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Regulatory Environment - Tax Cuts and Jobs Act of 2017 (Details) $ in Millions | 1 Months Ended
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May 31, 2018 customer | Feb. 28, 2018 Filings | Dec. 31, 2017 USD ($)
MPSC |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |
Number of filings required related to the Tax Cuts and Jobs Act of 2018 | Filings |  | 3 |
MPSC | WE |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |
Number of Electric Customers Served in Michigan | customer | 1 |  |
2018 and 2019 rates | Electric rates | Public Service Commission of Wisconsin (PSCW) | WE |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |
Percentage of current tax benefit from Tax Cuts and Jobs Act of 2017 to be used to reduce 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% |  |
2018 and 2019 rates | Electric rates | Public Service Commission of Wisconsin (PSCW) | WPS |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |
Percentage of current tax benefit from Tax Cuts and Jobs Act of 2017 to be used to reduce regulatory assets | 40.00% |  |
Percent of current tax benefit from Tax Cuts and Jobs Act of 2017 to be returned to customers via bill credits | 60.00% |  |
2018 and 2019 rates | Natural gas rates | Public Service Commission of Wisconsin (PSCW) | WE, WG, and WPS |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |
Percent of current tax benefit from Tax Cuts and Jobs Act of 2017 to be returned to customers via bill credits | 100.00% |  |
Tax Cuts and Jobs Act of 2017 | Regulated operations |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |
Estimated tax benefit related to the remeasurement of deferred income taxes from tax legislation | $ |  |  | $ 2,529

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- Definition Number of filings required related to the Tax Cuts and Jobs Act of 2018, which will be used to describe how benefits under this Act will be refunded to customers + References No definition available. + Details
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