Consolidated Statements of Income (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Statement [Abstract]
Sales	$ 641,744	$ 620,614	$ 717,229
Cost of sales	332,858	303,971	302,911
Gross Profit	308,886	316,643	414,318
Selling, general and administrative expenses	129,366	134,523	124,879
Research and development expenses	131,055	125,951	100,301
Operating Income	48,465	56,169	189,138
Interest and dividend income	7,012	7,657	7,642
Interest expense	(2,325)	(2,347)	(2,398)
Net realized investment gain	8,614	9,550	12,454
Other income (expense), net	(911)	183	(694)
Gain on bargain purchase of a business		1,753
Income before provision for income taxes	60,855	72,965	206,142
Provision for income taxes	(15,061)	(25,702)	(67,565)
Net Income	$ 45,794	$ 47,263	$ 138,577
Weighted average shares outstanding - basic	59,001	63,259	64,145
Weighted average shares outstanding - diluted	59,424	63,774	65,416
Earnings per common share - basic	$ 0.78	$ 0.75	$ 2.16
Earnings per common share - diluted	$ 0.77	$ 0.74	$ 2.12