Common Stock - Summary of Common Stock Shares Activity (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Common Stock Outstanding Roll Forward [Roll Forward]
Beginning balance (in shares)	13,905,599
Beginning balance	$ 41,949
Net loss	(7,184)	$ (6,384)
Stock-based compensation expense	274
Common stock issued through employee stock purchase plan	$ 5
Ending balance (in shares)	13,906,828
Ending balance	$ 35,044
Common Stock [Member]
Common Stock Outstanding Roll Forward [Roll Forward]
Beginning balance (in shares)	13,905,599
Beginning balance	$ 14
Common stock issued through employee stock purchase plan (in shares)	1,229
Ending balance (in shares)	13,906,828
Ending balance	$ 14
Additional Paid-in Capital [Member]
Common Stock Outstanding Roll Forward [Roll Forward]
Beginning balance	192,069
Stock-based compensation expense	274
Common stock issued through employee stock purchase plan	5
Ending balance	192,348
Retained Earnings [Member]
Common Stock Outstanding Roll Forward [Roll Forward]
Beginning balance	(150,134)
Net loss	(7,184)
Ending balance	$ (157,318)