Stock-Based Compensation - Summary of Stock Option Activity (Details) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Number of Shares, Granted		675,000
2016 Stock Incentive Plan [Member]
Number of Shares Common stock options, outstanding at Beginning balance	8,064,561	9,405,541
Number of Shares, Granted	234,000
Number of Shares, Exercised	(6,944)	(25,000)
Number of Shares, Forfeited	(601,179)	(1,197,776)
Number of Shares, Expired	(788,101)	(118,204)
Number of Shares Common stock options, outstanding at Ending balance	6,902,337	8,064,561
Number of Shares Common stock options, exercisable at Ending balance	6,027,418
Number of Shares Common stock options, not vested at Ending balance	874,919
Number of Shares Common stock options, available for future grants at Ending balance	3,097,663
Weighted Average Exercise Price, outstanding at Beginning balance	$ 0.62	$ 0.61
Weighted Average Exercise Price, Granted	0.90
Weighted Average Exercise Price, Exercised	0.56	0.17
Weighted Average Exercise Price, Forfeited	1.09	0.73
Weighted Average Exercise Price, Expired	0.53	1.09
Weighted Average Exercise Price, outstanding at Ending balance	0.86	$ 0.62
Weighted Average Exercise Price, exercisable at Ending balance	$ 0.90
Weighted Average Remaining Contractual Life (in Years), outstanding at Beginning balance	8 years 4 months 2 days	9 years 3 months 19 days
Weighted Average Remaining Contractual Life (in Years), outstanding at Ending balance	7 years 6 months	8 years 4 months 2 days
Weighted Average Remaining Contractual Life (in Years), exercisable at Ending balance	7 years 5 months 20 days
2019 Equity Incentive Plan [Member]
Number of Shares Common stock options, outstanding at Beginning balance	65,013,645
Number of Shares, Granted	25,393,768	68,180,863
Number of Shares, Forfeited	(8,342,377)	(3,167,218)
Number of Shares, Expired	(2,722)
Number of Shares Common stock options, outstanding at Ending balance	82,062,314	65,013,645
Number of Shares Common stock options, exercisable at Ending balance	13,608,686
Number of Shares Common stock options, not vested at Ending balance	68,453,628
Number of Shares Common stock options, available for future grants at Ending balance	2,937,686
Weighted Average Exercise Price, outstanding at Beginning balance	$ 0.53
Weighted Average Exercise Price, Granted	0.71	0.53
Weighted Average Exercise Price, Forfeited	0.61	0.53
Weighted Average Exercise Price, Expired	0.56
Weighted Average Exercise Price, outstanding at Ending balance	0.58	$ 0.53
Weighted Average Exercise Price, exercisable at Ending balance	$ 0.54
Weighted Average Remaining Contractual Life (in Years), outstanding at Beginning balance	9 years 5 months 5 days	0 years
Weighted Average Remaining Contractual Life (in Years), outstanding at Ending balance	8 years 7 months 24 days	9 years 5 months 5 days
Weighted Average Remaining Contractual Life (in Years), exercisable at Ending balance	8 years 5 months 27 days
Stock Options Outside 2016 Plan and 2019 Plan [Member]
Number of Shares Common stock options, outstanding at Beginning balance	3,724,667	2,414,000
Number of Shares, Granted		1,500,000
Number of Shares, Exercised		(2,000)
Number of Shares, Forfeited	(195,333)	(180,000)
Number of Shares, Expired	(477,334)	(7,333)
Number of Shares Common stock options, outstanding at Ending balance	3,052,000	3,724,667
Number of Shares Common stock options, exercisable at Ending balance	2,376,333
Number of Shares Common stock options, not vested at Ending balance	675,667
Weighted Average Exercise Price, outstanding at Beginning balance	$ 0.21	$ 0.36
Weighted Average Exercise Price, Granted		0.57
Weighted Average Exercise Price, Exercised		0.35
Weighted Average Exercise Price, Forfeited	0.46	0.35
Weighted Average Exercise Price, Expired	0.39	0.35
Weighted Average Exercise Price, outstanding at Ending balance	0.46	$ 0.21
Weighted Average Exercise Price, exercisable at Ending balance	$ 0.43
Weighted Average Remaining Contractual Life (in Years), outstanding at Beginning balance	9 years 15 days	9 years 11 months 8 days
Weighted Average Remaining Contractual Life (in Years), outstanding at Ending balance	8 years 26 days	9 years 15 days
Weighted Average Remaining Contractual Life (in Years), exercisable at Ending balance	6 years 2 months 12 days