Prepaid Expenses and Other Current Assets - Additional Information (Detail) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Prepaid expenses and other current assets	$ 590	$ 287
Prepaid insurance	423	92
Prepaid offering costs	51
Prepaid R&D clinical costs	35	177
Other costs	$ 81	$ 18