Stock-Based Compensation - Summary of Stock Option Activity under Equity Plans (Details) $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 30, 2021 USD ($) $ / shares shares
Shares
Options outstanding (in shares)	597,354
Granted (in shares)	0
Options outstanding (in shares)	597,354
Options exercisable (in shares)	597,354
Options vested and expected to vest (in shares)	597,354
Weighted Average Exercise Price
Options outstanding (in USD per share) | $ / shares	$ 5.86
Options outstanding (in USD per share) | $ / shares	5.86
Options exercisable (in USD per share) | $ / shares	5.86
Options vested and expected to vest (in USD per share) | $ / shares	$ 5.86
Weighted Average Remaining Contractual Life
Options outstanding	6 years 6 months 18 days
Options exercisable	6 years 6 months 18 days
Options vested and expected to vest	6 years 6 months 18 days
Aggregate Intrinsic Value
Options outstanding | $	$ 83
Options exercisable | $	83
Options vested and expected to vest | $	$ 83