v2.4.0.6

Common Equity (Narrative) (Details) (USD $) In Millions, except Share data, unless otherwise specified | 12 Months Ended
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Dec. 31, 2012
Schedule of Common Equity [Line Items] |
Shares available for issuance under the OIP, Shareowner Direct Plan and 401k Savings Plan | 8,400,000
Ownership percentage | 15.00%
Initial right entitlement, number of shares of common stock shareholders have the option to purchase (in shares) | 0.5
Exercise price, rights (in dollars per share) | 110
Percentage of exercise price upon change in beneficial ownership | 200.00%
IPL [Member] |
Schedule of Common Equity [Line Items] |
Common equity ratio, computation of ratio average, number of months | 13 months
Common equity ratio | 42.00%
Retained earnings free of dividend restrictions | $ 387
WPL [Member] |
Schedule of Common Equity [Line Items] |
Common equity ratio, computation of ratio average, number of months | 13 months
Common equity ratio | 51.03%
Retained earnings free of dividend restrictions | $ 119
Minimum [Member] |
Schedule of Common Equity [Line Items] |
Ownership percentage | 10.00%
Minimum [Member] | WPL [Member] |
Schedule of Common Equity [Line Items] |
Common equity ratio | 25.00%

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- Definition The rights under the Company Shareowner Rights Agreement will only become exercisable if a person or group has acquired, or announced an intention to acquire, 15% or more of the Company's outstanding common stock. + References No definition available. + Details
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- Details
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- Definition A segregation of retained earnings which is available for dividend distribution. Earnings not paid out as dividends but instead reinvested in the core business or used to pay off debt. Unappropriated profit is part of shareholder equity. Also called cumulative distributions or earned surplus or accumulated earnings or unappropriated profit. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 24 -Subparagraph a(4) -Article 7 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 31 -Article 5 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.30(a)(3)(ii)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03.23(4)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 + Details
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