XML 48 R25.htm IDEA: XBRL DOCUMENT
v3.20.2

Common Equity (Tables) | 6 Months Ended
--- | ---
Jun. 30, 2020
Schedule of Capitalization, Equity [Line Items] |
Common Share Activity | A summary of Alliant Energy’s common stock activity was as follows:
Shares outstanding, January 1, 2020 | 245,022,800 |
Equity forward agreements | 4,275,127 |
Shareowner Direct Plan | 248,220 |
Equity-based compensation plans | 98,205 |
Shares outstanding, June 30, 2020 | 249,644,352 |
Changes in Shareowners' Equity | A summary of changes in shareowners’ equity was as follows (in millions):
Alliant Energy | Total Alliant Energy Common Equity |  |  |  |
|  |  |  |  |  |  | Accumulated |  | Shares in |  | Cumulative |  |
|  |  | Additional |  |  |  | Other |  | Deferred |  | Preferred |  |
| Common |  | Paid-In |  | Retained |  | Comprehensive |  | Compensation |  | Stock |  | Total
| Stock |  | Capital |  | Earnings |  | Income (Loss) |  | Trust |  | of IPL |  | Equity
Three Months Ended June 30, 2020 |  |  |  |  |  |  |  |  |  |  |  |  |
Beginning balance, March 31, 2020 |  | $2.5 |  |  |  | $2,674.1 |  |  |  | $2,833.7 |  |  |  | $2.0 |  |  |  | ($9.9 | ) |  |  | $200.0 |  |  |  | $5,702.4 |
Net income attributable to Alliant Energy common shareowners |  |  |  |  | 134.4 |  |  |  |  |  |  |  |  | 134.4 |
Common stock dividends ($0.38 per share) |  |  |  |  | (94.6 | ) |  |  |  |  |  |  |  | (94.6 | )
Shareowner Direct Plan issuances |  |  |  | 6.4 |  |  |  |  |  |  |  |  |  |  | 6.4 |
Equity-based compensation plans and other |  |  | 2.6 |  |  |  |  |  |  | (0.3 | ) |  |  |  | 2.3 |
Other comprehensive loss, net of tax |  |  |  |  |  |  | (2.6 | ) |  |  |  |  |  | (2.6 | )
Ending balance, June 30, 2020 |  | $2.5 |  |  |  | $2,683.1 |  |  |  | $2,873.5 |  |  |  | ($0.6 | ) |  |  | ($10.2 | ) |  |  | $200.0 |  |  |  | $5,748.3 |
Three Months Ended June 30, 2019 |  |  |  |  |  |  |  |  |  |  |  |  |
Beginning balance, March 31, 2019 |  | $2.4 |  |  |  | $2,100.0 |  |  |  | $2,587.3 |  |  |  | $2.4 |  |  |  | ($9.7 | ) |  |  | $200.0 |  |  |  | $4,882.4 |
Net income attributable to Alliant Energy common shareowners |  |  |  |  | 94.6 |  |  |  |  |  |  |  |  | 94.6 |
Common stock dividends ($0.355 per share) |  |  |  |  | (84.1 | ) |  |  |  |  |  |  |  | (84.1 | )
Shareowner Direct Plan issuances |  |  |  | 6.0 |  |  |  |  |  |  |  |  |  |  | 6.0 |
Equity-based compensation plans and other |  |  | 2.4 |  |  |  |  |  |  | (0.3 | ) |  |  |  | 2.1 |
Other comprehensive loss, net of tax |  |  |  |  |  |  | (1.4 | ) |  |  |  |  |  | (1.4 | )
Ending balance, June 30, 2019 |  | $2.4 |  |  |  | $2,108.4 |  |  |  | $2,597.8 |  |  |  | $1.0 |  |  |  | ($10.0 | ) |  |  | $200.0 |  |  |  | $4,899.6 |
Alliant Energy | Total Alliant Energy Common Equity |  |  |  |
|  |  |  |  |  |  | Accumulated |  | Shares in |  | Cumulative |  |
|  |  | Additional |  |  |  | Other |  | Deferred |  | Preferred |  |
| Common |  | Paid-In |  | Retained |  | Comprehensive |  | Compensation |  | Stock |  | Total
| Stock |  | Capital |  | Earnings |  | Income (Loss) |  | Trust |  | of IPL |  | Equity
Six Months Ended June 30, 2020 |  |  |  |  |  |  |  |  |  |  |  |  |
Beginning balance, December 31, 2019 |  | $2.5 |  |  |  | $2,445.9 |  |  |  | $2,765.4 |  |  |  | $1.3 |  |  |  | ($10.0 | ) |  |  | $200.0 |  |  |  | $5,405.1 |
Net income attributable to Alliant Energy common shareowners |  |  |  |  | 304.4 |  |  |  |  |  |  |  |  | 304.4 |
Common stock dividends ($0.76 per share) |  |  |  |  | (187.6 | ) |  |  |  |  |  |  |  | (187.6 | )
Equity forward settlements and Shareowner Direct Plan issuances |  |  |  | 234.8 |  |  |  |  |  |  |  |  |  |  | 234.8 |
Equity-based compensation plans and other |  |  | 2.4 |  |  |  |  |  |  | (0.2 | ) |  |  |  | 2.2 |
Adoption of new accounting standard, net of tax (refer to Note 1(d)) |  |  |  |  | (8.7 | ) |  |  |  |  |  |  |  | (8.7 | )
Other comprehensive loss, net of tax |  |  |  |  |  |  | (1.9 | ) |  |  |  |  |  | (1.9 | )
Ending balance, June 30, 2020 |  | $2.5 |  |  |  | $2,683.1 |  |  |  | $2,873.5 |  |  |  | ($0.6 | ) |  |  | ($10.2 | ) |  |  | $200.0 |  |  |  | $5,748.3 |
Six Months Ended June 30, 2019 |  |  |  |  |  |  |  |  |  |  |  |  |
Beginning balance, December 31, 2018 |  | $2.4 |  |  |  | $2,045.5 |  |  |  | $2,545.9 |  |  |  | $1.7 |  |  |  | ($9.8 | ) |  |  | $200.0 |  |  |  | $4,785.7 |
Net income attributable to Alliant Energy common shareowners |  |  |  |  | 219.7 |  |  |  |  |  |  |  |  | 219.7 |
Common stock dividends ($0.71 per share) |  |  |  |  | (167.8 | ) |  |  |  |  |  |  |  | (167.8 | )
Equity forward settlements and Shareowner Direct Plan issuances |  |  | 60.6 |  |  |  |  |  |  |  |  |  |  | 60.6 |
Equity-based compensation plans and other |  |  | 2.3 |  |  |  |  |  |  | (0.2 | ) |  |  |  | 2.1 |
Other comprehensive loss, net of tax |  |  |  |  |  |  | (0.7 | ) |  |  |  |  |  | (0.7 | )
Ending balance, June 30, 2019 |  | $2.4 |  |  |  | $2,108.4 |  |  |  | $2,597.8 |  |  |  | $1.0 |  |  |  | ($10.0 | ) |  |  | $200.0 |  |  |  | $4,899.6 |
IPL | Total IPL Common Equity |  |  |  |
|  |  | Additional |  |  |  | Cumulative |  |
| Common |  | Paid-In |  | Retained |  | Preferred |  | Total
| Stock |  | Capital |  | Earnings |  | Stock |  | Equity
Three Months Ended June 30, 2020 |  |  |  |  |  |  |  |  |
Beginning balance, March 31, 2020 |  | $33.4 |  |  |  | $2,447.8 |  |  |  | $914.2 |  |  |  | $200.0 |  |  |  | $3,595.4 |
Net income available for common stock |  |  |  |  | 59.8 |  |  |  |  | 59.8 |
Common stock dividends |  |  |  |  | (59.1 | ) |  |  |  | (59.1 | )
Capital contributions from parent |  |  | 75.0 |  |  |  |  |  |  | 75.0 |
Ending balance, June 30, 2020 |  | $33.4 |  |  |  | $2,522.8 |  |  |  | $914.9 |  |  |  | $200.0 |  |  |  | $3,671.1 |
Three Months Ended June 30, 2019 |  |  |  |  |  |  |  |  |
Beginning balance, March 31, 2019 |  | $33.4 |  |  |  | $2,322.8 |  |  |  | $785.8 |  |  |  | $200.0 |  |  |  | $3,342.0 |
Net income available for common stock |  |  |  |  | 45.0 |  |  |  |  | 45.0 |
Common stock dividends |  |  |  |  | (41.9 | ) |  |  |  | (41.9 | )
Ending balance, June 30, 2019 |  | $33.4 |  |  |  | $2,322.8 |  |  |  | $788.9 |  |  |  | $200.0 |  |  |  | $3,345.1 |
IPL | Total IPL Common Equity |  |  |  |
|  |  | Additional |  |  |  | Cumulative |  |
| Common |  | Paid-In |  | Retained |  | Preferred |  | Total
| Stock |  | Capital |  | Earnings |  | Stock |  | Equity
Six Months Ended June 30, 2020 |  |  |  |  |  |  |  |  |
Beginning balance, December 31, 2019 |  | $33.4 |  |  |  | $2,347.8 |  |  |  | $890.6 |  |  |  | $200.0 |  |  |  | $3,471.8 |
Net income available for common stock |  |  |  |  | 142.4 |  |  |  |  | 142.4 |
Common stock dividends |  |  |  |  | (118.1 | ) |  |  |  | (118.1 | )
Capital contributions from parent |  |  | 175.0 |  |  |  |  |  |  | 175.0 |
Ending balance, June 30, 2020 |  | $33.4 |  |  |  | $2,522.8 |  |  |  | $914.9 |  |  |  | $200.0 |  |  |  | $3,671.1 |
Six Months Ended June 30, 2019 |  |  |  |  |  |  |  |  |
Beginning balance, December 31, 2018 |  | $33.4 |  |  |  | $2,222.8 |  |  |  | $774.5 |  |  |  | $200.0 |  |  |  | $3,230.7 |
Net income available for common stock |  |  |  |  | 98.3 |  |  |  |  | 98.3 |
Common stock dividends |  |  |  |  | (83.9 | ) |  |  |  | (83.9 | )
Capital contributions from parent |  |  | 100.0 |  |  |  |  |  |  | 100.0 |
Ending balance, June 30, 2019 |  | $33.4 |  |  |  | $2,322.8 |  |  |  | $788.9 |  |  |  | $200.0 |  |  |  | $3,345.1 |
WPL |  |  | Additional |  |  |  | Total
| Common |  | Paid-In |  | Retained |  | Common
| Stock |  | Capital |  | Earnings |  | Equity
Three Months Ended June 30, 2020 |  |  |  |  |  |  |
Beginning balance, March 31, 2020 |  | $66.2 |  |  |  | $1,459.0 |  |  |  | $910.9 |  |  |  | $2,436.1 |
Net income |  |  |  |  | 57.6 |  |  | 57.6 |
Common stock dividends |  |  |  |  | (41.9 | ) |  | (41.9 | )
Ending balance, June 30, 2020 |  | $66.2 |  |  |  | $1,459.0 |  |  |  | $926.6 |  |  |  | $2,451.8 |
Three Months Ended June 30, 2019 |  |  |  |  |  |  |
Beginning balance, March 31, 2019 |  | $66.2 |  |  |  | $1,309.0 |  |  |  | $804.0 |  |  |  | $2,179.2 |
Net income |  |  |  |  | 42.0 |  |  | 42.0 |
Common stock dividends |  |  |  |  | (36.0 | ) |  | (36.0 | )
Ending balance, June 30, 2019 |  | $66.2 |  |  |  | $1,309.0 |  |  |  | $810.0 |  |  |  | $2,185.2 |
WPL |  |  | Additional |  |  |  | Total
| Common |  | Paid-In |  | Retained |  | Common
| Stock |  | Capital |  | Earnings |  | Equity
Six Months Ended June 30, 2020 |  |  |  |  |  |  |
Beginning balance, December 31, 2019 |  | $66.2 |  |  |  | $1,434.0 |  |  |  | $863.4 |  |  |  | $2,363.6 |
Net income |  |  |  |  | 147.2 |  |  | 147.2 |
Common stock dividends |  |  |  |  | (84.0 | ) |  | (84.0 | )
Capital contributions from parent |  |  | 25.0 |  |  |  |  | 25.0 |
Ending balance, June 30, 2020 |  | $66.2 |  |  |  | $1,459.0 |  |  |  | $926.6 |  |  |  | $2,451.8 |
Six Months Ended June 30, 2019 |  |  |  |  |  |  |
Beginning balance, December 31, 2018 |  | $66.2 |  |  |  | $1,309.0 |  |  |  | $774.3 |  |  |  | $2,149.5 |
Net income |  |  |  |  | 107.7 |  |  | 107.7 |
Common stock dividends |  |  |  |  | (72.0 | ) |  | (72.0 | )
Ending balance, June 30, 2019 |  | $66.2 |  |  |  | $1,309.0 |  |  |  | $810.0 |  |  |  | $2,185.2 |
IPL [Member] |
Schedule of Capitalization, Equity [Line Items] |
Changes in Shareowners' Equity | A summary of changes in shareowners’ equity was as follows (in millions):
Alliant Energy | Total Alliant Energy Common Equity |  |  |  |
|  |  |  |  |  |  | Accumulated |  | Shares in |  | Cumulative |  |
|  |  | Additional |  |  |  | Other |  | Deferred |  | Preferred |  |
| Common |  | Paid-In |  | Retained |  | Comprehensive |  | Compensation |  | Stock |  | Total
| Stock |  | Capital |  | Earnings |  | Income (Loss) |  | Trust |  | of IPL |  | Equity
Three Months Ended June 30, 2020 |  |  |  |  |  |  |  |  |  |  |  |  |
Beginning balance, March 31, 2020 |  | $2.5 |  |  |  | $2,674.1 |  |  |  | $2,833.7 |  |  |  | $2.0 |  |  |  | ($9.9 | ) |  |  | $200.0 |  |  |  | $5,702.4 |
Net income attributable to Alliant Energy common shareowners |  |  |  |  | 134.4 |  |  |  |  |  |  |  |  | 134.4 |
Common stock dividends ($0.38 per share) |  |  |  |  | (94.6 | ) |  |  |  |  |  |  |  | (94.6 | )
Shareowner Direct Plan issuances |  |  |  | 6.4 |  |  |  |  |  |  |  |  |  |  | 6.4 |
Equity-based compensation plans and other |  |  | 2.6 |  |  |  |  |  |  | (0.3 | ) |  |  |  | 2.3 |
Other comprehensive loss, net of tax |  |  |  |  |  |  | (2.6 | ) |  |  |  |  |  | (2.6 | )
Ending balance, June 30, 2020 |  | $2.5 |  |  |  | $2,683.1 |  |  |  | $2,873.5 |  |  |  | ($0.6 | ) |  |  | ($10.2 | ) |  |  | $200.0 |  |  |  | $5,748.3 |
Three Months Ended June 30, 2019 |  |  |  |  |  |  |  |  |  |  |  |  |
Beginning balance, March 31, 2019 |  | $2.4 |  |  |  | $2,100.0 |  |  |  | $2,587.3 |  |  |  | $2.4 |  |  |  | ($9.7 | ) |  |  | $200.0 |  |  |  | $4,882.4 |
Net income attributable to Alliant Energy common shareowners |  |  |  |  | 94.6 |  |  |  |  |  |  |  |  | 94.6 |
Common stock dividends ($0.355 per share) |  |  |  |  | (84.1 | ) |  |  |  |  |  |  |  | (84.1 | )
Shareowner Direct Plan issuances |  |  |  | 6.0 |  |  |  |  |  |  |  |  |  |  | 6.0 |
Equity-based compensation plans and other |  |  | 2.4 |  |  |  |  |  |  | (0.3 | ) |  |  |  | 2.1 |
Other comprehensive loss, net of tax |  |  |  |  |  |  | (1.4 | ) |  |  |  |  |  | (1.4 | )
Ending balance, June 30, 2019 |  | $2.4 |  |  |  | $2,108.4 |  |  |  | $2,597.8 |  |  |  | $1.0 |  |  |  | ($10.0 | ) |  |  | $200.0 |  |  |  | $4,899.6 |
Alliant Energy | Total Alliant Energy Common Equity |  |  |  |
|  |  |  |  |  |  | Accumulated |  | Shares in |  | Cumulative |  |
|  |  | Additional |  |  |  | Other |  | Deferred |  | Preferred |  |
| Common |  | Paid-In |  | Retained |  | Comprehensive |  | Compensation |  | Stock |  | Total
| Stock |  | Capital |  | Earnings |  | Income (Loss) |  | Trust |  | of IPL |  | Equity
Six Months Ended June 30, 2020 |  |  |  |  |  |  |  |  |  |  |  |  |
Beginning balance, December 31, 2019 |  | $2.5 |  |  |  | $2,445.9 |  |  |  | $2,765.4 |  |  |  | $1.3 |  |  |  | ($10.0 | ) |  |  | $200.0 |  |  |  | $5,405.1 |
Net income attributable to Alliant Energy common shareowners |  |  |  |  | 304.4 |  |  |  |  |  |  |  |  | 304.4 |
Common stock dividends ($0.76 per share) |  |  |  |  | (187.6 | ) |  |  |  |  |  |  |  | (187.6 | )
Equity forward settlements and Shareowner Direct Plan issuances |  |  |  | 234.8 |  |  |  |  |  |  |  |  |  |  | 234.8 |
Equity-based compensation plans and other |  |  | 2.4 |  |  |  |  |  |  | (0.2 | ) |  |  |  | 2.2 |
Adoption of new accounting standard, net of tax (refer to Note 1(d)) |  |  |  |  | (8.7 | ) |  |  |  |  |  |  |  | (8.7 | )
Other comprehensive loss, net of tax |  |  |  |  |  |  | (1.9 | ) |  |  |  |  |  | (1.9 | )
Ending balance, June 30, 2020 |  | $2.5 |  |  |  | $2,683.1 |  |  |  | $2,873.5 |  |  |  | ($0.6 | ) |  |  | ($10.2 | ) |  |  | $200.0 |  |  |  | $5,748.3 |
Six Months Ended June 30, 2019 |  |  |  |  |  |  |  |  |  |  |  |  |
Beginning balance, December 31, 2018 |  | $2.4 |  |  |  | $2,045.5 |  |  |  | $2,545.9 |  |  |  | $1.7 |  |  |  | ($9.8 | ) |  |  | $200.0 |  |  |  | $4,785.7 |
Net income attributable to Alliant Energy common shareowners |  |  |  |  | 219.7 |  |  |  |  |  |  |  |  | 219.7 |
Common stock dividends ($0.71 per share) |  |  |  |  | (167.8 | ) |  |  |  |  |  |  |  | (167.8 | )
Equity forward settlements and Shareowner Direct Plan issuances |  |  | 60.6 |  |  |  |  |  |  |  |  |  |  | 60.6 |
Equity-based compensation plans and other |  |  | 2.3 |  |  |  |  |  |  | (0.2 | ) |  |  |  | 2.1 |
Other comprehensive loss, net of tax |  |  |  |  |  |  | (0.7 | ) |  |  |  |  |  | (0.7 | )
Ending balance, June 30, 2019 |  | $2.4 |  |  |  | $2,108.4 |  |  |  | $2,597.8 |  |  |  | $1.0 |  |  |  | ($10.0 | ) |  |  | $200.0 |  |  |  | $4,899.6 |
IPL | Total IPL Common Equity |  |  |  |
|  |  | Additional |  |  |  | Cumulative |  |
| Common |  | Paid-In |  | Retained |  | Preferred |  | Total
| Stock |  | Capital |  | Earnings |  | Stock |  | Equity
Three Months Ended June 30, 2020 |  |  |  |  |  |  |  |  |
Beginning balance, March 31, 2020 |  | $33.4 |  |  |  | $2,447.8 |  |  |  | $914.2 |  |  |  | $200.0 |  |  |  | $3,595.4 |
Net income available for common stock |  |  |  |  | 59.8 |  |  |  |  | 59.8 |
Common stock dividends |  |  |  |  | (59.1 | ) |  |  |  | (59.1 | )
Capital contributions from parent |  |  | 75.0 |  |  |  |  |  |  | 75.0 |
Ending balance, June 30, 2020 |  | $33.4 |  |  |  | $2,522.8 |  |  |  | $914.9 |  |  |  | $200.0 |  |  |  | $3,671.1 |
Three Months Ended June 30, 2019 |  |  |  |  |  |  |  |  |
Beginning balance, March 31, 2019 |  | $33.4 |  |  |  | $2,322.8 |  |  |  | $785.8 |  |  |  | $200.0 |  |  |  | $3,342.0 |
Net income available for common stock |  |  |  |  | 45.0 |  |  |  |  | 45.0 |
Common stock dividends |  |  |  |  | (41.9 | ) |  |  |  | (41.9 | )
Ending balance, June 30, 2019 |  | $33.4 |  |  |  | $2,322.8 |  |  |  | $788.9 |  |  |  | $200.0 |  |  |  | $3,345.1 |
IPL | Total IPL Common Equity |  |  |  |
|  |  | Additional |  |  |  | Cumulative |  |
| Common |  | Paid-In |  | Retained |  | Preferred |  | Total
| Stock |  | Capital |  | Earnings |  | Stock |  | Equity
Six Months Ended June 30, 2020 |  |  |  |  |  |  |  |  |
Beginning balance, December 31, 2019 |  | $33.4 |  |  |  | $2,347.8 |  |  |  | $890.6 |  |  |  | $200.0 |  |  |  | $3,471.8 |
Net income available for common stock |  |  |  |  | 142.4 |  |  |  |  | 142.4 |
Common stock dividends |  |  |  |  | (118.1 | ) |  |  |  | (118.1 | )
Capital contributions from parent |  |  | 175.0 |  |  |  |  |  |  | 175.0 |
Ending balance, June 30, 2020 |  | $33.4 |  |  |  | $2,522.8 |  |  |  | $914.9 |  |  |  | $200.0 |  |  |  | $3,671.1 |
Six Months Ended June 30, 2019 |  |  |  |  |  |  |  |  |
Beginning balance, December 31, 2018 |  | $33.4 |  |  |  | $2,222.8 |  |  |  | $774.5 |  |  |  | $200.0 |  |  |  | $3,230.7 |
Net income available for common stock |  |  |  |  | 98.3 |  |  |  |  | 98.3 |
Common stock dividends |  |  |  |  | (83.9 | ) |  |  |  | (83.9 | )
Capital contributions from parent |  |  | 100.0 |  |  |  |  |  |  | 100.0 |
Ending balance, June 30, 2019 |  | $33.4 |  |  |  | $2,322.8 |  |  |  | $788.9 |  |  |  | $200.0 |  |  |  | $3,345.1 |
WPL |  |  | Additional |  |  |  | Total
| Common |  | Paid-In |  | Retained |  | Common
| Stock |  | Capital |  | Earnings |  | Equity
Three Months Ended June 30, 2020 |  |  |  |  |  |  |
Beginning balance, March 31, 2020 |  | $66.2 |  |  |  | $1,459.0 |  |  |  | $910.9 |  |  |  | $2,436.1 |
Net income |  |  |  |  | 57.6 |  |  | 57.6 |
Common stock dividends |  |  |  |  | (41.9 | ) |  | (41.9 | )
Ending balance, June 30, 2020 |  | $66.2 |  |  |  | $1,459.0 |  |  |  | $926.6 |  |  |  | $2,451.8 |
Three Months Ended June 30, 2019 |  |  |  |  |  |  |
Beginning balance, March 31, 2019 |  | $66.2 |  |  |  | $1,309.0 |  |  |  | $804.0 |  |  |  | $2,179.2 |
Net income |  |  |  |  | 42.0 |  |  | 42.0 |
Common stock dividends |  |  |  |  | (36.0 | ) |  | (36.0 | )
Ending balance, June 30, 2019 |  | $66.2 |  |  |  | $1,309.0 |  |  |  | $810.0 |  |  |  | $2,185.2 |
WPL |  |  | Additional |  |  |  | Total
| Common |  | Paid-In |  | Retained |  | Common
| Stock |  | Capital |  | Earnings |  | Equity
Six Months Ended June 30, 2020 |  |  |  |  |  |  |
Beginning balance, December 31, 2019 |  | $66.2 |  |  |  | $1,434.0 |  |  |  | $863.4 |  |  |  | $2,363.6 |
Net income |  |  |  |  | 147.2 |  |  | 147.2 |
Common stock dividends |  |  |  |  | (84.0 | ) |  | (84.0 | )
Capital contributions from parent |  |  | 25.0 |  |  |  |  | 25.0 |
Ending balance, June 30, 2020 |  | $66.2 |  |  |  | $1,459.0 |  |  |  | $926.6 |  |  |  | $2,451.8 |
Six Months Ended June 30, 2019 |  |  |  |  |  |  |
Beginning balance, December 31, 2018 |  | $66.2 |  |  |  | $1,309.0 |  |  |  | $774.3 |  |  |  | $2,149.5 |
Net income |  |  |  |  | 107.7 |  |  | 107.7 |
Common stock dividends |  |  |  |  | (72.0 | ) |  | (72.0 | )
Ending balance, June 30, 2019 |  | $66.2 |  |  |  | $1,309.0 |  |  |  | $810.0 |  |  |  | $2,185.2 |
WPL [Member] |
Schedule of Capitalization, Equity [Line Items] |
Changes in Shareowners' Equity | A summary of changes in shareowners’ equity was as follows (in millions):
Alliant Energy | Total Alliant Energy Common Equity |  |  |  |
|  |  |  |  |  |  | Accumulated |  | Shares in |  | Cumulative |  |
|  |  | Additional |  |  |  | Other |  | Deferred |  | Preferred |  |
| Common |  | Paid-In |  | Retained |  | Comprehensive |  | Compensation |  | Stock |  | Total
| Stock |  | Capital |  | Earnings |  | Income (Loss) |  | Trust |  | of IPL |  | Equity
Three Months Ended June 30, 2020 |  |  |  |  |  |  |  |  |  |  |  |  |
Beginning balance, March 31, 2020 |  | $2.5 |  |  |  | $2,674.1 |  |  |  | $2,833.7 |  |  |  | $2.0 |  |  |  | ($9.9 | ) |  |  | $200.0 |  |  |  | $5,702.4 |
Net income attributable to Alliant Energy common shareowners |  |  |  |  | 134.4 |  |  |  |  |  |  |  |  | 134.4 |
Common stock dividends ($0.38 per share) |  |  |  |  | (94.6 | ) |  |  |  |  |  |  |  | (94.6 | )
Shareowner Direct Plan issuances |  |  |  | 6.4 |  |  |  |  |  |  |  |  |  |  | 6.4 |
Equity-based compensation plans and other |  |  | 2.6 |  |  |  |  |  |  | (0.3 | ) |  |  |  | 2.3 |
Other comprehensive loss, net of tax |  |  |  |  |  |  | (2.6 | ) |  |  |  |  |  | (2.6 | )
Ending balance, June 30, 2020 |  | $2.5 |  |  |  | $2,683.1 |  |  |  | $2,873.5 |  |  |  | ($0.6 | ) |  |  | ($10.2 | ) |  |  | $200.0 |  |  |  | $5,748.3 |
Three Months Ended June 30, 2019 |  |  |  |  |  |  |  |  |  |  |  |  |
Beginning balance, March 31, 2019 |  | $2.4 |  |  |  | $2,100.0 |  |  |  | $2,587.3 |  |  |  | $2.4 |  |  |  | ($9.7 | ) |  |  | $200.0 |  |  |  | $4,882.4 |
Net income attributable to Alliant Energy common shareowners |  |  |  |  | 94.6 |  |  |  |  |  |  |  |  | 94.6 |
Common stock dividends ($0.355 per share) |  |  |  |  | (84.1 | ) |  |  |  |  |  |  |  | (84.1 | )
Shareowner Direct Plan issuances |  |  |  | 6.0 |  |  |  |  |  |  |  |  |  |  | 6.0 |
Equity-based compensation plans and other |  |  | 2.4 |  |  |  |  |  |  | (0.3 | ) |  |  |  | 2.1 |
Other comprehensive loss, net of tax |  |  |  |  |  |  | (1.4 | ) |  |  |  |  |  | (1.4 | )
Ending balance, June 30, 2019 |  | $2.4 |  |  |  | $2,108.4 |  |  |  | $2,597.8 |  |  |  | $1.0 |  |  |  | ($10.0 | ) |  |  | $200.0 |  |  |  | $4,899.6 |
Alliant Energy | Total Alliant Energy Common Equity |  |  |  |
|  |  |  |  |  |  | Accumulated |  | Shares in |  | Cumulative |  |
|  |  | Additional |  |  |  | Other |  | Deferred |  | Preferred |  |
| Common |  | Paid-In |  | Retained |  | Comprehensive |  | Compensation |  | Stock |  | Total
| Stock |  | Capital |  | Earnings |  | Income (Loss) |  | Trust |  | of IPL |  | Equity
Six Months Ended June 30, 2020 |  |  |  |  |  |  |  |  |  |  |  |  |
Beginning balance, December 31, 2019 |  | $2.5 |  |  |  | $2,445.9 |  |  |  | $2,765.4 |  |  |  | $1.3 |  |  |  | ($10.0 | ) |  |  | $200.0 |  |  |  | $5,405.1 |
Net income attributable to Alliant Energy common shareowners |  |  |  |  | 304.4 |  |  |  |  |  |  |  |  | 304.4 |
Common stock dividends ($0.76 per share) |  |  |  |  | (187.6 | ) |  |  |  |  |  |  |  | (187.6 | )
Equity forward settlements and Shareowner Direct Plan issuances |  |  |  | 234.8 |  |  |  |  |  |  |  |  |  |  | 234.8 |
Equity-based compensation plans and other |  |  | 2.4 |  |  |  |  |  |  | (0.2 | ) |  |  |  | 2.2 |
Adoption of new accounting standard, net of tax (refer to Note 1(d)) |  |  |  |  | (8.7 | ) |  |  |  |  |  |  |  | (8.7 | )
Other comprehensive loss, net of tax |  |  |  |  |  |  | (1.9 | ) |  |  |  |  |  | (1.9 | )
Ending balance, June 30, 2020 |  | $2.5 |  |  |  | $2,683.1 |  |  |  | $2,873.5 |  |  |  | ($0.6 | ) |  |  | ($10.2 | ) |  |  | $200.0 |  |  |  | $5,748.3 |
Six Months Ended June 30, 2019 |  |  |  |  |  |  |  |  |  |  |  |  |
Beginning balance, December 31, 2018 |  | $2.4 |  |  |  | $2,045.5 |  |  |  | $2,545.9 |  |  |  | $1.7 |  |  |  | ($9.8 | ) |  |  | $200.0 |  |  |  | $4,785.7 |
Net income attributable to Alliant Energy common shareowners |  |  |  |  | 219.7 |  |  |  |  |  |  |  |  | 219.7 |
Common stock dividends ($0.71 per share) |  |  |  |  | (167.8 | ) |  |  |  |  |  |  |  | (167.8 | )
Equity forward settlements and Shareowner Direct Plan issuances |  |  | 60.6 |  |  |  |  |  |  |  |  |  |  | 60.6 |
Equity-based compensation plans and other |  |  | 2.3 |  |  |  |  |  |  | (0.2 | ) |  |  |  | 2.1 |
Other comprehensive loss, net of tax |  |  |  |  |  |  | (0.7 | ) |  |  |  |  |  | (0.7 | )
Ending balance, June 30, 2019 |  | $2.4 |  |  |  | $2,108.4 |  |  |  | $2,597.8 |  |  |  | $1.0 |  |  |  | ($10.0 | ) |  |  | $200.0 |  |  |  | $4,899.6 |
IPL | Total IPL Common Equity |  |  |  |
|  |  | Additional |  |  |  | Cumulative |  |
| Common |  | Paid-In |  | Retained |  | Preferred |  | Total
| Stock |  | Capital |  | Earnings |  | Stock |  | Equity
Three Months Ended June 30, 2020 |  |  |  |  |  |  |  |  |
Beginning balance, March 31, 2020 |  | $33.4 |  |  |  | $2,447.8 |  |  |  | $914.2 |  |  |  | $200.0 |  |  |  | $3,595.4 |
Net income available for common stock |  |  |  |  | 59.8 |  |  |  |  | 59.8 |
Common stock dividends |  |  |  |  | (59.1 | ) |  |  |  | (59.1 | )
Capital contributions from parent |  |  | 75.0 |  |  |  |  |  |  | 75.0 |
Ending balance, June 30, 2020 |  | $33.4 |  |  |  | $2,522.8 |  |  |  | $914.9 |  |  |  | $200.0 |  |  |  | $3,671.1 |
Three Months Ended June 30, 2019 |  |  |  |  |  |  |  |  |
Beginning balance, March 31, 2019 |  | $33.4 |  |  |  | $2,322.8 |  |  |  | $785.8 |  |  |  | $200.0 |  |  |  | $3,342.0 |
Net income available for common stock |  |  |  |  | 45.0 |  |  |  |  | 45.0 |
Common stock dividends |  |  |  |  | (41.9 | ) |  |  |  | (41.9 | )
Ending balance, June 30, 2019 |  | $33.4 |  |  |  | $2,322.8 |  |  |  | $788.9 |  |  |  | $200.0 |  |  |  | $3,345.1 |
IPL | Total IPL Common Equity |  |  |  |
|  |  | Additional |  |  |  | Cumulative |  |
| Common |  | Paid-In |  | Retained |  | Preferred |  | Total
| Stock |  | Capital |  | Earnings |  | Stock |  | Equity
Six Months Ended June 30, 2020 |  |  |  |  |  |  |  |  |
Beginning balance, December 31, 2019 |  | $33.4 |  |  |  | $2,347.8 |  |  |  | $890.6 |  |  |  | $200.0 |  |  |  | $3,471.8 |
Net income available for common stock |  |  |  |  | 142.4 |  |  |  |  | 142.4 |
Common stock dividends |  |  |  |  | (118.1 | ) |  |  |  | (118.1 | )
Capital contributions from parent |  |  | 175.0 |  |  |  |  |  |  | 175.0 |
Ending balance, June 30, 2020 |  | $33.4 |  |  |  | $2,522.8 |  |  |  | $914.9 |  |  |  | $200.0 |  |  |  | $3,671.1 |
Six Months Ended June 30, 2019 |  |  |  |  |  |  |  |  |
Beginning balance, December 31, 2018 |  | $33.4 |  |  |  | $2,222.8 |  |  |  | $774.5 |  |  |  | $200.0 |  |  |  | $3,230.7 |
Net income available for common stock |  |  |  |  | 98.3 |  |  |  |  | 98.3 |
Common stock dividends |  |  |  |  | (83.9 | ) |  |  |  | (83.9 | )
Capital contributions from parent |  |  | 100.0 |  |  |  |  |  |  | 100.0 |
Ending balance, June 30, 2019 |  | $33.4 |  |  |  | $2,322.8 |  |  |  | $788.9 |  |  |  | $200.0 |  |  |  | $3,345.1 |
WPL |  |  | Additional |  |  |  | Total
| Common |  | Paid-In |  | Retained |  | Common
| Stock |  | Capital |  | Earnings |  | Equity
Three Months Ended June 30, 2020 |  |  |  |  |  |  |
Beginning balance, March 31, 2020 |  | $66.2 |  |  |  | $1,459.0 |  |  |  | $910.9 |  |  |  | $2,436.1 |
Net income |  |  |  |  | 57.6 |  |  | 57.6 |
Common stock dividends |  |  |  |  | (41.9 | ) |  | (41.9 | )
Ending balance, June 30, 2020 |  | $66.2 |  |  |  | $1,459.0 |  |  |  | $926.6 |  |  |  | $2,451.8 |
Three Months Ended June 30, 2019 |  |  |  |  |  |  |
Beginning balance, March 31, 2019 |  | $66.2 |  |  |  | $1,309.0 |  |  |  | $804.0 |  |  |  | $2,179.2 |
Net income |  |  |  |  | 42.0 |  |  | 42.0 |
Common stock dividends |  |  |  |  | (36.0 | ) |  | (36.0 | )
Ending balance, June 30, 2019 |  | $66.2 |  |  |  | $1,309.0 |  |  |  | $810.0 |  |  |  | $2,185.2 |
WPL |  |  | Additional |  |  |  | Total
| Common |  | Paid-In |  | Retained |  | Common
| Stock |  | Capital |  | Earnings |  | Equity
Six Months Ended June 30, 2020 |  |  |  |  |  |  |
Beginning balance, December 31, 2019 |  | $66.2 |  |  |  | $1,434.0 |  |  |  | $863.4 |  |  |  | $2,363.6 |
Net income |  |  |  |  | 147.2 |  |  | 147.2 |
Common stock dividends |  |  |  |  | (84.0 | ) |  | (84.0 | )
Capital contributions from parent |  |  | 25.0 |  |  |  |  | 25.0 |
Ending balance, June 30, 2020 |  | $66.2 |  |  |  | $1,459.0 |  |  |  | $926.6 |  |  |  | $2,451.8 |
Six Months Ended June 30, 2019 |  |  |  |  |  |  |
Beginning balance, December 31, 2018 |  | $66.2 |  |  |  | $1,309.0 |  |  |  | $774.3 |  |  |  | $2,149.5 |
Net income |  |  |  |  | 107.7 |  |  | 107.7 |
Common stock dividends |  |  |  |  | (72.0 | ) |  | (72.0 | )
Ending balance, June 30, 2019 |  | $66.2 |  |  |  | $1,309.0 |  |  |  | $810.0 |  |  |  | $2,185.2 |

X
- Definition Tabular disclosure of an entity's capital units or capital shares, including the value of capital units or capital shares, units authorized, units outstanding and other information necessary to a fair presentation. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 946 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.6-04.16) -URI http://asc.fasb.org/extlink&oid=6488278&loc=d3e603758-122996 + Details
Name: | us-gaap_ScheduleOfCapitalUnitsTextBlock
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_ScheduleOfCapitalizationEquityLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of changes in the separate accounts comprising stockholders' equity (in addition to retained earnings) and of the changes in the number of shares of equity securities during at least the most recent annual fiscal period and any subsequent interim period presented is required to make the financial statements sufficiently informative if both financial position and results of operations are presented. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21463-112644 + Details
Name: | us-gaap_ScheduleOfStockholdersEquityTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
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: |