Stockholders' Equity - Preferred Stock and Convertible Preferred Stock (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Preferred stock
Class of Stock [Line Items]
Preferred stock, outstanding (in shares)	0	0
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares authorized (in shares)	5,000,000	5,000,000
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock	$ 0	$ 0
Series B Convertible Preferred Stock
Class of Stock [Line Items]
Preferred stock, outstanding (in shares)	200	200
Preferred stock, shares issued (in shares)	200	200
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares designated (in shares)	147,000	147,000
Preferred stock	$ 1	$ 1
Series D Convertible Preferred Stock
Class of Stock [Line Items]
Preferred stock, outstanding (in shares)	0	14,052.93
Preferred stock, shares issued (in shares)	0	14,052.93
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares designated (in shares)	21,300	21,300
Preferred stock	$ 0	$ 14
Series E Convertible Preferred Stock
Class of Stock [Line Items]
Preferred stock, outstanding (in shares)	0	3,260.70
Preferred stock, shares issued (in shares)	0	3,260.70
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares designated (in shares)	7,000	7,000
Preferred stock	$ 0	$ 3
Series F Convertible Preferred Stock
Class of Stock [Line Items]
Preferred stock, outstanding (in shares)	0	0
Preferred stock, shares issued (in shares)	0	0
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares designated (in shares)	10,621	10,621
Preferred stock	$ 0	$ 0