Pension Plans, Other Postretirement Benefits, and Defined-Contribution Plans - Change in Benefit Obligation Table (Detail) (USD $)	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Pension Plans, Defined Benefit [Member]
Change in benefit obligation
Benefit obligation at beginning of year	$ 2,024,000,000	[1]	$ 1,882,000,000
Service cost	76,000,000		78,000,000		69,000,000
Interest cost	85,000,000		85,000,000		84,000,000
Plan amendments			(12,000,000)
Actuarial (gain) loss	224,000,000		94,000,000
Participant contributions	1,000,000		1,000,000
Benefit payments	(117,000,000)		(103,000,000)
Foreign-currency exchange-rate changes	4,000,000		(1,000,000)
Benefit obligation at end of year	2,297,000,000	[1]	2,024,000,000	[1]	1,882,000,000
Table Text Block Supplement [Abstract]
Accumulated benefit obligation for all definted-benefit pensions plans	2,100,000,000		1,900,000,000
Other Postretirement Benefit Plans, Defined Benefit [Member]
Change in benefit obligation
Benefit obligation at beginning of year	354,000,000		316,000,000
Service cost	9,000,000		9,000,000		9,000,000
Interest cost	16,000,000		16,000,000		16,000,000
Actuarial (gain) loss	(1,000,000)		30,000,000
Participant contributions	3,000,000		4,000,000
Benefit payments	(22,000,000)		(21,000,000)
Benefit obligation at end of year	$ 359,000,000		$ 354,000,000		$ 316,000,000

[1] The accumulated benefit obligation for all defined-benefit pension plans was $2.1 billion at December 31, 2012, and $1.9 billion at December 31, 2011.