Stock-Based Compensation - Summary of Stock Option Activity (Detail) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Shares, Outstanding at beginning balance	5,335,850
Shares, Granted	702,000
Shares, Expired/cancelled	(1,265,890)
Shares, Outstanding at ending balance	4,771,960	5,335,850
Shares, Expected to vest	2,897,757
Shares, Options exercisable	1,874,203
Weighted Average Exercise Price, Outstanding at beginning balance	$ 2.60
Weighted Average Exercise Price, Granted	0.52
Weighted Average Exercise Price, Expired/cancelled	4.27
Weighted Average Exercise Price, Outstanding at ending balance	1.85	$ 2.60
Weighted Average Exercise Price, Expected to vest	1.51
Weighted Average Exercise Price, Options exercisable	$ 2.39
Weighted Average Remaining Contractual Term, Outstanding	7 years 2 months 15 days	6 years 2 months 23 days
Weighted Average Remaining Contractual Term, Expected to vest	9 years 29 days
Weighted Average Remaining Contractual Term, Options exercisable	4 years 3 months 21 days
Aggregate Intrinsic Value, Outstanding	$ 20,920	$ 2,866
Aggregate Intrinsic Value, Expected to vest	$ 20,920