Summary of Activity under Stock-Based Compensation Plans (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Stock Options Number Outstanding
Beginning Balance	781,804
Granted	444,460
Cancelled or Expired	(393,323)
Exercised	0	(5,180)
Ending Balance	832,941	781,804
Vested or expected to vest at December 31, 2016	801,667
Exercisable at December 31, 2016	429,816
Stock Options Average Exercise Price per share
Beginning Balance	$ 11.48
Granted	4.36
Cancelled or Expired	12.15
Ending Balance	7.11	$ 11.48
Vested or expected to vest at December 31, 2016	7.18
Exercisable at December 31, 2016	$ 8.58
Stock Options Remaining Contractual Life (in years)
Remaining Contractual Life	8 years 2 months 23 days
Vested or expected to vest at December 31, 2016	8 years 2 months 9 days
Exercisable at December 31, 2016	7 years 6 months 29 days