Stockholders' Equity and Stock Based Compensation - Summary of Stock Options (Details) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2021 USD ($) $ / shares shares	Dec. 31, 2020 USD ($) $ / shares shares
Number of Shares
Beginning balance (in shares) | shares	2,096,000
Stock options granted (in shares) | shares	0
Stock options exercised (in shares) | shares	(210,000)
Stock options cancelled / forfeited / expired (in shares) | shares	(203,000)
Ending balance (in shares) | shares	1,683,000	2,096,000
Weighted-Average Exercise Price
Beginning balance (in USD per share) | $ / shares	$ 0.23
Stock options granted (in USD per share) | $ / shares	0
Stock options exercised (in USD per share) | $ / shares	220
Stock options cancelled / forfeited / expired (in USD per share) | $ / shares	60.00
Ending balance (in USD per share) | $ / shares	$ 250	$ 0.23
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Weighted-Average Remaining Contractual Term (in years)	3 years 9 months 18 days	4 years 1 month 6 days
Aggregate intrinsic value | $	$ 71,401	$ 33,947