions, unless otherwise specified | 12 Months Ended
--- | ---
Dec. 31, 2014 | Dec. 31, 2013 | Dec. 31, 2012
WPL [Member] | Sheboygan Falls Energy Facility [Member] |  |  |
Property, Plant and Equipment [Line Items] |  |  |
Interest expense | $ 10.4 us-gaap_CapitalLeasesIncomeStatementInterestExpense / dei_LegalEntityAxis = lnt_WplMember / us-gaap_PropertyPlantAndEquipmentByTypeAxis = lnt_SheboyganFallsEnergyFacilityMember | $ 10.9 us-gaap_CapitalLeasesIncomeStatementInterestExpense / dei_LegalEntityAxis = lnt_WplMember / us-gaap_PropertyPlantAndEquipmentByTypeAxis = lnt_SheboyganFallsEnergyFacilityMember | $ 11.3 us-gaap_CapitalLeasesIncomeStatementInterestExpense / dei_LegalEntityAxis = lnt_WplMember / us-gaap_PropertyPlantAndEquipmentByTypeAxis = lnt_SheboyganFallsEnergyFacilityMember
Depreciation and amortization | 6.2 us-gaap_CapitalLeasesIncomeStatementAmortizationExpense / dei_LegalEntityAxis = lnt_WplMember / us-gaap_PropertyPlantAndEquipmentByTypeAxis = lnt_SheboyganFallsEnergyFacilityMember | 6.2 us-gaap_CapitalLeasesIncomeStatementAmortizationExpense / dei_LegalEntityAxis = lnt_WplMember / us-gaap_PropertyPlantAndEquipmentByTypeAxis = lnt_SheboyganFallsEnergyFacilityMember | 6.2 us-gaap_CapitalLeasesIncomeStatementAmortizationExpense / dei_LegalEntityAxis = lnt_WplMember / us-gaap_PropertyPlantAndEquipmentByTypeAxis = lnt_SheboyganFallsEnergyFacilityMember
Total lease expenses included in income statements | $ 16.6 lnt_CapitalLeasesIncomeStatementLeaseExpenses / dei_LegalEntityAxis = lnt_WplMember / us-gaap_PropertyPlantAndEquipmentByTypeAxis = lnt_SheboyganFallsEnergyFacilityMember | $ 17.1 lnt_CapitalLeasesIncomeStatementLeaseExpenses / dei_LegalEntityAxis = lnt_WplMember / us-gaap_PropertyPlantAndEquipmentByTypeAxis = lnt_SheboyganFallsEnergyFacilityMember | $ 17.5 lnt_CapitalLeasesIncomeStatementLeaseExpenses / dei_LegalEntityAxis = lnt_WplMember / us-gaap_PropertyPlantAndEquipmentByTypeAxis = lnt_SheboyganFallsEnergyFacilityMember

X
- Definition Capital Leases, Income Statement, Lease Expenses + References No definition available. + Details
Name: | lnt_CapitalLeasesIncomeStatementLeaseExpenses
Namespace Prefix: | lnt_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The charge for the use of long-lived depreciable capital leased assets for the period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 840 -SubTopic 30 -Section 45 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6455314&loc=d3e45031-112735 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 840 -Section 55 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6501752&loc=d3e56872-110439 + Details
Name: | us-gaap_CapitalLeasesIncomeStatementAmortizationExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The financing charge for leasing arrangements meeting the criteria for capitalization. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 840 -SubTopic 30 -Section 45 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6455314&loc=d3e45031-112735 + Details
Name: | us-gaap_CapitalLeasesIncomeStatementInterestExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration