CONSOLIDATED STATEMENTS OF CAPITALIZATION (Parenthetical) (USD $)			12 Months Ended
	Dec. 31, 2011 Common Stock [Member]	Dec. 31, 2010 Common Stock [Member]	Dec. 31, 2011 First Mortgage Bonds [Member] Series Due Oct. 1, 2012 [Member]	Dec. 31, 2011 First Mortgage Bonds [Member] Series Due March 1, 2013 [Member]	Dec. 31, 2011 First Mortgage Bonds [Member] Series Due April 1, 2014 [Member]	Dec. 31, 2011 First Mortgage Bonds [Member] Series Due Sept. 1, 2017 [Member]	Dec. 31, 2011 First Mortgage Bonds [Member] Series Due Aug. 1, 2018 [Member]	Dec. 31, 2011 First Mortgage Bonds [Member] Series Due Jan. 1, 2019 [Member]	Dec. 31, 2011 First Mortgage Bonds [Member] Series Due Nov. 15, 2020 [Member]	Dec. 31, 2011 First Mortgage Bonds [Member] Series Due Sept. 1, 2037 [Member]	Dec. 31, 2011 First Mortgage Bonds [Member] Series Due Aug. 1, 2038 [Member]	Dec. 31, 2011 First Mortgage Bonds [Member] Series Due Aug. 15, 2041 [Member]	Dec. 31, 2011 First Mortgage Bonds [Member] Series Due June 1, 2019 [Member]	Dec. 31, 2011 Capital Lease Obligations [Member]
Long-Term Debt
Debt instrument, interest rate stated percentage (in hundredths)			7.875%	4.875%	5.50%	4.375%	5.80%	5.10%	3.20%	6.25%	6.50%	4.75%	5.125%
Debt instrument, interest rate stated percentage rate range, minimum														11.20%
Debt instrument, interest rate stated percentage rate range, maximum														14.30%
Debt instrument, maturity date			Oct. 01, 2012	Mar. 01, 2013	Apr. 01, 2014	Sep. 01, 2017	Aug. 01, 2018	Jan. 01, 2019	Nov. 15, 2020	Sep. 01, 2037	Aug. 01, 2038	Aug. 15, 2041	Jun. 01, 2019
Common Stockholder's Equity
Common stock, shares authorized (in shares)	100	100
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares outstanding (in shares)	100	100