v2.4.0.6

Segments Of Business (Schedule Of Segment Of Business) (Details) (USD $) In Millions, unless otherwise specified | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2012 | Sep. 30, 2011 | Sep. 30, 2012 | Sep. 30, 2011
Segment Reporting Information [Line Items] |  |  |  |
Operating revenues | $ 887.6 | $ 870.9 | $ 2,343.6 | $ 2,460.6
Operating income (loss) | 213.7 | 209.4 | 418.1 | 407.3
Income (loss) from continuing operations, net of tax | 149.0 | 136.9 | 253.8 | 259.2
Income (loss) from discontinued operations, net of tax | 1.7 | (14.9) | (2.3) | (12.6)
Net income (loss) attributable to Alliant Energy common shareowners | 150.7 | 122.0 | 251.5 | 246.6
Alliant Energy [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Operating revenues | 887.6 | 870.9 | 2,343.6 | 2,460.6
Operating income (loss) | 213.7 | 209.4 | 418.1 | 407.3
Income (loss) from continuing operations, net of tax | 149.0 | 136.9 | 253.8 | 259.2
Income (loss) from discontinued operations, net of tax | 1.7 | (14.9) | (2.3) | (12.6)
Net income (loss) attributable to Alliant Energy common shareowners | 150.7 | 122.0 | 251.5 | 246.6
IPL [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Operating revenues | 497.7 | 484.5 | 1,257.1 | 1,336.1
Operating income (loss) | 112.0 | 116.5 | 171.3 | 182.1
Net income (loss) attributable to Alliant Energy common shareowners | 103.3 | 98.3 | 115.2 | 117.7
WPL [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Operating revenues | 376.6 | 374.6 | 1,046.8 | 1,089.9
Operating income (loss) | 93.4 | 86.9 | 219.5 | 207.2
Net income (loss) attributable to Alliant Energy common shareowners | 55.9 | 50.6 | 122.2 | 118.3
Electric [Member] | Alliant Energy [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Operating revenues | 815.3 | 796.9 | 2,000.3 | 2,037.7
Operating income (loss) | 203.1 | 206.1 | 354.0 | 357.6
Electric [Member] | IPL [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Operating revenues | 456.6 | 443.2 | 1,070.7 | 1,097.3
Operating income (loss) | 109.5 | 117.5 | 149.3 | 162.3
Electric [Member] | WPL [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Operating revenues | 358.7 | 353.7 | 929.6 | 940.4
Operating income (loss) | 93.6 | 88.6 | 204.7 | 195.3
Gas [Member] | Alliant Energy [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Operating revenues | 46.8 | 46.4 | 263.9 | 342.5
Operating income (loss) | 0.8 | (2.8) | 32.1 | 34.0
Gas [Member] | IPL [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Operating revenues | 29.6 | 27.5 | 149.2 | 198.1
Operating income (loss) | 0.6 | (1.3) | 15.6 | 15.1
Gas [Member] | WPL [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Operating revenues | 17.2 | 18.9 | 114.7 | 144.4
Operating income (loss) | 0.2 | (1.5) | 16.5 | 18.9
Other Utility [Member] | Alliant Energy [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Operating revenues | 12.2 | 15.8 | 39.7 | 45.8
Operating income (loss) | 1.5 | 0.1 | 4.7 | (2.3)
Other Utility [Member] | IPL [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Operating revenues | 11.5 | 13.8 | 37.2 | 40.7
Operating income (loss) | 1.9 | 0.3 | 6.4 | 4.7
Other Utility [Member] | WPL [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Operating revenues | 0.7 | 2.0 | 2.5 | 5.1
Operating income (loss) | (0.4) | (0.2) | (1.7) | (7.0)
Utility Business [Member] | Alliant Energy [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Operating revenues | 874.3 | 859.1 | 2,303.9 | 2,426.0
Operating income (loss) | 205.4 | 203.4 | 390.8 | 389.3
Income (loss) from continuing operations, net of tax | 159.2 | 148.9 | 237.4 | 236.0
Income (loss) from discontinued operations, net of tax | 0 | 0 | 0 | 0
Net income (loss) attributable to Alliant Energy common shareowners | 159.2 | 148.9 | 237.4 | 236.0
Non-Regulated [Member] | Other Segments [Member] | Alliant Energy [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Operating revenues | 13.3 | 11.8 | 39.7 | 34.6
Operating income (loss) | 8.3 | 6.0 | 27.3 | 18.0
Income (loss) from continuing operations, net of tax | (10.2) | (12.0) | 16.4 | 23.2
Income (loss) from discontinued operations, net of tax | 1.7 | (14.9) | (2.3) | (12.6)
Net income (loss) attributable to Alliant Energy common shareowners | $ (8.5) | $ (26.9) | $ 14.1 | $ 10.6

X
- Definition This element represents the income or loss from continuing operations attributable to the parent which may also be defined as revenue less expenses and taxes from ongoing operations before extraordinary items but after deduction of those portions of income or loss from continuing operations that are allocable to noncontrolling interests, if any. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3602-108585 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Research Bulletin (ARB) -Number 51 -Paragraph 29 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 45 -Paragraph 18 -URI http://asc.fasb.org/extlink&oid=6921628&loc=SL4613673-111683 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Research Bulletin (ARB) -Number 51 -Paragraph 28 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Research Bulletin (ARB) -Number 51 -Paragraph 38 -Subparagraph b(1) -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 7: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.13) -URI http://asc.fasb.org/extlink&oid=6880815&loc=d3e20235-122688 + Details
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- Definition This element represents the overall income (loss) from a disposal group that is classified as a component of the entity, net of income tax, reported as a separate component of income before extraordinary items before deduction or consideration of the amount which may be allocable to noncontrolling interests, if any. Includes the following (net of tax): income (loss) from operations during the phase-out period, gain (loss) on disposal, provision (or any reversals of earlier provisions) for loss on disposal, and adjustments of a prior period gain (loss) on disposal. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6360339&loc=d3e1361-107760 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 144 -Paragraph 47 -Subparagraph c -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Research Bulletin (ARB) -Number 51 -Paragraph 29 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.14) -URI http://asc.fasb.org/extlink&oid=6880815&loc=d3e20235-122688 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 144 -Paragraph 43 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04.12) -URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913 Reference 7: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Paragraph 13 -Article 7 Reference 8: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Article 5 -Section 03 -Paragraph 15 Reference 9: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 20 -Section 45 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6892542&loc=d3e957-107759 + Details
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- Definition Net income after adjustments for dividends on preferred stock (declared in the period) and/or cumulative preferred stock (accumulated for the period). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 128 -Paragraph 9 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 45 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=6920599&loc=d3e1377-109256 + Details
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- Definition Aggregate revenue recognized during the period (derived from goods sold, services rendered, insurance premiums, or other activities that constitute an entity's earning process). For financial services companies, also includes investment and interest income, and sales and trading gains. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Article 5 -Section 03 -Paragraph 1 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.1) -URI http://asc.fasb.org/extlink&oid=6880815&loc=d3e20235-122688 + Details
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