CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
CURRENT ASSETS:
Cash and cash equivalents	$ 148,187	$ 93,655
Short-term marketable securities	98,494	189,236
Accounts receivable, net of allowances for doubtful accounts of $751 and $734 in 2018 and 2017, respectively	6,843	16,798
Inventories	68,824	57,087
Prepaid expenses and other current assets	10,619	7,758
Total current assets	332,967	364,534
PROPERTY AND EQUIPMENT, net	111,063	111,705
INTANGIBLE ASSETS, net	23,751	25,419
GOODWILL	91,849	91,849
DEFERRED TAX ASSETS	3,181	2,364
OTHER ASSETS	25,216	25,203
Total assets	588,027	621,074
CURRENT LIABILITIES:
Accounts payable	26,518	33,211
Accrued payroll and related expenses	12,053	12,064
Taxes payable	1,254	1,767
Other accrued liabilities	4,588	4,009
Total current liabilities	44,413	51,051
LONG-TERM INCOME TAXES PAYABLE	17,635	18,259
DEFERRED TAX LIABILITIES	55	138
OTHER LIABILITIES	4,095	3,944
Total liabilities	66,198	73,392
COMMITMENTS AND CONTINGENCIES (Notes 11, 12 and 13)
STOCKHOLDERS’ EQUITY:
Common stock	28	29
Additional paid-in capital	152,380	198,384
Accumulated other comprehensive loss	(2,088)	(2,139)
Retained earnings	371,509	351,408
Total stockholders’ equity	521,829	547,682
Total liabilities and stockholders’ equity	$ 588,027	$ 621,074