CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 45,837	$ 28,187
Marketable securities	20,943	25,736
Accounts receivable, net of allowance for doubtful accounts of $2,631 and $2,605, respectively	35,609	31,366
Inventories	57,944	52,573
Prepaid expenses and other	7,855	5,448
Total current assets	168,188	143,310
Property, plant and equipment	178,752	180,278
Less - accumulated depreciation	(71,952)	(70,867)
Property, plant and equipment, net	106,800	109,411
Purchased intangible assets, net	2,927	3,665
Deferred tax assets	5,873	4,582
Other assets	21,029	18,677
Total assets	304,817	279,645
Current liabilities:
Accounts payable	27,336	17,574
Accrued expenses	7,727	5,301
Accrued income taxes	7,975	7,279
Accrued employee compensation and benefits	6,625	7,160
Contract liabilities	7,205	4,928
Current portion of long-term debt	0	3,125
Other current liabilities	1,505	1,741
Total current liabilities	58,373	47,108
Long-term debt	0	8,139
Deferred tax liabilities	1,211	2,254
Other long-term liabilities	26,803	25,230
Total liabilities	86,387	82,731
Commitments and contingencies (Note 12)
Stockholders’ equity
Preferred stock, $0.05 par value; 4,000,000 shares authorized; no issued and outstanding shares	0	0
Common stock, $0.05 par value; 25,000,000 shares authorized; 15,833,470 and 15,389,285 shares outstanding, respectively	820	796
Additional paid-in capital	144,094	117,387
Retained earnings	116,089	115,657
Other cumulative comprehensive loss	(24,929)	(22,962)
Treasury stock, at cost, and company stock held for deferred compensation, at par; 566,343 and 528,274 shares, respectively	(17,644)	(13,964)
Total stockholders’ equity	218,430	196,914
Total liabilities and stockholders’ equity	$ 304,817	$ 279,645