Employee Benefits - Funded Status of Pension and Other Postretirement Benefit Plans (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Plan assets at fair value	$ 2,305	$ 2,001
Pension Benefits [Member]
Benefit obligation, beginning of year	2,494	2,114
Service cost	88	79	75
Interest cost	124	120	112
Actuarial loss (gain)	256	256
Benefits paid	(74)	(75)
Foreign currency translation effect	6
Benefit obligation, end of year	2,894	2,494	2,114
Plan assets at fair value	2,305	2,001
Funded status at end of year, included in other liabilities	589	493
Other Postretirement Benefits [Member]
Benefit obligation, beginning of year	454	392
Service cost	12	11	11
Interest cost	20	22	21
Actuarial loss (gain)	(4)	40
Benefits paid	(12)	(11)
Foreign currency translation effect
Benefit obligation, end of year	470	454	392
Plan assets at fair value	96	73
Funded status at end of year, included in other liabilities	$ 374	$ 381