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SHORT-TERM DEBT AND LINES OF CREDIT - REVOLVING CREDIT FACILITIES (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Revolving credit facilities
Short-term credit capacity	$ 3,140.0
Letters of credit issued inside credit facilities	2.3
Available capacity under existing credit facility	1,926.2
Term loan
Revolving credit facilities
Term loan outstanding	340.0	$ 0.0
Commercial paper
Revolving credit facilities
Commercial paper outstanding	871.5	$ 830.8
WE \| Credit facility maturing October 2022
Revolving credit facilities
Short-term credit capacity	500.0
WPS \| Credit facility maturing October 2022
Revolving credit facilities
Short-term credit capacity	400.0
WG \| Credit facility maturing October 2022
Revolving credit facilities
Short-term credit capacity	350.0
PGL \| Credit facility maturing October 2022
Revolving credit facilities
Short-term credit capacity	350.0
WEC Energy Group \| Term loan agreement maturing March 2021
Revolving credit facilities
Short-term credit capacity	340.0
WEC Energy Group \| Credit facility maturing October 2022
Revolving credit facilities
Short-term credit capacity	$ 1,200.0