Income Taxes (Tables)

6 Months Ended

Jun. 30, 2018

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						Six Months Ended
	June 30,						June 30,
millions except percentages	2018			2017			2018			2017
Current income tax expense (benefit)	$	147		$	(522	)	$	237		$	240
Deferred income tax expense (benefit)	(22		)	484			14			(181		)
Total income tax expense (benefit)	$	125		$	(38	)	$	251		$	59
Income (loss) before income taxes	142			(372		)	442			(550		)
Effective tax rate	88		%	10		%	57		%	(11		)%