Shareholders' Equity - Summary of Stock Option Activity (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Roll Forward
Number of Shares, Beginning Balance	1,778,697	1,553,360
Granted, Number of Shares	903,248	564,450
Exercised, Number of Shares	(371,845)	(250,196)
Forfeited, Number of Shares	(396,161)	(81,666)
Expired, Number of Shares	(67,171)	(7,251)
Number of Shares, Ending Balance	1,846,768	1,778,697	1,553,360
Vested and expected to vest, Number of Shares, Ending Balance	1,676,601
Exercisable, Number of Shares, Ending Balance	771,265
Weighted Average Exercise Price, Beginning Balance	$ 4.43	$ 3.50
Granted, Weighted Average Exercise Price	5.24	6.37
Exercised, Weighted Average Exercise Price	3.17	3.18
Forfeited, Weighted Average Exercise Price	5.32	4.01
Expired, Weighted Average Exercise Price	5.91	2.82
Weighted Average Exercise Price, Ending Balance	4.84	$ 4.43	$ 3.50
Vested and expected to vest, Weighted Average Exercise Price, Ending Balance	4.79
Exercisable, Weighted Average Exercise Price, Ending Balance	$ 4.15
Weighted Average Remaining Contractual Life (in years)	8 years 2 months 9 days	7 years 9 months 29 days	7 years 15 days
Vested and expected to vest, Weighted Average Remaining Contractual Life (in years)	8 years 18 days
Exercisable, Weighted Average Remaining Contractual Life (in years)	6 years 7 months 17 days
Aggregate Intrinsic Value	$ 2,138,361
Vested and expected to vest, Aggregate Intrinsic Value	2,036,356
Exercisable, Aggregate Intrinsic Value	$ 1,425,867