Amount of cash outflow for realized tax benefit related to deductible compensation cost reported on the entity's tax return for equity instruments in excess of the compensation cost for those instruments recognized for financial reporting purposes.

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Stock-Based Compensation - Summary of Stock Option Activity (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 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	$ 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	147,000	241,000	820,350	1,198,000
Number of Options, Exercised			(24,346)
Number of Options, Expired			(167,964)
Number of Options, Forfeited			(113,791)
Number of Options, Outstanding	4,964,766		4,964,766
Number of Options, Options exercisable	2,756,734		2,756,734
Weighted-Average Exercise Price, Outstanding			$ 14.73
Weighted-Average Exercise Price, Granted			16.04
Weighted-Average Exercise Price, Exercised			11.34
Weighted-Average Exercise Price, Expired			13.85
Weighted-Average Exercise Price, Forfeited			16.21
Weighted-Average Exercise Price, Outstanding	$ 14.96		$ 14.96
2019 Inducement Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Options, Granted	0		0