Consolidated Balance Sheets (Unaudited) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Current assets:
Cash and cash equivalents	$ 53,465	$ 51,262
Restricted cash	47	46
Accounts receivable, net of allowance for doubtful accounts of $68 and $83	21,736	16,227
Inventories	13,719	12,829
Income taxes receivable		120
Deferred income taxes	260	260
Marketable securities	30,872	21,832
Other current assets	1,658	1,354
Total current assets	121,757	103,930
Property, plant and equipment, net	58,402	56,959
Other assets	6,350	6,639
Total assets	186,509	167,528
Current liabilities:
Accounts payable	4,805	4,402
Accrued expenses and other liabilities	5,893	7,466
Income taxes payable	342
Dividends payable	2,337	2,318
Total current liabilities	13,377	14,186
Deferred income taxes	6,918	6,917
Other noncurrent liabilities	244	1,149
Total liabilities	20,539	22,252
Commitments and contingencies
Shareholders' equity:
Preferred stock, 2,000,000 shares authorized, par value $0.001, no shares outstanding
Common stock, 40,000,000 shares authorized, par value $0.001, 25,981,534 and 25,756,442 shares outstanding	26	26
Capital in excess of par value	55,771	48,944
Retained earnings	112,508	98,426
Accumulated other comprehensive loss	(2,335)	(2,120)
Total shareholders' equity	165,970	145,276
Total liabilities and shareholders' equity	$ 186,509	$ 167,528