Note 5 - Assets Held for Rent (Details Textual) - USD ($)	3 Months Ended	9 Months Ended
Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Assets Held for Rent, Depreciation	$ 186,000	$ 51,000	$ 581,000	$ 51,000

The amount of depreciation expenses recognized for assets held for rent.

No definition available.

Name:	blfs_AssetsHeldForRentDepreciation
Namespace Prefix:	blfs_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration