Document and Entity Information Document	3 Months Ended
	Sep. 30, 2012
Entity Information [Line Items]
Entity Registrant Name	OMNICARE INC
Entity Central Index Key	0000353230
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Document Type	10-Q
Document Period End Date	Sep. 30, 2012
Document Fiscal Year Focus	2012
Document Fiscal Period Focus	Q3
Amendment Flag	false
Entity Common Stock, Shares Outstanding	110,534,710