Short-term Debt and Lines of Credit - Revolving Credit Facilities (Details) - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015
Line of Credit Facility [Line Items]
Short-term credit capacity	$ 2,500.0
Letters of credit issued inside credit facilities	26.0
Commercial Paper	927.8	$ 1,095.0
Available capacity under existing agreements	1,546.2
WEC Energy Group | Credit facility maturing December 2020
Line of Credit Facility [Line Items]
Short-term credit capacity	1,050.0
Wisconsin Electric | Credit facility maturing December 2020
Line of Credit Facility [Line Items]
Short-term credit capacity	500.0
WPS | Credit facility maturing December 2020
Line of Credit Facility [Line Items]
Short-term credit capacity	250.0
Wisconsin Gas | Credit facility maturing December 2020
Line of Credit Facility [Line Items]
Short-term credit capacity	350.0
PGL | Credit facility maturing December 2020
Line of Credit Facility [Line Items]
Short-term credit capacity	$ 350.0