REGULATORY ENVIRONMENT - WI 2018 and 2019 RATES (Details) - 2018 and 2019 rates - Public Service Commission of Wisconsin (PSCW) $ in Millions	1 Months Ended
	Sep. 30, 2017 USD ($)
Public Utilities, General Disclosures [Line Items]
Approved return on equity (as a percent)	10.00%
Authorized Revenue Requirement For ReACT	$ 275.0
Percentage of first 50 basis points of additional utility earnings shared with customers	50.00%
Return on equity in excess of authorized amount (as a percent)	0.50%