Subsequent Event (Details) (Subsequent Event [Member], USD $) In Millions, unless otherwise specified	Jan. 12, 2015
Subsequent Event [Member]
Subsequent Event [Line Items]
Carrying value of Michigan assets to be sold	$ 292
Unrecovered plant costs to be sought from customers	$ 190

Unrecovered plant costs to be sought from customers

No definition available.

Name:	wec_Unrecoveredplantcoststobesoughtfromcustomers
Namespace Prefix:	wec_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant