CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 170,851	$ 164,413	$ 71,176
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	34,930	31,454	23,743
Amortization of intangibles	2,415	3,494	4,359
Loss on disposal of property and equipment	1,371	3,105	525
Stock-based compensation expense	22,364	37,609	30,912
Amortization of premium on marketable securities	3,292	1,590	705
Deferred income taxes	(2,566)	(13,240)	(592)
Increase (decrease) in accounts receivable allowance for credit losses	690	18	(336)
Change in operating assets and liabilities:
Accounts receivable	19,867	(5,501)	(11,300)
Inventories	(36,154)	3,612	(12,498)
Prepaid expenses and other assets	7,343	4,326	9,153
Accounts payable	(3,836)	4,067	5,697
Taxes payable and accrued liabilities	(5,224)	(4,079)	4,095
Net cash provided by operating activities	215,343	230,868	125,639
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of property and equipment	(39,211)	(47,272)	(70,598)
Proceeds from sale of property and equipment	1,202	35	651
Purchases of marketable securities	(55,820)	(554,018)	(109,703)
Proceeds from sales and maturities of marketable securities	172,165	368,457	151,385
Net cash provided by (used in) investing activities	78,336	(232,798)	(28,265)
CASH FLOWS FROM FINANCING ACTIVITIES:
Issuance of common stock under employee stock plans	6,162	7,710	10,527
Repurchase of common stock	(311,094)	(73,938)	(2,636)
Payments of dividends to stockholders	(41,492)	(32,599)	(25,081)
Net cash used in financing activities	(346,424)	(98,827)	(17,190)
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	(52,745)	(100,757)	80,184
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	158,117	258,874	178,690
CASH AND CASH EQUIVALENTS AT END OF PERIOD	105,372	158,117	258,874
SUPPLEMENTAL DISCLOSURE OF NON-CASH INVESTING AND FINANCING ACTIVITIES:
Unpaid property and equipment	1,082	10,879	5,937
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION:
Cash paid (received) for income taxes, net	$ 17,880	$ 25,644	$ (1,973)