CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
CURRENT ASSETS:
Cash and cash equivalents	$ 125,795	$ 134,137
Short-term marketable securities	92,901	94,451
Accounts receivable, net of allowances for doubtful accounts of $526 and $706 in 2019 and 2018, respectively	20,545	11,072
Inventories	85,080	80,857
Prepaid expenses and other current assets	16,798	11,915
Total current assets	341,119	332,432
PROPERTY AND EQUIPMENT, net	113,713	114,117
INTANGIBLE ASSETS, net	20,073	21,152
GOODWILL	91,849	91,849
DEFERRED TAX ASSETS	5,733	6,906
OTHER ASSETS	28,018	22,241
Total assets	600,505	588,697
CURRENT LIABILITIES:
Accounts payable	33,432	31,552
Accrued payroll and related expenses	11,512	12,131
Taxes payable	706	933
Other accrued liabilities	5,271	3,750
Total current liabilities	50,921	48,366
LONG-TERM INCOME TAXES PAYABLE	8,789	8,652
DEFERRED TAX LIABILITIES	204	216
OTHER LIABILITIES	9,290	4,391
Total liabilities	69,204	61,625
COMMITMENTS AND CONTINGENCIES (Notes 11, 12, 13 and 14)
STOCKHOLDERS’ EQUITY:
Common stock	28	28
Additional paid-in capital	127,769	126,164
Accumulated other comprehensive loss	(1,361)	(1,689)
Retained earnings	404,865	402,569
Total stockholders’ equity	531,301	527,072
Total liabilities and stockholders’ equity	$ 600,505	$ 588,697