Income Taxes - Schedule of Current and Deferred Components of Income Tax Expense (Benefit) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income tax expense (benefit):
Federal income tax expense (benefit), Current	$ 6	$ 157	$ 71
Federal income tax expense (benefit), Deferred	85	(63)	102
State and city income tax expense (benefit), Current	15	22	13
State and city income tax expense (benefit), Deferred	9	17	13
Foreign income tax expense (benefit)	13	37	21
Income tax expense (benefit)	$ 128	$ 170	$ 220