Business Segments - Schedule of Revenue Information by Product (Parenthetical) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 26, 2020	Sep. 28, 2019	Sep. 26, 2020	Sep. 28, 2019
Entity Wide Information Revenue From External Customer [Line Items]
Total revenues	$ 8,803	$ 10,664	$ 24,043	$ 31,685
Service Contract Revenues
Entity Wide Information Revenue From External Customer [Line Items]
Total revenues	$ 302	$ 437	$ 929	$ 1,041