Schedule I - Short-Term Notes Payable to Related Parties (Details) - WEC Energy Group - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Notes to parent company financial statements
Short-term notes payable to related parties	$ 241.3	$ 119.0
WBS
Notes to parent company financial statements
Short-term notes payable to related parties	131.1	0.0
WECC
Notes to parent company financial statements
Short-term notes payable to related parties	109.3	108.4
Wisvest
Notes to parent company financial statements
Short-term notes payable to related parties	$ 0.9	$ 10.6