ACQUISITION CONSIDERATION TRANSFERRED (Details) - Forward Wind Energy Center Acquisition $ in Millions	1 Months Ended
Apr. 30, 2018 USD ($) utility	Apr. 02, 2018 wind_turbines MW
Business Acquisition [Line Items]
Number of utilities along with WPS that entered in an agreement to purchase Forward Wind Energy Center \| utility	2
Number of wind turbines at Forward Wind Energy Center \| wind_turbines		86
Capacity of Foward Wind Energy Center \| MW		129
Purchase price	$ 172.9
WPS
Business Acquisition [Line Items]
Purchase price	$ 77.1
WPS's share of Forward Wind Energy Center's purchase price	44.60%
Percentage of Forward Wind Energy Center's output purchased by WPS		44.60%

Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer.

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