SONGS NDT 1 (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended			12 Months Ended
	Mar. 31, 2014		Mar. 31, 2013	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Cost	$ 634			$ 627
Gross Unrealized Gains	427			417
Gross Unrealized Loss	(6)			(10)
Estimated Fair Value	1,055			1,034
Proceeds from sales	195		134
Gross realized gains	4		5
Gross realized losses	4		3
Total Debt Securities
Schedule of Available-for-sale Securities [Line Items]
Cost	393			381
Gross Unrealized Gains	13			8
Gross Unrealized Loss	(5)			(8)
Estimated Fair Value	401			381
Debt Securities Issued By The U.S. Treasury And Other U.S. Government Corporations And Agencies
Schedule of Available-for-sale Securities [Line Items]
Cost	109	[1]		116
Gross Unrealized Gains	3	[1]		3
Gross Unrealized Loss	(1)	[1]		(2)
Estimated Fair Value	111	[1]		117
Municipal Bonds
Schedule of Available-for-sale Securities [Line Items]
Cost	108	[2]		110
Gross Unrealized Gains	5	[2]		2
Gross Unrealized Loss	(1)	[2]		(1)
Estimated Fair Value	112	[2]		111
Other Debt Securities
Schedule of Available-for-sale Securities [Line Items]
Cost	176	[3]		155
Gross Unrealized Gains	5	[3]		3
Gross Unrealized Loss	(3)	[3]		(5)
Estimated Fair Value	178	[3]		153
Equity Securities
Schedule of Available-for-sale Securities [Line Items]
Cost	210			207
Gross Unrealized Gains	414			409
Gross Unrealized Loss	(1)			(2)
Estimated Fair Value	623			614
Cash And Cash Equivalents
Schedule of Available-for-sale Securities [Line Items]
Cost	31			39
Gross Unrealized Gains	0			0
Gross Unrealized Loss	0			0
Estimated Fair Value	$ 31			$ 39

[1] Maturity dates are 2015-2056.

[2] Maturity dates are 2014-2062.

[3] Maturity dates are 2014-2111.