Separation, Benefit Plan Termination (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011 Former Omnicare Executive [Member]	Dec. 31, 2010 Former President &CEO and Former Senior VP & Secretary [Member]
Restructuring Cost and Reserve [Line Items]
Omnicare executive separation, benefit plan termination total separation costs	$ 21		$ 40
omnicare executive separation, benefit plan termination restricted stock awards costs		$ 1