Income Taxes (Tables)

3 Months Ended

Mar. 31, 2012

Income Tax Disclosure [Abstract]

Factors Causing Variation in Effective Tax Rate From US Federal Statutory Rate

The differences that caused our effective income tax rates to vary from the 35% U.S. federal statutory rate for income taxes were as follows:

	Three Months Ended
	March 31,
	2012			2011
	(in millions)
Income tax benefit at the federal statutory rate	$	289		$	141
Effect of:
State income taxes, net of federal income tax effect	25			9
Change in valuation allowance	(348		)	(196		)
Other, net	(3		)	9
Income tax expense	$	(37	)	$	(37	)
Effective income tax rate	(4.5		)%	(9.2		)%