Stockholders' Equity (Deficit) - Summary of Stock Option Activity (Details) $ / shares in Units, shares in Thousands, $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2021 USD ($) $ / shares shares	Dec. 31, 2020 USD ($) $ / shares shares
Equity [Abstract]
Options awards outstanding, Beginning balance | shares	23,782
Options awards outstanding, Exercised | shares	(54)
Options awards outstanding, Cancelled/Forfeited | shares	(148)
Options awards outstanding, Expired | shares	(123)
Options awards outstanding, Ending balance | shares	23,457	23,782
Options award outstanding, weighted average exercise price, Beginning balance | $ / shares	$ 4.80
Options award outstanding, weighted average exercise price, Exercised | $ / shares	0.41
Options award outstanding, weighted average exercise price, Cancelled/Forfeited | $ / shares	3.37
Options award outstanding, weighted average exercise price, Expired | $ / shares	5.90
Options award outstanding, weighted average exercise price, Ending balance | $ / shares	$ 4.82	$ 4.80
Options award outstanding, aggregate intrinsic value | $	$ 100	$ 152
Options award outstanding, weighted average remaining contractual life	4 years 8 months 12 days	5 years 2 months 12 days
Options award exercisable | shares	20,753	19,863
Options award exercisable, weighted average exercise price | $ / shares	$ 5.05	$ 5.06
Options award exercisable, aggregate intrinsic value | $	$ 79	$ 117
Options award exercisable, weighted average remaining contractual life	4 years 2 months 12 days	4 years 7 months 6 days