Income Taxes - Current and Deferred Components of Income Tax Expense (Benefit) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income tax expense (benefit):
Federal income tax expense (benefit), Current	$ 79	$ 370	$ 705
Federal income tax expense (benefit), Deferred	(234)	(23)	(232)
State and city income tax expense (benefit), Current	21	12	19
State and city income tax expense (benefit), Deferred	5	6	1
Foreign income tax expense (benefit)	86	92	163
Income tax expense (benefit)	$ (43)	$ 457	$ 656