Statements of Changes In Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional paid-in Capital	Accumulated deficit
Beginning Balances at Dec. 31, 2015	$ 8,730	$ 382	$ 150,450	$ (142,102)
Beginning Balances (in shares) at Dec. 31, 2015		38,220
Funds received from sale of DSPP units and shares	4,338	$ 28	4,310
Funds received from sale of DSPP units and shares (in shares)		2,796
Value of bonds converted to shares	8		8
Value of bonds converted to shares, (in shares)		6
Funds received from option exercises	16	$ 16
Funds received from option exercises (in shares)		1,556
Value of options granted to employees, directors and others as non-cash compensation	3,086		3,086
Net loss	(8,513)			(8,513)
Ending Balances at Dec. 31, 2016	7,665	$ 426	157,854	(150,615)
Ending Balances (in shares) at Dec. 31, 2016		42,578
Funds received from sale of DSPP units and shares	22,994	$ 113	22,881
Funds received from sale of DSPP units and shares (in shares)		11,298
Value of bonds converted to shares	149		149
Value of bonds converted to shares, (in shares)		43
Bond interest paid in shares	346	$ 3	343
Bond interest paid in shares (in shares)		289
Funds received from option exercises	551	$ 17	534
Funds received from option exercises (in shares)		1,680
Value of options granted to employees, directors and others as non-cash compensation	2,724		2,724
Net loss	(9,989)			(9,989)
Ending Balances at Dec. 31, 2017	24,440	$ 559	184,485	(160,604)
Ending Balances (in shares) at Dec. 31, 2017		55,888
Funds received from sale of DSPP units and shares	13,781	$ 94	13,687
Funds received from sale of DSPP units and shares (in shares)		9,466
Funds received from Rights Offering	3,038	$ 7	3,031
Funds received from Rights Offering (in shares)		656
Value of bonds converted to shares	176		176
Value of bonds converted to shares, (in shares)		41
Bond interest paid in shares	331	$ 1	330
Bond interest paid in shares (in shares)		71
Funds received from option exercises	19	$ 3	16
Funds received from option exercises (in shares)		283
Value of options granted to employees, directors and others as non-cash compensation	1,855		1,855
Net loss	(38,511)			(38,511)
Ending Balances at Dec. 31, 2018	$ 5,129	$ 664	$ 203,580	$ (199,115)
Ending Balances (in shares) at Dec. 31, 2018		66,405