Equipment, net and construction in progress (Details) - USD ($)	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Equipment, furniture and fixtures [Abstract]
Equipment, furniture and fixtures	$ 5,196,000		$ 4,871,000
Construction in progress	3,415,000		406,000
Accumulated depreciation	(2,959,000)		(2,419,000)
Equipment net, and construction in progress	5,652,000		$ 2,858,000
Equipment, furniture , and fixtures included in capital lease borrowings		$ 115,000
Leasehold improvements for Asterias' facility	3,400,000
Depreciation expense	512,000	523,000
Increase in accumulated depreciation	541,000
Tenant improvement allowance under lease agreement	4,400,000
Amount qualifying for reimbursement under the tenant improvement allowance	3,300,000
Reimbursement from landlord on construction in progress	$ 560,000	$ 0