Income Taxes (Tables)

6 Months Ended

Jun. 30, 2015

Income Tax Disclosure [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	2015			2014			2015			2014
Income tax expense (benefit)	$	77		$	428		$	(1,315	)	$	1,092
Income (loss) before income taxes	185			694			(4,443		)	(1,268		)
Effective tax rate	42		%	62		%	30		%	(86		)%