Shareholders' Equity - Summary of Stock Option Activity (Detail) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Roll Forward
Number of Shares, Beginning Balance	1,846,768
Granted, Number of Shares	188,625
Exercised, Number of Shares	(45,241)
Forfeited, Number of Shares	(54,043)
Expired, Number of Shares	(29,325)
Number of Shares, Ending Balance	1,906,784	1,846,768
Vested and expected to vest, Number of Shares, Ending Balance	1,773,550
Exercisable, Number of Shares, Ending Balance	874,714
Weighted Average Exercise Price, Beginning Balance	$ 4.84
Granted, Weighted Average Exercise Price	5.22
Exercised, Weighted Average Exercise Price	3.71
Forfeited, Weighted Average Exercise Price	5.30
Expired, Weighted Average Exercise Price	5.67
Weighted Average Exercise Price, Ending Balance	4.88	$ 4.84
Vested and expected to vest, Weighted Average Exercise Price, Ending Balance	4.85
Exercisable, Weighted Average Exercise Price, Ending Balance	$ 4.31
Weighted Average Remaining Contractual Life (in years)	7 years 9 months 14 days	8 years 2 months 9 days
Vested and expected to vest, Weighted Average Remaining Contractual Life (in years)	7 years 8 months 9 days
Exercisable, Weighted Average Remaining Contractual Life (in years)	6 years 5 months 23 days
Aggregate Intrinsic Value	$ 1,248,990	$ 2,138,361
Vested and expected to vest, Aggregate Intrinsic Value	1,231,129
Exercisable, Aggregate Intrinsic Value	$ 1,098,971