LEGAL PROCEEDINGS (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
Sep. 30, 2013
Optimer
LEGAL PROCEEDINGS
Amount of potentially improper payment to research laboratory identified	$ 0.3
Hospira, Inc.
LEGAL PROCEEDINGS
Period for which filing of lawsuit prevents the FDA from approving the ANDA under U.S. law	30 months
Strides, Inc.
LEGAL PROCEEDINGS
Period for which filing of lawsuit prevents the FDA from approving the ANDA under U.S. law	30 months

Represents the period under U.S. Law in force, for which the filing of the lawsuit automatically prevents the FDA from approving the abbreviated new drug application (ANDA) from the plaintiff's receipt of defendant's notification letter, unless the court enters judgment in favor of the defendant prior to that period.

No definition available.

Name:	cbst_PeriodForWhichFilingOfLawsuitPreventsFDAFromApprovingTheANDAUnderUSLaw
Namespace Prefix:	cbst_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration