CONDENSED CONSOLIDATED STATEMENTS OF INCOME (UNAUDITED) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Revenues:
Products	$ 189,914	$ 188,859	$ 361,915	$ 349,344
Services	40,401	33,172	72,473	65,842
Total revenues	230,315	222,031	434,388	415,186
Cost and expenses:
Products	104,208	113,312	195,539	209,985
Services	20,785	19,891	40,241	39,546
Total cost of sales	124,993	133,203	235,780	249,531
Selling, general and administrative	25,520	23,273	49,455	38,902
Engineering and product development	10,848	9,340	21,632	18,361
Total costs and expenses	161,361	165,816	306,867	306,794
Operating income	68,954	56,215	127,521	108,392
Interest income	266	167	349	283
Interest expense	(5)	(6)	(12)	(20)
Income before income taxes	69,215	56,376	127,858	108,655
Income tax provision	17,891	13,449	33,916	25,886
Net income	$ 51,324	$ 42,927	$ 93,942	$ 82,769
Earnings per common share:
Basic	$ 1.27	$ 1.06	$ 2.32	$ 2.04
Diluted	$ 1.27	$ 1.05	$ 2.31	$ 2.03
Weighted average common shares outstanding:
Basic	40,327	40,636	40,501	40,583
Diluted	40,562	40,821	40,723	40,767