CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
CURRENT ASSETS:
Cash and cash equivalents	$ 148,551	$ 93,655
Short-term marketable securities	99,766	189,236
Accounts receivable, net of allowances for doubtful accounts of $904 and $734 in 2018 and 2017, respectively	13,742	16,798
Inventories	74,201	57,087
Prepaid expenses and other current assets	12,573	7,758
Total current assets	348,833	364,534
PROPERTY AND EQUIPMENT, net	113,841	111,705
INTANGIBLE ASSETS, net	22,452	25,419
GOODWILL	91,849	91,849
DEFERRED TAX ASSETS	3,673	2,364
OTHER ASSETS	23,779	25,203
Total assets	604,427	621,074
CURRENT LIABILITIES:
Accounts payable	34,469	33,211
Accrued payroll and related expenses	9,706	12,064
Taxes payable	1,311	1,767
Other accrued liabilities	5,019	4,009
Total current liabilities	50,505	51,051
LONG-TERM INCOME TAXES PAYABLE	17,952	18,259
DEFERRED TAX LIABILITIES	52	138
OTHER LIABILITIES	4,786	3,944
Total liabilities	73,295	73,392
COMMITMENTS AND CONTINGENCIES (Notes 11, 12 and 13)
STOCKHOLDERS’ EQUITY:
Common stock	28	29
Additional paid-in capital	148,696	198,384
Accumulated other comprehensive loss	(2,076)	(2,139)
Retained earnings	384,484	351,408
Total stockholders’ equity	531,132	547,682
Total liabilities and stockholders’ equity	$ 604,427	$ 621,074