Equipment, net and construction in progress (Details) (USD $)	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014	Jun. 30, 2014
Equipment, furniture and fixtures [Abstract]
Equipment, furniture and fixtures	$ 4,928,857us-gaap_PropertyPlantAndEquipmentGross		$ 4,870,516us-gaap_PropertyPlantAndEquipmentGross
Construction in progress	606,641us-gaap_ConstructionInProgressGross		405,730us-gaap_ConstructionInProgressGross
Accumulated depreciation	(2,670,829)		(2,418,400)
Equipment net, and construction in progress	2,864,669us-gaap_PropertyPlantAndEquipmentNet		2,857,846us-gaap_PropertyPlantAndEquipmentNet
Equipment, furniture , and fixtures included in capital lease borrowings				115,000us-gaap_CapitalLeaseObligations
Leasehold improvements for Asterias' facility	606,641us-gaap_LeaseholdImprovementsGross
Depreciation expense	262,600us-gaap_Depreciation	256,945us-gaap_Depreciation
Increase in accumulated depreciation	252,429
Tenant improvement allowance under lease agreement	4,400,000
Amount qualifying for reimbursement under the tenant improvement allowance	560,970
Reimbursement from landlord on construction in progress	$ 283,764btx_ProceedsFromConstructionInProgress	$ 0btx_ProceedsFromConstructionInProgress

Refers to proceeds from landlord on construction in progress.

No definition available.

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- Definition

Amount of quality for reimbursement under the tenant improvement allowance to lease agreement which use to construct a laboratory and production facility.

+ References

No definition available.

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- Definition

Amount of allowance for tenant related to lease agreement which use to construct a laboratory and production facility.

+ References

No definition available.

+ Details

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- Definition

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 360

-SubTopic 10

-Section 50

-Paragraph 1

-Subparagraph (c)

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-Topic 210

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-Section S99

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 14

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- Definition

The change during the period, from the beginning balance of accumulated depreciation, depletion and amortization (relating to property, plant and equipment) to the ending balance.

+ References

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- Definition

Amount equal to the present value (the principal) at the beginning of the lease term of minimum lease payments during the lease term (excluding that portion of the payments representing executory costs such as insurance, maintenance, and taxes to be paid by the lessor, together with any profit thereon) net of payments or other amounts applied to the principal through the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 16

-Article 7

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 840

-SubTopic 30

-Section 50

-Paragraph 1

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6455398&loc=d3e45280-112737

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- Definition

Amount of structure or a modification to a structure under construction. Includes recently completed structures or modifications to structures that have not been placed into service.

+ References

+ Details

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- Definition

The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585

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- Definition

Amount before accumulated depreciation of additions or improvements to assets held under a lease arrangement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 360

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- Definition

Amount before accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

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- Definition

Amount after accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business to produce goods and services and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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