Decommissioning Trust Funds (Tables)

12 Months Ended

Dec. 31, 2011

Decommissioning Trust Fund [Abstract]

Securities held

	Fair Value		Total Unrealized Gains		Total Unrealized Losses
	(In Millions)
2011
Equity Securities	$	2,129	$	423	$	14
Debt Securities		1,659		115		5
Total	$	3,788	$	538	$	19
2010
Equity Securities	$	2,076	$	436	$	9
Debt Securities		1,520		67		12
Total	$	3,596	$	503	$	21

Available for sale Securities Continuous Unrealized Loss Position Fair Value

The fair value and gross unrealized losses of available-for-sale equity and debt securities, summarized by investment type and length of time that the securities have been in a continuous loss position, are as follows as of December 31, 2011:

	Equity Securities				Debt Securities
	Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses
	(In Millions)
Less than 12 months	$	130	$	9	$	123	$	3
More than 12 months		43		5		60		2
Total	$	173	$	14	$	183	$	5

The fair value and gross unrealized losses of available-for-sale equity and debt securities, summarized by investment type and length of time that the securities have been in a continuous loss position, are as follows as of December 31, 2010:

	Equity Securities				Debt Securities
	Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses
	(In Millions)
Less than 12 months	$	15	$	1	$	474	$	11
More than 12 months		105		8		4		1
Total	$	120	$	9	$	478	$	12

Fair value of debt securities by contractual maturities

	2011		2010
	(In Millions)
less than 1 year	$	69	$	37
1 year - 5 years		566		557
5 years - 10 years		583		512
10 years - 15 years		187		163
15 years - 20 years		42		47
20 years+		212		204
Total	$	1,659	$	1,520