Stock-Based Compensation - Additional Information (Details) - USD ($)	1 Months Ended			3 Months Ended		9 Months Ended		12 Months Ended
	Feb. 28, 2021	Jan. 31, 2021	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total shares of common stock reserved				1,550,887		1,550,887		3,566,199
Weighted-average grant date fair value of stock options granted to employees and directors						$ 2.53	$ 2.73
Aggregate grant date fair value of stock options vested						$ 309,081	$ 719,632
Total unrecognized compensation cost related to stock options granted to employees				$ 778,278		$ 778,278		$ 926,591
Common stock, par value				$ 0.0001	$ 0.0001	$ 0.0001	$ 0.0001	$ 0.0001
Stock based compensation expense				$ 156,000	$ 91,000	$ 388,000	$ 661,000
General and Administrative Expense
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock based compensation expense				$ 111,000	$ 54,000	270,000	565,000
Keystone
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock, par value			$ 4.00
Keystone | General and Administrative Expense
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock based compensation expense							$ 80,000
Angel Pond L L C
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock, par value	$ 3.90	$ 2.44
Angel Pond L L C | General and Administrative Expense
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock based compensation expense						$ 30,000
Common Stock | Keystone
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares issued for services			20,000
Common Stock | Angel Pond L L C
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares issued for services	3,842	6,137
Maximum | Common Stock | Keystone | Stock Purchase Agreement
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock issued under purchase agreement			$ 5,000,000
2018 Omnibus Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total shares of common stock reserved				425,000		425,000
Percentage of total shares of common stock reserved						2.00%
Additional shares of common stock						447,744
2018 Omnibus Incentive Plan | Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of voting power of all classes of stock to be owned by optionee to determine the exercise price						10.00%
Exercise price as a percentage of fair value of common stock on grant date if optionee owns stock representing more than 10 percent of voting power of all classes of stock						110.00%
Employee Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total unrecognized compensation cost related to stock options granted to employees, weighted-average recognition period						2 years 2 months 1 day		2 years 11 months 15 days
Employee Stock Options | 2011 Employee Equity Plan | Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options granted, expiration year						5 years
Employee Stock Options | 2011 Employee Equity Plan | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options granted, expiration year						10 years
Employee Stock Options | 2018 Omnibus Incentive Plan | Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options granted, expiration year						5 years
Employee Stock Options | 2018 Omnibus Incentive Plan | Minimum | Board of Directors
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period of stock option grants						0 years
Employee Stock Options | 2018 Omnibus Incentive Plan | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options granted, expiration year						10 years
Employee Stock Options | 2018 Omnibus Incentive Plan | Maximum | Board of Directors
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period of stock option grants						8 years