Nature of Business, Financial Condition and Basis of Presentation - Additional Information (Detail) $ / shares in Units, $ in Thousands		3 Months Ended
	Dec. 21, 2016 $ / shares	Mar. 31, 2017 USD ($) $ / shares	Mar. 31, 2016 USD ($)	Dec. 31, 2016 USD ($) $ / shares	Dec. 31, 2015 USD ($)
Accounting Policies [Abstract]
Net loss		$ (5,934)	$ (3,605)
Accumulated deficit		(382,654)		$ (376,720)
Cash and cash equivalents		$ 20,393	$ 8,672	$ 27,888	$ 17,031
Common stock, par value | $ / shares	$ 0.01	$ 0.01		$ 0.01
Reverse split of common stock	one-for-twenty
Reverse stock split ratio	0.05
Future minimum operating lease obligations		$ 4,074