Schedule I - Cash Dividends Received from Subsidiaries (Details) - WEC Energy Group - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Notes to parent company financial statements
Cash dividends received from subsidiaries	$ 734.4	$ 538.8	$ 720.0
WE
Notes to parent company financial statements
Cash dividends received from subsidiaries	455.0	240.0	390.0
WG
Notes to parent company financial statements
Cash dividends received from subsidiaries	75.0	30.0	33.0
We Power
Notes to parent company financial statements
Cash dividends received from subsidiaries	197.9	262.8	297.0
ATC Holding LLC
Notes to parent company financial statements
Cash dividends received from subsidiaries	$ 6.5	$ 6.0	$ 0.0