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Summary of Significant Accounting Policies Operating Revenues (Details) $ in Millions	1 Months Ended	12 Months Ended
	Aug. 31, 2018 MW	Dec. 31, 2018 USD ($) contract performance_obligations	Oct. 19, 2018
Bishop Hill III Wind Energy Center
Disaggregation of Operating Revenues
WEC's ownership interest in Bishop Hill III Wind Energy Center	80.00%
Capacity of Bishop Hill III Wind Energy Center \| MW	132
Additional Ownership Interest in Bishop Hill III Wind Energy Center		10.00%
Duration of offtake agreement for the sale of energy produced	22 years
Electric
Disaggregation of Operating Revenues
Number of performance obligations		1
Percent fuel costs can vary from the rate case approved costs before deferral is required		2.00%
Number of days payment is due		30 days
Electric \| Wholesale
Disaggregation of Operating Revenues
Number of performance obligations		2
Number of contracts \| contract		1
Natural gas
Disaggregation of Operating Revenues
Number of days payment is due		30 days
Other non-utility revenues \| Bishop Hill III Wind Energy Center
Disaggregation of Operating Revenues
Number of performance obligations		1
WEC's ownership interest in Bishop Hill III Wind Energy Center	80.00%
Capacity of Bishop Hill III Wind Energy Center \| MW	132
Additional Ownership Interest in Bishop Hill III Wind Energy Center			10.00%
Duration of offtake agreement for the sale of energy produced	22 years
Other non-utility revenues \| We Power revenues
Disaggregation of Operating Revenues
Revenues amortized from deferred revenue during the period \| $		$ 25.3
Other non-utility revenues \| Appliance service repairs \| Maximum
Disaggregation of Operating Revenues
Duration of contract for remaining performance obligations in contract		1 year