Warrants (Details) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 29, 2019 USD ($) shares	Mar. 30, 2018 USD ($)	Dec. 31, 2018 Measurement_Input	Jul. 31, 2018 shares	Sep. 26, 2016 $ / shares shares
Class of Warrant or Right [Line Items]
Warrants, Exercise Price of Warrants | $ / shares					$ 4.76
Reduction to net revenues - amortization of the Warrant | $	$ 25	$ 111
Comcast Product Supply Agreement [Member]
Class of Warrant or Right [Line Items]
Right to purchase shares vested					781,617
Comcast Milestones Achievement [Member]
Class of Warrant or Right [Line Items]
Right to purchase shares vested				1,172,425
Comcast Milestone Acceptance Of Completion Of Field Trials [Member]
Class of Warrant or Right [Line Items]
Right to Purchase Additional Shares Subject to Vesting	781,617
Measurement Input, Expected Dividend Rate [Member] | Comcast Warrant Vesting Tranche July 31, 2018 [Member]
Class of Warrant or Right [Line Items]
Warrants and Rights Outstanding, Measurement Input | Measurement_Input			0
Maximum [Member] | Comcast Warrant Expires September 26, 2023 [Member]
Class of Warrant or Right [Line Items]
Warrant Grant to Purchase Shares of Common Stock					7,816,162