Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Total property and equipment, gross	$ 3,389	$ 3,050
Less: Accumulated depreciation	(1,919)	(1,561)
Total property and equipment, net	1,470	1,489
Laboratory equipment
Total property and equipment, gross	1,514	1,429
Computer equipment and software
Total property and equipment, gross	318	313
Furniture and fixtures
Total property and equipment, gross	44	44
Leasehold improvements
Total property and equipment, gross	1,412	1,228
Construction-in-process
Total property and equipment, gross	$ 101	$ 36