CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 102,072	$ 81,679
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	17,174	15,274
Amortization of intangibles	1,328	1,905
Loss on disposal of property and equipment	1,034	38
Stock-based compensation expense	12,692	17,680
Amortization of premium on marketable securities	1,867	300
Deferred income taxes	(3,282)	1,182
Increase in accounts receivable allowance for credit losses	259	91
Change in operating assets and liabilities:
Accounts receivable	13,154	(5,533)
Inventories	(11,992)	13,235
Prepaid expenses and other assets	4,075	(4,501)
Accounts payable	5,577	8,053
Taxes payable and accrued liabilities	(2,539)	(4,433)
Net cash provided by operating activities	141,419	124,970
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of property and equipment	(27,944)	(19,294)
Proceeds from sale of property and equipment	1,202	35
Purchases of marketable securities	(20,710)	(188,753)
Proceeds from sales and maturities of marketable securities	125,527	160,083
Net cash provided by (used in) investing activities	78,075	(47,929)
CASH FLOWS FROM FINANCING ACTIVITIES:
Issuance of common stock under employee stock plans	3,057	3,652
Repurchase of common stock	(292,349)	(26,374)
Payments of dividends to stockholders	(20,936)	(15,712)
Net cash used in financing activities	(310,228)	(38,434)
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	(90,734)	38,607
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	158,117	258,874
CASH AND CASH EQUIVALENTS AT END OF PERIOD	67,383	297,481
SUPPLEMENTAL DISCLOSURE OF NON-CASH INVESTING AND FINANCING ACTIVITIES:
Unpaid property and equipment	2,984	5,070
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION:
Cash paid for income taxes, net	$ 14,657	$ 10,084