CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 29, 2019	Sep. 30, 2018	Sep. 29, 2019	Sep. 30, 2018
Revenues:
Total revenues	$ 582,038	$ 566,848	$ 1,640,315	$ 1,581,244
Cost of revenues:
Total cost of revenues (exclusive of acquired intangible assets amortization shown separately below)	237,000	233,155	683,724	670,385
Gross profit	345,038	333,693	956,591	910,859
Operating expenses:
Selling and administrative	109,166	100,199	319,990	290,115
Engineering and development	77,804	77,049	236,030	226,799
Acquired intangible assets amortization	9,647	11,142	30,363	28,633
Restructuring and other	(6,500)	1,710	(11,792)	3,785
Total operating expenses	190,117	190,100	574,591	549,332
Income from operations	154,921	143,593	382,000	361,527
Non-operating (income) expense:
Interest income	(5,159)	(6,213)	(18,641)	(17,620)
Interest expense	5,682	5,557	17,195	18,087
Other (income) expense, net	2,665	3,405	6,557	4,385
Income before income taxes	151,733	140,844	376,889	356,675
Income tax provision	15,873	20,863	34,494	48,684
Net income	$ 135,860	$ 119,981	$ 342,395	$ 307,991
Net income per common share:
Basic	$ 0.80	$ 0.65	$ 2.00	$ 1.62
Diluted	$ 0.75	$ 0.63	$ 1.92	$ 1.57
Weighted average common shares-basic	169,641	185,744	171,471	190,576
Weighted average common shares-diluted	180,494	190,505	178,685	196,300
Product [Member]
Revenues:
Total revenues	$ 488,170	$ 470,994	$ 1,339,123	$ 1,308,969
Cost of revenues:
Total cost of revenues (exclusive of acquired intangible assets amortization shown separately below)	197,196	195,339	555,863	557,074
Service [Member]
Revenues:
Total revenues	93,868	95,854	301,192	272,275
Cost of revenues:
Total cost of revenues (exclusive of acquired intangible assets amortization shown separately below)	$ 39,804	$ 37,816	$ 127,861	$ 113,311