Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 17,248	$ 7,908
Certificates of deposit	10,760	10,080
Investments held to maturity at amortized cost	15,195	12,444
Accounts receivable, net	42,001	50,024
Income tax receivable	0	4,702
Notes receivable	25	23
Inventories, net	42,479	38,499
Prepaid expenses and other	2,483	533
Total current assets	130,191	124,213
Property, plant and equipment:
Land	2,233	2,233
Buildings	70,655	68,806
Machinery and equipment	148,645	143,100
Furniture and fixtures	11,661	11,270
Total property, plant and equipment	233,194	225,409
Less: Accumulated depreciation	127,417	124,348
Property, plant and equipment, net	105,777	101,061
Certificates of deposit	0	1,880
Investments held to maturity at amortized cost	0	5,039
Note receivable	701	661
Total assets	236,669	232,854
Current liabilities:
Revolving credit facility	0	0
Accounts payable	3,604	6,178
Accrued liabilities	34,435	37,235
Total current liabilities	38,039	43,413
Deferred revenue	1,154	698
Deferred tax liabilities	7,676	8,706
Donations	$ 1,130	$ 1,119
Commitments and contingencies
Stockholders' equity:
Preferred stock, $.001 par value, 5,000,000 shares authorized, no shares issued	$ 0	$ 0
Common stock, $.004 par value, 100,000,000 shares authorized, 53,059,669 and 53,012,363 issued and outstanding at March 31, 2016 and December 31, 2015, respectively	212	212
Additional paid-in capital	0	0
Retained earnings	188,458	178,706
Total stockholders' equity	188,670	178,918
Total liabilities and stockholders' equity	$ 236,669	$ 232,854