Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Treasury Stock, Common [Member]	Total
Balance at Dec. 26, 2020	$ 42,190	$ 448,194	$ 26,230	$ (4,326)	$ 0	$ 512,288
Common stock repurchases	0	0	0	0	(7,324)	(7,324)
Net income (loss)	0	0	167,325	0	0	167,325
Changes in cumulative translation adjustment	0	0	0	(22,956)	0	(22,956)
Adjustments related to postretirement benefits, net of tax	0	0	0	2,602	0	2,602
Changes in unrealized gains and losses on investments, net of tax	0	0	0	(67)	0	(67)
Exercise of stock options	250	2,260	0	0	0	2,510
Shares issued under ESPP	161	3,403	0	0	0	3,564
Shares issued for restricted stock units vested	704	(704)	0	0	0	0
Repurchase and retirement of stock	(242)	(10,222)	0	0	0	(10,464)
Impact of sale of PCB Test business	0	0	0	(2,515)	0	(2,515)
Share-based compensation expense	0	14,420	0	0	0	14,420
Sale of common stock, net of issuance costs	5,693	217,426	0	0	0	223,119
Balance at Dec. 25, 2021	48,756	674,777	193,555	(27,262)	(7,324)	882,502
Common stock repurchases	0	0	0	0	(50,719)	(50,719)
Net income (loss)	0	0	96,847	0	0	96,847
Changes in cumulative translation adjustment	0	0	0	(17,950)	0	(17,950)
Adjustments related to postretirement benefits, net of tax	0	0	0	5,894	0	5,894
Changes in unrealized gains and losses on investments, net of tax	0	0	0	(694)	0	(694)
Exercise of stock options	12	105	0	0	0	117
Shares issued under ESPP	161	3,470	0	0	0	3,631
Shares issued for restricted stock units vested	529	(529)	0	0	0	0
Repurchase and retirement of stock	(182)	(5,523)	0	0	0	(5,705)
Share-based compensation expense	0	14,918	0	0	0	14,918
Balance at Dec. 31, 2022	49,276	687,218	290,402	(40,012)	(58,043)	928,841
Common stock repurchases	0	0	0	0	(23,641)	(23,641)
Net income (loss)	0	0	28,156	0	0	28,156
Changes in cumulative translation adjustment	0	0	0	6,815	0	6,815
Adjustments related to postretirement benefits, net of tax	0	0	0	(2,375)	0	(2,375)
Changes in unrealized gains and losses on investments, net of tax	0	0	0	793	0	793
Shares issued under ESPP	147	3,785	0	0	0	3,932
Shares issued for restricted stock units vested	6	(20,174)	0	0	20,168	0
Share-based compensation expense	0	17,237	0	0	0	17,237
Repurchase and retirement of stock	0	(1,920)	0	0	(7,668)	(9,588)
Balance at Dec. 30, 2023	$ 49,429	$ 686,146	$ 318,558	$ (34,779)	$ (69,184)	$ 950,170