Stockholders' Deficit - Warrant Activity (Details) - Warrants Fundraising - shares	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Class of Warrant or Right [Line Items]
Warrants outstanding, beginning balance (in shares)	54,298,850	38,111,211
Issued (in shares)	2,775,000	17,000,000
Expired (in shares)	(1,104,540)	(812,361)
Warrants outstanding, ending balance (in shares)	55,969,310	54,298,850