Debt instrument closing fee.

No definition available.

Name:	bdsi_DebtInstrumentClosingFee
Namespace Prefix:	bdsi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Exit fee percent.

+ References

No definition available.

+ Details

Name:	bdsi_ExitFeePercent
Namespace Prefix:	bdsi_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Final payment fees percentage.

+ References

No definition available.

+ Details

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

- Definition

Libor floor rate.

+ References

No definition available.

+ Details

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

- Definition

Line of credit facility remaining repayment term.

+ References

No definition available.

+ Details

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

- Definition

Line of credit facility repayment term.

+ References

No definition available.

+ Details

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

- Definition

Prepayment premium as percentage of loan prepaid in first year.

+ References

No definition available.

+ Details

Name:	bdsi_PrepaymentPremiumAsPercentageOfLoanPrepaidInFirstYear
Namespace Prefix:	bdsi_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Prepayment premium as percentage of loan prepaid in subsequent year.

+ References

No definition available.

+ Details

Name:	bdsi_PrepaymentPremiumAsPercentageOfLoanPrepaidInSubsequentYear
Namespace Prefix:	bdsi_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Exercise price per share or per unit of warrants or rights outstanding.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(i)(4))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

+ Details

Name:	us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

Number of securities into which the class of warrant or right may be converted. For example, but not limited to, 500,000 warrants may be converted into 1,000,000 shares.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(i)(2))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- 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

Amount of the required periodic payments applied to principal.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The percentage points added to the reference rate to compute the variable rate on the interest rate derivative.

+ References

No definition available.

+ Details

Name:	us-gaap_DerivativeBasisSpreadOnVariableRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-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=6877327&loc=d3e13212-122682

+ Details

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

- Definition

The effective interest rate at the end of the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-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=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_LineOfCreditFacilityInterestRateAtPeriodEnd
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
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-Name Accounting Standards Codification
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-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

- Definition

Amount of cash inflow from contractual arrangement with the lender, including but not limited to, letter of credit, standby letter of credit and revolving credit arrangements.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Financing Activities
-URI http://asc.fasb.org/extlink&oid=6513228

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (b)
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(f))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	dei_LegalEntityAxis=bdsi_MidCapFinancialTrustMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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Period Type:

Note Payable - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions				12 Months Ended
	Feb. 21, 2017	May 05, 2016	May 29, 2015	Dec. 31, 2016	Dec. 24, 2016	Jul. 31, 2016	Dec. 31, 2014
Debt Instrument [Line Items]
Number of warrants to purchase common stock							2,217,520
Mid Cap Financial Trust [Member]
Debt Instrument [Line Items]
Exercise price of warrants to purchase common stock				$ 3.53		$ 4.20
Mid Cap Financial Trust [Member] \| Subsequent Event [Member]
Debt Instrument [Line Items]
Net proceeds in aggregate amount	$ 29.4
Secured Loan Facility [Member]
Debt Instrument [Line Items]
Term of loan			42 months
Interest rate				8.45%
LIBOR floor rate				0.50%
Principal payment per month				$ 1.0
Closing fee from the prior loan			$ 0.4
Final payment fee rate				2.75%
Loan amount prepaid in the first year following execution of credit agreement				5.00%
Loan amount prepaid in each year thereafter				3.00%
Interest rate at period end				8.95%
Exit fee percentage recorded as deferred loan costs				2.75%
Secured Loan Facility [Member] \| Mid Cap Financial Trust [Member]
Debt Instrument [Line Items]
Secured loan facility			30.0
Net proceeds in aggregate amount			$ 20.1
Number of warrants to purchase common stock					84,986
Exercise price of warrants to purchase common stock					$ 3.53
Remaining repayment term of loan		23 months
Total Midcap obligation				$ 29.3
Secured Loan Facility [Member] \| Mid Cap Financial Trust [Member] \| Subsequent Event [Member]
Debt Instrument [Line Items]
Net proceeds in aggregate amount	$ 29.4