Share-Based Compensation - Summary of Options Outstanding and Exercisable on an As-Converted Basis (Details) - $ / shares	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020	Dec. 31, 2019
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options Outstanding	55,584,301	50,427,065	40,028,465
Life Remaining (years)	3 years 2 months 19 days	3 years 8 months 19 days	4 years 1 month 13 days
Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options Outstanding	55,584,301
Exercisable Options	37,016,058
Life Remaining (years)	3 years 2 months 19 days
Stock Options Granted on July 31, 2019, One | Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Strike Price	$ 1.00
Options Outstanding	7,983,332
Exercisable Options	7,983,332
Life Remaining (years)	1 year 2 months 12 days
Stock Options Granted on July 31, 2019, Two | Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Strike Price	$ 1.00
Options Outstanding	1,166,667
Exercisable Options	1,166,667
Life Remaining (years)	2 years 3 days
Stock Options Granted on July 31, 2019, Three | Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Strike Price	$ 1.50
Options Outstanding	441,666
Exercisable Options	441,666
Life Remaining (years)	2 years 8 months 12 days
Stock Options Granted on July 31, 2019, Four | Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Strike Price	$ 1.50
Options Outstanding	800,000
Exercisable Options	333,334
Life Remaining (years)	2 years 8 months 19 days
Stock Options Granted on July 31, 2019, Five | Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Strike Price	$ 0.10
Options Outstanding	6,245,840
Exercisable Options	6,245,840
Life Remaining (years)	2 years 11 months 15 days
Stock Options Granted on August 22, 2019, One | Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Strike Price	$ 1.00
Options Outstanding	6,148,750
Exercisable Options	1,881,450
Life Remaining (years)	2 years 10 months 24 days
Stock Options Granted on August 22, 2019, Two | Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Strike Price	$ 0.80
Options Outstanding	5,748,854
Exercisable Options	2,814,575
Life Remaining (years)	2 years 10 months 24 days
Stock Options Granted on November 1, 2019 | Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Strike Price	$ 0.80
Options Outstanding	1,200,000
Exercisable Options	400,000
Life Remaining (years)	3 years 1 month 2 days
Stock Options Granted on February 3, 2020 | Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Strike Price	$ 0.80
Options Outstanding	358,332
Exercisable Options	158,333
Life Remaining (years)	3 years 4 months 6 days
Stock Options Granted on June 8, 2020 | Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Strike Price	$ 0.80
Options Outstanding	25,000
Exercisable Options	8,333
Life Remaining (years)	3 years 4 months 6 days
Stock Options Granted on July 31, 2020 | Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Strike Price	$ 0.80
Options Outstanding	1,200,000
Exercisable Options	1,200,000
Life Remaining (years)	3 years 10 months 2 days
Stock Options Granted on September 15, 2020 | Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Strike Price	$ 0.86
Options Outstanding	7,915,860
Exercisable Options	7,315,860
Life Remaining (years)	3 years 11 months 15 days
Stock Options Granted on October 2, 2020 | Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Strike Price	$ 0.77
Options Outstanding	3,000,000
Exercisable Options	1,500,000
Life Remaining (years)	4 years 3 days
Stock Options Granted on November 24, 2020 | Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Strike Price	$ 0.94
Options Outstanding	1,775,000
Exercisable Options	1,775,000
Life Remaining (years)	4 years 1 month 24 days
Stock Options Granted on December 2, 2020 | Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Strike Price	$ 1.11
Options Outstanding	2,900,000
Exercisable Options	1,450,000
Life Remaining (years)	4 years 2 months 4 days
Stock Options Granted on December 21, 2020 | Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Strike Price	$ 1.06
Options Outstanding	1,200,000
Life Remaining (years)	4 years 2 months 23 days
Stock Options Granted on March 18, 2021 | Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Strike Price	$ 1.63
Options Outstanding	6,650,000
Exercisable Options	2,216,667
Life Remaining (years)	4 years 5 months 19 days
Stock Options Granted on April 2, 2021 | Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Strike Price	$ 1.36
Options Outstanding	200,000
Exercisable Options	66,667
Life Remaining (years)	4 years 5 months 19 days
Stock Options Granted on April 21, 2021 | Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Strike Price	$ 1.58
Options Outstanding	175,000
Exercisable Options	58,333
Life Remaining (years)	4 years 5 months 19 days
Stock Options Granted on June 23, 2021 | Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Strike Price	$ 1.56
Options Outstanding	450,000
Life Remaining (years)	4 years 8 months 23 days