CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Current assets:
Cash and cash equivalents	$ 18,943	$ 24,590
Short-term investments	20,164	20,279
Accounts receivable	12,383	11,223
Inventories	25,644	24,582
Prepaid expenses	865	2,313
Deferred income taxes	755	755
Assets, Current, Total	78,754	83,742
Long-term investments	15,347	10,336
Property, plant and equipment	117,649	114,975
Less accumulated depreciation and amortization	60,235	58,605
Property, Plant and Equipment, Net, Total	57,414	56,370
Other assets and deferred charges:
Patents	958	999
Goodwill	9,730	9,730
Other	851	718
Prepaid Expense and Other Assets, Noncurrent, Total	11,539	11,447
Assets, Total	163,054	161,895
Current liabilities:
Accounts payable and accrued liabilities	6,995	9,208
Accrued income and other taxes	1,534	835
Liabilities, Current, Total	8,529	10,043
Line of credit
Other non-current liabilities	13,321	13,338
Stockholders' equity:
Common shares, par value $0.10 per share; authorized 10,000 shares, issued 3,420 shares	342	342
Paid-in capital	27,194	25,452
Retained earnings	158,002	153,618
Treasury shares,1,410 at March 31, 2012 and 1,404 at December 31, 2011, at cost	(44,334)	(40,898)
Total stockholders' equity	141,204	138,514
Liabilities and Equity, Total	$ 163,054	$ 161,895