Consolidated Statements of Income (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Revenue	$ 104,407	$ 95,737	$ 210,801	$ 196,606
Costs and expenses
Cost of revenue	63,205	61,025	110,653	106,704
Selling, general and administrative	20,701	18,656	38,704	35,765
Research and development	9,896	9,017	19,614	18,012
Total costs and expenses	93,802	88,698	168,971	160,481
Operating income	10,605	7,039	41,830	36,125
Equity in net income of affiliate	5,391	5,453	3,035	2,921
Income before interest and income tax expense	15,996	12,492	44,865	39,046
Interest income	11	8	31	14
Interest expense	132	104	261	268
Income before income tax expense	15,875	12,396	44,635	38,792
Income tax expense	5,912	4,812	16,865	14,961
Net income	$ 9,963	$ 7,584	$ 27,770	$ 23,831
Income per weighted-average common share
Basic	$ 0.38	$ 0.28	$ 1.04	$ 0.88
Diluted	$ 0.37	$ 0.27	$ 1.02	$ 0.86
Weighted-average common shares used in calculations
Basic	26,318	27,159	26,782	27,119
Potentially dilutive securities	486	449	491	483
Diluted	26,804	27,608	27,273	27,602
Dividends declared per common share outstanding	$ 0.10	$ 0.10	$ 0.20	$ 0.20