Stockholders' Deficit - Summary of Stock Option Activity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Equity [Abstract]
Options awards outstanding, Beginning balance	23,782	25,030	20,873
Options awards outstanding, Granted	60	737	4,620
Options awards outstanding, Exercised	(111)	(1,182)	(344)
Options awards outstanding, Cancelled/Forfeited	(5,048)	(416)	(93)
Options awards outstanding, Expired	(1,028)	(387)	(26)
Options awards outstanding, Ending balance	17,655	23,782	25,030	20,873
Options award outstanding, weighted average exercise price, Beginning balance	$ 4.80	$ 4.65	$ 4.93
Options award outstanding, weighted average exercise price, Granted	1.21	1.58	3.10
Options award outstanding, weighted average exercise price, Exercised	0.03	0.23	0.32
Options award outstanding, weighted average exercise price, Cancelled/Forfeited	6.01	3.80	5.16
Options award outstanding, weighted average exercise price, Expired	4.02	3.76	5.57
Options award outstanding, weighted average exercise price, Ending balance	$ 4.52	$ 4.80	$ 4.65	$ 4.93
Options award outstanding, aggregate intrinsic value		$ 152	$ 3,668	$ 12,240
Options award exercised, aggregate intrinsic value	$ 61	$ 1,739	$ 1,427
Options awards outstanding, Weighted Average Remaining Contractual Life (in Years)	3 years 9 months 18 days	5 years 2 months 12 days	5 years 9 months 18 days	5 years 10 months 24 days
Options awards exercisable, Option Awards	16,776	19,863	18,026	16,069
Options awards exercisable, Weighted Average Exercise Price	$ 4.62	$ 5.06	$ 4.88	$ 4.61
Options awards exercisable, Aggregate Intrinsic Value		$ 117	$ 3,320	$ 12,240
Options awards exercisable, Weighted Average Remaining Contractual Life (in Years)	3 years 7 months 6 days	4 years 7 months 6 days	4 years 7 months 6 days	5 years 1 month 6 days