Property, plant and equipment, net (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016		Dec. 31, 2015	Dec. 31, 2014
Property and equipment, net [Abstract]
Accumulated depreciation and amortization	$ (2,980,000)	[1]	$ (3,451,000)
Property and equipment, net	5,529,000	[1]	7,539,000
Depreciation and amortization expense	1,180,000		1,078,000	$ 1,051,000
Leasehold Improvements [Abstract]
Leasehold improvements	1,600,000
Equipment Furniture and Fixtures [Member]
Property and equipment, net [Abstract]
Property plant and equipment	4,718,000	[1]	5,274,000
Leasehold Improvements [Member]
Property and equipment, net [Abstract]
Property plant and equipment	3,791,000	[1]	5,623,000
Leasehold Improvements [Abstract]
Tenant improvement allowance under lease agreement	1,400,000
Nonreimbursement leasehold improvement from landlord	200,000
Construction in Progress [Member]
Property and equipment, net [Abstract]
Property plant and equipment	0	[1]	93,000
Property, Plant Equipment under Capital Leases [Member]
Property and equipment, net [Abstract]
Property plant and equipment	$ 626,000		$ 33,800

[1] (1) Reflects the effect of the Asterias Deconsolidation.