Income Taxes (Tables)

6 Months Ended

Jun. 30, 2012

Income Tax Expense (Benefit), Continuing Operations, Income Tax Reconciliation [Abstract]

Schedule of Effective Income Tax Rate Reconciliation

The following table summarizes the difference between income tax expense at the United States statutory rate of 35% and the income tax expense (benefit) at effective worldwide tax rates for the periods presented:

	Three Months Ended June 30,						Six Months Ended June 30,
Millions of dollars	2012			2011			2012			2011
Earnings (loss) before income taxes	$	124		$	(370	)	$	257		$	(216	)
Income tax expense computed at United States statutory tax rate	$	43		$	(130	)	$	90		$	(75	)
U.S. government tax incentive - Energy Tax Credits	—			(79		)	—			(133		)
Valuation allowance release	(55		)	—			(55		)	—
Foreign government tax incentive - BEFIEX	(3		)	(28		)	(7		)	(39		)
Other	19			31			12			17
Income tax expense (benefit) computed at effective worldwide tax rates	$	4		$	(206	)	$	40		$	(230	)