SONGS NDT 1 (Details) - USD ($) $ in Millions		3 Months Ended			6 Months Ended			12 Months Ended
		Jun. 30, 2015		Jun. 30, 2014	Jun. 30, 2015		Jun. 30, 2014	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Cost		$ 694			$ 694			$ 675
Gross Unrealized Gains					464			466
Gross Unrealized Loss					(13)			(10)
Estimated fair value		1,145			1,145			1,131
Proceeds from sales	[1]	127		$ 155	221		$ 350
Gross realized gains		4		0	6		4
Gross realized losses		(3)		$ (1)	(7)		$ (5)
Total Debt Securities
Schedule of Available-for-sale Securities [Line Items]
Cost		455			455			430
Gross Unrealized Gains					14			21
Gross Unrealized Loss					(10)			(6)
Estimated fair value		459			459			445
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		94	[2]		94	[2]		103
Gross Unrealized Gains					4	[2]		6
Gross Unrealized Loss					0	[2]		0
Estimated fair value		98	[2]		98	[2]		109
Municipal Bonds
Schedule of Available-for-sale Securities [Line Items]
Cost		147	[3]		147	[3]		121
Gross Unrealized Gains					6	[3]		8
Gross Unrealized Loss					(1)	[3]		0
Estimated fair value		152	[3]		152	[3]		129
Other Debt Securities
Schedule of Available-for-sale Securities [Line Items]
Cost		214	[3]		214	[3]		206
Gross Unrealized Gains					4	[3]		7
Gross Unrealized Loss					(9)	[3]		(6)
Estimated fair value		209	[3]		209	[3]		207
Equity Securities
Schedule of Available-for-sale Securities [Line Items]
Cost		218			218			215
Gross Unrealized Gains					450			444
Gross Unrealized Loss					(3)			(4)
Estimated fair value		665			665			655
Cash And Cash Equivalents
Schedule of Available-for-sale Securities [Line Items]
Cost		21			21			30
Gross Unrealized Gains					0			1
Gross Unrealized Loss					0			0
Estimated fair value		$ 21			$ 21			$ 31

[1] Excludes securities that are held to maturity.

[2] Maturity dates are 2016-2060.

[3] Maturity dates are 2015-2115.