Amount of increase (decrease) in the value of a contingent consideration liability, including, but not limited to, differences arising upon settlement.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3602-108585

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 50
-Paragraph 4
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=120321790&loc=d3e7008-128479

+ Details

Name:	us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of liability recognized arising from contingent consideration in a business combination.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=120321790&loc=d3e6927-128479

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 35
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=116859824&loc=d3e6819-128478

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 25
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=6911189&loc=d3e6408-128476

+ Details

Name:	us-gaap_BusinessCombinationContingentConsiderationLiability
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Value of input used to measure contingent consideration liability from business combination.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-URI http://asc.fasb.org/extlink&oid=123874694&loc=d3e19207-110258

+ Details

Name:	us-gaap_BusinessCombinationContingentConsiderationLiabilityMeasurementInput
Namespace Prefix:	us-gaap_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant

- Definition

Value of input used to measure outstanding warrant and right embodying unconditional obligation requiring redemption by transferring asset at specified or determinable date or upon event certain to occur.

+ References

+ Details

Name:	us-gaap_WarrantsAndRightsOutstandingMeasurementInput
Namespace Prefix:	us-gaap_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputPriceVolatilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=blfs_AsteroMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputDiscountRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputRiskFreeInterestRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=blfs_CBSAcquisitionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=blfs_SciSafeHoldingsIncMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MeasurementInputTypeAxis=blfs_MeasurementInputAssetPriceVolatilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MeasurementInputTypeAxis=blfs_MeasurementInputRevenueVolatilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Note 2 - Fair Value Measurement (Details Textual)	3 Months Ended		6 Months Ended
Note 2 - Fair Value Measurement (Details Textual)	Jun. 30, 2021 USD ($)	Jun. 30, 2020 USD ($)	Jun. 30, 2021 USD ($)	Jun. 30, 2020 USD ($)	Dec. 31, 2020 USD ($)	Oct. 01, 2020 USD ($)	Nov. 10, 2019	Apr. 01, 2019
Business Combination, Contingent Consideration Arrangements, Change in Amount of Contingent Consideration, Liability	$ 1,718,000	$ (1,463,000)	$ 1,226,000	$ (1,526,000)
Measurement Input, Price Volatility [Member] \| Minimum [Member]
Warrants and Rights Outstanding, Measurement Input					0.568
Measurement Input, Price Volatility [Member] \| Maximum [Member]
Warrants and Rights Outstanding, Measurement Input					0.846
Astero [Member]
Business Combination, Contingent Consideration, Liability, Total	0		0		$ 81,000
Business Combination, Contingent Consideration Arrangements, Change in Amount of Contingent Consideration, Liability	(81,000)		(81,000)
Astero [Member] \| Measurement Input, Discount Rate [Member]
Business Combination, Contingent Consideration, Liability, Measurement Input								0.175
Astero [Member] \| Measurement Input, Risk Free Interest Rate [Member] \| Minimum [Member]
Business Combination, Contingent Consideration, Liability, Measurement Input								0.0229
Astero [Member] \| Measurement Input, Risk Free Interest Rate [Member] \| Maximum [Member]
Business Combination, Contingent Consideration, Liability, Measurement Input								0.0241
Astero [Member] \| Measurement Input, Price Volatility [Member]
Business Combination, Contingent Consideration, Liability, Measurement Input								0.56
CBS Acquisition [Member]
Business Combination, Contingent Consideration, Liability, Total	$ 140,000		$ 140,000		140,000
CBS Acquisition [Member] \| Measurement Input, Discount Rate [Member]
Business Combination, Contingent Consideration, Liability, Measurement Input	0.210		0.210				0.260
CBS Acquisition [Member] \| Measurement Input, Risk Free Interest Rate [Member]
Business Combination, Contingent Consideration, Liability, Measurement Input	0.0023		0.0023				0.0174
CBS Acquisition [Member] \| Measurement Input, Price Volatility [Member]
Business Combination, Contingent Consideration, Liability, Measurement Input	0.63		0.63				0.70
SciSafe Holdings, Inc [Member]
Business Combination, Contingent Consideration, Liability, Total	$ 8,200,000		$ 8,200,000		$ 6,900,000	$ 3,700,000
Business Combination, Contingent Consideration Arrangements, Change in Amount of Contingent Consideration, Liability	$ 1,800,000		$ 1,300,000
SciSafe Holdings, Inc [Member] \| Measurement Input, Discount Rate [Member]
Business Combination, Contingent Consideration, Liability, Measurement Input	0.052		0.052			0.045
SciSafe Holdings, Inc [Member] \| Measurement Input, Risk Free Interest Rate [Member]
Business Combination, Contingent Consideration, Liability, Measurement Input	0.46		0.46			0.0020
SciSafe Holdings, Inc [Member] \| Measurement Input, Asset Price Volatility [Member]
Business Combination, Contingent Consideration, Liability, Measurement Input	0.63		0.63			0.60
SciSafe Holdings, Inc [Member] \| Measurement Input, Revenue Volatility [Member]
Business Combination, Contingent Consideration, Liability, Measurement Input	0.17		0.17			0.15