ACQUISITIONS - THUNDERHEAD (Details) - Thunderhead Wind Energy LLC $ in Millions	9 Months Ended
	Sep. 30, 2019 USD ($) MW
Business Acquisition [Line Items]
WEC's ownership interest in Thunderhead Wind Energy LLC	80.00%
Capacity of Thunderhead Wind Energy | MW	300
Acquisition purchase price | $	$ 338
Duration of offtake agreement for the sale of energy produced	12 years
Bonus depreciation percentage	100.00%