Income Taxes - Schedule of Provision for Income Taxes on Income from Continuing Operations (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current:
Federal	$ 0	$ 0	$ 0
Foreign	98	133	115
State and local	(2)	1	(1)
Current provision for income taxes, total	96	134	114
Deferred:
Federal	489	1,208	196
Foreign	37	136	29
State and local	(78)	(2)	0
Deferred provision for income taxes, total	448	1,342	225
Total	$ 544	$ 1,476	$ 339