Long Term Debt (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2015
Wis Elec Debenture due June 1, 2025 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount		$ 250
Debt Instrument, Interest Rate, Stated Percentage		3.10%
Wis Elec Debenture due June 1, 2044 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 250
Debt Instrument, Interest Rate, Stated Percentage	4.25%
Wis Elec Debentures due April 1, 2014 [Member]
Debt Instrument [Line Items]
Extinguishment of Debt, Amount	$ 300