CONSOLIDATED STATEMENTS OF CAPITALIZATION - USD ($) $ in Thousands		Dec. 31, 2015	Dec. 31, 2014
Schedule of Capitalization, Long-term Debt [Line Items]
Unamortized discount		$ (3,131)	$ (2,519)
Total long-term debt, including current maturities		667,593	568,291
Less: current maturities		1,131	1,235
Total long-term debt		666,462	567,056
Common Stockholders' Equity
Common stock — 1,000,000 shares authorized of $100 par value; 933,000 shares outstanding at Dec. 31, 2015 and 2014, respectively		93,300	93,300
Additional paid in capital		394,553	322,276
Retained earnings		302,741	282,398
Accumulated other comprehensive loss		(209)	(285)
Total common stockholder’s equity		790,385	697,689
First Mortgage Bonds | Series Due Oct. 1, 2018
Schedule of Capitalization, Long-term Debt [Line Items]
Long-term debt, gross		150,000	150,000
First Mortgage Bonds | Series Due June 15, 2024
Schedule of Capitalization, Long-term Debt [Line Items]
Long-term debt, gross		200,000	100,000
First Mortgage Bonds | Series Due Sept. 1, 2038
Schedule of Capitalization, Long-term Debt [Line Items]
Long-term debt, gross		200,000	200,000
First Mortgage Bonds | Series Due Oct. 1, 2042
Schedule of Capitalization, Long-term Debt [Line Items]
Long-term debt, gross		100,000	100,000
City of La Crosse Resource Recovery Bond | Series Due Nov. 1, 2021
Schedule of Capitalization, Long-term Debt [Line Items]
Long-term debt, gross	[1]	18,600	18,600
Fort McCoy System Acquisition | Due Oct. 15, 2030
Schedule of Capitalization, Long-term Debt [Line Items]
Long-term debt, gross		490	523
Other
Schedule of Capitalization, Long-term Debt [Line Items]
Long-term debt, gross		$ 1,634	$ 1,687

[1] Resource recovery financing