Carrying value as of the balance sheet date of short-term borrowings using unsecured obligations issued by banks, corporations and other borrowers to investors. The maturities of these money market securities generally do not exceed 270 days.

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SHORT-TERM DEBT AND LINES OF CREDIT - REVOLVING CREDIT FACILITIES (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Revolving credit facilities
Short-term credit capacity	$ 2,800.0
Available capacity under existing credit facility	1,217.3
Commercial paper
Revolving credit facilities
Commercial paper outstanding	1,580.4	$ 1,436.9
Letter of credit
Revolving credit facilities
Letters of credit issued inside credit facilities	2.3
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 \| Credit facility maturing October 2022
Revolving credit facilities
Short-term credit capacity	$ 1,200.0