Stockholders' Equity (Deficit) - Narrative (Details) - $ / shares	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019
Class of Warrant or Right [Line Items]
Preferred stock, shares authorized (in shares)	49,995,966	49,995,966
Preferred stock, shares issued (in shares)	175.53	105.33
Preferred stock, shares outstanding (in shares)	175.53	105.33
Common stock, shares authorized (in shares)	500,000,000	500,000,000
Common stock, shares issued (in shares)	140,325,114	139,060,180
Common stock, shares outstanding (in shares)	140,325,114	139,060,180
Warrants Fundraising
Class of Warrant or Right [Line Items]
Warrants conversion feature, units outstanding	39,501,211		38,111,211
Exercise price of warrants or rights (in dollars per share)	$ 1.66
Warrants Fundraising | Minimum
Class of Warrant or Right [Line Items]
Exercise price of warrants or rights (in dollars per share)	0.37
Warrants Fundraising | Maximum
Class of Warrant or Right [Line Items]
Exercise price of warrants or rights (in dollars per share)	$ 5.38