Note 4 - Deferred Rent (Details Textual) - USD ($)	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Amortization of Deferred Rent	$ 31,749	$ 31,749	$ 95,248	$ 95,249

The amount of amortization charged against earnings during the period for deferred rent.

No definition available.

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