Organization and Basis of Presentation (Consolidated Variable Interest Entities) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2013	Dec. 31, 2012
Assets [Abstract]
Cash and cash equivalents	$ 98	$ 52	$ 218	$ 65
Restricted cash	57	123
Accounts receivable	1,811	1,542
Other current assets	178	209
Property, plant and equipment, net	15,985	15,800
Securitized regulatory assets	182	231
Other assets	193	198
Total Assets	26,161	25,935
Liabilities [Abstract]
Current portion long-term debt, including, capital leases	1,069	898
Current regulatory liabilities	175	302
Other current liabilities	489	495
Mortgage bonds, notes and other	6,438	6,618
Securitization bonds	0	105
Capital lease obligations	5	11
Other long term liabilities	266	297
Variable Interest Entity Securitization [Member]
Assets [Abstract]
Cash and cash equivalents	0	0
Restricted cash	36	100
Accounts receivable	40	34
Inventories	0	0
Other current assets	0	0
Property, plant and equipment, net	0	0
Securitized regulatory assets	182	231
Other assets	3	4
Total Assets	261	369
Liabilities [Abstract]
Accounts payable and accrued current liabilities	1	7
Current portion long-term debt, including, capital leases	202	196
Current regulatory liabilities	41	43
Other current liabilities	0	0
Mortgage bonds, notes and other	0	0
Securitization bonds	0	105
Capital lease obligations	0	0
Other long term liabilities	8	8
Total Liabilities	252	359
Variable Interest Entity, Primary Beneficiary [Member]
Assets [Abstract]
Cash and cash equivalents	15	12
Restricted cash	6	8
Accounts receivable	11	16
Inventories	19	118
Other current assets	1	1
Property, plant and equipment, net	92	99
Securitized regulatory assets	0	0
Other assets	8	8
Total Assets	152	262
Liabilities [Abstract]
Accounts payable and accrued current liabilities	12	23
Current portion long-term debt, including, capital leases	9	9
Current regulatory liabilities	0	0
Other current liabilities	4	4
Mortgage bonds, notes and other	19	21
Securitization bonds	0	0
Capital lease obligations	4	7
Other long term liabilities	2	2
Total Liabilities	50	66
Consolidated Variable Interest Entity [Member]
Assets [Abstract]
Cash and cash equivalents	15	12
Restricted cash	42	108
Accounts receivable	51	50
Inventories	19	118
Other current assets	1	1
Property, plant and equipment, net	92	99
Securitized regulatory assets	182	231
Other assets	11	12
Total Assets	413	631
Liabilities [Abstract]
Accounts payable and accrued current liabilities	13	30
Current portion long-term debt, including, capital leases	211	205
Current regulatory liabilities	41	43
Other current liabilities	4	4
Mortgage bonds, notes and other	19	21
Securitization bonds	0	105
Capital lease obligations	4	7
Other long term liabilities	10	10
Total Liabilities	$ 302	$ 425