Commitments And Contingencies (Third-Party Power Purchase Agreements) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Qualifying Facilities [Member]
Third-Party Power Purchase Agreements [Line Items]
Long term contract for purchase commitments, date of contract expiration, beginning date	2015
Long term contract for purchase commitments, date of contract expiration, ending date	2028
Present value of fixed capacity payments, portion classified as current liabilities	$ 20	$ 23
Present value of fixed capacity payments, portion classified as noncurrent liabilities	54	74
Capitalized asset for fixed capacity payments for corresponding assets	74	97
Capitalized asset for fixed capacity payments, accumulated amortization	108	176
Renewable Energy [Member]
Third-Party Power Purchase Agreements [Line Items]
Long term contract for purchase commitments, date of contract expiration, beginning date	2016
Long term contract for purchase commitments, date of contract expiration, ending date	2043
Power Purchases and Electric Capacity [Member]
Third-Party Power Purchase Agreements [Line Items]
Long term contract for purchase commitments, date of contract expiration, beginning date	2015
Long term contract for purchase commitments, date of contract expiration, ending date	2033
Costs Of Power Purchase	$ 3,600	$ 3,000	$ 2,300