CONDENSED CONSOLIDATED STATEMENT OF CHANGES IN CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' EQUITY - USD ($)	Series 1, Series 2, and 2019 Bridge Note warrants Common Stock Common stock - voting	Series 1, Series 2, and 2019 Bridge Note warrants Additional paid-in capital	Series 1, Series 2, and 2019 Bridge Note warrants	Series 2 warrants and inducement offer conversion of Series B-1 convertible preferred stock Common Stock Common stock - voting	Series 2 warrants and inducement offer conversion of Series B-1 convertible preferred stock Additional paid-in capital	Series 2 warrants and inducement offer conversion of Series B-1 convertible preferred stock	PIPE Financing Warrants, Dec 2019	Private Investment in Public Entities Common Stock Common stock - voting	Private Investment in Public Entities Additional paid-in capital	Private Investment in Public Entities	Common Stock Common stock - voting	Common Stock Common stock - non-voting	Additional paid-in capital	Accumulated deficit	Series A convertible preferred stock	Series B convertible preferred stock	Series B-1 convertible preferred stock	Series B-2 convertible preferred stock	Total
Beginning Balance at Dec. 31, 2018															$ 9,000,000
Beginning Balance (in shares) at Dec. 31, 2018															5,524,926
Ending Balance at Mar. 31, 2019															$ 9,000,000
Ending Balance (in shares) at Mar. 31, 2019															5,524,926
Beginning Balance at Dec. 31, 2018												$ 4,000	$ 99,930,000	$ (94,551,000)					$ 5,383,000
Beginning Balance (in shares) at Dec. 31, 2018											351,472	40,301,237
Increase (decrease) in Stockholders' Equity (Deficit)
Issuance of common stock, net of offering costs													2,502,000						2,502,000
Issuance of common stock, net of offering costs (in shares)											190,476
Issuance of common stock in exchange of notes payable and accrued interest											$ 1,000		6,072,000						6,073,000
Issuance of common stock in exchange of notes payable and accrued interest (in shares)											268,066
Issuance of common stock in exchange of accrued interest, January 2019													447,000						447,000
Issuance of common stock in exchange of accrued interest, January 2019 (in shares)											19,752
Issuance of common stock, net of offering costs, March 2019													266,000						266,000
Issuance of common stock, net of offering costs, March 2019 (in shares)											19,019
Stock-based compensation													427,000						427,000
Net loss														(8,304,000)					(8,304,000)
Ending Balance at Mar. 31, 2019											$ 1,000	$ 4,000	109,644,000	(102,855,000)					$ 6,794,000
Ending Balance (in shares) at Mar. 31, 2019											848,785	40,301,237
Beginning Balance at Dec. 31, 2018															$ 9,000,000
Beginning Balance (in shares) at Dec. 31, 2018															5,524,926
Ending Balance at Dec. 31, 2019															$ 9,895,000	$ 476,000		$ 1,236,000
Ending Balance (in shares) at Dec. 31, 2019															5,524,926	1,971	0	10,165	5,537,062
Beginning Balance at Dec. 31, 2018												$ 4,000	99,930,000	(94,551,000)					$ 5,383,000
Beginning Balance (in shares) at Dec. 31, 2018											351,472	40,301,237
Increase (decrease) in Stockholders' Equity (Deficit)
Issuance of common stock in PIPE financing, net of issuance costs of $51							$ 1,035,000
Ending Balance at Dec. 31, 2019											$ 1,000	$ 4,000	142,046,000	(133,090,000)					$ 10,673,000
Ending Balance (in shares) at Dec. 31, 2019											14,273,061	40,301,237
Ending Balance at Mar. 31, 2020															$ 10,375,000	$ 476,000		$ 916,000
Ending Balance (in shares) at Mar. 31, 2020															5,524,926	1,971	0	7,534	5,534,431
Increase (decrease) in Stockholders' Equity (Deficit)
Value Of Shares Issued On Exercise Of Warrants		$ 392,000	$ 392,000	$ 1,000	$ 2,340,000	$ 2,341,000
Shares Issued On Exercise Of Warrants	548,962			1,250,000
Issuance of common stock in PIPE financing, net of issuance costs of $51									$ 668,000	$ 668,000
Issuance of common stock (In shares)								1,714,283
Underwriter settlement offering cost													(185,000)						$ (185,000)
Conversion of Series B-2 convertible preferred stock into common stock													320,000					$ (320,000)
Conversion of Series B-2 convertible preferred stock into common stock (shares)											(499,890)							(2,631)
Accretion to redemption value of Series A redeemable convertible preferred stock													(480,000)		$ 480,000				(480,000)
Stock-based compensation													760,000						760,000
Net loss														(7,936,000)					(7,936,000)
Ending Balance at Mar. 31, 2020											$ 2,000	$ 4,000	$ 145,861,000	$ (141,026,000)					$ 6,233,000
Ending Balance (in shares) at Mar. 31, 2020											18,286,196	40,301,237