Condensed Statement of Changes in Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Common Stock		Additional paid-in Capital	Accumulated deficit	Total
Beginning Balances at Dec. 31, 2017	$ 559		$ 184,485	$ (160,604)	$ 24,440
Beginning Balances (in shares) at Dec. 31, 2017	55,888
Funds received from RO	$ 7		3,074		3,081
Funds received from RO (in shares)	656
Funds received from sale of DSPP units and shares	$ 25		5,928		5,953
Funds received from sale of DSPP units and shares (in shares)	2,490
Value of bonds converted to shares		[1]	168		168
Value of bonds converted to shares (in shares)	37
Bonds interest paid in shares	$ 1		330		331
Bonds interest paid in shares (in shares)	71
Funds received from option exercises	$ 1		17		18
Funds received from option exercises (in shares)	138
Value of options granted to employees, directors and others as non-cash compensation			1,581		1,581
Net loss				(7,492)	(7,492)
Ending Balances at Jun. 30, 2018	$ 593		195,583	(168,096)	28,080
Ending Balances (in shares) at Jun. 30, 2018	59,280
Beginning Balances at Mar. 31, 2018	$ 573		189,699	(166,855)	23,417
Beginning Balances (in shares) at Mar. 31, 2018	57,345
Funds received from RO	$ 7		3,074		3,081
Funds received from RO (in shares)	656
Funds received from sale of DSPP units and shares	$ 11		2,107		2,118
Funds received from sale of DSPP units and shares (in shares)	1,070
Value of bonds converted to shares		[1]	20		20
Value of bonds converted to shares (in shares)	5
Bonds interest paid in shares	$ 1		330		331
Bonds interest paid in shares (in shares)	71
Funds received from option exercises	$ 1		17		18
Funds received from option exercises (in shares)	133
Value of options granted to employees, directors and others as non-cash compensation			336		336
Net loss				(1,241)	(1,241)
Ending Balances at Jun. 30, 2018	$ 593		195,583	(168,096)	28,080
Ending Balances (in shares) at Jun. 30, 2018	59,280
Beginning Balances at Dec. 31, 2018	$ 664		203,580	(199,115)	5,129
Beginning Balances (in shares) at Dec. 31, 2018	66,405
Funds received from sale of DSPP units and shares	$ 115		5,521		5,636
Funds received from sale of DSPP units and shares (in shares)	11,486
Value of bonds converted to shares		[1]	2		2
Value of bonds converted to shares (in shares)	5
Bonds interest paid in shares	$ 4		323		327
Bonds interest paid in shares (in shares)	422
Funds received from option exercises	$ 1				1
Funds received from option exercises (in shares)	53
Value of options granted to employees, directors and others as non-cash compensation			40		40
Net loss				(3,483)	(3,483)
Ending Balances at Jun. 30, 2019	$ 784		209,466	(202,598)	7,652
Ending Balances (in shares) at Jun. 30, 2019	78,371
Beginning Balances at Mar. 31, 2019	$ 711		206,077	(201,285)	5,503
Beginning Balances (in shares) at Mar. 31, 2019	71,066
Funds received from sale of DSPP units and shares	$ 69		3,039		3,108
Funds received from sale of DSPP units and shares (in shares)	6,878
Value of bonds converted to shares		[1]	2		2
Value of bonds converted to shares (in shares)	5
Bonds interest paid in shares	$ 4		323		327
Bonds interest paid in shares (in shares)	422
Value of options granted to employees, directors and others as non-cash compensation			25		25
Net loss				(1,313)	(1,313)
Ending Balances at Jun. 30, 2019	$ 784		$ 209,466	$ (202,598)	$ 7,652
Ending Balances (in shares) at Jun. 30, 2019	78,371

[1] Less than one thousand.