Note Payable (MidCap Loan) - Additional Information (Detail) - Secured Loan Facility [Member] - USD ($) $ in Millions		3 Months Ended
May. 29, 2015	Mar. 31, 2016
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%
Mid Cap [Member]
Debt Instrument [Line Items]
Secured loan facility	30.0
Net proceeds in aggregate amount	$ 20.1
Rate of interest applicable to obligations		4.00%
Loan, gross		$ 30.0
Unamortized discount		$ 1.0

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

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

- Definition

Increase in interest rate upon default in credit agreement

+ References

No definition available.

+ Details

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

- 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 repayment term.

+ References

No definition available.

+ Details

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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

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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

Amount of long-term debt before deduction of unamortized discount or premium. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, with initial maturities beyond one year or the normal operating cycle, if longer.

+ 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

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 20
-Article 5

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 03
-Paragraph 16
-Article 9

+ Details

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

+ Details

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

- 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

+ 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

+ Details

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

- Definition

The effective interest rate during the reporting period.

+ References

+ Details

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

- 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)
-URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3255-108585

Reference 3: 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.(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

- Definition

Amount of deferred fees paid by borrowers and unamortized costs incurred to originate loans and leases, unamortized loan commitments and loan syndication fees, and premiums over or discounts from face amounts of loans that are being amortized into income as an adjustment to yield. Excludes amounts for loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6378536&loc=d3e10092-111533

+ Details

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

- Details

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Namespace Prefix:
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Balance Type:
Period Type:

- Details

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