Schedule II - Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 30, 2017	Dec. 31, 2016	Dec. 26, 2015
Allowance for Doubtful Accounts Receivable [Member]
Valuation And Qualifying Accounts Disclosure [Line Items]
Balance at beginning of period	$ 73	$ 150	$ 253
Additions to Allowance	78		10
Charges Utilized/Write-offs	(25)	(77)	(113)
Balance at end of period	126	73	150
Valuation Allowance for Deferred Tax Assets [Member]
Valuation And Qualifying Accounts Disclosure [Line Items]
Balance at beginning of period	10,980	36,786	35,835
Additions to Allowance	2,984	1,643	951
Charges Utilized/Write-offs	(262)	(27,449)
Balance at end of period	$ 13,702	$ 10,980	$ 36,786