Financing (Details) (USD $)	3 Months Ended		0 Months Ended		0 Months Ended
	Mar. 31, 2013 First mortgage bonds EDE	Mar. 31, 2013 3.73% First Mortgage Bonds due 2033	Oct. 30, 2012 3.73% First Mortgage Bonds due 2033 Issuance of debt	Mar. 31, 2013 4.32% First Mortgage Bonds due 2043	Oct. 30, 2012 4.32% First Mortgage Bonds due 2043 Issuance of debt	Oct. 30, 2012 4.50% Series due June 15, 2013	Mar. 31, 2013 4.50% Series due June 15, 2013
Financing
Interest rate, stated percentage		3.73%		4.32%			4.50%
Debt to be redeemed						$ 98,000,000
Aggregate principal amount of debt entered into in private placement			30,000,000		120,000,000
Maximum principal amount outstanding at any one time	$ 1,000,000,000