SUBSEQUENT EVENTS (Details)	Nov. 07, 2012
Subsequent Event [Line Items]
Days within which a response from FDA is expected	60 days
FDA's goal for completing the Priority Review	6 months

The number of days subsequent to the filing date of the supplemental Biologics License Application ("sBLA") within which the entity expects to receive a response from the U.S. Food and Drug Administration regarding the requested Priority Review designation for the sBLA.

No definition available.

Name:	bstc_DaysWithinWhichResponseFromFdaIsExpected
Namespace Prefix:	bstc_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	instant