Stockholders' Equity - Summary of Stockholders' Equity Transactions (Detail) - USD ($)			3 Months Ended		9 Months Ended		12 Months Ended
	Jul. 27, 2016	Mar. 25, 2015	Oct. 01, 2016	Sep. 26, 2015	Oct. 01, 2016	Sep. 26, 2015	Dec. 31, 2015
Beginning balance					$ 13,122,000
Issuance of common stock (net of costs)					1,900,000
Conversion of Series B preferred stock to common stock					0
Issuance of Series C preferred stock					0
Cancellation of shares from reverse stock split					0
Stock-based compensation					776,000
Net loss			$ (2,874,000)	$ (2,373,000)	(8,582,000)	$ (6,203,000)	$ (8,600,000)
Ending balance			7,216,000		7,216,000		13,122,000
Common Stock [Member]
Beginning balance					$ 3,000
Beginning balance, Shares					2,640,547
Issuance of common stock (net of costs), Shares	293,604	204,186			293,604
Conversion of Series B preferred stock to common stock					$ 0
Conversion of Series B preferred stock to common stock , Shares					342,667
Issuance of Series C preferred stock					$ 0
Cancellation of shares from reverse stock split					$ 0
Cancellation of shares from reverse stock split, Shares					(36)
Ending balance			$ 3,000		$ 3,000		$ 3,000
Ending balance, Shares			3,276,782		3,276,782		2,640,547
Capital in Excess of Par Value [Member]
Beginning balance					$ 304,089,000
Issuance of common stock (net of costs)					1,900,000
Conversion of Series B preferred stock to common stock					0
Issuance of Series C preferred stock					0
Cancellation of shares from reverse stock split					0
Stock-based compensation					776,000
Ending balance			$ 306,765,000		306,765,000		$ 304,089,000
Accumulated Deficit [Member]
Beginning balance					(290,970,000)
Conversion of Series B preferred stock to common stock					0
Issuance of Series C preferred stock					0
Cancellation of shares from reverse stock split					0
Net loss					(8,582,000)
Ending balance			$ (299,552,000)		$ (299,552,000)		$ (290,970,000)
Convertible Preferred Stock [Member]
Beginning balance, Shares					330,873
Conversion of Series B preferred stock to common stock					$ 0
Conversion of Series B preferred stock to common stock , Shares					(1,799)
Issuance of Series C preferred stock					$ 0
Issuance of Series C preferred stock, Shares					1,295
Cancellation of shares from reverse stock split					$ 0
Ending balance, Shares			330,369		330,369		330,873