Stockholders' Equity (Details)					1 Months Ended		12 Months Ended
	Jun. 03, 2019	Sep. 11, 2018 shares	May 29, 2018	Jul. 31, 2017 item	Jun. 30, 2019	Jun. 30, 2018 shares	Dec. 31, 2019 shares	Dec. 31, 2018 shares
Stockholders' Equity
Number of voting rights entitled for each share of common stock held | item				1
Reverse stock split ratio	0.0143		0.0667		0.015	0.0667
Number of pre-funded warrants issued							20,637,761
Shares of common stock reserved for issuance
Options issued and outstanding							3,902,675	42,059
Options available for grant under stock option plans							479,829	2,327
RSUs awards issued and outstanding							5,613	5,613
Warrants issued and outstanding							19,421,892	34,681
Convertible warrants							9,580	10,849
Total							27,200,498	145,870
Inducement options issued and outstanding
Shares of common stock reserved for issuance
Options issued and outstanding							74	2,984
Common stock - voting
Stockholders' Equity
Shares issued (in shares)								17,075
Blank check preferred stock
Stockholders' Equity
Common stock, shares authorized						10,000,000
Series A convertible preferred stock
Shares of common stock reserved for issuance
Convertible warrants							473,565	47,357
Series B convertible preferred stock
Shares of common stock reserved for issuance
Convertible warrants							985,500
Series B-2 Convertible Preferred Stock Member
Shares of common stock reserved for issuance
Convertible warrants							1,931,350
Common Stock
Stockholders' Equity
Common stock, shares authorized						210,000,000
Shares issued (in shares)		1,071
Common Stock | Common stock - voting
Stockholders' Equity
Common stock, shares authorized						150,000,000	150,000,000	150,000,000
Common Stock | Common stock - non-voting
Stockholders' Equity
Common stock, shares authorized						50,000,000	50,000,000	50,000,000
Convertible non-voting common stock
Stockholders' Equity
Reverse stock split ratio							1