Stock-based Compensation - Summary of Stock Option Activity (Detail)	12 Months Ended
	Dec. 31, 2015 USD ($) $ / shares shares
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Total Number of Shares, Beginning Balance | shares	3,000,264
Total Number of Shares, Granted | shares	405,164
Total Number of Shares, Exercised | shares	0
Total Number of Shares, Cancelled | shares	(81,667)
Total Number of Shares, Ending Balance | shares	3,323,761
Total Number of Shares, Exercisable | shares	2,501,807
Weighted-Average Exercise Price Per Share, Beginning Balance | $ / shares	$ 3.39
Weighted-Average Exercise Price Per Share, Granted | $ / shares	0.55
Weighted-Average Exercise Price Per Share, Exercised | $ / shares	0
Weighted-Average Exercise Price Per Share, Cancelled | $ / shares	3.07
Weighted-Average Exercise Price Per Share, Ending Balance | $ / shares	3.05
Weighted-Average Exercise Price Per Share, Exercisable | $ / shares	$ 3.29
Weighted-Average Remaining Contractual Term, Ending Balance	7 years 1 month 24 days
Weighted-Average Remaining Contractual Term, Exercisable	6 years 9 months 11 days
Aggregate Intrinsic Value, Ending Balance | $	$ 0
Aggregate Intrinsic Value, Exercisable | $	$ 0