Basis of Presentation (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Assets [Abstract]
Restricted cash	$ 50	$ 127
Accounts receivable	751	709
Securitized regulatory assets	456	577
Other assets	141	142
Total Assets	17,711	17,493
Liabilities [Abstract]
Current portion long-term debt, including, capital leases	258	470
Other current liabilities	182	215
Securitization bonds	302	479
Other long-term liabilities	103	115
Notes, Loans and Financing Receivable, Net, Noncurrent	4	4
Variable Interest Entity Securitization [Member]
Assets [Abstract]
Restricted cash	50	107
Accounts receivable	39	34
Securitized regulatory assets	456	577
Other assets	8	10
Total Assets	553	728
Liabilities [Abstract]
Accounts payable and accrued current liabilities	3	14
Current portion long-term debt, including, capital leases	177	164
Other current liabilities	55	55
Securitization bonds	302	479
Other long-term liabilities	7	7
Total Liabilities	$ 544	$ 719