Restructuring Charges- Activity in Restructuring Reserve (Detail) (Operational Efficiency Initiatives 2011, USD $) In Millions, unless otherwise specified	3 Months Ended		12 Months Ended
	Mar. 31, 2013	Dec. 31, 2012	Dec. 31, 2012	Dec. 31, 2011
Restructuring Reserve [Roll Forward]
Beginning Balance	$ 92		$ 107
Net additional charges (net recovery/gain)	(5)	2	(2)	107
Utilization	(13)		(13)
Ending balance	84	92	92	107
Severance
Restructuring Reserve [Roll Forward]
Beginning Balance	92		78
Net additional charges (net recovery/gain)	(5)		55
Utilization	(13)		(41)
Ending balance	84	92	92
Other
Restructuring Reserve [Roll Forward]
Beginning Balance	0		29
Net additional charges (net recovery/gain)	0		(57)
Utilization	0		28
Ending balance	$ 0	$ 0	$ 0