Income Taxes (Tables)

6 Months Ended

Jun. 30, 2013

Table Text Block [Abstract]

Schedule of Income Taxes and Effective Tax Rate

 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		%