Pension Plans, Other Postretirement Benefits, and Defined-Contribution Plans - Change in Benefit Obligation Table (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017		Dec. 31, 2016		Dec. 31, 2015
Pension Plans, Defined Benefit [Member]
Change in benefit obligation
Benefit obligation at beginning of year		$ 2,301	[1]	$ 2,431
Service cost		87		99		$ 118
Interest cost		84		95		101
Actuarial (gain) loss	[2]	130		211
Participant contributions		0		0
Benefit payments		(396)		(513)
Foreign-currency exchange-rate changes		12		(22)
Benefit obligation at end of year (2)		2,218	[1]	2,301	[1]	2,431
Termination benefits				44
Settlement (loss) gain		(19)
Accumulated benefit obligation for all defined-benefit pension plans		1,900		2,000
Other Postretirement Benefits Plan [Member]
Change in benefit obligation
Benefit obligation at beginning of year		296	[1]	266
Service cost		2		3		9
Interest cost		12		12		15
Actuarial (gain) loss	[2]	14		34
Participant contributions		5		4
Benefit payments		(27)		(23)
Foreign-currency exchange-rate changes		0		0
Benefit obligation at end of year (2)		$ 302	[1]	$ 296	[1]	$ 266

[1] The accumulated benefit obligation for all defined-benefit pension plans was $1.9 billion at December 31, 2017 and $2.0 billion at December 31, 2016.

[2] Includes $19 million of settlement losses for pension benefits at December 31, 2017, and $44 million of termination benefits at December 31, 2016, associated with the Company’s workforce reduction program initiated in the first quarter of 2016. See Note 18—Restructuring Charges.