CONSOLIDATED STATEMENTS OF CAPITALIZATION (Parenthetical)	12 Months Ended
	Dec. 31, 2014
First Mortgage Bonds [Member] | Series Due Oct. 1, 2018 [Member]
Long-Term Debt
Debt instrument, interest rate stated percentage (in hundredths)	5.25%
Debt instrument, maturity date	Oct. 01, 2018
First Mortgage Bonds [Member] | Series Due June 15, 2024
Long-Term Debt
Debt instrument, interest rate stated percentage (in hundredths)	3.30%
Debt instrument, maturity date	Jun. 15, 2024
First Mortgage Bonds [Member] | Series Due Sept. 1, 2038 [Member]
Long-Term Debt
Debt instrument, interest rate stated percentage (in hundredths)	6.375%
Debt instrument, maturity date	Sep. 01, 2038
First Mortgage Bonds [Member] | Series Due Oct. 1, 2042
Long-Term Debt
Debt instrument, interest rate stated percentage (in hundredths)	3.70%
Debt instrument, maturity date	Oct. 01, 2042
City of La Crosse Resource Recovery Bond [Member] | Series Due Nov. 1, 2021 [Member]
Long-Term Debt
Debt instrument, interest rate stated percentage (in hundredths)	6.00%
Debt instrument, maturity date	Nov. 01, 2021
Fort McCoy System Acquisition [Member] | Due Oct. 15, 2030 [Member]
Long-Term Debt
Debt instrument, interest rate stated percentage (in hundredths)	7.00%
Debt instrument, maturity date	Oct. 15, 2030