Shareholders' Equity - Summary of Stock Option Activity (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Roll Forward
Number of Shares, Beginning Balance	1,515,621	1,539,618
Granted, Number of Shares	848,208	328,080
Exercised, Number of Shares	(393,128)	(31,925)
Forfeited, Number of Shares	(122,280)	(130,131)
Expired, Number of Shares	(295,061)	(190,021)
Number of Shares, Ending Balance	1,553,360	1,515,621	1,539,618
Vested and expected to vest, Number of Shares, Ending Balance	1,441,285
Exercisable, Number of Shares, Ending Balance	571,589
Weighted Average Exercise Price, Beginning Balance	$ 3.36	$ 3.55
Granted, Weighted Average Exercise Price	$ 3.53	$ 3.03
Exercised, Weighted Average Exercise Price	$ 2.50	$ 2.49
Forfeited, Weighted Average Exercise Price	$ 3.28	$ 3.23
Expired, Weighted Average Exercise Price	$ 4.34	$ 4.58
Weighted Average Exercise Price, Ending Balance	$ 3.50	$ 3.36	$ 3.55
Vested and expected to vest, Weighted Average Exercise Price, Ending Balance	$ 3.49
Exercisable, Weighted Average Exercise Price, Ending Balance	$ 3.44
Weighted Average Remaining Contractual Life (in years)	7 years 15 days	3 years 11 months 5 days	4 years 2 months 27 days
Vested and expected to vest, Weighted Average Remaining Contractual Life (in years)	6 years 10 months 17 days
Exercisable, Weighted Average Remaining Contractual Life (in years)	4 years 15 days
Aggregate Intrinsic Value	$ 1,820,452
Vested and expected to vest, Aggregate Intrinsic Value	1,706,553
Exercisable, Aggregate Intrinsic Value	$ 786,385