Restructuring and Other Charges - Activity and Reserve Balances for Restructuring Charges (Detail) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Restructuring Cost and Reserve [Line Items]
Restructuring reserve beginning balance	$ 59	$ 93
Cash payments	(46)	(86)
Restructuring charges	54	97
Other	9	(45)
Restructuring reserve ending balance	76	59
Layoff Costs [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring reserve beginning balance	50	84
Cash payments	(41)	(73)
Restructuring charges	54	70
Other	10	(31)
Restructuring reserve ending balance	73	50
Other Exit Costs [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring reserve beginning balance	9	9
Cash payments	(5)	(13)
Restructuring charges		27
Other	(1)	(14)
Restructuring reserve ending balance	$ 3	$ 9