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REGULATORY ENVIRONMENT (Details) $ in Millions | 1 Months Ended | 3 Months Ended |
--- | --- | --- | ---
Apr. 30, 2018 utility | Mar. 31, 2018 USD ($) customer Assurance | Feb. 28, 2018 USD ($) day Filings | Dec. 31, 2017 USD ($) | Nov. 30, 2017 USD ($) | Oct. 31, 2017 USD ($) MW | Sep. 30, 2017 USD ($) utility | Jan. 31, 2017 | Aug. 31, 2016 MW | Mar. 31, 2018 customer change Assurance | Mar. 31, 2017 | Apr. 02, 2018 wind_turbines MW
Regulatory environment |  |  |  |  |  |  |  |  |  |  |  |
Corporate federal tax rate |  |  |  |  |  |  |  |  |  | 21.00% | 35.00% |
Forward Wind Energy Center | Subsequent event |  |  |  |  |  |  |  |  |  |  |  |
Regulatory environment |  |  |  |  |  |  |  |  |  |  |  |
Number of wind turbines at Forward Wind Energy Center | wind_turbines |  |  |  |  |  |  |  |  |  |  |  | 86
Capacity of Foward Wind Energy Center | MW |  |  |  |  |  |  |  |  |  |  |  | 129
WE | Public Service Commission of Wisconsin (PSCW) | 2018 and 2019 rates |  |  |  |  |  |  |  |  |  |  |  |
Regulatory environment |  |  |  |  |  |  |  |  |  |  |  |
Approved return on equity (as a percent) |  |  |  |  |  |  | 10.20% |  |  |  |  |
Income Statement impact of flow through of repair related deferred tax liabilities | change |  |  |  |  |  |  |  |  |  | 0 |  |
WE | Michigan Public Service Commission (MPSC) |  |  |  |  |  |  |  |  |  |  |  |
Regulatory environment |  |  |  |  |  |  |  |  |  |  |  |
Number of retail electric customers served in Michigan | customer |  | 1 |  |  |  |  |  |  |  | 1 |  |
WG | Public Service Commission of Wisconsin (PSCW) | 2018 and 2019 rates |  |  |  |  |  |  |  |  |  |  |  |
Regulatory environment |  |  |  |  |  |  |  |  |  |  |  |
Approved return on equity (as a percent) |  |  |  |  |  |  | 10.30% |  |  |  |  |
WPS | Forward Wind Energy Center | Subsequent event |  |  |  |  |  |  |  |  |  |  |  |
Regulatory environment |  |  |  |  |  |  |  |  |  |  |  |
Number of utilities along with WPS that entered in an agreement to purchase Forward Wind Energy Center | utility | 2 |  |  |  |  |  |  |  |  |  |  |
WPS | Public Service Commission of Wisconsin (PSCW) | Forward Wind Energy Center | Subsequent event |  |  |  |  |  |  |  |  |  |  |  |
Regulatory environment |  |  |  |  |  |  |  |  |  |  |  |
Number of utilities along with WPS that entered in an agreement to purchase Forward Wind Energy Center | utility | 2 |  |  |  |  |  |  |  |  |  |  |
Number of wind turbines at Forward Wind Energy Center | wind_turbines |  |  |  |  |  |  |  |  |  |  |  | 86
Capacity of Foward Wind Energy Center | MW |  |  |  |  |  |  |  |  |  |  |  | 129
WPS | Public Service Commission of Wisconsin (PSCW) | 2018 and 2019 rates |  |  |  |  |  |  |  |  |  |  |  |
Regulatory environment |  |  |  |  |  |  |  |  |  |  |  |
Approved return on equity (as a percent) |  |  |  |  |  |  | 10.00% |  |  |  |  |
Authorized revenue requirement for the ReACT project |  |  |  |  |  |  | $ 275.0 |  |  |  |  |
AFUDC |  |  |  |  |  |  | 51.0 |  |  |  |  |
Estimated cost of the ReACT project, excluding AFUDC |  |  |  |  |  |  | $ 342.0 |  |  |  |  |
WE, WG, and WPS | Public Service Commission of Wisconsin (PSCW) | Natural gas storage facilities in Michigan |  |  |  |  |  |  |  |  |  |  |  |
Regulatory environment |  |  |  |  |  |  |  |  |  |  |  |
Percentage of natural gas storage needs provided by the facilities |  |  |  |  |  |  |  | 33.33% |  |  |  |
WE, WG, and WPS | Public Service Commission of Wisconsin (PSCW) | 2018 and 2019 rates |  |  |  |  |  |  |  |  |  |  |  |
Regulatory environment |  |  |  |  |  |  |  |  |  |  |  |
Number of utilities with earnings sharing mechanism | utility |  |  |  |  |  |  | 3 |  |  |  |  |
Percentage of first 50 basis points of additional utility earnings shared with customers |  |  |  |  |  |  | 50.00% |  |  |  |  |
Return on equity in excess of authorized amount (as a percent) |  |  |  |  |  |  | 0.50% |  |  |  |  |
WE, WG, and WPS | Public Service Commission of Wisconsin (PSCW) | 2018 and 2019 rates | Natural gas rates | Subsequent event |  |  |  |  |  |  |  |  |  |  |  |
Regulatory environment |  |  |  |  |  |  |  |  |  |  |  |
Percent of current tax benefit from Tax Cuts and Jobs Act of 2017 to be returned to customers via bill credits | 100.00% |  |  |  |  |  |  |  |  |  |  |
WE and WPS | Public Service Commission of Wisconsin (PSCW) | 2018 and 2019 rates | Electric rates | Subsequent event |  |  |  |  |  |  |  |  |  |  |  |
Regulatory environment |  |  |  |  |  |  |  |  |  |  |  |
Percentage of current tax benefit from Tax Cuts and Jobs Act of 2017 to be used to reduce certain regulatory assets | 80.00% |  |  |  |  |  |  |  |  |  |  |
Percent of current tax benefit from Tax Cuts and Jobs Act of 2017 to be returned to customers via bill credits | 20.00% |  |  |  |  |  |  |  |  |  |  |
PGL | Illinois Commerce Commission (ICC) |  |  |  |  |  |  |  |  |  |  |  |
Regulatory environment |  |  |  |  |  |  |  |  |  |  |  |
Amount of rate base reduction as a result of a settlement |  |  | $ 5.4 |  |  |  |  |  |  |  |  |
Amount to be refunded to ratepayers as a result of a settlement |  |  | $ 4.7 |  |  |  |  |  |  |  |  |
Amount of assurance that PGL's QIP rider costs will be recoverable | Assurance |  | 0 |  |  |  |  |  |  |  | 0 |  |
MGU and UMERC | Michigan Public Service Commission (MPSC) |  |  |  |  |  |  |  |  |  |  |  |
Regulatory environment |  |  |  |  |  |  |  |  |  |  |  |
Number of filings required related to the Tax Cuts and Jobs Act of 2017 | Filings |  |  | 3 |  |  |  |  |  |  |  |  |
Number of days between the first and second filing related to the impact on base rates for the change in tax expense associated with the Tax Cuts and Jobs Act of 2017 | day |  |  | 30 |  |  |  |  |  |  |  |  |
MERC | Minnesota Public Utilities Commission (MPUC) | 2018 rates | Natural gas rates |  |  |  |  |  |  |  |  |  |  |  |
Regulatory environment |  |  |  |  |  |  |  |  |  |  |  |
Requested rate increase |  |  |  |  |  | $ 12.6 |  |  |  |  |  |
Requested rate increase (as a percent) |  |  |  |  |  | 5.05% |  |  |  |  |  |
Requested return on equity (as a percent) |  |  |  |  |  | 10.30% |  |  |  |  |  |
Requested common equity component average (as a percent) |  |  |  |  |  | 50.90% |  |  |  |  |  |
Interim rate increase |  | $ 7.0 |  |  | $ 9.5 |  |  |  |  |  |  |
Interim rate increase, (as a percent) |  | 2.81% |  |  | 3.78% |  |  |  |  |  |  |
Interim rate reduction |  | $ 2.5 |  |  |  |  |  |  |  |  |  |
Interim rates return on equity (as a percent) |  | 9.10% |  |  |  |  |  |  |  |  |  |
Interim rates common equity component average (as a percent) |  | 50.90% |  |  |  |  |  |  |  |  |  |
UMERC |  |  |  |  |  |  |  |  |  |  |  |
Regulatory environment |  |  |  |  |  |  |  |  |  |  |  |
Capacity of natural gas-fired generation facility (in megawatts) | MW |  |  |  |  |  | 180 |  |  |  |  |  |
UMERC | Michigan Public Service Commission (MPSC) |  |  |  |  |  |  |  |  |  |  |  |
Regulatory environment |  |  |  |  |  |  |  |  |  |  |  |
Term of electric power purchase agreement (in years) |  |  |  |  |  |  |  |  | 20 years |  |  |
Capacity of natural gas-fired generation facility (in megawatts) | MW |  |  |  |  |  |  |  |  | 180 |  |  |
Estimated cost of constructing a power plant |  |  |  |  |  | $ 266.0 |  |  |  |  |  |
Estimated cost of constructing a power plant, including AFUDC |  |  |  |  |  | $ 277.0 |  |  |  |  |  |
Portion of the power plant costs recoverable from Tilden Mining Company (as a percent) |  |  |  |  |  | 50.00% |  |  |  |  |  |
Portion of the power plant costs recoverable from utility customers (as a percent) |  |  |  |  |  | 50.00% |  |  |  |  |  |
Utility Operations | Tax Cuts And Jobs Act Of 2017 |  |  |  |  |  |  |  |  |  |  |  |
Regulatory environment |  |  |  |  |  |  |  |  |  |  |  |
Change in deferred taxes from tax legislation |  |  |  | $ 2,450.0 |  |  |  |  |  |  |  |

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