CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY - USD ($)	Common Stock [Member]	Capital in Excess of Par Value [Member]	Accumulated Other Comprehensive Income [Member]	Accumulated Deficit [Member]	Total
Beginning balance at Dec. 31, 2018	$ 1,000	$ 170,392,000	$ 21,000	$ (99,134,000)	$ 71,280,000
Beginning balance (in shares) at Dec. 31, 2018	124,642,593
Stock issued in connection with option exercises	$ 1,000	0	0	0	1,000
Net shares issued for options exercised (in shares)	17,407
Equity-based compensation	$ 0	449,000	0	0	449,000
Equity-based compensation (in shares)	0
Unrealized gain (loss) on short-term investment securities	$ 0	0	147,000	0	147,000
Reclassification of losses (gains) to net loss	0	0	16,000	0	16,000
Net loss	0	0	0	(2,073,000)	(2,073,000)
Ending balance at Mar. 31, 2019	$ 2,000	170,841,000	184,000	(101,207,000)	69,820,000
Ending balance (in shares) at Mar. 31, 2019	124,660,000
Beginning balance at Dec. 31, 2018	$ 1,000	170,392,000	21,000	(99,134,000)	71,280,000
Beginning balance (in shares) at Dec. 31, 2018	124,642,593
Net loss					(10,115,000)
Ending balance at Jun. 30, 2019	$ 2,000	171,358,000	201,000	(109,249,000)	62,312,000
Ending balance (in shares) at Jun. 30, 2019	124,673,936
Beginning balance at Mar. 31, 2019	$ 2,000	170,841,000	184,000	(101,207,000)	69,820,000
Beginning balance (in shares) at Mar. 31, 2019	124,660,000
Net shares issued for options exercised (in shares)	13,936
Equity-based compensation		517,000			517,000
Unrealized gain (loss) on short-term investment securities			89,000		89,000
Reclassification of losses (gains) to net loss			(72,000)		(72,000)
Net loss				(8,042,000)	(8,042,000)
Ending balance at Jun. 30, 2019	$ 2,000	171,358,000	201,000	(109,249,000)	62,312,000
Ending balance (in shares) at Jun. 30, 2019	124,673,936
Beginning balance at Dec. 31, 2019	$ 1,000	187,735,000	7,000	(125,693,000)	62,050,000
Beginning balance (in shares) at Dec. 31, 2019	138,362,809
Stock issued in connection with RSU vesting	$ 0	0	0	0	0
Stock issued in connection with RSU vesting (in shares)	491,384
Equity-based compensation	$ 0	480,000	0	0	480,000
Equity-based compensation (in shares)	0
Unrealized gain (loss) on short-term investment securities	$ 0	0	(196,000)	0	(196,000)
Reclassification of losses (gains) to net loss	0	0	3,000	0	3,000
Net loss	0	0	0	(4,029,000)	(4,029,000)
Ending balance at Mar. 31, 2020	$ 1,000	188,215,000	(186,000)	(129,722,000)	58,308,000
Ending balance (in shares) at Mar. 31, 2020	138,854,193
Beginning balance at Dec. 31, 2019	$ 1,000	187,735,000	7,000	(125,693,000)	62,050,000
Beginning balance (in shares) at Dec. 31, 2019	138,362,809
Net loss					(9,086,000)
Ending balance at Jun. 30, 2020	$ 1,000	188,591,000	52,000	(134,779,000)	53,865,000
Ending balance (in shares) at Jun. 30, 2020	138,854,193
Beginning balance at Mar. 31, 2020	$ 1,000	188,215,000	(186,000)	(129,722,000)	58,308,000
Beginning balance (in shares) at Mar. 31, 2020	138,854,193
Equity-based compensation		376,000			376,000
Unrealized gain (loss) on short-term investment securities			241,000		241,000
Reclassification of losses (gains) to net loss			(3,000)		(3,000)
Net loss				(5,057,000)	(5,057,000)
Ending balance at Jun. 30, 2020	$ 1,000	$ 188,591,000	$ 52,000	$ (134,779,000)	$ 53,865,000
Ending balance (in shares) at Jun. 30, 2020	138,854,193