Additional Amount Of Debt Facility that Can be availed

No definition available.

Name:	bdsi_DebtInstrumentAdditionalFacilityThatCanBeObtained
Namespace Prefix:	bdsi_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Debt Instrument, Interest Only Payment Term

+ References

No definition available.

+ Details

Name:	bdsi_DebtInstrumentInterestOnlyPaymentTerm
Namespace Prefix:	bdsi_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Repayments Of Lines Of Credit, Accrued Interest Portion

+ References

No definition available.

+ Details

Name:	bdsi_RepaymentsOfLinesOfCreditAccruedInterestPortion
Namespace Prefix:	bdsi_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Variable Rate, Floor

+ References

No definition available.

+ Details

Name:	bdsi_VariableRateFloor
Namespace Prefix:	bdsi_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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

- Definition

Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentTerm
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

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

- Definition

The cash outflow for a borrowing supported by a written promise to pay an obligation.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3291-108585

+ Details

Name:	us-gaap_RepaymentsOfNotesPayable
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	us-gaap_LongtermDebtTypeAxis=bdsi_BioPharmaCreditPlcMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_LondonInterbankOfferedRateLIBORMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Notes Payable - Additional Information (Detail) - USD ($)		9 Months Ended
	Sep. 23, 2021	Sep. 30, 2021	Sep. 30, 2020	May 23, 2019
Debt Instrument [Line Items]
Repayment on notes payable		$ 20,000,000	$ 0
Bio Pharma Credit Plc
Debt Instrument [Line Items]
Secured credit term loan				$ 60,000,000
Additional facility funds that can be obtained				$ 20,000,000
Interest only, payment term		36 months
Repayment on notes payable		$ 20,000,000
Repayment of loan, accrued interest portion	$ 1,500,000
Bio Pharma Credit Plc \| London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Debt instrument, term		72 months
Basis spread on variable rate		7.50%
Variable rate floor		2.00%