Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2012

Accounting Policies [Abstract]

Schedule of Comprehensive Income (Loss) [Table Text Block]

	Year Ended December 31, 2012
	Net Unrealized Gain/(Loss) on Derivatives			Net Unrealized Gain/(Loss) on Investments			Benefit Obligations			Foreign Currency Translation		Accumulated Other Comprehensive Loss
	(In millions)
Beginning balances January 1, 2012	$	(4	)	$	(30	)	$	(125	)	$	1	$	(158	)
Current period change, net of tax	—			1			(2		)	1		—
Ending balances December 31, 2012	$	(4	)	$	(29	)	$	(127	)	$	2	$	(158	)

Schedule of Finite-Lived Intangible Assets by Major Class [Table Text Block]

Summary of intangible assets as of December 31, 2012 and 2011:

	2012		2011
	(In millions)
Emission allowances	$	6	$	10
Renewable energy credits	44		39
Contract intangible assets	139		65
	189		114
Less accumulated amortization	34		28
Intangible assets, net	155		$	86
Less current intangible assets	20		$	13
	$	135	$	73