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Network
2413402 - Disclosure - Asset Retirement Obligations (AROs) (Reconciliation Of Changes In Asset Retirement Obligations) (Details)
(http://www.alliantenergy.com/role/AssetRetirementObligationsArosReconciliationOfChangesInAssetRetirementObligationsDetails)
TableSchedule of Asset Retirement Obligations [Table]
Slicers (applies to each fact value in each table cell)
Reporting Entity [Axis]0000352541 (http://www.sec.gov/CIK)
Schedule of Asset Retirement Obligations [Line Items]Period [Axis]
2013-01-01 - 2013-12-31
2012-01-01 - 2012-12-31
Project [Axis]Project [Axis]
Project [Domain]Sixth Street [Member]Franklin County Wind Project [Member]NelsonDewey [Member]Project [Domain]
Legal Entity [Axis]Legal Entity [Axis]Legal Entity [Axis]Legal Entity [Axis]Legal Entity [Axis]
Ipl [Member]Wpl [Member]Entity [Domain]Ipl [Member]Resources [Member]Wpl [Member]Ipl [Member]Wpl [Member]Entity [Domain]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
 
 
 
 
 
 
 
 
 
Balance, January 1
45,500,000  
46,900,000  
101,500,000  
 
 
 
56,200,000  
34,900,000  
91,100,000  
Revisions in estimated cash flows
100,000 1
5,500,000 1
5,600,000 1
(8,200,000) 
 
 
(9,200,000)1
2,800,000 1
(6,400,000)1
Liabilities settled
(600,000) 
(1,700,000) 
(2,300,000) 
 
 
 
(3,300,000) 
(100,000) 
(3,400,000) 
Liabilities incurred
1,200,000 2
0 2
1,200,000 2
 
9,100,000  
7,600,000  
0 2
7,700,000 2
16,800,000 2
Accretion expense
1,700,000  
1,700,000  
3,700,000  
 
 
 
1,800,000  
1,600,000  
3,400,000  
Balance, December 31
47,900,000  
 
52,400,000  
 
109,700,000  
 
 
 
 
 
 
 
45,500,000  
 
46,900,000  
 
101,500,000  
 
1: In 2012, IPL recorded revisions in estimated cash flows of ($8.2) million based on revised remediation timing and cost information for asbestos remediation at Sixth Street.
2: In 2012, Resources recorded AROs of $9.1 million related to its Franklin County wind project and WPL recorded AROs of $7.6 million related to Nelson Dewey.