Stockholders' Equity (Narrative) (Details) $ / shares in Units, $ in Thousands							3 Months Ended
	Jan. 22, 2020 shares	Dec. 24, 2019 USD ($) $ / shares shares	May 07, 2019 USD ($) $ / shares shares	May 03, 2019 USD ($) shares	Dec. 12, 2018 USD ($) shares	Oct. 02, 2018	Mar. 31, 2020 USD ($) shares	Mar. 31, 2019 USD ($)	Dec. 31, 2019 shares
Subsidiary, Sale of Stock [Line Items]
Total common shares reserved for future issuance (in shares)							85,216,000
Warrants Exercised							0
Reverse stock split ratio						0.0833
Stock-based compensation expenses | $							$ 823	$ 959
Private Placement
Subsidiary, Sale of Stock [Line Items]
Share sold (in shares)				9,730,534
Warrants callable			9,730,534
Sale of stock price (usd per share) | $ / shares			$ 1.205
Consideration received | $				$ 16,700
Convertible Preferred stock into common stock			10
Warrant exercise period				5 years
Warrant exercise price (usd per share) | $ / shares			$ 1.08
Milestone Closing
Subsidiary, Sale of Stock [Line Items]
Consideration received | $		$ 24,600
At The Moment
Subsidiary, Sale of Stock [Line Items]
Share sold (in shares)					1,903,880
Consideration received | $					$ 2,100
Commission fee rate					3.00%
Commissions paid | $					$ 100
Shares issued (in shares)									0
Preferred Class A | Private Placement
Subsidiary, Sale of Stock [Line Items]
Warrants callable			4,158,980
Sale of stock price (usd per share) | $ / shares			$ 10.80
Nonvoting convertible preferred stock issued			415,898
Class A-2 Convertible Preferred Stock
Subsidiary, Sale of Stock [Line Items]
Convertible Preferred stock into common stock							656,682
Reverse stock split ratio		10
Class A-2 Convertible Preferred Stock | Milestone Closing
Subsidiary, Sale of Stock [Line Items]
Share sold (in shares)		3,288,390
Warrants callable		32,883,900
Consideration received | $		$ 26,000
Warrant exercise price (usd per share) | $ / shares		$ 0.666
Warrants, term		5 years
Class A-1 Convertible Preferred Stock
Subsidiary, Sale of Stock [Line Items]
Convertible Preferred stock into common stock							0
Warrant | Preferred Class A | Private Placement
Subsidiary, Sale of Stock [Line Items]
Sale of stock price (usd per share) | $ / shares			$ 0.125
Common stock
Subsidiary, Sale of Stock [Line Items]
Conversions of convertible preferred stock (in shares)							6,566,820
Directors, Executive Officers and Employees | Private Placement
Subsidiary, Sale of Stock [Line Items]
Share sold (in shares)				526,083
Directors, Executive Officers and Employees | Preferred Class A | Private Placement
Subsidiary, Sale of Stock [Line Items]
Warrants callable			526,083
Proceeds from issuance of right to purchase common shares | $			$ 600
Certain Directors and Executive Officers [Member] | Class A-2 Convertible Preferred Stock | Milestone Closing
Subsidiary, Sale of Stock [Line Items]
Share sold (in shares)		121,581
Warrants callable		1,215,810
Consideration received | $		$ 1,000
2019 Plan
Subsidiary, Sale of Stock [Line Items]
Number of additional shares authorized (in shares)	4,166,860
Number of additional shares authorized yearly increase (in shares)	5.00%
Common stock available for future grant (in shares)							1,571,199
Total common shares reserved for future issuance (in shares)							1,762,220