Restatement of Previously Issued 2017 Consolidated Information, Balance Sheet (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended		9 Months Ended		12 Months Ended
	Mar. 31, 2018	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Jun. 30, 2018	Jun. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Previously Issued 2017 Consolidated Information [Abstract]
Loss on extinguishment of debentures		$ (20,160)	$ 0	$ 0		$ 0		$ (20,160)	$ 0	$ (20,160)
Gain in fair value of embedded conversion feature	$ 0	1,993	2,903	(1,738)	$ 0	1,165	$ 0	3,158	0	3,158
Other accrued liabilities	(16)			74	(3)	167	(754)	255	1,006	602
Deferred Tax Assets, Valuation Allowance									46,706	46,878
Balance Sheet [Abstract]
Intangible assets, net	11,122	12,302	13,298	13,858	10,670	13,298	10,217	12,302	9,765	11,825	$ 13,412
Total assets	37,205	39,864	42,902	43,207	46,052	42,902	46,540	39,864	47,507	39,131	43,193
Deferred revenues	1,725	1,952	2,210	2,132	1,802	2,210	1,877	1,952	2,099	1,871	2,230
Other accrued liabilities	3,541	3,233	3,359	3,266	3,754	3,359	4,247	3,233	4,500	3,581	2,909
Total current liabilities	11,586	9,062	11,436	10,414	7,084	11,436	9,512	9,062	8,615	10,473	9,045
Senior secured convertible debentures, net										0	5,083
Derivative liability senior secured convertible debentures		0	1,993	4,896		1,993		0		0	3,158
Warranty liability	24	255	676	1,333	263	676	615	255	0	67	662
Total liabilities	19,582	19,110	29,045	32,036	15,449	29,045	17,149	19,110	16,259	19,251	28,156
Convertible Preferred Stock $.10 par value		4	0			0		4
Common Stock $.001 par value	4	3	3	2	30	3	30	3	30	4	2
Additional paid-in capital	223,848	223,780	197,810	197,583	238,673	197,810	239,040	223,780	241,988	223,829	197,475
Accumulated deficit	(206,233)	(203,035)	(183,958)	(186,417)	(208,101)	(183,958)	(209,683)	(203,035)	(210,771)	(203,957)	(182,443)
Accumulated other comprehensive income	0	2	2	2	0	2		2			2
Total stockholders' equity	17,623	20,754	13,857	11,171	30,603	13,857	29,388	20,754	31,248	19,880	15,037
Series B Convertible Preferred Stock [Member]
Balance Sheet [Abstract]
Convertible Preferred Stock $.10 par value											1
Series C Convertible Preferred Stock [Member]
Balance Sheet [Abstract]
Convertible Preferred Stock $.10 par value	4			1	1		1		$ 1	4
Previously Reported [Member]
Previously Issued 2017 Consolidated Information [Abstract]
Loss on extinguishment of debentures		(11,799)	0	0		0		(11,799)
Gain in fair value of embedded conversion feature				0
Balance Sheet [Abstract]
Intangible assets, net	10,672	12,302	13,298	13,858	10,270	13,298	9,867	12,302		11,325	13,412
Total assets	36,755	39,864	42,902	43,207	45,652	42,902	46,190	39,864		38,631	43,193
Deferred revenues	440	350	413	334	393	413	327	350		291	235
Other accrued liabilities	2,216	1,899	2,160	2,214	2,330	2,160	2,697	1,899		2,360	1,992
Total current liabilities	8,976	6,126	8,440	7,564	4,251	8,440	4,791	6,126		7,672	6,133
Senior secured convertible debentures, net										0	12,028
Derivative liability senior secured convertible debentures		0	0	0		0		0		0	0
Warranty liability	0	28	109	237	0	109	0	28		3	105
Total liabilities	16,948	15,947	31,288	30,615	12,352	31,288	12,813	15,947		16,386	28,474
Convertible Preferred Stock $.10 par value		4	0			0		4
Common Stock $.001 par value	4	3	3	2	30	3	30	3		4	2
Additional paid-in capital	251,662	251,594	225,624	225,397	266,487	225,624	266,854	251,594		251,643	225,289
Accumulated deficit	(231,863)	(227,686)	(214,015)	(212,810)	(233,218)	(214,015)	(233,508)	(227,686)		(229,406)	(210,575)
Accumulated other comprehensive income	0	2	2	2	0	2		2			2
Total stockholders' equity	19,807	23,917	11,614	12,592	33,300	11,614	33,377	23,917		22,245	14,719
Previously Reported [Member] | Series B Convertible Preferred Stock [Member]
Balance Sheet [Abstract]
Convertible Preferred Stock $.10 par value											1
Previously Reported [Member] | Series C Convertible Preferred Stock [Member]
Balance Sheet [Abstract]
Convertible Preferred Stock $.10 par value	4			1	1		1			4
Restatement Adjustment [Member]
Previously Issued 2017 Consolidated Information [Abstract]
Other accrued liabilities										1,221
Balance Sheet [Abstract]
Intangible assets, net	500				450		400				0
Total assets	500	0	0	0	450	0	400	0			0
Deferred revenues	1,580	1,797	1,798	1,995	1,285	1,798	1,409	1,797			1,995
Other accrued liabilities	1,221	1,199	1,052	917	1,325	1,052	1,424	1,199			917
Total current liabilities	2,801	2,996	2,850	2,912	2,610	2,850	2,941	2,996			2,912
Senior secured convertible debentures, net											(6,945)
Derivative liability senior secured convertible debentures		1,993	4,896	3,158		4,896		1,993			3,158
Warranty liability	64	567	1,096	557	23	1,096	155	567			557
Total liabilities	2,865	(2,243)	1,421	(318)	2,634	1,421	3,097	(2,243)			(318)
Convertible Preferred Stock $.10 par value		0						0
Common Stock $.001 par value		0						0			0
Additional paid-in capital	(27,814)	(27,814)	(27,814)	(27,814)	(27,814)	(27,814)	(27,814)	(27,814)			(27,814)
Accumulated deficit	25,449	30,057	26,393	28,132	25,630	26,393	25,117	30,057			28,132
Accumulated other comprehensive income		0						0			0
Total stockholders' equity	(2,365)	2,243	(1,421)	318	(2,184)	(1,421)	(2,697)	2,243			318
Restatement Adjustment [Member] | Series B Convertible Preferred Stock [Member]
Balance Sheet [Abstract]
Convertible Preferred Stock $.10 par value											0
Sales and Use Tax [Member]
Balance Sheet [Abstract]
Intangible assets, net										0
Total assets	0	0	0	0	0	0	0	0
Deferred revenues										0
Other accrued liabilities	104	135	147	135	99	147	128	135		304
Total current liabilities	104	135	147	135	99	147	128	135		304
Senior secured convertible debentures, net										0
Derivative liability senior secured convertible debentures										0
Total liabilities	104	135	147	135	99	147	128	135		304
Common Stock $.001 par value										0
Additional paid-in capital										0
Accumulated deficit	(104)	(135)	(147)	(135)	(99)	(147)	(128)	(135)		(304)
Total stockholders' equity	(104)	(135)	(147)	(135)	(99)	(147)	(128)	(135)		(304)
Sales and Use Tax [Member] | Series C Convertible Preferred Stock [Member]
Balance Sheet [Abstract]
Convertible Preferred Stock $.10 par value										0
Warrants [Member]
Balance Sheet [Abstract]
Intangible assets, net										0
Total assets	0	0	0	0	0	0	0	0
Deferred revenues										0
Other accrued liabilities										0
Total current liabilities	0		0	0	0	0	514
Senior secured convertible debentures, net										0
Derivative liability senior secured convertible debentures										0
Warranty liability	(40)	(340)	(529)	539	240	(529)	460	(340)		(493)
Total liabilities	(40)	(340)	(529)	539	240	(529)	974	(340)		(493)
Common Stock $.001 par value										0
Additional paid-in capital										0
Accumulated deficit	40	340	529	(539)	(240)	529	(974)	340		493
Total stockholders' equity	40	340	529	(539)	(240)	529	(974)	340		493
Warrants [Member] | Series C Convertible Preferred Stock [Member]
Balance Sheet [Abstract]
Convertible Preferred Stock $.10 par value										0
Debentures [Member]
Previously Issued 2017 Consolidated Information [Abstract]
Loss on extinguishment of debentures		(8,361)						(8,361)
Gain in fair value of embedded conversion feature		1,993	2,903	(1,738)		1,165		3,158
Balance Sheet [Abstract]
Intangible assets, net										0
Total assets		0	0	0		0	0	0
Deferred revenues										0
Other accrued liabilities										0
Total current liabilities			0	0		0
Senior secured convertible debentures, net										6,945
Derivative liability senior secured convertible debentures		(1,993)	(2,903)	1,738		(2,903)		(1,993)		(3,158)
Total liabilities		5,806	(3,281)	1,262		(3,281)		5,806		3,787
Common Stock $.001 par value										0
Additional paid-in capital										0
Accumulated deficit		(5,806)	3,281	(1,262)		3,281		(5,806)		(3,787)
Total stockholders' equity		(5,806)	3,281	(1,262)		3,281		(5,806)		(3,787)
Debentures [Member] | Series C Convertible Preferred Stock [Member]
Balance Sheet [Abstract]
Convertible Preferred Stock $.10 par value										0
Intangible Impairment [Member]
Balance Sheet [Abstract]
Intangible assets, net	(50)				(50)		(50)			500
Total assets	(50)	0	0	0	(50)	0	(50)	0		500
Deferred revenues										0
Other accrued liabilities										0
Total current liabilities	0	0	0	0	0	0		0
Senior secured convertible debentures, net										0
Derivative liability senior secured convertible debentures										0
Total liabilities	0	0	0	0	0	0	0	0		0
Common Stock $.001 par value										0
Additional paid-in capital										0
Accumulated deficit	(50)	0			(50)		(50)	0		500
Total stockholders' equity	(50)	0	0	0	(50)	0	(50)	0		500
Intangible Impairment [Member] | Series C Convertible Preferred Stock [Member]
Balance Sheet [Abstract]
Convertible Preferred Stock $.10 par value										0
Deferred Revenue [Member]
Balance Sheet [Abstract]
Intangible assets, net										0
Total assets	0	0	0	0	0	0	0	0
Deferred revenues	(295)	(195)	(1)	(197)	124	(1)	140	(195)		(415)
Other accrued liabilities										0
Total current liabilities	(295)	(195)	(1)	(197)	124	(1)	140	(195)		(415)
Senior secured convertible debentures, net										0
Derivative liability senior secured convertible debentures										0
Warranty liability										0
Total liabilities	(295)	(195)	(1)	(197)	101	(1)	140	(195)		(415)
Common Stock $.001 par value										0
Additional paid-in capital										0
Accumulated deficit	295	195	1	197	(124)	1	(140)	195		415
Total stockholders' equity	$ 295	$ 195	$ 1	197	$ (124)	1	$ (140)	195		415
Deferred Revenue [Member] | Series C Convertible Preferred Stock [Member]
Balance Sheet [Abstract]
Convertible Preferred Stock $.10 par value										0
Other Adjustments [Member]
Balance Sheet [Abstract]
Intangible assets, net										0
Deferred revenues										0
Other accrued liabilities										0
Derivative liability senior secured convertible debentures										0
Warranty liability										0
Common Stock $.001 par value										0
Additional paid-in capital										0
Accumulated deficit										0
Total stockholders' equity										0
Other Adjustments [Member] | Series C Convertible Preferred Stock [Member]
Balance Sheet [Abstract]
Convertible Preferred Stock $.10 par value										0
Effect of Adoption Higher / (Lower) [Member]
Previously Issued 2017 Consolidated Information [Abstract]
Loss on extinguishment of debentures								8,361		8,361
Gain in fair value of embedded conversion feature				1,738		(1,165)		(3,158)		3,158
Other accrued liabilities				$ 135		$ 282		$ 417		304
Deferred Tax Assets, Operating Loss Carryforwards, State and Local										(9,700)
Deferred Tax Assets, Valuation Allowance										$ (9,700)
Balance Sheet [Abstract]
Additional paid-in capital											(27,300)
Accumulated deficit											$ (31,087)