Long Term Debt (Details) - USD ($) $ in Millions	1 Months Ended
	Jul. 31, 2015	Jun. 30, 2015	Apr. 30, 2014	May. 31, 2015	May. 31, 2014
Long Term Debt (Textuals)
Long-term Debt Assumed in Business Combination		$ 3,100.0
Fair Value Adjustment to Long-term Debt		45.7
WEC Senior Notes due June 15, 2018 [Member]
Long Term Debt (Textuals)
Issuance of long-term debt		$ 300.0
Interest rate on long-term debt		1.65%
WEC Senior Notes due June 15, 2020 [Member]
Long Term Debt (Textuals)
Issuance of long-term debt		$ 400.0
Interest rate on long-term debt		2.45%
WEC Senior Notes due June 15, 2025 [Member]
Long Term Debt (Textuals)
Issuance of long-term debt		$ 500.0
Interest rate on long-term debt		3.55%
Wis Elec Debenture due June 1, 2025 [Member]
Long Term Debt (Textuals)
Issuance of long-term debt				$ 250.0
Interest rate on long-term debt				3.10%
Wis Elec Debenture due June 1, 2044 [Member]
Long Term Debt (Textuals)
Issuance of long-term debt					$ 250.0
Interest rate on long-term debt					4.25%
Wis Elec Debentures due April 1, 2014 [Member]
Long Term Debt (Textuals)
Retirement of long-term debt			$ 300.0
Subsequent Event [Member] | TEG Senior Notes due June 1, 2016 [Member]
Long Term Debt (Textuals)
Offer to buy back $55 million 8% Senior Note	$ 55.0