Employee Share-Based Compensation Plans - Summary of Stock Option Activity Under the Equity Plans (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Shares Under Options, Beginning Balance	3,735,233	4,009,028
Shares under options, Granted	304,000	352,500
Shares Under Options, Exercised	(259,549)	(346,189)
Shares Under Options, Forfeited or expired	(29,901)	(280,106)
Shares Under Options, Ending Balance	3,749,783	3,735,233
Weighted Average Exercise Price, Beginning Balance	$ 3.85	$ 3.89
Shares Under Options, Vested and expected to vest at December 31, 2015	3,616,886
Weighted Average Exercise Price, Granted	$ 7.05	6.92
Shares Under Options, Exercisable at December 31, 2015	3,159,129
Weighted Average Exercise Price, Exercised	$ 3.21	3.69
Weighted Average Exercise Price, Forfeited or expired	3.80	8.45
Weighted Average Exercise Price, Ending Balance	4.15	$ 3.85
Weighted Average Exercise Price, Vested and expected to vest at December 31, 2015	4.07
Weighted Average Exercise Price, Exercisable at December 31, 2015	$ 3.71
Weighted Average Remaining Contractual Term, Outstanding	2 years 11 months 5 days	3 years 6 months 4 days
Weighted Average Remaining Contractual Term, Vested and Expected to vest	2 years 9 months 29 days
Weighted Average Remaining Contractual Term, Exercisable	2 years 5 months 9 days
Aggregate Intrinsic Value, Outstanding	$ 14,456	$ 13,667
Aggregate Intrinsic Value, Vested and expected to vest	11,974
Aggregate Intrinsic Value, Exercisable	$ 13,582