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 Aug. 15, 2041 [Member]	Dec. 31, 2011 Unsecured Senior Notes [Member] Senior E Due Oct. 1, 2016 [Member]	Dec. 31, 2011 Unsecured Senior Notes [Member] Senior G Due Dec. 1, 2018 [Member]	Dec. 31, 2011 Unsecured Senior Notes [Member] Senior C and D Due Oct. 1, 2033 [Member]	Dec. 31, 2011 Unsecured Senior Notes [Member] Senior F Due Oct. 1, 2036 [Member]	Dec. 31, 2011 Pollution Control Obligations, Securing Pollution Control Revenue Bonds [Member] Due July 1, 2011 [Member]	Dec. 31, 2011 Pollution Control Obligations, Securing Pollution Control Revenue Bonds [Member] Due Sept. 1, 2016 [Member]
Long-Term Debt
Debt instrument, interest rate stated percentage (in hundredths)			4.50%	5.60%	8.75%	6.00%	6.00%	5.20%	5.75%
Debt instrument, maturity date			Aug. 15, 2041	Oct. 01, 2016	Dec. 01, 2018	Oct. 01, 2033	Oct. 01, 2036	Jul. 01, 2011	Sep. 01, 2016
Common Stockholders' Equity
Common stock, shares authorized (in shares)	200	200
Common stock, par value (in dollars per share)	$ 1.00	$ 1.00
Common stock, shares outstanding (in shares)	100	100