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 - SHORT-TERM BORROWINGS (Details) - USD ($) $ in Millions		3 Months Ended
	Mar. 30, 2020	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Short-term borrowings
Issuance of term loan		$ 0.0	$ 340.0
WEC Senior Notes 0.80% due 2024 \| WEC Energy Group
Short-term borrowings
Debt instrument stated interest rate percentage		0.80%
Commercial paper
Short-term borrowings
Commercial paper outstanding		$ 1,580.4		$ 1,436.9
Weighted-average interest rate on amounts outstanding		0.19%		0.21%
Average amount outstanding during the period		$ 1,445.3
Weighted-average interest rate during the period		0.18%
Term loan \| WEC Energy Group
Short-term borrowings
Term loan outstanding		$ 0.0		$ 340.0
Weighted-average interest rate on amounts outstanding				0.99%
Weighted-average interest rate during the period		0.99%
Issuance of term loan	$ 340.0
Length of term loan	364 days