Segment Reporting - Reconciliation of Segment Profits to Income Before Taxes (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Segment Reporting Information [Line Items]
Income Before Taxes	$ 2,218	$ 2,352	$ 7,405	$ 5,753
Interest income	47	32	177	102
Interest expense	(178)	(176)	(524)	(522)
Equity income from affiliates	158	161	410	354
Depreciation and amortization			(5,317)	(5,566)
Research and development	(1,918)	(1,954)	(5,944)	(6,048)
Restructuring costs	(110)	(119)	(473)	(773)
Arbitration settlement charge				(500)
Pharmaceutical Segment [Member]
Segment Reporting Information [Line Items]
Income Before Taxes	6,265	6,355	19,767	19,014
Other segment sales [Member]
Segment Reporting Information [Line Items]
Income Before Taxes	819	783	2,397	2,300
Total segment profits [Member]
Segment Reporting Information [Line Items]
Income Before Taxes	7,084	7,138	22,164	21,314
Other (losses) profits [Member]
Segment Reporting Information [Line Items]
Income Before Taxes	(4)	5	(32)	(9)
Unallocated [Member]
Segment Reporting Information [Line Items]
Interest income	47	32	177	102
Interest expense	(178)	(176)	(524)	(522)
Equity income from affiliates	(5)	(1)	(14)	(82)
Depreciation and amortization	(486)	(619)	(1,620)	(1,814)
Research and development	(1,689)	(1,712)	(5,263)	(5,330)
Amortization of purchase accounting adjustments	(1,232)	(1,284)	(3,687)	(3,788)
Restructuring costs	(110)	(119)	(473)	(773)
Arbitration settlement charge				(500)
Other unallocated, net	$ (1,209)	$ (912)	$ (3,323)	$ (2,845)