Stockholders' Equity (Share Activity) (Details) - shares	3 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020
Activity of Shares [Roll Forward]
Common stock, shares outstanding (in shares)			67,432,712
Common stock, shares outstanding (in shares)	87,047,832
Class A-1 Convertible Preferred Stock | 2019 SPA and 2020 SPA
Activity of Shares [Roll Forward]
Preferred stock, shares outstanding (in shares)	257,000	257,000	257,000	257,000	416,000	416,000
Conversions/Exercises (in shares)	0	0	0	0	(159,000)	0
Preferred stock, shares outstanding (in shares)	257,000	257,000	257,000	257,000	257,000	416,000
Class A-2 Convertible Preferred Stock | 2019 SPA and 2020 SPA
Activity of Shares [Roll Forward]
Preferred stock, shares outstanding (in shares)	1,331,000	1,338,000	1,416,000	1,961,000	2,632,000	3,288,000
Conversions/Exercises (in shares)	0	(7,000)	(78,000)	(322,000)	(671,000)	(656,000)
Preferred stock, shares outstanding (in shares)	1,331,000	1,331,000	1,338,000	1,639,000	1,961,000	2,632,000
Class A-3 Convertible Preferred Stock | 2019 SPA and 2020 SPA
Activity of Shares [Roll Forward]
Preferred stock, shares outstanding (in shares)	259,000	259,000	259,000	0	0	0
Conversions/Exercises (in shares)	0	0	0	0	0	0
Preferred stock, shares outstanding (in shares)	259,000	259,000	259,000	0	0	0
Warrants | 2019 SPA and 2020 SPA
Activity of Shares [Roll Forward]
Warrants outstanding (in shares)	61,868,000	62,118,000	66,038,000	46,774,000	46,774,000	46,774,000
Conversions/Exercises (in shares)	0	(250,000)	(3,920,000)	0	0	0
Warrants outstanding (in shares)	61,868,000	61,868,000	62,118,000	46,774,000	46,774,000	46,774,000
Common Stock | 2019 SPA and 2020 SPA
Activity of Shares [Roll Forward]
Common stock, shares outstanding (in shares)			0			0
Conversions/Exercises (in shares)	0	326,000	3,199,000	3,217,000	8,296,000	6,567,000
Common stock, shares outstanding (in shares)