Provision for (Benefit from) Income Taxes (Detail) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Current
Federal		$ (7)	$ 0	$ (1)
State		36	5	3
Foreign		59	37	63
Current income tax provision (benefit)		88	42	65
Deferred
Federal		63	(205)	51
State		(39)	(5)	5
Foreign		(10)	18	(5)
Deferred income tax provision		(14)	192	(51)
Provision for (benefit from) income taxes		102	(150)	$ 116
Provision adjustment due to corporate tax rate change [Member]
Deferred
Deferred income tax provision		$ (30)	317
Provision adjustment due to anticipated repatriation of foreign earnings [Member]
Deferred
Deferred income tax provision	$ (30)		$ (104)