Income Taxes - Components of Income Tax Provision (Benefit) for Continuing Operations (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
United States - Federal, Current income tax expense (benefit)	$ (27)	$ (7)	$ (1)
United States - Federal, Deferred income taxes and other accruals expense (benefit)	1,948	(995)	156
United States - State, Current & Deferred income taxes and other accruals expense (benefit)	23	(61)	57
United States, Current & Deferred income taxes and other accruals expense (benefit)	1,944	(1,063)	212
Foreign, Current income tax expense (benefit)	36	4	453
Foreign, Deferred income taxes and other accruals expense (benefit)	235	(231)	79
Foreign, Current & Deferred income taxes and other accruals expense (benefit)	271	(227)	532
Provision (benefit) for income taxes - before adjustments due to income tax law changes	2,215	(1,290)	744
Adjustment of deferred taxes for foreign income tax law changes	7	(9)
Total Provision (Benefit) For Income Taxes	$ 2,222	$ (1,299)	$ 744