Acquired product rights - Additional Information (Details) $ in Millions	Aug. 03, 2021 USD ($)
Asset Acquisition [Line Items]
Price of acquisition	$ 9
ELYXYB
Asset Acquisition [Line Items]
Up-front payment	6
Additional payment	9
Milestone payments, total	262
ELYXYB \| Minimum
Asset Acquisition [Line Items]
Milestone payment, net sales	4
Milestone payment requirement, net sales	50
ELYXYB \| Maximum
Asset Acquisition [Line Items]
Milestone payment, net sales	100
Milestone payment requirement, net sales	$ 1,000

Asset Acquisition, Price Of Acquisition Expected, Additional Payment

No definition available.

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