Summary of Stock Option Activity (Detail)	3 Months Ended
	Mar. 31, 2016 $ / shares shares
Shares
Beginning Balance | shares	3,342,325
Granted | shares	277,500
Exercised | shares	0
Options forfeited/cancelled | shares	(18,520)
Ending Balance | shares	3,601,305
Weighted Average Exercise Price
Beginning Balance | $ / shares	$ 5.70
Granted | $ / shares	1.37
Exercised | $ / shares	0
Options forfeited/cancelled | $ / shares	6.48
Ending Balance | $ / shares	$ 5.36