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v3.19.1

Regulatory Matters (Tables) | 3 Months Ended
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Mar. 31, 2019
Regulatory Assets [Line Items] |
Regulatory Assets | Regulatory assets were comprised of the following items (in millions):
| Alliant Energy |  | IPL |  | WPL
| March 31, 2019 |  | December 31, 2018 |  | March 31, 2019 |  | December 31, 2018 |  | March 31, 2019 |  | December 31, 2018
Tax-related |  | $802.9 |  |  |  | $820.6 |  |  |  | $770.2 |  |  |  | $783.1 |  |  |  | $32.7 |  |  |  | $37.5 |
Pension and OPEB costs | 532.6 |  |  | 542.3 |  |  | 269.3 |  |  | 274.0 |  |  | 263.3 |  |  | 268.3 |
Asset retirement obligations | 112.1 |  |  | 110.8 |  |  | 77.5 |  |  | 76.3 |  |  | 34.6 |  |  | 34.5 |
EGUs retired early | 107.3 |  |  | 111.6 |  |  | 53.6 |  |  | 55.4 |  |  | 53.7 |  |  | 56.2 |
IPL’s DAEC PPA amendment | 106.5 |  |  | — |  |  | 106.5 |  |  | — |  |  | — |  |  | — |
Emission allowances | 23.0 |  |  | 23.6 |  |  | 23.0 |  |  | 23.6 |  |  | — |  |  | — |
Derivatives | 16.9 |  |  | 28.0 |  |  | 8.0 |  |  | 15.1 |  |  | 8.9 |  |  | 12.9 |
Other | 91.1 |  |  | 100.4 |  |  | 43.3 |  |  | 51.5 |  |  | 47.8 |  |  | 48.9 |
|  | $1,792.4 |  |  |  | $1,737.3 |  |  |  | $1,351.4 |  |  |  | $1,279.0 |  |  |  | $441.0 |  |  |  | $458.3 |
Regulatory Liabilities | Regulatory liabilities were comprised of the following items (in millions):
| Alliant Energy |  | IPL |  | WPL
| March 31, 2019 |  | December 31, 2018 |  | March 31, 2019 |  | December 31, 2018 |  | March 31, 2019 |  | December 31, 2018
Tax-related |  | $858.1 |  |  |  | $890.6 |  |  |  | $366.2 |  |  |  | $390.1 |  |  |  | $491.9 |  |  |  | $500.5 |
Cost of removal obligations | 402.7 |  |  | 401.2 |  |  | 273.4 |  |  | 273.3 |  |  | 129.3 |  |  | 127.9 |
Electric transmission cost recovery | 104.8 |  |  | 104.0 |  |  | 53.0 |  |  | 47.7 |  |  | 51.8 |  |  | 56.3 |
Commodity cost recovery | 43.2 |  |  | 16.8 |  |  | 32.2 |  |  | 11.9 |  |  | 11.0 |  |  | 4.9 |
WPL’s earnings sharing mechanism | 25.0 |  |  | 25.4 |  |  | — |  |  | — |  |  | 25.0 |  |  | 25.4 |
Other | 48.6 |  |  | 55.2 |  |  | 24.0 |  |  | 31.9 |  |  | 24.6 |  |  | 23.3 |
|  | $1,482.4 |  |  |  | $1,493.2 |  |  |  | $748.8 |  |  |  | $754.9 |  |  |  | $733.6 |  |  |  | $738.3 |
IPL [Member] |
Regulatory Assets [Line Items] |
Regulatory Assets | Regulatory assets were comprised of the following items (in millions):
| Alliant Energy |  | IPL |  | WPL
| March 31, 2019 |  | December 31, 2018 |  | March 31, 2019 |  | December 31, 2018 |  | March 31, 2019 |  | December 31, 2018
Tax-related |  | $802.9 |  |  |  | $820.6 |  |  |  | $770.2 |  |  |  | $783.1 |  |  |  | $32.7 |  |  |  | $37.5 |
Pension and OPEB costs | 532.6 |  |  | 542.3 |  |  | 269.3 |  |  | 274.0 |  |  | 263.3 |  |  | 268.3 |
Asset retirement obligations | 112.1 |  |  | 110.8 |  |  | 77.5 |  |  | 76.3 |  |  | 34.6 |  |  | 34.5 |
EGUs retired early | 107.3 |  |  | 111.6 |  |  | 53.6 |  |  | 55.4 |  |  | 53.7 |  |  | 56.2 |
IPL’s DAEC PPA amendment | 106.5 |  |  | — |  |  | 106.5 |  |  | — |  |  | — |  |  | — |
Emission allowances | 23.0 |  |  | 23.6 |  |  | 23.0 |  |  | 23.6 |  |  | — |  |  | — |
Derivatives | 16.9 |  |  | 28.0 |  |  | 8.0 |  |  | 15.1 |  |  | 8.9 |  |  | 12.9 |
Other | 91.1 |  |  | 100.4 |  |  | 43.3 |  |  | 51.5 |  |  | 47.8 |  |  | 48.9 |
|  | $1,792.4 |  |  |  | $1,737.3 |  |  |  | $1,351.4 |  |  |  | $1,279.0 |  |  |  | $441.0 |  |  |  | $458.3 |
Regulatory Liabilities | Regulatory liabilities were comprised of the following items (in millions):
| Alliant Energy |  | IPL |  | WPL
| March 31, 2019 |  | December 31, 2018 |  | March 31, 2019 |  | December 31, 2018 |  | March 31, 2019 |  | December 31, 2018
Tax-related |  | $858.1 |  |  |  | $890.6 |  |  |  | $366.2 |  |  |  | $390.1 |  |  |  | $491.9 |  |  |  | $500.5 |
Cost of removal obligations | 402.7 |  |  | 401.2 |  |  | 273.4 |  |  | 273.3 |  |  | 129.3 |  |  | 127.9 |
Electric transmission cost recovery | 104.8 |  |  | 104.0 |  |  | 53.0 |  |  | 47.7 |  |  | 51.8 |  |  | 56.3 |
Commodity cost recovery | 43.2 |  |  | 16.8 |  |  | 32.2 |  |  | 11.9 |  |  | 11.0 |  |  | 4.9 |
WPL’s earnings sharing mechanism | 25.0 |  |  | 25.4 |  |  | — |  |  | — |  |  | 25.0 |  |  | 25.4 |
Other | 48.6 |  |  | 55.2 |  |  | 24.0 |  |  | 31.9 |  |  | 24.6 |  |  | 23.3 |
|  | $1,482.4 |  |  |  | $1,493.2 |  |  |  | $748.8 |  |  |  | $754.9 |  |  |  | $733.6 |  |  |  | $738.3 |
WPL [Member] |
Regulatory Assets [Line Items] |
Regulatory Assets | Regulatory assets were comprised of the following items (in millions):
| Alliant Energy |  | IPL |  | WPL
| March 31, 2019 |  | December 31, 2018 |  | March 31, 2019 |  | December 31, 2018 |  | March 31, 2019 |  | December 31, 2018
Tax-related |  | $802.9 |  |  |  | $820.6 |  |  |  | $770.2 |  |  |  | $783.1 |  |  |  | $32.7 |  |  |  | $37.5 |
Pension and OPEB costs | 532.6 |  |  | 542.3 |  |  | 269.3 |  |  | 274.0 |  |  | 263.3 |  |  | 268.3 |
Asset retirement obligations | 112.1 |  |  | 110.8 |  |  | 77.5 |  |  | 76.3 |  |  | 34.6 |  |  | 34.5 |
EGUs retired early | 107.3 |  |  | 111.6 |  |  | 53.6 |  |  | 55.4 |  |  | 53.7 |  |  | 56.2 |
IPL’s DAEC PPA amendment | 106.5 |  |  | — |  |  | 106.5 |  |  | — |  |  | — |  |  | — |
Emission allowances | 23.0 |  |  | 23.6 |  |  | 23.0 |  |  | 23.6 |  |  | — |  |  | — |
Derivatives | 16.9 |  |  | 28.0 |  |  | 8.0 |  |  | 15.1 |  |  | 8.9 |  |  | 12.9 |
Other | 91.1 |  |  | 100.4 |  |  | 43.3 |  |  | 51.5 |  |  | 47.8 |  |  | 48.9 |
|  | $1,792.4 |  |  |  | $1,737.3 |  |  |  | $1,351.4 |  |  |  | $1,279.0 |  |  |  | $441.0 |  |  |  | $458.3 |
Regulatory Liabilities | Regulatory liabilities were comprised of the following items (in millions):
| Alliant Energy |  | IPL |  | WPL
| March 31, 2019 |  | December 31, 2018 |  | March 31, 2019 |  | December 31, 2018 |  | March 31, 2019 |  | December 31, 2018
Tax-related |  | $858.1 |  |  |  | $890.6 |  |  |  | $366.2 |  |  |  | $390.1 |  |  |  | $491.9 |  |  |  | $500.5 |
Cost of removal obligations | 402.7 |  |  | 401.2 |  |  | 273.4 |  |  | 273.3 |  |  | 129.3 |  |  | 127.9 |
Electric transmission cost recovery | 104.8 |  |  | 104.0 |  |  | 53.0 |  |  | 47.7 |  |  | 51.8 |  |  | 56.3 |
Commodity cost recovery | 43.2 |  |  | 16.8 |  |  | 32.2 |  |  | 11.9 |  |  | 11.0 |  |  | 4.9 |
WPL’s earnings sharing mechanism | 25.0 |  |  | 25.4 |  |  | — |  |  | — |  |  | 25.0 |  |  | 25.4 |
Other | 48.6 |  |  | 55.2 |  |  | 24.0 |  |  | 31.9 |  |  | 24.6 |  |  | 23.3 |
|  | $1,482.4 |  |  |  | $1,493.2 |  |  |  | $748.8 |  |  |  | $754.9 |  |  |  | $733.6 |  |  |  | $738.3 |

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