CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 25, 2021	Sep. 26, 2020	Sep. 25, 2021	Sep. 26, 2020	Dec. 26, 2020
Cash flows from operating activities:
Net income	$ 20,497	$ 22,891	$ 58,027	$ 59,250
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation			19,256	14,491
Amortization			16,362	20,249
Reduction in the carrying amount of right-of-use assets			5,412	4,294
Stock-based compensation expense			21,585	16,774
Provision for excess and obsolete inventories			11,621	9,763
Non-cash restructuring charges			1,592	0
Gain on contingent consideration			(95)	(3,771)
Other adjustments to reconcile net income to net cash provided by operating activities			1,627	(977)
Changes in assets and liabilities:
Accounts receivable			1,157	5,712
Inventories			(30,335)	(18,566)
Prepaid expenses and other current assets			3,631	(5,619)
Other assets			(333)	219
Accounts payable			1,488	18,054
Accrued liabilities			(6,951)	4,754
Other liabilities			47	272
Deferred revenues			2,000	3,806
Operating lease liabilities			(5,654)	(4,496)
Net cash provided by operating activities			100,437	124,209
Cash flows from investing activities:
Acquisition of property, plant and equipment			(51,353)	(41,887)
Acquisition of business, net of cash acquired			0	(34,999)
Proceeds from sale of a subsidiary			0	82
Purchases of marketable securities			(114,898)	(29,721)
Proceeds from maturities and sales of marketable securities			71,275	50,330
Net cash used in investing activities			(94,976)	(56,195)
Cash flows from financing activities:
Proceeds from issuances of common stock			10,647	9,588
Purchase of common stock through stock repurchase program			(23,951)	0
Tax withholdings related to net share settlements of equity awards			(12,643)	(15,382)
Payment of contingent consideration			(3,873)	0
Proceeds from term loan			0	18,000
Principal repayments on term loans			(7,049)	(41,098)
Payment of term loan debt issuance costs			0	(78)
Net cash used in financing activities			(36,869)	(28,970)
Effect of exchange rate changes on cash, cash equivalents and restricted cash			(2,216)	1,262
Net increase (decrease) in cash, cash equivalents and restricted cash			(33,624)	40,306
Cash, cash equivalents and restricted cash, beginning of period			191,098	147,937	$ 147,937
Cash, cash equivalents and restricted cash, end of period	157,474	188,243	157,474	188,243	191,098
Non-cash investing and financing activities:
Increase in accounts payable and accrued liabilities related to property, plant and equipment purchases			4,684	3,041
Increase in accrued liabilities related to tax withholdings related to net share settlements of equity awards			6,952	0
Operating lease, right-of-use assets obtained in exchange for lease obligations			11,699	1,549
Supplemental disclosure of cash flow information:
Cash paid for income taxes, net			6,795	7,475
Cash paid for interest			496	683
Operating cash outflows from operating leases			6,420	5,566
Reconciliation of cash, cash equivalents and restricted cash:
Cash and cash equivalents	153,781	185,368	153,781	185,368	187,225
Restricted cash, current	2,019	1,477	2,019	1,477
Restricted cash, non-current	1,674	1,398	1,674	1,398
Total cash, cash equivalents and restricted cash	$ 157,474	$ 188,243	$ 157,474	$ 188,243	$ 191,098