Fair Value Measurements - Estimated Fair Value of Warrant Liability (Details)	1 Months Ended	12 Months Ended
	May 31, 2020 $ / shares shares	Dec. 31, 2020 USD ($) Y $ / shares shares	May 22, 2020 USD ($) $ / shares	Apr. 30, 2020 $ / shares	Dec. 31, 2019 USD ($) $ / shares	Jul. 31, 2019	Jul. 23, 2019 $ / shares
Series A Warrants | Stock price
Fair Value Assumptions and Methodology for Assets and Liabilities
Warrant liability		0.82			0.65
Series A Warrants | Strike price
Fair Value Assumptions and Methodology for Assets and Liabilities
Warrant liability		787.50			787.50
Series A Warrants | Expected life
Fair Value Assumptions and Methodology for Assets and Liabilities
Weighted-average expected term (years)		1 year 4 months 28 days			2 years 4 months 28 days
Series A Warrants | Volatility
Fair Value Assumptions and Methodology for Assets and Liabilities
Warrant liability		148			143.41
Series A Warrants | Risk free rate
Fair Value Assumptions and Methodology for Assets and Liabilities
Warrant liability		0.13			1.62
Series 1 warrants
Fair Value Assumptions and Methodology for Assets and Liabilities
Weighted-average expected term (years)						5 years
Series 3 warrants
Fair Value Assumptions and Methodology for Assets and Liabilities
Weighted-average expected term (years)	5 years
Warrants exercised | shares		8,456,352
Warrants conversion | shares	1	1
Series 3 warrants | Stock price
Fair Value Assumptions and Methodology for Assets and Liabilities
Warrant liability	0.05	0.82	0.44
Series 3 warrants | Strike price
Fair Value Assumptions and Methodology for Assets and Liabilities
Warrant liability	0.44	0.00	0.05
Series 3 warrants | Expected life
Fair Value Assumptions and Methodology for Assets and Liabilities
Weighted-average expected term (years)	5 years 6 months	4 years 10 months 21 days	5 years 6 months
Series 3 warrants | Volatility
Fair Value Assumptions and Methodology for Assets and Liabilities
Warrant liability	141	142	142
Series 3 warrants | Risk free rate
Fair Value Assumptions and Methodology for Assets and Liabilities
Warrant liability	0.34	0.36	0.34
Underwriter Warrants | Stock price
Fair Value Assumptions and Methodology for Assets and Liabilities
Warrant liability		0.82		2.50	0.65
Underwriter Warrants | Strike price
Fair Value Assumptions and Methodology for Assets and Liabilities
Warrant liability		52.50		0.45	52.50
Underwriter Warrants | Expected life
Fair Value Assumptions and Methodology for Assets and Liabilities
Weighted-average expected term (years)		2 years 9 months 4 days		4 years 3 months	3 years 9 months 4 days
Underwriter Warrants | Volatility
Fair Value Assumptions and Methodology for Assets and Liabilities
Warrant liability		156		141	143.00
Underwriter Warrants | Risk free rate
Fair Value Assumptions and Methodology for Assets and Liabilities
Warrant liability		0.17		0.29	1.69
2019 Bridge Note Warrants | Stock price
Fair Value Assumptions and Methodology for Assets and Liabilities
Warrant liability							1.73
2019 Bridge Note Warrants | Strike price
Fair Value Assumptions and Methodology for Assets and Liabilities
Warrant liability							2.00
2019 Bridge Note Warrants | Expected life
Fair Value Assumptions and Methodology for Assets and Liabilities
Weighted-average expected term (years)							4 years 9 months 18 days
2019 Bridge Note Warrants | Volatility
Fair Value Assumptions and Methodology for Assets and Liabilities
Warrant liability							145.84
2019 Bridge Note Warrants | Risk free rate
Fair Value Assumptions and Methodology for Assets and Liabilities
Warrant liability							1.76
Warrant liability | Series A Warrants
Fair Value Assumptions and Methodology for Assets and Liabilities
Fair value of warrant | $		$ 0			$ 0
Change in fair value | $		0
Warrant liability | Series 3 warrants
Fair Value Assumptions and Methodology for Assets and Liabilities
Fair value of warrant | $		175,000	$ 3,700,000
Change in fair value | $		$ 2,500,000
Warrants exercised | shares		8,456,352
Warrants conversion | shares		1
Warrant liability | Underwriter Warrants
Fair Value Assumptions and Methodology for Assets and Liabilities
Fair value of warrant | $		$ 4,000			3,000
Change in fair value | $		$ 1,000
Warrant liability | LOC Warrants
Fair Value Assumptions and Methodology for Assets and Liabilities
Fair value of warrant | $					0
Warrant liability | 2019 Bridge Note Warrants
Fair Value Assumptions and Methodology for Assets and Liabilities
Fair value of warrant | $					$ 0
2019 Bridge Notes | Stock price | Minimum
Fair Value Assumptions and Methodology for Assets and Liabilities
Warrant liability		4.84
2019 Bridge Notes | Stock price | Maximum
Fair Value Assumptions and Methodology for Assets and Liabilities
Warrant liability		32.90
2019 Bridge Notes | Expected life
Fair Value Assumptions and Methodology for Assets and Liabilities
Warrant liability | Y		5.0
2019 Bridge Notes | Risk free rate | Minimum
Fair Value Assumptions and Methodology for Assets and Liabilities
Warrant liability		1.76
2019 Bridge Notes | Risk free rate | Maximum
Fair Value Assumptions and Methodology for Assets and Liabilities
Warrant liability		2.23