CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 01, 2018	Jul. 02, 2017	Jul. 01, 2018	Jul. 02, 2017
Revenues:
Total revenues	$ 526,929	$ 696,901	$ 1,014,396	$ 1,153,814
Cost of revenues:
Total cost of revenues (exclusive of acquired intangible assets amortization shown separately below)	219,595	306,263	437,230	498,159
Gross profit	307,334	390,638	577,166	655,655
Operating expenses:
Selling and administrative	99,410	90,111	189,916	174,903
Engineering and development	75,342	82,270	149,750	158,248
Acquired intangible assets amortization	9,793	8,166	17,491	16,118
Restructuring and other	2,389	2,288	2,076	4,799
Total operating expenses	186,934	182,835	359,233	354,068
Income from operations	120,400	207,803	217,933	301,587
Non-operating (income) expense:
Interest income	(5,427)	(3,292)	(11,407)	(6,812)
Interest expense	5,639	5,509	12,530	10,911
Other (income) expense, net	176	(1,291)	979	(1,405)
Income before income taxes	120,012	206,877	215,831	298,893
Income tax provision	18,975	31,901	27,821	38,696
Net income	$ 101,037	$ 174,976	$ 188,010	$ 260,197
Net income per common share:
Basic	$ 0.53	$ 0.88	$ 0.97	$ 1.30
Diluted	$ 0.52	$ 0.87	$ 0.94	$ 1.29
Weighted average common shares-basic	190,730	198,774	192,992	199,390
Weighted average common shares-diluted	194,909	201,529	199,197	201,732
Cash dividend declared per common share	$ 0.09	$ 0.07	$ 0.18	$ 0.14
Product [Member]
Revenues:
Total revenues	$ 434,051	$ 610,356	$ 837,976	$ 983,560
Cost of revenues:
Total cost of revenues (exclusive of acquired intangible assets amortization shown separately below)	180,777	267,752	361,735	422,634
Service [Member]
Revenues:
Total revenues	92,878	86,545	176,420	170,254
Cost of revenues:
Total cost of revenues (exclusive of acquired intangible assets amortization shown separately below)	$ 38,818	$ 38,511	$ 75,495	$ 75,525