Stock-Based Compensation - Summary of RSU Activity Under Plans (Detail) - Equity Incentive Plan 2019 - RSU's - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Number of Shares
Non-vested shares at the beginning of the year	103,000	14,000
Granted (in shares)	9,000	120,000
Vested (in shares)	(43,000)	(30,000)
Cancelled (in shares)	(4,000)	(1,000)
Non-vested shares at the end of the period	65,000	103,000
Weighted Average Grant-Date Fair Value
Weighted average grant date fair value	$ 3.75	$ 24.31
Granted (in dollars per share)	1.74	3.79
Vested (in dollars per share)	3.72	12.89
Cancelled (in dollars per shares)	4.00	25.13
Weighted average grant date fair value	$ 3.48	$ 3.75