Warrants (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 25, 2020	Sep. 27, 2019	Sep. 25, 2020	Sep. 27, 2019	Jan. 10, 2020	Dec. 20, 2019	Dec. 17, 2019	Sep. 26, 2016
Class of Warrant or Right [Line Items]
Class of Warrant or Right, Exercise Price of Warrants or Rights								$ 4.76
Reduction to net revenues - amortization of the Warrant			$ 1,307	$ 13,137
Comcast Warrants Exercise in its Entirety [Member]
Class of Warrant or Right [Line Items]
Right to purchase shares vested							3,217,547
Comcast Warrants Exercise Shares Delivered [Member]
Class of Warrant or Right [Line Items]
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right						804,387
Comcast Warrants Exercised Shares Remaining to be Issued [Member]
Class of Warrant or Right [Line Items]
Right to purchase shares vested					2,413,160
Maximum [Member] | Comcast Warrant Expires September 26, 2023 [Member]
Class of Warrant or Right [Line Items]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights								7,816,162
Revenue from Contract with Customer Benchmark [Member]
Class of Warrant or Right [Line Items]
Reduction to net revenues - amortization of the Warrant	$ 400	$ 13,100	$ 1,300	$ 13,100