Condensed Consolidated Income Statements - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 27, 2020	Jun. 29, 2019	Jun. 27, 2020	Jun. 29, 2019
Revenues [Abstract]
Revenues	$ 638,418	$ 580,419	$ 1,256,375	$ 1,157,161
Costs and Expenses:
Marketing and sales	120,476	116,208	246,220	233,038
Research and development	250,821	231,814	492,489	460,024
General and administrative	35,641	34,407	69,233	64,509
Amortization of acquired intangibles	4,590	3,159	8,796	6,467
Restructuring and other credits	(275)	(313)	(1,342)	(1,002)
Total costs and expenses	486,468	446,744	965,074	895,090
Income from operations	151,950	133,675	291,301	262,071
Interest expense	(5,914)	(4,976)	(10,551)	(10,367)
Other income (expense), net	4,630	(110)	96	5,131
Income before provision for income taxes	150,666	128,589	280,846	256,835
Provision for income taxes	19,378	21,354	25,570	29,045
Net income	$ 131,288	$ 107,235	$ 255,276	$ 227,790
Net income per share - basic (usd per share)	$ 0.48	$ 0.39	$ 0.93	$ 0.83
Net Income per share - diluted (usd per share)	$ 0.47	$ 0.38	$ 0.91	$ 0.81
Weighted average common shares outstanding - basic (in shares)	273,432	273,159	273,488	273,155
Weighted average common shares outstanding - diluted (in shares)	279,080	281,054	279,207	280,877
Product and maintenance [Member]
Revenues [Abstract]
Revenues	$ 601,356	$ 548,028	$ 1,183,055	$ 1,091,546
Costs and Expenses:
Cost of sales	55,669	43,388	111,115	93,910
Service [Member]
Revenues [Abstract]
Revenues	37,062	32,391	73,320	65,615
Costs and Expenses:
Cost of sales	$ 19,546	$ 18,081	$ 38,563	$ 38,144