Schedule II - Valuation and Qualifying Accounts - Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 25, 2021		Dec. 26, 2020	Dec. 28, 2019
SEC Schedule, 12-09, Allowance, Credit Loss [Member]
Balance, beginning of year		$ 128		$ 9	$ 40
Additions (reductions) not charged to expense	[1]	14		(1)	24
Additions (reduction) charged (credited) to expense		149		79	(28)
Deductions/write-offs		1		(41)	27
Balance, end of year		290		128	9
SEC Schedule, 12-09, Reserve, Inventory [Member]
Balance, beginning of year		26,937		20,958	23,938
Additions (reductions) not charged to expense	[1]	(2,926)	[2]	4,611	1,285
Additions (reduction) charged (credited) to expense		7,102		8,117	4,792
Deductions/write-offs		8,101		6,749	9,057
Balance, end of year		$ 23,012		$ 26,937	$ 20,958

[1] Changes in reserve balances resulting from foreign currency impact and reclassifications from other reserves.

[2] Reductions not charged to expense includes $2,206 transferred as part of the sale of our PCB Test business.