Income Taxes

6 Months Ended

Jun. 30, 2013

Disclosure Text Block [Abstract]

Income Tax Disclosure

13. Income Taxes

       The following summarizes income tax expense (benefit) and effective tax rates:

	Three Months Ended   June 30,						Six Months Ended   June 30,
millions except percentages	2013			2012			2013			2012
Income tax expense (benefit)	$	567		$	164		$	1,023		$	516
Effective tax rate	37		%	174		%	41		%	20		%

       The increase from the 35% U.S. federal statutory rate for the three and six months ended June 30, 2013, and the three months ended June 30, 2012, was primarily attributable to the tax impact from foreign operations and Algerian exceptional profits taxes.

       The decrease from the 35% U.S. federal statutory rate for the six months ended June 30, 2012, was primarily attributable to the non-taxable resolution of the Algeria exceptional profits tax dispute. This amount was partially offset by the tax impact from foreign operations and Algerian exceptional profits taxes.