Condensed Consolidated Statements of Income (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Revenues:
Products	$ 176,099	$ 189,914	$ 363,623	$ 361,915
Services	39,177	40,401	77,655	72,473
Total revenues	215,276	230,315	441,278	434,388
Cost and expenses:
Products	98,349	104,208	204,356	195,539
Services	19,315	20,785	38,446	40,241
Total cost of sales	117,664	124,993	242,802	235,780
Selling, general and administrative	33,633	25,520	50,591	49,455
Engineering and product development	11,400	10,848	23,613	21,632
Total costs and expenses	162,697	161,361	317,006	306,867
Operating income	52,579	68,954	124,272	127,521
Interest income	165	266	214	349
Interest expense	(3)	(5)	(6)	(12)
Income before income taxes	52,741	69,215	124,480	127,858
Income tax provision	13,528	17,891	31,603	33,916
Net income	$ 39,213	$ 51,324	$ 92,877	$ 93,942
Earnings per common share:
Basic	$ 1.01	$ 1.27	$ 2.40	$ 2.32
Diluted	$ 1.01	$ 1.27	$ 2.39	$ 2.31
Weighted average common shares outstanding:
Basic	38,686	40,327	38,729	40,501
Diluted	38,888	40,562	38,912	40,723