Consolidated Statements of Income (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Revenue	$ 107,410	$ 104,407	$ 219,194	$ 210,801
Costs and expenses
Cost of revenue	65,323	63,205	114,924	110,653
Selling, general and administrative	24,547	20,701	47,045	38,704
Research and development	10,117	9,896	19,431	19,614
Total costs and expenses	99,987	93,802	181,400	168,971
Operating income	7,423	10,605	37,794	41,830
Equity in net income of affiliate	5,495	5,391	3,108	3,035
Income before interest and income tax expense	12,918	15,996	40,902	44,865
Interest income	20	11	42	31
Interest expense	131	132	296	261
Income before income tax expense	12,807	15,875	40,648	44,635
Income tax expense	5,754	5,912	17,305	16,865
Net income	$ 7,053	$ 9,963	$ 23,343	$ 27,770
Income per weighted-average common share
Basic	$ 0.26	$ 0.38	$ 0.87	$ 1.04
Diluted	$ 0.26	$ 0.37	$ 0.85	$ 1.02
Weighted-average common shares used in calculations
Basic	26,878	26,318	26,786	26,782
Potentially dilutive securities	567	486	580	491
Diluted	27,445	26,804	27,366	27,273
Dividends declared per common share outstanding	$ 0.10	$ 0.10	$ 0.20	$ 0.20