Organization and Basis of Presentation (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Assets [Abstract]
Restricted cash	$ 96	$ 100
Accounts receivable	688	723
Securitized regulatory assets	34	231
Other current and long-term assets	182	149
Total Assets	18,649	17,410
Liabilities [Abstract]
Current portion long-term debt, including capital leases	118	504
Current regulatory liabilities	150	278
Securitization bonds	0	105
Other current and long-term liabilities	105	101
Variable Interest Entity Securitization [Member]
Assets [Abstract]
Restricted cash	96	100
Accounts receivable	26	34
Securitized regulatory assets	34	231
Other current and long-term assets	1	4
Total Assets	157	369
Liabilities [Abstract]
Accounts payable and accrued current liabilities	3	7
Current portion long-term debt, including capital leases	105	196
Current regulatory liabilities	32	43
Securitization bonds	0	105
Other current and long-term liabilities	9	8
Total Liabilities	$ 149	$ 359