CONSOLIDATED BALANCE SHEETS (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Current Assets:
Cash and cash equivalents ($220 and $266 related to VIEs at December 31, 2011 and 2012, respectively)	$ 646	$ 220
Accounts and notes receivable, net ($52 and $68 related to VIEs at December 31, 2011 and 2012, respectively)	222	201
Accounts and notes receivable—affiliated companies	448	1,027
Accrued unbilled revenues	80	72
Inventory	94	80
Taxes receivable	7	2
Deferred tax asset	1	3
Other ($42 and $54 related to VIEs at December 31, 2011 and 2012, respectively)	77	65
Total current assets	1,575	1,670
Property, Plant and Equipment [Abstract]
Property, plant and equipment, net	5,365	5,043
Other Assets:
Regulatory assets ($2,289 and $3,545 related to VIEs at December 31, 2011 and 2012, respectively)	3,388	3,726
Notes receivable—affiliated companies	750	750
Other	41	35
Total other assets	4,179	4,511
Total Assets	11,119	11,224
Current Liabilities:
Current portion of VIE transition and system restoration bonds long-term debt	447	307
Current portion of other long-term debt	450	46
Accounts payable	83	113
Accounts and notes payable—affiliated companies	92	32
Taxes accrued	95	101
Interest accrued	87	96
Other	112	98
Total current liabilities	1,366	793
Other Liabilities:
Accumulated deferred income taxes, net	2,097	2,113
Benefit obligations	268	252
Regulatory liabilities	473	441
Notes payable—affiliated companies	151	151
Other	40	78
Total other liabilities	3,029	3,035
Long-Term Debt:
VIE transition and system restoration bonds	3,400	2,215
Other	1,595	2,047
Total long-term debt	4,995	4,262
Commitments And Contingencies (Note 10)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract]
Member’s Equity	1,729	3,134
Total Liabilities and Member’s Equity	$ 11,119	$ 11,224