DOCUMENT AND ENTITY INFORMATION	9 Months Ended
	Sep. 30, 2018 shares
Document Entity Information [Abstract]
Entity registrant name	WEC Energy Group, Inc.
Entity central index key	0000783325
Current fiscal year end date	--12-31
Entity filer category	Large Accelerated Filer
Document type	10-Q
Document period end date	Sep. 30, 2018
Document fiscal year focus	2018
Document fiscal period focus	Q3
Amendment flag	false
Entity common stock, shares outstanding	315,526,051
Emerging growth company	false
Small company	false