Restructuring and Other Charges - Activity and Reserve Balances for Restructuring Charges (Detail) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Restructuring Reserve [Roll Forward]
Restructuring reserve beginning balance	$ 58	$ 59	$ 59
Cash payments	(20)		(65)
Restructuring charges	9		65
Other	9		1
Restructuring reserve ending balance	38		58
Restructuring and other charges	7	73
Layoff Costs
Restructuring Reserve [Roll Forward]
Restructuring reserve beginning balance	56	50	50
Cash payments	(20)		(59)
Restructuring charges	9		64
Other	9		(1)
Restructuring reserve ending balance	36		56
Other Exit Costs
Restructuring Reserve [Roll Forward]
Restructuring reserve beginning balance	2	9	9
Cash payments	0		(6)
Restructuring charges	0		1
Other	0		2
Restructuring reserve ending balance	2		2
Restructuring and other charges		$ 19
Pension Costs [Member]
Restructuring Reserve [Roll Forward]
Restructuring and other charges	$ 5
Stock Awards Reversal [Member]
Restructuring Reserve [Roll Forward]
Restructuring and other charges			$ 13