Restructuring and Other Charges - Activity and Reserve Balances for Restructuring Charges (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Restructuring Cost and Reserve [Line Items]
Restructuring reserve beginning balance	$ 45	$ 66	$ 152
Cash payments	(102)	(73)	(109)
Restructuring charges	119	90	200
Other	(15)	(38)	(177)
Restructuring reserve ending balance	47	45	66
Layoff Costs [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring reserve beginning balance	11	38	137
Cash payments	(7)	(30)	(74)
Restructuring charges	2	23	32
Other	(1)	(20)	(57)
Restructuring reserve ending balance	5	11	38
Other Costs [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring reserve beginning balance	34	28	15
Cash payments	(95)	(43)	(35)
Restructuring charges	117	67	168
Other	(14)	(18)	(120)
Restructuring reserve ending balance	$ 42	$ 34	$ 28