Regulatory Environment - WI 2020 and 2021 Rates (Details) $ in Millions	1 Months Ended
	May 31, 2021 USD ($)	Dec. 31, 2019 USD ($) utility
WEPCo Environmental Trust Finance I, LLC | WEPCo Environmental Trust Bonds 1.578%, due 2035
Public Utilities, General Disclosures
Proceeds from Issuance of Debt	$ 118.8
Interest rate	1.578%
Public Service Commission of Wisconsin (PSCW) | 2020 and 2021 rates
Public Utilities, General Disclosures
Number of utilities filing rate request | utility		3
Number of utilities with earnings sharing mechanism | utility		3
Percentage of first 25 basis points of additional earnings retained by the utility		100.00%
Return on equity in excess of authorized amount (as a percent)		0.25%
Percentage of additional earnings between 25 and 75 basis points refunded to customers		50.00%
Return on equity in excess of first 25 basis points above authorized amount (as a percent)		0.50%
Percentage of earnings in excess of 75 basis points refunded to customers		100.00%
Public Service Commission of Wisconsin (PSCW) | 2020 and 2021 rates | Electric rates | Tax Cuts and Jobs Act of 2017
Public Utilities, General Disclosures
Amortization period		2 years
Public Service Commission of Wisconsin (PSCW) | 2020 and 2021 rates | Natural gas rates | Tax Cuts and Jobs Act of 2017
Public Utilities, General Disclosures
Number of utilities filing rate request | utility		3
Amortization period		4 years
Public Service Commission of Wisconsin (PSCW) | WE | 2020 rates | Electric rates
Public Utilities, General Disclosures
Approved rate increase		$ 15.3
Approved rate increase (as a percent)		0.50%
Public Service Commission of Wisconsin (PSCW) | WE | 2020 rates | Electric rates | Tax Cuts and Jobs Act of 2017
Public Utilities, General Disclosures
Amortization of regulatory liabilities		$ 65.0
Public Service Commission of Wisconsin (PSCW) | WE | 2020 rates | Natural gas rates
Public Utilities, General Disclosures
Approved rate increase		$ 10.4
Approved rate increase (as a percent)		2.80%
Public Service Commission of Wisconsin (PSCW) | WE | 2020 rates | Natural gas rates | Tax Cuts and Jobs Act of 2017
Public Utilities, General Disclosures
Amortization of regulatory liabilities		$ (5.0)
Public Service Commission of Wisconsin (PSCW) | WE | 2020 rates | Steam rates
Public Utilities, General Disclosures
Approved rate increase		$ 1.9
Approved rate increase (as a percent)		8.60%
Public Service Commission of Wisconsin (PSCW) | WE | 2021 rates | Electric rates | Tax Cuts and Jobs Act of 2017
Public Utilities, General Disclosures
Amortization of regulatory liabilities		$ 65.0
Public Service Commission of Wisconsin (PSCW) | WE | 2021 rates | Natural gas rates | Tax Cuts and Jobs Act of 2017
Public Utilities, General Disclosures
Amortization of regulatory liabilities		$ (5.0)
Public Service Commission of Wisconsin (PSCW) | WE | 2020 and 2021 rates
Public Utilities, General Disclosures
Approved return on equity (as a percent)		10.00%
Approved common equity component average (as a percent)		52.50%
Public Service Commission of Wisconsin (PSCW) | WE | 2020 and 2021 rates | Electric rates
Public Utilities, General Disclosures
Pleasant Prairie power plant's book value to be securitized		$ 100.0
Public Service Commission of Wisconsin (PSCW) | WPS | 2020 rates | Electric rates
Public Utilities, General Disclosures
Approved rate increase		$ 15.8
Approved rate increase (as a percent)		1.60%
Public Service Commission of Wisconsin (PSCW) | WPS | 2020 rates | Electric rates | Tax Cuts and Jobs Act of 2017
Public Utilities, General Disclosures
Amortization of regulatory liabilities		$ 11.0
Public Service Commission of Wisconsin (PSCW) | WPS | 2020 rates | Natural gas rates
Public Utilities, General Disclosures
Approved rate increase		$ 4.3
Approved rate increase (as a percent)		1.40%
Public Service Commission of Wisconsin (PSCW) | WPS | 2020 rates | Natural gas rates | Tax Cuts and Jobs Act of 2017
Public Utilities, General Disclosures
Amortization of regulatory liabilities		$ 5.0
Public Service Commission of Wisconsin (PSCW) | WPS | 2021 rates | Electric rates | Tax Cuts and Jobs Act of 2017
Public Utilities, General Disclosures
Amortization of regulatory liabilities		39.0
Public Service Commission of Wisconsin (PSCW) | WPS | 2021 rates | Natural gas rates | Tax Cuts and Jobs Act of 2017
Public Utilities, General Disclosures
Amortization of regulatory liabilities		$ 5.0
Public Service Commission of Wisconsin (PSCW) | WPS | 2020 and 2021 rates
Public Utilities, General Disclosures
Approved return on equity (as a percent)		10.00%
Approved common equity component average (as a percent)		52.50%
Public Service Commission of Wisconsin (PSCW) | WPS | 2020 and 2021 rates | Electric rates
Public Utilities, General Disclosures
Authorized revenue requirement for ReACT		$ 275.0
Cost of the ReACT project, excluding AFUDC		$ 342.0
Public Service Commission of Wisconsin (PSCW) | WPS | 2020 and 2021 rates | Electric rates | ReACT
Public Utilities, General Disclosures
Recovery period of regulatory asset		8 years
Public Service Commission of Wisconsin (PSCW) | WPS | 2020 and 2021 rates | Electric rates | Earnings sharing mechanisms
Public Utilities, General Disclosures
Amortization of regulatory liabilities		$ 21.0
Amortization period		2 years
Public Service Commission of Wisconsin (PSCW) | WG | 2020 rates | Natural gas rates
Public Utilities, General Disclosures
Approved rate increase		$ (1.5)
Approved rate increase (as a percent)		(0.20%)
Public Service Commission of Wisconsin (PSCW) | WG | 2020 rates | Natural gas rates | Tax Cuts and Jobs Act of 2017
Public Utilities, General Disclosures
Amortization of regulatory liabilities		$ 3.0
Public Service Commission of Wisconsin (PSCW) | WG | 2021 rates | Natural gas rates | Tax Cuts and Jobs Act of 2017
Public Utilities, General Disclosures
Amortization of regulatory liabilities		$ 3.0
Public Service Commission of Wisconsin (PSCW) | WG | 2020 and 2021 rates
Public Utilities, General Disclosures
Approved return on equity (as a percent)		10.20%
Approved common equity component average (as a percent)		52.50%
Public Service Commission of Wisconsin (PSCW) | WEPCo Environmental Trust Finance I, LLC | WEPCo Environmental Trust Bonds 1.578%, due 2035
Public Utilities, General Disclosures
Proceeds from Issuance of Debt	$ 118.8
Interest rate	1.578%