Retirement Plans (Detail) (United States Pension Plans of US Entity, Defined Benefit, USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
United States Pension Plans of US Entity, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 37	$ 31	$ 75	$ 60
Interest cost	153	137	298	272
Expected return on plan assets	(189)	(179)	(373)	(357)
Actuarial loss	78	55	154	106
Amortization of prior service cost	8	8	16	16
Net periodic benefit expense	$ 87	$ 52	$ 170	$ 97