Condensed Consolidated Income Statements - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 26, 2020	Sep. 28, 2019	Sep. 26, 2020	Sep. 28, 2019
Revenues [Abstract]
Revenues	$ 666,607	$ 579,603	$ 1,922,982	$ 1,736,764
Costs and Expenses:
Marketing and sales	123,738	121,368	369,958	354,406
Research and development	250,934	240,542	743,423	700,566
General and administrative	35,928	33,204	105,161	97,713
Amortization of acquired intangibles	4,438	2,874	13,234	9,341
Restructuring and other charges (credits)	13	(186)	(1,329)	(1,188)
Total costs and expenses	497,335	458,777	1,462,409	1,353,867
Income from operations	169,272	120,826	460,573	382,897
Interest expense	(5,325)	(4,240)	(15,876)	(14,607)
Other income, net	1,766	122	1,862	5,253
Income before provision for income taxes	165,713	116,708	446,559	373,543
Provision for income taxes	4,083	15,194	29,653	44,239
Net income	$ 161,630	$ 101,514	$ 416,906	$ 329,304
Net income per share - basic (usd per share)	$ 0.59	$ 0.37	$ 1.52	$ 1.21
Net Income per share - diluted (usd per share)	$ 0.58	$ 0.36	$ 1.49	$ 1.17
Weighted average common shares outstanding - basic (in shares)	273,996	273,329	273,633	273,224
Weighted average common shares outstanding - diluted (in shares)	280,024	280,666	279,455	280,817
Product and maintenance [Member]
Revenues [Abstract]
Revenues	$ 630,329	$ 548,105	$ 1,813,384	$ 1,639,651
Costs and Expenses:
Cost of sales	64,800	41,715	175,915	135,625
Service [Member]
Revenues [Abstract]
Revenues	36,278	31,498	109,598	97,113
Costs and Expenses:
Cost of sales	$ 17,484	$ 19,260	$ 56,047	$ 57,404