Income Taxes - Schedule of Current and Deferred Components of Income Tax Expense (Benefit) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income tax expense (benefit):
Federal income tax expense (benefit), Current	$ 71	$ 79	$ 370
Federal income tax expense (benefit), Deferred	102	(234)	(23)
State and city income tax expense (benefit), Current	13	21	12
State and city income tax expense (benefit), Deferred	13	5	6
Foreign income tax expense (benefit)	21	86	92
Income tax expense (benefit)	$ 220	$ (43)	$ 457