CONDENSED CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Revenues:
Products	$ 101,277	$ 157,790	$ 352,519	$ 521,413
Services	22,363	43,612	80,121	121,267
Total revenues	123,640	201,402	432,640	642,680
Cost of sales:
Products	63,879	88,923	206,208	293,279
Services	13,754	19,209	44,402	57,655
Total cost of sales	77,633	108,132	250,610	350,934
Selling, general and administrative	12,504	17,280	31,487	67,871
Engineering and product development	10,570	11,735	33,050	35,348
Total costs and expenses	100,707	137,147	315,147	454,153
Operating income	22,933	64,255	117,493	188,527
Interest income	945	345	1,968	559
Interest expense	(1)	(4)	(15)	(10)
Income before income taxes	23,877	64,596	119,446	189,076
Income tax provision	4,864	13,819	27,527	45,422
Net income	$ 19,013	$ 50,777	$ 91,919	$ 143,654
Earnings per common share:
Basic (in dollars per share)	$ 0.51	$ 1.32	$ 2.45	$ 3.72
Diluted (in dollars per share)	$ 0.51	$ 1.32	$ 2.44	$ 3.70
Weighted average common shares outstanding:
Basic (in shares)	37,371	38,347	37,562	38,601
Diluted (in shares)	37,554	38,548	37,699	38,789