Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 20,223	$ 20,022
Short-term investments	27,073	24,080
Accounts receivable	19,690	17,166
Inventories	29,965	29,015
Prepaid expenses and other current assets	6,022	3,181
Total Current Assets	102,973	93,464
Long-term investments	10,046	9,945
Property, plant and equipment	165,571	160,413
Less accumulated depreciation and amortization	99,015	95,148
Property plant and equipment net	66,556	65,265
Other assets and deferred charges:
Patents	1,837	1,929
Goodwill	9,730	9,730
Other	1,529	1,609
Prepaid Expense and Other Assets, Noncurrent, Total	13,096	13,268
Total assets	192,671	181,942
Current liabilities:
Accounts payable and accrued liabilities	8,111	8,663
Accrued income and other taxes	1,272	410
Total Current Liabilities	9,383	9,073
Line of credit	0	0
Other non-current liabilities	10,965	9,881
Stockholders' equity:
Common stock, par value $0.10 per share; authorized 10,000 shares, issued 3,420 shares	342	342
Paid-in capital	48,017	37,448
Accumulated other comprehensive income (loss)	(408)	(474)
Retained earnings	256,035	239,946
Treasury shares, 1,584 at June 30, 2017 and 1,596 at December 31, 2016, at cost	(131,663)	(114,274)
Total stockholders' equity	172,323	162,988
Total liabilities and stockholders' equity	$ 192,671	$ 181,942

Sum of the carrying values as of the balance sheet date of obligations incurred through that date and due within one year (or the operating cycle, if longer), including liabilities incurred (and for which invoices have typically been received) and payable to vendors for goods and services received, taxes, interest, rent and utilities, accrued salaries and bonuses, payroll taxes and fringe benefits.

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount due from customers or clients, within one year of the balance sheet date (or the normal operating cycle, whichever is longer), for goods or services (including trade receivables) that have been delivered or sold in the normal course of business, reduced to the estimated net realizable fair value by an allowance established by the entity of the amount it deems uncertain of collection.