SUBSEQUENT EVENTS (Details) - Subsequent Event [Member] - Endo [Member] - USD ($) $ in Thousands	Feb. 11, 2016	Feb. 05, 2016
Subsequent Event [Line Items]
Deferred revenue on licensing agreements		$ 8,250
Opt in fee receivable for each indication		$ 500
Proceeds from licensing agreement	$ 8,250

The opt in fee receivable for each indication during the period.

No definition available.

Name:	bstc_OptInFeeReceivableForEachIndication
Namespace Prefix:	bstc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The cash inflow (outflow) relating to licensing agreement during the period.

+ References

No definition available.

+ Details

Name:	bstc_ProceedsFromLicensingAgreement
Namespace Prefix:	bstc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Total carrying amount of consideration received or receivable as of the balance sheet date representing potential earnings that were not as yet recognized as revenue or other forms of income in conformity with GAAP.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 605
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB TOPIC 13.A.4(a).Q1 Response)
-URI http://asc.fasb.org/extlink&oid=27012821&loc=d3e214044-122780

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 13
-Section A

+ Details

Name:	us-gaap_DeferredRevenueAndCredits
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

+ References

No definition available.

+ Details

Name:	us-gaap_SubsequentEventLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MajorCustomersAxis=bstc_EndoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: