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Commitments and Contingencies - Environmental Matters (Details) T in Millions, $ in Millions | 1 Months Ended | 12 Months Ended | 15 Months Ended
--- | --- | --- | ---
Oct. 31, 2020 States | Dec. 31, 2020 USD ($) performance_obligations T MW | Dec. 31, 2019 USD ($) | Mar. 31, 2019 MW
Climate Change | Electric |  |  |  |
Air Quality |  |  |  |
No other source category, except for EGUs, should contribute to GHG emissions above this percentage threshold |  | 3.00% |  |
Company goal met in 2019 for percentage of carbon dioxide emissions reductions by 2030 |  |  | 40.00% |
Company goal for percentage of carbon dioxide emissions reduction below 2005 levels by 2030 |  | 70.00% |  |
Company near-term goal for percentage carbon dioxide emission reduction goal by 2025 |  | 55.00% |  |
Capacity of coal generation retired since the beginning of 2018, in megawatts | MW |  |  |  | 1,800
Capacity of fossil-fueled generation to be retired by 2025, in megawatts | MW |  | 1,800 |  |
Per mile rate of methane emission reduction |  | 30.00% |  |
Carbon dioxide emissions | T |  | 20.1 |  |
Climate Change | Natural gas |  |  |  |
Air Quality |  |  |  |
Carbon dioxide emissions | T |  | 27.4 |  |
Cross State Air Pollution Rule Update Rule Revision | Electric |  |  |  |
Air Quality |  |  |  |
Number of states in group 2 for CSAPR update rule revision | States | 9 |  |  |
Number of states affected by the CSAPR update rule revision | States | 21 |  |  |
Steam Electric Effluent Guidelines | Electric |  |  |  |
Water Quality |  |  |  |
Number of new ELG rule requirements that affect our electric utilities | performance_obligations |  | 2 |  |
Expected capital investment to achieve required discharge limits |  | $ 110.0 |  |
Manufactured Gas Plant Remediation | Natural gas |  |  |  |
Manufactured Gas Plant Remediation |  |  |  |
Regulatory assets recorded for remediation of manufactured gas plant sites |  | 638.2 | $ 685.5 |
Reserves for future environmental remediation of manufactured gas plant sites |  | $ 532.9 | $ 589.2 |
Renewables, Efficiency, and Conservation | Electric | Wisconsin |  |  |  |
Renewables, Efficiency, and Conservation |  |  |  |
Annual state renewable portfolio requirement, as a percent |  | 10.00% |  |
Percent of annual operating revenues used to fund renewable program |  | 1.20% |  |
Renewables, Efficiency, and Conservation | Electric | Wisconsin | WE |  |  |  |
Renewables, Efficiency, and Conservation |  |  |  |
Required renewable energy percent achieved |  | 8.27% |  |
Renewables, Efficiency, and Conservation | Electric | Wisconsin | WPS |  |  |  |
Renewables, Efficiency, and Conservation |  |  |  |
Required renewable energy percent achieved |  | 9.74% |  |
Renewables, Efficiency, and Conservation | Electric | Michigan |  |  |  |
Renewables, Efficiency, and Conservation |  |  |  |
Annual state renewable portfolio requirement for 2019 and 2020, as a percent |  | 12.50% |  |
Energy optimization target, as a percent |  | 1.00% |  |
State renewable portfolio requirement for 2021, as a percent |  | 15.00% |  |

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