CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 30, 2019	Mar. 31, 2018
Revenues:
Total net sales	$ 513,862	$ 530,670
Costs and operating expenses:
Selling and administrative expenses	134,339	130,407
Research and development expenses	35,060	34,480
Purchased intangibles amortization	2,281	1,659
Litigation settlement		(1,672)
Total costs and operating expenses	392,711	386,295
Operating income	121,151	144,375
Other (expense) income	(525)	346
Interest expense	(11,563)	(13,838)
Interest income	8,315	9,666
Income before income taxes	117,378	140,549
Provision for income taxes	8,392	28,598
Net income	$ 108,986	$ 111,951
Net income per basic common share	$ 1.52	$ 1.42
Weighted-average number of basic common shares	71,704	78,883
Net income per diluted common share	$ 1.51	$ 1.40
Weighted-average number of diluted common shares and equivalents	72,415	79,715
Product [Member]
Revenues:
Total net sales	$ 320,503	$ 339,117
Costs and operating expenses:
Costs and operating expenses	132,390	140,466
Service [Member]
Revenues:
Total net sales	193,359	191,553
Costs and operating expenses:
Costs and operating expenses	$ 88,641	$ 80,955