Income Taxes - Allocation of Total Income Taxes (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Income Tax Benefit/(Loss) Applicable To: [Abstract]
Income/(loss) from continuing operations, before income taxes	$ (2,012)	$ 46	$ (2,246)	$ 7,042
Income tax benefit/(provision)	$ (31)	$ 4	$ (71)	$ (188)
Effective tax rate	(1.50%)	(8.70%)	(3.20%)	2.70%