Summary of Activity under Stock-Based Compensation Plans (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Stock Options Number Outstanding
Beginning Balance	897,115
Cancelled or expired	(110,131)
Exercised	(5,180)	(27,733)
Ending Balance	781,804	897,115
Vested or expected to vest at December 31, 2015	744,258
Exercisable at December 31, 2015	495,206
Stock Options Average Exercise Price per share
Beginning Balance	$ 12.09
Cancelled or expired	16.64
Exercised	8.01
Ending Balance	11.48	$ 12.09
Vested or expected to vest at December 31, 2015	11.59
Exercisable at December 31, 2015	$ 12.88
Stock Options Remaining Contractual Life (in years)
Remaining Contractual Life	6 years 8 months 19 days
Vested or expected to vest at December 31, 2015	6 years 6 months 15 days
Exercisable at December 31, 2015	5 years 10 months 6 days