Organization and Basis of Presentation (Consolidated Variable Interest Entities) (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2013	Dec. 31, 2012
Assets [Abstract]
Cash and cash equivalents	$ 60	$ 52	$ 71	$ 65
Restricted cash	61	123
Accounts receivable	1,257	1,542
Property, plant and equipment, net	16,499	15,800
Securitized regulatory assets, noncurrent	86	231
Total Assets	26,376	25,935
Liabilities [Abstract]
Current portion long-term debt, including, capital leases	274	898
Current regulatory liabilities	164	302
Mortgage bonds, notes and other	7,426	6,618
Capital lease obligations	3	11
Variable Interest Entity, Primary Beneficiary Securitization [Member]
Assets [Abstract]
Cash and cash equivalents	0	0
Restricted cash	40	100
Accounts receivable	40	34
Inventories	0	0
Property, plant and equipment, net	0	0
Securitized regulatory assets, noncurrent	86	231
Other current and long-term assets	2	4
Total Assets	168	369
Liabilities [Abstract]
Accounts payable and accrued current liabilities	1	7
Current portion long-term debt, including, capital leases	105	196
Current regulatory liabilities	44	43
Mortgage bonds, notes and other	0	0
Securitization bonds	0	105
Capital lease obligations	0	0
Other current and long-term liabilities	9	8
Total Liabilities	159	359
Variable Interest Entity, Primary Beneficiary Other [Member]
Assets [Abstract]
Cash and cash equivalents	12	12
Restricted cash	6	8
Accounts receivable	15	16
Inventories	34	118
Property, plant and equipment, net	84	99
Securitized regulatory assets, noncurrent	0	0
Other current and long-term assets	7	9
Total Assets	158	262
Liabilities [Abstract]
Accounts payable and accrued current liabilities	9	23
Current portion long-term debt, including, capital leases	9	9
Current regulatory liabilities	0	0
Mortgage bonds, notes and other	17	21
Securitization bonds	0	0
Capital lease obligations	3	7
Other current and long-term liabilities	5	6
Total Liabilities	43	66
Variable Interest Entity, Primary Beneficiary [Member]
Assets [Abstract]
Cash and cash equivalents	12	12
Restricted cash	46	108
Accounts receivable	55	50
Inventories	34	118
Property, plant and equipment, net	84	99
Securitized regulatory assets, noncurrent	86	231
Other current and long-term assets	9	13
Total Assets	326	631
Liabilities [Abstract]
Accounts payable and accrued current liabilities	10	30
Current portion long-term debt, including, capital leases	114	205
Current regulatory liabilities	44	43
Mortgage bonds, notes and other	17	21
Securitization bonds	0	105
Capital lease obligations	3	7
Other current and long-term liabilities	14	14
Total Liabilities	$ 202	$ 425