CONDENSED CONSOLIDATED STATEMENTS OF INCOME (UNAUDITED) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Revenues:
Products	$ 116,048	$ 176,099	$ 251,242	$ 363,623
Services	26,391	39,177	57,758	77,655
Total revenues	142,439	215,276	309,000	441,278
Cost of sales:
Products	65,407	98,349	142,329	204,356
Services	14,474	19,315	30,648	38,446
Total cost of sales	79,881	117,664	172,977	242,802
Selling, general and administrative	5,762	33,633	18,983	50,591
Engineering and product development	11,579	11,400	22,480	23,613
Total costs and expenses	97,222	162,697	214,440	317,006
Operating income	45,217	52,579	94,560	124,272
Interest income	541	165	1,023	214
Interest expense	(10)	(3)	(14)	(6)
Income before income taxes	45,748	52,741	95,569	124,480
Income tax provision	9,611	13,528	22,663	31,603
Net income	$ 36,137	$ 39,213	$ 72,906	$ 92,877
Earnings per common share:
Basic (in dollars per share)	$ 0.96	$ 1.01	$ 1.94	$ 2.40
Diluted (in dollars per share)	$ 0.96	$ 1.01	$ 1.93	$ 2.39
Weighted average common shares outstanding:
Basic (in shares)	37,564	38,686	37,658	38,729
Diluted (in shares)	37,713	38,888	37,779	38,912