Retirement Plans (Detail) (United States Pension Plans of US Entity, Defined Benefit, USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
United States Pension Plans of US Entity, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 38	$ 31	$ 113	$ 91
Interest cost	154	136	452	408
Expected return on plan assets	(190)	(178)	(563)	(535)
Actuarial loss	76	53	230	159
Amortization of prior service cost	8	7	24	23
Net periodic benefit expense	$ 86	$ 49	$ 256	$ 146