Selected Balance Sheet Information (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Other Current Assets [Line Items]
Intrexon prepaid research and development expenses	$ 950	$ 1,067
Prepaid Clinical Research Organization expenses	9,089	0
Prepaid insurance	65	228
Other prepaid expenses	227	253
Total	$ 10,331	$ 1,548