Stock-Based Compensation - Summary of Stock Option Activity (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Excess tax benefits from stock option activity or stock-based compensation expense recognized in cash flows from operations	$ 0	$ 0
2014 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Options, Outstanding	4,450,517
Number of Options, Granted	673,350	957,000
Number of Options, Exercised	(7,500)
Number of Options, Expired	(161,089)
Number of Options, Forfeited	(24,688)
Number of Options, Outstanding	4,930,590
Number of Options, Outstanding, Weighted average remaining contractual life as of March 31, 2020	7 years 8 months 4 days
Number of Options, Options exercisable	2,484,710
Number of Options, Exercisable, Weighted average remaining contractual life as of March 31, 2020	6 years 5 months 19 days
Number of Options, Options vested and expected to vest at December 31, 2019	4,930,590
Number of Options, Vested and expected to vest, Weighted average remaining contractual life as of March 31, 2020	7 years 8 months 4 days
Weighted-Average Exercise Price, Outstanding	$ 14.73
Weighted-Average Exercise Price, Granted	16.11
Weighted-Average Exercise Price, Exercised	9.94
Weighted-Average Exercise Price, Expired	13.64
Weighted-Average Exercise Price, Forfeited	16.51
Weighted-Average Exercise Price, Outstanding	14.95
Weighted-Average Exercise Price, Options exercisable, March 31, 2020	13.10
Weighted-Average Exercise Price, Options vested and expected to vest at March 31, 2020	$ 14.95
Aggregate Intrinsic Value, Outstanding at March 31, 2020	$ 5,099,000
Aggregate Intrinsic Value, Options exercisable at March 31, 2020	4,763,000
Aggregate Intrinsic Value, Options vested and expected to vest at March 31, 2020	$ 5,099,000
2019 Inducement Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Options, Granted	0