v2.4.0.6

Valuation And Qualifying Accounts and Reserves (Details) (USD $) In Millions, unless otherwise specified | 12 Months Ended
--- | ---
Dec. 31, 2012 | Dec. 31, 2011 | Dec. 31, 2010
Accumulated Provision for Uncollectible Accounts [Member] |  |  |  |  |  |
Valuation and Qualifying Accounts Disclosure [Line Items] |  |  |  |  |  |
Beginning Balance | $ 4.2 | [1] | $ 3.2 | [1] | $ 4.5 | [1]
Charged to Expense | 6.6 | [1] | 7.8 | [1] | 6.8 | [1]
Charged to Other Accounts | 1.2 | [1],[2] | 1.9 | [1],[2] | 1.8 | [1],[2]
Deductions | 8.0 | [1],[3] | 8.7 | [1],[3] | 9.9 | [1],[3]
Ending Balance | 4.0 | [1] | 4.2 | [1] | 3.2 | [1]
Accumulated Provision for Uncollectible Accounts [Member] | IPL [Member] |  |  |  |  |  |
Valuation and Qualifying Accounts Disclosure [Line Items] |  |  |  |  |  |
Beginning Balance | 0.9 | [1] | 0.4 | [1] | 2.5 | [1]
Charged to Expense | 6.4 | [1] | 7.4 | [1] | 5.6 | [1]
Charged to Other Accounts | 0 | [1],[2] | 0 | [1],[2] | 0 | [1],[2]
Deductions | 6.6 | [1],[3] | 6.9 | [1],[3] | 7.7 | [1],[3]
Ending Balance | 0.7 | [1] | 0.9 | [1] | 0.4 | [1]
Accumulated Provision for Uncollectible Accounts [Member] | WPL [Member] |  |  |  |  |  |
Valuation and Qualifying Accounts Disclosure [Line Items] |  |  |  |  |  |
Beginning Balance | 1.9 |  | 1.7 |  | 2.0 |
Charged to Expense | 0.1 |  | 0.1 |  | 0.1 |
Charged to Other Accounts | 1.2 | [2] | 1.9 | [2] | 1.8 | [2]
Deductions | 1.4 | [3] | 1.8 | [3] | 2.2 | [3]
Ending Balance | 1.8 |  | 1.9 |  | 1.7 |
Accumulated Provision for Other Reserves [Member] |  |  |  |  |  |
Valuation and Qualifying Accounts Disclosure [Line Items] |  |  |  |  |  |
Beginning Balance | 25.9 | [4] | 24.0 | [4] | 20.9 | [4]
Charged to Expense | 9.6 | [4] | 8.8 | [4] | 11.5 | [4]
Charged to Other Accounts | 0 | [2],[4] | 0 | [2],[4] | 0 | [2],[4]
Deductions | 2.1 | [3],[4] | 6.9 | [3],[4] | 8.4 | [3],[4]
Ending Balance | 33.4 | [4] | 25.9 | [4] | 24.0 | [4]
Accumulated Provision for Other Reserves [Member] | IPL [Member] |  |  |  |  |  |
Valuation and Qualifying Accounts Disclosure [Line Items] |  |  |  |  |  |
Beginning Balance | 10.2 | [4] | 8.8 | [4] | 9.0 | [4]
Charged to Expense | 2.1 | [4] | 3.6 | [4] | 2.0 | [4]
Charged to Other Accounts | 0 | [2],[4] | 0 | [2],[4] | 0 | [2],[4]
Deductions | 0.7 | [3],[4] | 2.2 | [3],[4] | 2.2 | [3],[4]
Ending Balance | 11.6 | [4] | 10.2 | [4] | 8.8 | [4]
Accumulated Provision for Other Reserves [Member] | WPL [Member] |  |  |  |  |  |
Valuation and Qualifying Accounts Disclosure [Line Items] |  |  |  |  |  |
Beginning Balance | 11.7 | [4] | 12.8 | [4] | 10.7 | [4]
Charged to Expense | 3.1 | [4] | 3.7 | [4] | 7.5 | [4]
Charged to Other Accounts | 0 | [2],[4] | 0 | [2],[4] | 0 | [2],[4]
Deductions | 1.3 | [3],[4] | 4.8 | [3],[4] | 5.4 | [3],[4]
Ending Balance | $ 13.5 | [4] | $ 11.7 | [4] | $ 12.8 | [4]
[1] | Refer to Note 4(a) of the “Combined Notes to Consolidated Financial Statements” for discussion of IPL’s sales of accounts receivable program.
[2] | Accumulated provision for uncollectible accounts: In accordance with its regulatory treatment, certain amounts provided by Wisconsin Power and Light Company are recorded in regulatory assets.
[3] | Deductions are of the nature for which the reserves were created. In the case of the accumulated provision for uncollectible accounts, deductions from this reserve are reduced by recoveries of amounts previously written off.
[4] | Other reserves are largely related to injury and damage claims arising in the ordinary course of business.

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- Definition Total of allowances and reserves, the valuation and qualifying accounts that are either netted against the cost of an asset (in order to value it at its carrying value) or that reflect a liability established to represent expected future costs. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 09 -Article 12 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=6881521&loc=d3e24092-122690 + Details
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- Definition Total of allowances and reserves, the valuation and qualifying accounts that are either netted against the cost of an asset (in order to value it at its carrying value) or that reflect a liability established to represent expected future costs, charged to accounts other than costs and expenses in a given period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 09 -Article 12 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=6881521&loc=d3e24092-122690 + Details
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- Definition Total of the deductions in a given period to allowances and reserves, the valuation and qualifying accounts that are either netted against the cost of an asset (in order to value it at its carrying value) or that reflect a liability established to represent expected future costs, representing receivables written off as uncollectible and portions of the reserves utilized, respectively. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 09 -Article 12 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=6881521&loc=d3e24092-122690 + Details
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