Contingencies (Details) (USD $)	1 Months Ended	3 Months Ended		6 Months Ended		12 Months Ended		1 Months Ended	6 Months Ended						3 Months Ended	12 Months Ended	1 Months Ended	6 Months Ended			3 Months Ended	6 Months Ended			6 Months Ended
	Apr. 30, 2011	Jun. 30, 2011 Defendants Derivatives	Jun. 30, 2010	Jun. 30, 2011 Years Derivatives Plaintiffs Segments Defendants	Jun. 30, 2010	Dec. 31, 2010 Remicade and Simponi [Member]	Jun. 30, 2011 Fosamax [Member] Plaintiffs Claims	Dec. 31, 2010 Fosamax [Member] ONJ Litigation [Member]	Jun. 30, 2011 Fosamax [Member] ONJ Litigation [Member] Claims	Jun. 30, 2011 Fosamax [Member] ONJ Litigation [Member] New Jersey [Member] Claims	Jun. 30, 2011 Fosamax [Member] Other Bone Injury [Member] Claims	Jun. 30, 2011 Fosamax [Member] Other Bone Injury [Member] New Jersey [Member] Claims	Jun. 30, 2011 NuvaRing [Member] Claims	Jun. 30, 2011 NuvaRing [Member] New Jersey [Member] Claims	Jun. 30, 2011 DOJ and EPA Matters [Member]	Dec. 31, 2010 Department of Justice [Member]	Apr. 30, 2011 Johnson & Johnson [Member]	Jun. 30, 2011 AWP Litigation and Investigation [Member]	Jun. 30, 2011 Vytorin shareholder lawsuits [Member]	Jun. 30, 2011 Vytorin ERISA lawsuits [Member]	Jun. 30, 2011 Vioxx Litigation [Member]	Jun. 30, 2011 Vioxx Litigation [Member]	Dec. 31, 2010 Vioxx Litigation [Member]	Jun. 30, 2011 Vioxx Product Liability [Member] PlaintiffGroups	Jun. 30, 2011 Other Vioxx Lawsuits [Member] Claims	Jun. 30, 2011 Vioxx Securities Lawsuit [Member]	Jun. 30, 2011 Vioxx ERISA Lawsuits [Member]
Loss Contingencies [Line Items]
Number of cases pending against the Company							1,650		1,115		535		815
Number of plaintiff groups							2,050
Number of lawsuits in federal court									910				690												30
Number of lawsuits in New Jersey state court										190		430		122
Plaintiff Groups eligible for the Settlement Program, claims remain pending																								30
Plaintiff groups not eligible for Settlement Program claims remain pending																								100
Upper limit of directors and officers insurance coverage																			$ 250,000,000	$ 265,000,000						$ 175,000,000	$ 275,000,000
Gain (loss) recorded related to legal contingency				(500,000,000)												(950,000,000)
Amount of Vioxx legal defense costs reserve																					58,000,000	58,000,000	76,000,000
Charge recorded for future legal defense costs																					19,000,000	19,000,000
Initial group of cases to complete fact discovery									25
Number of cases pending in other state courts											3		4
Trial pool cases which are the subject of fact discovery													26
Additional trial pool cases selected													10
Sales		12,151,000,000	11,346,000,000	23,732,000,000	22,768,000,000	2,800,000,000
Verdict amount in favor of the plaintiff								8,000,000										13,800,000
Reduced verdict amount								1,500,000
Contribution income (profit) split to partner				42.00%
Aggregate amount spent in legal defense costs worldwide related to Vioxx Litigation																					21,000,000	37,000,000
Amount of one-time legal settlement payment	500,000,000																500,000,000
Civil penalties sought against Merck by DOJ and EPA															2,000,000
Payments for fines for environmental matters															$ 260,000
Contingencies and Environmental Liabilities (Textuals) [Abstract]
Revenue percentage represented by retained territories				70.00%
Contribution income (profit) split to Company				58.00%
Revenue percentage represented by relinquished territories				30.00%
Number of plaintiffs filed amended complaint				2,200
Number of other defendants in environmental matters		12		12
Number of other defendants in phase 1 trial		3		3