Note 4 - Deferred Rent - Summary of Deferred Rent (Details) - USD ($)	Jun. 30, 2018	Dec. 31, 2017
Landlord-funded leasehold improvements	$ 1,124,790	$ 1,124,790
Less accumulated amortization	(693,024)	(629,525)
Total	431,766	495,265
Straight line rent adjustment	121,278	127,158
Total deferred rent	$ 553,044	$ 622,423

Amount of accumulated amortization of landlord-funded leasehold improvements.

No definition available.

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- Definition

Amount of landlord-funded leasehold improvements before accumulated amortization.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
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Period Type:	instant

- Definition

Amount of landlord-funded leasehold improvements after accumulated amortization.

+ References

No definition available.

+ Details

Name:	blfs_LandlordfundedLeaseholdImprovementsNet
Namespace Prefix:	blfs_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of straight-line rent adjustment.

+ References

No definition available.

+ Details

Name:	blfs_StraightlineRentAdjustment
Namespace Prefix:	blfs_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The cumulative difference between the rental payments required by a lease agreement and the rental income or expense recognized on a straight-line basis, or other systematic and rational basis more representative of the time pattern in which use or benefit is granted or derived from the leased property, expected to be recognized in income or expense over the term of the leased property by the lessor or lessee, respectively.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 20
-Section 25
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=77902458&loc=d3e39896-112707

+ Details

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Period Type:	instant