Exercise price per share or per unit of warrants or rights outstanding.

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Number of securities into which the class of warrant or right may be converted. For example, but not limited to, 500,000 warrants may be converted into 1,000,000 shares.

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Number of warrants or rights outstanding.

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The number of warrants or rights which entitle the entity to receive future services in exchange for the unvested, forfeitable warrants or rights.

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Amount of expense (income) related to adjustment to fair value of warrant liability.

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Fair value of share-based compensation granted to nonemployees as payment for services rendered or acknowledged claims.

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Value of outstanding derivative securities that permit the holder the right to purchase securities (usually equity) from the issuer at a specified price.

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Value of input used to measure outstanding warrant and right embodying unconditional obligation requiring redemption by transferring asset at specified or determinable date or upon event certain to occur.

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Warrants (Details) $ / shares in Units, $ in Thousands		3 Months Ended		9 Months Ended
Warrants (Details) $ / shares in Units, $ in Thousands	Jul. 31, 2018 USD ($) Measurement_Input shares	Sep. 28, 2018 USD ($)	Sep. 29, 2017 USD ($)	Sep. 28, 2018 USD ($)	Sep. 29, 2017 USD ($)	Sep. 26, 2016 USD ($) $ / shares shares
Class of Warrant or Right [Line Items]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights						7,816,162
Class of Warrant or Right, Exercise Price of Warrants or Rights \| $ / shares						$ 4.76
Warrants and Rights Outstanding \| $						$ 1,600
Fair Value Adjustment of Warrants \| $		$ 790		$ 1,185
Comcast Product Supply Agreement [Member]
Class of Warrant or Right [Line Items]
Class of Warrant or Right, Outstanding						781,617
Comcast Milestones Achievement [Member]
Class of Warrant or Right [Line Items]
Class of Warrant or Right, Unissued						1,954,042
Comcast Milestone Acceptance Of Completion Of Field Trials [Member]
Class of Warrant or Right [Line Items]
Class of Warrant or Right, Outstanding	1,172,425
Class of Warrant or Right, Unissued						1,172,425
Fair Value of Warrants On Vesting Date Using Black-Scholes Option Model \| $	$ 2,300
Comcast Specified Tranches [Member]
Class of Warrant or Right [Line Items]
Class of Warrant or Right, Unissued						781,617
Comcast Exceeding Specified Cumulative Purchase Volume [Member]
Class of Warrant or Right [Line Items]
Class of Warrant or Right, Unissued						1,172,425
Sales Revenue, Goods, Net [Member] \| Comcast Product Supply Agreement [Member]
Class of Warrant or Right [Line Items]
Fair Value Adjustment of Warrants \| $		$ 800	$ (400)	$ 1,200	$ 38
Measurement Input, Expected Term [Member] \| Comcast Product Supply Agreement [Member]
Class of Warrant or Right [Line Items]
Fair Value Assumptions, Expected Term (Deprecated 2018-01-31)	5 years 2 months 12 days
Measurement Input, Risk Free Interest Rate [Member] \| Comcast Product Supply Agreement [Member]
Class of Warrant or Right [Line Items]
Fair Value Assumptions, Expected Volatility Rate (Deprecated 2018-01-31) \| Measurement_Input	0.45
Measurement Input, Price Volatility [Member] \| Comcast Product Supply Agreement [Member]
Class of Warrant or Right [Line Items]
Fair Value Assumptions, Expected Volatility Rate (Deprecated 2018-01-31) \| Measurement_Input	0.029
Measurement Input, Expected Dividend Rate [Member] \| Comcast Product Supply Agreement [Member]
Class of Warrant or Right [Line Items]
Fair Value Assumptions, Expected Volatility Rate (Deprecated 2018-01-31) \| Measurement_Input	0.000