CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 148,036	$ 123,713
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	26,055	23,400
Amortization of intangibles	1,871	2,699
Loss on disposal of property and equipment	1,162	2,200
Stock-based compensation expense	15,710	27,325
Amortization of premium on marketable securities	2,638	775
Deferred income taxes	(7,390)	(12)
Increase in accounts receivable allowance for credit losses	690	17
Change in operating assets and liabilities:
Accounts receivable	24,628	(2,979)
Inventories	(20,826)	11,064
Prepaid expenses and other assets	8,428	(4,973)
Accounts payable	(5,874)	6,633
Taxes payable and accrued liabilities	(3,883)	(6,157)
Net cash provided by operating activities	191,245	183,705
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of property and equipment	(33,444)	(30,305)
Proceeds from sale of property and equipment	1,202	35
Purchases of marketable securities	(27,244)	(381,903)
Proceeds from sales and maturities of marketable securities	161,014	284,036
Net cash provided by (used in) investing activities	101,528	(128,137)
CASH FLOWS FROM FINANCING ACTIVITIES:
Issuance of common stock under employee stock plans	6,162	7,710
Repurchase of common stock	(292,349)	(36,165)
Payments of dividends to stockholders	(31,229)	(23,552)
Net cash used in financing activities	(317,416)	(52,007)
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	(24,643)	3,561
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	158,117	258,874
CASH AND CASH EQUIVALENTS AT END OF PERIOD	133,474	262,435
SUPPLEMENTAL DISCLOSURE OF NON-CASH INVESTING AND FINANCING ACTIVITIES:
Unpaid property and equipment	2,555	4,983
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION:
Cash paid for income taxes, net	$ 17,834	$ 16,272