Document and Entity Information Document - USD ($) $ in Billions	9 Months Ended
	Sep. 30, 2015	Jun. 30, 2015
Entity Information [Line Items]
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, 2015
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q3
Amendment Flag	false
Entity Common Stock, Shares Outstanding	315,684,451
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float		$ 14.2