CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 6,875	$ 46,248
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	8,961	8,408
Amortization of intangibles	543	724
Loss on disposal of property and equipment	7	75
Stock-based compensation expense	7,368	9,013
Amortization of premium on marketable securities	404	937
Deferred income taxes	(738)	(936)
Increase (decrease) in accounts receivable allowance for credit losses	(454)	75
Change in operating assets and liabilities:
Accounts receivable	705	10,660
Inventories	(7,024)	(3,849)
Prepaid expenses and other assets	(2,302)	1,552
Accounts payable	2,926	(1,709)
Taxes payable and accrued liabilities	(686)	3,399
Net cash provided by operating activities	16,585	74,597
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of property and equipment	(4,082)	(14,700)
Proceeds from sale of property and equipment	0	1,202
Purchases of marketable securities	(36,922)	(15,121)
Proceeds from sales and maturities of marketable securities	22,693	108,817
Net cash provided by (used in) investing activities	(18,311)	80,198
CASH FLOWS FROM FINANCING ACTIVITIES:
Issuance of common stock under employee stock plans	3,098	3,057
Repurchase of common stock	(1,687)	(134,689)
Payments of dividends to stockholders	(10,868)	(10,656)
Net cash used in financing activities	(9,457)	(142,288)
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	(11,183)	12,507
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	105,372	158,117
CASH AND CASH EQUIVALENTS AT END OF PERIOD	94,189	170,624
SUPPLEMENTAL DISCLOSURE OF NON-CASH INVESTING AND FINANCING ACTIVITIES:
Unpaid property and equipment	2,762	5,042
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION:
Cash paid for income taxes, net	$ 3,665	$ 1,163