XML 40 R19.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Segments Of Business | 9 Months Ended
--- | ---
Sep. 30, 2018
Segment Reporting Information [Line Items] |
Segments Of Business | SEGMENTS OF BUSINESS In the fourth quarter of 2017, Alliant Energy and WPL modified the segment reporting related to ATC Holdings, consistent with information used by their chief operating decision maker to evaluate performance and allocate resources. As of December 31, 2017, ATC Holdings are no longer included in Alliant Energy’s utility electric operations reportable segment or WPL’s electric operations reportable segment. As a result, all prior period amounts impacted by this change were reclassified to conform to the new presentation. Alliant Energy’s related amounts were reclassified from “Electric Utility” to “ATC Holdings, Non-Utility, Parent and Other” in the table below. There was no resulting change to WPL’s segment reporting for the three and nine months ended September 30, 2017. Alliant Energy - Certain financial information relating to Alliant Energy’s business segments is as follows. Intersegment revenues were not material to Alliant Energy’s operations.
|  |  |  |  |  |  |  |  | ATC Holdings, |  | Alliant
| Utility |  | Non-Utility, |  | Energy
| Electric |  | Gas |  | Other |  | Total |  | Parent and Other |  | Consolidated
| (in millions)
Three Months Ended September 30, 2018 |  |  |  |  |  |  |  |  |  |  |
Revenues |  | $861.2 |  |  |  | $44.8 |  |  |  | $12.3 |  |  |  | $918.3 |  |  |  | $10.3 |  |  |  | $928.6 |
Operating income (loss) | 248.7 |  |  | (2.0 | ) |  | 0.6 |  |  | 247.3 |  |  | 8.8 |  |  | 256.1 |
Net income attributable to Alliant Energy common shareowners |  |  |  |  |  |  | 202.8 |  |  | 2.7 |  |  | 205.5 |
Three Months Ended September 30, 2017 |  |  |  |  |  |  |  |  |  |  |
Revenues |  | $840.6 |  |  |  | $45.8 |  |  |  | $11.2 |  |  |  | $897.6 |  |  |  | $9.3 |  |  |  | $906.9 |
Operating income (loss) | 236.7 |  |  | (1.7 | ) |  | (7.7 | ) |  | 227.3 |  |  | 9.0 |  |  | 236.3 |
Net income (loss) attributable to Alliant Energy common shareowners |  |  |  |  |  |  | 170.2 |  |  | (1.4 | ) |  | 168.8 |
|  |  |  |  |  |  |  |  | ATC Holdings, |  | Alliant
| Utility |  | Non-Utility, |  | Energy
| Electric |  | Gas |  | Other |  | Total |  | Parent and Other |  | Consolidated
| (in millions)
Nine Months Ended September 30, 2018 |  |  |  |  |  |  |  |  |  |  |
Revenues |  | $2,296.2 |  |  |  | $299.0 |  |  |  | $36.2 |  |  |  | $2,631.4 |  |  |  | $29.6 |  |  |  | $2,661.0 |
Operating income | 510.2 |  |  | 34.9 |  |  | 2.9 |  |  | 548.0 |  |  | 25.0 |  |  | 573.0 |
Net income attributable to Alliant Energy common shareowners |  |  |  |  |  |  | 395.0 |  |  | 31.8 |  |  | 426.8 |
Nine Months Ended September 30, 2017 |  |  |  |  |  |  |  |  |  |  |
Revenues |  | $2,199.1 |  |  |  | $262.7 |  |  |  | $34.4 |  |  |  | $2,496.2 |  |  |  | $29.9 |  |  |  | $2,526.1 |
Operating income (loss) | 486.9 |  |  | 31.3 |  |  | (6.7 | ) |  | 511.5 |  |  | 25.7 |  |  | 537.2 |
Amounts attributable to Alliant Energy common shareowners: |  |  |  |  |  |  |  |  |  |  |
Income from continuing operations, net of tax |  |  |  |  |  |  | 333.8 |  |  | 28.3 |  |  | 362.1 |
Income from discontinued operations, net of tax |  |  |  |  |  |  | — |  |  | 1.4 |  |  | 1.4 |
Net income |  |  |  |  |  |  | 333.8 |  |  | 29.7 |  |  | 363.5 |
IPL - Certain financial information relating to IPL’s business segments is as follows. Intersegment revenues were not material to IPL’s operations.
| Electric |  | Gas |  | Other |  | Total
| (in millions)
Three Months Ended September 30, 2018 |  |  |  |  |  |  |
Revenues |  | $509.2 |  |  |  | $26.7 |  |  |  | $11.7 |  |  |  | $547.6 |
Operating income (loss) | 144.7 |  |  | (3.1 | ) |  | 1.5 |  |  | 143.1 |
Earnings available for common stock |  |  |  |  |  |  | 126.5 |
Three Months Ended September 30, 2017 |  |  |  |  |  |  |
Revenues |  | $489.0 |  |  |  | $27.4 |  |  |  | $11.0 |  |  |  | $527.4 |
Operating income (loss) | 140.0 |  |  | (1.8 | ) |  | (4.4 | ) |  | 133.8 |
Earnings available for common stock |  |  |  |  |  |  | 120.4 |
Nine Months Ended September 30, 2018 |  |  |  |  |  |  |
Revenues |  | $1,337.0 |  |  |  | $177.0 |  |  |  | $34.2 |  |  |  | $1,548.2 |
Operating income | 275.7 |  |  | 16.3 |  |  | 4.4 |  |  | 296.4 |
Earnings available for common stock |  |  |  |  |  |  | 224.9 |
Nine Months Ended September 30, 2017 |  |  |  |  |  |  |
Revenues |  | $1,217.6 |  |  |  | $147.2 |  |  |  | $33.3 |  |  |  | $1,398.1 |
Operating income (loss) | 239.2 |  |  | 15.4 |  |  | (1.4 | ) |  | 253.2 |
Earnings available for common stock |  |  |  |  |  |  | 200.4 |
WPL - Certain financial information relating to WPL’s business segments is as follows. Intersegment revenues were not material to WPL’s operations.
| Electric |  | Gas |  | Other |  | Total
| (in millions)
Three Months Ended September 30, 2018 |  |  |  |  |  |  |
Revenues |  | $352.0 |  |  |  | $18.1 |  |  |  | $0.6 |  |  |  | $370.7 |
Operating income (loss) | 104.0 |  |  | 1.1 |  |  | (0.9 | ) |  | 104.2 |
Earnings available for common stock |  |  |  |  |  |  | 76.3 |
Three Months Ended September 30, 2017 |  |  |  |  |  |  |
Revenues |  | $351.6 |  |  |  | $18.4 |  |  |  | $0.2 |  |  |  | $370.2 |
Operating income (loss) | 96.7 |  |  | 0.1 |  |  | (3.3 | ) |  | 93.5 |
Earnings available for common stock |  |  |  |  |  |  | 49.8 |
Nine Months Ended September 30, 2018 |  |  |  |  |  |  |
Revenues |  | $959.2 |  |  |  | $122.0 |  |  |  | $2.0 |  |  |  | $1,083.2 |
Operating income (loss) | 234.5 |  |  | 18.6 |  |  | (1.5 | ) |  | 251.6 |
Earnings available for common stock |  |  |  |  |  |  | 170.1 |
Nine Months Ended September 30, 2017 |  |  |  |  |  |  |
Revenues |  | $981.5 |  |  |  | $115.5 |  |  |  | $1.1 |  |  |  | $1,098.1 |
Operating income (loss) | 247.7 |  |  | 15.9 |  |  | (5.3 | ) |  | 258.3 |
Earnings available for common stock |  |  |  |  |  |  | 133.4 |
IPL [Member] |
Segment Reporting Information [Line Items] |
Segments Of Business | SEGMENTS OF BUSINESS In the fourth quarter of 2017, Alliant Energy and WPL modified the segment reporting related to ATC Holdings, consistent with information used by their chief operating decision maker to evaluate performance and allocate resources. As of December 31, 2017, ATC Holdings are no longer included in Alliant Energy’s utility electric operations reportable segment or WPL’s electric operations reportable segment. As a result, all prior period amounts impacted by this change were reclassified to conform to the new presentation. Alliant Energy’s related amounts were reclassified from “Electric Utility” to “ATC Holdings, Non-Utility, Parent and Other” in the table below. There was no resulting change to WPL’s segment reporting for the three and nine months ended September 30, 2017. Alliant Energy - Certain financial information relating to Alliant Energy’s business segments is as follows. Intersegment revenues were not material to Alliant Energy’s operations.
|  |  |  |  |  |  |  |  | ATC Holdings, |  | Alliant
| Utility |  | Non-Utility, |  | Energy
| Electric |  | Gas |  | Other |  | Total |  | Parent and Other |  | Consolidated
| (in millions)
Three Months Ended September 30, 2018 |  |  |  |  |  |  |  |  |  |  |
Revenues |  | $861.2 |  |  |  | $44.8 |  |  |  | $12.3 |  |  |  | $918.3 |  |  |  | $10.3 |  |  |  | $928.6 |
Operating income (loss) | 248.7 |  |  | (2.0 | ) |  | 0.6 |  |  | 247.3 |  |  | 8.8 |  |  | 256.1 |
Net income attributable to Alliant Energy common shareowners |  |  |  |  |  |  | 202.8 |  |  | 2.7 |  |  | 205.5 |
Three Months Ended September 30, 2017 |  |  |  |  |  |  |  |  |  |  |
Revenues |  | $840.6 |  |  |  | $45.8 |  |  |  | $11.2 |  |  |  | $897.6 |  |  |  | $9.3 |  |  |  | $906.9 |
Operating income (loss) | 236.7 |  |  | (1.7 | ) |  | (7.7 | ) |  | 227.3 |  |  | 9.0 |  |  | 236.3 |
Net income (loss) attributable to Alliant Energy common shareowners |  |  |  |  |  |  | 170.2 |  |  | (1.4 | ) |  | 168.8 |
|  |  |  |  |  |  |  |  | ATC Holdings, |  | Alliant
| Utility |  | Non-Utility, |  | Energy
| Electric |  | Gas |  | Other |  | Total |  | Parent and Other |  | Consolidated
| (in millions)
Nine Months Ended September 30, 2018 |  |  |  |  |  |  |  |  |  |  |
Revenues |  | $2,296.2 |  |  |  | $299.0 |  |  |  | $36.2 |  |  |  | $2,631.4 |  |  |  | $29.6 |  |  |  | $2,661.0 |
Operating income | 510.2 |  |  | 34.9 |  |  | 2.9 |  |  | 548.0 |  |  | 25.0 |  |  | 573.0 |
Net income attributable to Alliant Energy common shareowners |  |  |  |  |  |  | 395.0 |  |  | 31.8 |  |  | 426.8 |
Nine Months Ended September 30, 2017 |  |  |  |  |  |  |  |  |  |  |
Revenues |  | $2,199.1 |  |  |  | $262.7 |  |  |  | $34.4 |  |  |  | $2,496.2 |  |  |  | $29.9 |  |  |  | $2,526.1 |
Operating income (loss) | 486.9 |  |  | 31.3 |  |  | (6.7 | ) |  | 511.5 |  |  | 25.7 |  |  | 537.2 |
Amounts attributable to Alliant Energy common shareowners: |  |  |  |  |  |  |  |  |  |  |
Income from continuing operations, net of tax |  |  |  |  |  |  | 333.8 |  |  | 28.3 |  |  | 362.1 |
Income from discontinued operations, net of tax |  |  |  |  |  |  | — |  |  | 1.4 |  |  | 1.4 |
Net income |  |  |  |  |  |  | 333.8 |  |  | 29.7 |  |  | 363.5 |
IPL - Certain financial information relating to IPL’s business segments is as follows. Intersegment revenues were not material to IPL’s operations.
| Electric |  | Gas |  | Other |  | Total
| (in millions)
Three Months Ended September 30, 2018 |  |  |  |  |  |  |
Revenues |  | $509.2 |  |  |  | $26.7 |  |  |  | $11.7 |  |  |  | $547.6 |
Operating income (loss) | 144.7 |  |  | (3.1 | ) |  | 1.5 |  |  | 143.1 |
Earnings available for common stock |  |  |  |  |  |  | 126.5 |
Three Months Ended September 30, 2017 |  |  |  |  |  |  |
Revenues |  | $489.0 |  |  |  | $27.4 |  |  |  | $11.0 |  |  |  | $527.4 |
Operating income (loss) | 140.0 |  |  | (1.8 | ) |  | (4.4 | ) |  | 133.8 |
Earnings available for common stock |  |  |  |  |  |  | 120.4 |
Nine Months Ended September 30, 2018 |  |  |  |  |  |  |
Revenues |  | $1,337.0 |  |  |  | $177.0 |  |  |  | $34.2 |  |  |  | $1,548.2 |
Operating income | 275.7 |  |  | 16.3 |  |  | 4.4 |  |  | 296.4 |
Earnings available for common stock |  |  |  |  |  |  | 224.9 |
Nine Months Ended September 30, 2017 |  |  |  |  |  |  |
Revenues |  | $1,217.6 |  |  |  | $147.2 |  |  |  | $33.3 |  |  |  | $1,398.1 |
Operating income (loss) | 239.2 |  |  | 15.4 |  |  | (1.4 | ) |  | 253.2 |
Earnings available for common stock |  |  |  |  |  |  | 200.4 |
WPL - Certain financial information relating to WPL’s business segments is as follows. Intersegment revenues were not material to WPL’s operations.
| Electric |  | Gas |  | Other |  | Total
| (in millions)
Three Months Ended September 30, 2018 |  |  |  |  |  |  |
Revenues |  | $352.0 |  |  |  | $18.1 |  |  |  | $0.6 |  |  |  | $370.7 |
Operating income (loss) | 104.0 |  |  | 1.1 |  |  | (0.9 | ) |  | 104.2 |
Earnings available for common stock |  |  |  |  |  |  | 76.3 |
Three Months Ended September 30, 2017 |  |  |  |  |  |  |
Revenues |  | $351.6 |  |  |  | $18.4 |  |  |  | $0.2 |  |  |  | $370.2 |
Operating income (loss) | 96.7 |  |  | 0.1 |  |  | (3.3 | ) |  | 93.5 |
Earnings available for common stock |  |  |  |  |  |  | 49.8 |
Nine Months Ended September 30, 2018 |  |  |  |  |  |  |
Revenues |  | $959.2 |  |  |  | $122.0 |  |  |  | $2.0 |  |  |  | $1,083.2 |
Operating income (loss) | 234.5 |  |  | 18.6 |  |  | (1.5 | ) |  | 251.6 |
Earnings available for common stock |  |  |  |  |  |  | 170.1 |
Nine Months Ended September 30, 2017 |  |  |  |  |  |  |
Revenues |  | $981.5 |  |  |  | $115.5 |  |  |  | $1.1 |  |  |  | $1,098.1 |
Operating income (loss) | 247.7 |  |  | 15.9 |  |  | (5.3 | ) |  | 258.3 |
Earnings available for common stock |  |  |  |  |  |  | 133.4 |
WPL [Member] |
Segment Reporting Information [Line Items] |
Segments Of Business | SEGMENTS OF BUSINESS In the fourth quarter of 2017, Alliant Energy and WPL modified the segment reporting related to ATC Holdings, consistent with information used by their chief operating decision maker to evaluate performance and allocate resources. As of December 31, 2017, ATC Holdings are no longer included in Alliant Energy’s utility electric operations reportable segment or WPL’s electric operations reportable segment. As a result, all prior period amounts impacted by this change were reclassified to conform to the new presentation. Alliant Energy’s related amounts were reclassified from “Electric Utility” to “ATC Holdings, Non-Utility, Parent and Other” in the table below. There was no resulting change to WPL’s segment reporting for the three and nine months ended September 30, 2017. Alliant Energy - Certain financial information relating to Alliant Energy’s business segments is as follows. Intersegment revenues were not material to Alliant Energy’s operations.
|  |  |  |  |  |  |  |  | ATC Holdings, |  | Alliant
| Utility |  | Non-Utility, |  | Energy
| Electric |  | Gas |  | Other |  | Total |  | Parent and Other |  | Consolidated
| (in millions)
Three Months Ended September 30, 2018 |  |  |  |  |  |  |  |  |  |  |
Revenues |  | $861.2 |  |  |  | $44.8 |  |  |  | $12.3 |  |  |  | $918.3 |  |  |  | $10.3 |  |  |  | $928.6 |
Operating income (loss) | 248.7 |  |  | (2.0 | ) |  | 0.6 |  |  | 247.3 |  |  | 8.8 |  |  | 256.1 |
Net income attributable to Alliant Energy common shareowners |  |  |  |  |  |  | 202.8 |  |  | 2.7 |  |  | 205.5 |
Three Months Ended September 30, 2017 |  |  |  |  |  |  |  |  |  |  |
Revenues |  | $840.6 |  |  |  | $45.8 |  |  |  | $11.2 |  |  |  | $897.6 |  |  |  | $9.3 |  |  |  | $906.9 |
Operating income (loss) | 236.7 |  |  | (1.7 | ) |  | (7.7 | ) |  | 227.3 |  |  | 9.0 |  |  | 236.3 |
Net income (loss) attributable to Alliant Energy common shareowners |  |  |  |  |  |  | 170.2 |  |  | (1.4 | ) |  | 168.8 |
|  |  |  |  |  |  |  |  | ATC Holdings, |  | Alliant
| Utility |  | Non-Utility, |  | Energy
| Electric |  | Gas |  | Other |  | Total |  | Parent and Other |  | Consolidated
| (in millions)
Nine Months Ended September 30, 2018 |  |  |  |  |  |  |  |  |  |  |
Revenues |  | $2,296.2 |  |  |  | $299.0 |  |  |  | $36.2 |  |  |  | $2,631.4 |  |  |  | $29.6 |  |  |  | $2,661.0 |
Operating income | 510.2 |  |  | 34.9 |  |  | 2.9 |  |  | 548.0 |  |  | 25.0 |  |  | 573.0 |
Net income attributable to Alliant Energy common shareowners |  |  |  |  |  |  | 395.0 |  |  | 31.8 |  |  | 426.8 |
Nine Months Ended September 30, 2017 |  |  |  |  |  |  |  |  |  |  |
Revenues |  | $2,199.1 |  |  |  | $262.7 |  |  |  | $34.4 |  |  |  | $2,496.2 |  |  |  | $29.9 |  |  |  | $2,526.1 |
Operating income (loss) | 486.9 |  |  | 31.3 |  |  | (6.7 | ) |  | 511.5 |  |  | 25.7 |  |  | 537.2 |
Amounts attributable to Alliant Energy common shareowners: |  |  |  |  |  |  |  |  |  |  |
Income from continuing operations, net of tax |  |  |  |  |  |  | 333.8 |  |  | 28.3 |  |  | 362.1 |
Income from discontinued operations, net of tax |  |  |  |  |  |  | — |  |  | 1.4 |  |  | 1.4 |
Net income |  |  |  |  |  |  | 333.8 |  |  | 29.7 |  |  | 363.5 |
IPL - Certain financial information relating to IPL’s business segments is as follows. Intersegment revenues were not material to IPL’s operations.
| Electric |  | Gas |  | Other |  | Total
| (in millions)
Three Months Ended September 30, 2018 |  |  |  |  |  |  |
Revenues |  | $509.2 |  |  |  | $26.7 |  |  |  | $11.7 |  |  |  | $547.6 |
Operating income (loss) | 144.7 |  |  | (3.1 | ) |  | 1.5 |  |  | 143.1 |
Earnings available for common stock |  |  |  |  |  |  | 126.5 |
Three Months Ended September 30, 2017 |  |  |  |  |  |  |
Revenues |  | $489.0 |  |  |  | $27.4 |  |  |  | $11.0 |  |  |  | $527.4 |
Operating income (loss) | 140.0 |  |  | (1.8 | ) |  | (4.4 | ) |  | 133.8 |
Earnings available for common stock |  |  |  |  |  |  | 120.4 |
Nine Months Ended September 30, 2018 |  |  |  |  |  |  |
Revenues |  | $1,337.0 |  |  |  | $177.0 |  |  |  | $34.2 |  |  |  | $1,548.2 |
Operating income | 275.7 |  |  | 16.3 |  |  | 4.4 |  |  | 296.4 |
Earnings available for common stock |  |  |  |  |  |  | 224.9 |
Nine Months Ended September 30, 2017 |  |  |  |  |  |  |
Revenues |  | $1,217.6 |  |  |  | $147.2 |  |  |  | $33.3 |  |  |  | $1,398.1 |
Operating income (loss) | 239.2 |  |  | 15.4 |  |  | (1.4 | ) |  | 253.2 |
Earnings available for common stock |  |  |  |  |  |  | 200.4 |
WPL - Certain financial information relating to WPL’s business segments is as follows. Intersegment revenues were not material to WPL’s operations.
| Electric |  | Gas |  | Other |  | Total
| (in millions)
Three Months Ended September 30, 2018 |  |  |  |  |  |  |
Revenues |  | $352.0 |  |  |  | $18.1 |  |  |  | $0.6 |  |  |  | $370.7 |
Operating income (loss) | 104.0 |  |  | 1.1 |  |  | (0.9 | ) |  | 104.2 |
Earnings available for common stock |  |  |  |  |  |  | 76.3 |
Three Months Ended September 30, 2017 |  |  |  |  |  |  |
Revenues |  | $351.6 |  |  |  | $18.4 |  |  |  | $0.2 |  |  |  | $370.2 |
Operating income (loss) | 96.7 |  |  | 0.1 |  |  | (3.3 | ) |  | 93.5 |
Earnings available for common stock |  |  |  |  |  |  | 49.8 |
Nine Months Ended September 30, 2018 |  |  |  |  |  |  |
Revenues |  | $959.2 |  |  |  | $122.0 |  |  |  | $2.0 |  |  |  | $1,083.2 |
Operating income (loss) | 234.5 |  |  | 18.6 |  |  | (1.5 | ) |  | 251.6 |
Earnings available for common stock |  |  |  |  |  |  | 170.1 |
Nine Months Ended September 30, 2017 |  |  |  |  |  |  |
Revenues |  | $981.5 |  |  |  | $115.5 |  |  |  | $1.1 |  |  |  | $1,098.1 |
Operating income (loss) | 247.7 |  |  | 15.9 |  |  | (5.3 | ) |  | 258.3 |
Earnings available for common stock |  |  |  |  |  |  | 133.4 |

X
- Definition The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -URI http://asc.fasb.org/topic&trid=2134510 + Details
Name: | us-gaap_SegmentReportingDisclosureTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_SegmentReportingInformationLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | dei_LegalEntityAxis=lnt_IplMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=lnt_WplMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |