Cover Page - shares	9 Months Ended
	Sep. 30, 2021	Nov. 03, 2021
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2021
Document Transition Report	false
Entity File Number	001-31361
Entity Registrant Name	BioDelivery Sciences International, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	35-2089858
Entity Address, Address Line One	4131 ParkLake Ave., Suite 225
Entity Address, City or Town	Raleigh
Entity Address, State or Province	NC
Entity Address, Postal Zip Code	27612
City Area Code	919
Local Phone Number	582-9050
Title of 12(b) Security	Common stock, par value $0.001
Trading Symbol	BDSI
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity common stock, shares outstanding (in shares)		98,795,939
Amendment Flag	false
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q3
Entity Central Index Key	0001103021
Current Fiscal Year End Date	--12-31