Stockholders' Equity - Summary of Stockholders' Equity Transactions (Detail) - USD ($)				3 Months Ended		6 Months Ended		12 Months Ended
	Oct. 10, 2019	May 23, 2019	Jul. 30, 2018	Jun. 27, 2020	Jun. 29, 2019	Jun. 27, 2020	Jun. 29, 2019	Dec. 31, 2019
Beginning balance				$ 1,833,000	$ 4,434,000	$ 1,503,000	$ 6,745,000	$ 6,745,000
Issuance of common stock (net of costs)					1,421,000		1,421,000
Warrant exercises				1,089,000		2,477,000
Stock-based compensation				22,000	23,000	43,000	47,000
Net loss				(744,000)	(2,591,000)	(1,823,000)	(4,926,000)	(9,200,000)
Ending balance				2,200,000	3,287,000	2,200,000	3,287,000	1,503,000
Common Stock [Member]
Beginning balance				$ 23,000	$ 4,000	$ 18,000	$ 3,000	$ 3,000
Beginning balance, Shares				23,283,609	3,802,609	17,731,893	3,270,609	3,270,609
Conversion of Series E preferred stock to common stock, Shares							532,000
Conversion of Series E preferred stock to common stock							$ 1,000
Issuance of common stock (net of costs), Shares	11,834,000	119,000	2,571,429		1,700,000		1,700,000
Issuance of common stock (net of costs)					$ 2,000		$ 2,000
Warrant exercises, Shares				4,225,940		9,777,656
Warrant exercises				$ 5,000		$ 10,000
Ending balance				$ 28,000	$ 6,000	$ 28,000	$ 6,000	$ 18,000
Ending balance, Shares				27,509,549	5,502,609	27,509,549	5,502,609	17,731,893
Capital in Excess of Par Value [Member]
Beginning balance				$ 331,862,000	$ 326,509,000	$ 330,458,000	$ 326,486,000	$ 326,486,000
Conversion of Series E preferred stock to common stock							(1,000)
Issuance of common stock (net of costs)					1,419,000		1,419,000
Warrant exercises				1,084,000		2,467,000
Stock-based compensation				22,000	23,000	43,000	47,000
Ending balance				332,968,000	327,951,000	332,968,000	327,951,000	330,458,000
Accumulated Deficit [Member]
Beginning balance				(330,052,000)	(322,079,000)	(328,973,000)	(319,744,000)	(319,744,000)
Net loss				(744,000)	(2,591,000)	(1,823,000)	(4,926,000)
Ending balance				$ (330,796,000)	$ (324,670,000)	$ (330,796,000)	$ (324,670,000)	$ (328,973,000)
Convertible Preferred Stock [Member]
Beginning balance, Shares				328,925	328,925	328,925	330,787	330,787
Conversion of Series E preferred stock to common stock, Shares							(1,862)
Ending balance				$ 0		$ 0
Ending balance, Shares				328,925	328,925	328,925	328,925	328,925