CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Apr. 04, 2021	Mar. 29, 2020
Cash flows from operating activities:
Net income	$ 205,512	$ 176,191
Adjustments to reconcile net income from operations to net cash provided by operating activities:
Depreciation	23,910	18,489
Stock-based compensation	12,232	10,460
Amortization	9,822	13,391
Loss on convertible debt conversion	4,069
Provision for excess and obsolete inventory	2,285	4,057
Contingent consideration adjustment	(7,227)	(10,020)
(Gains) losses on investments	(2,491)	4,657
Deferred taxes	(1,057)	(1,825)
Other	200	503
Changes in operating assets and liabilities, net of businesses acquired:
Accounts receivable	(87,512)	(126,779)
Inventories	(35,870)	15,818
Prepayments and other assets	(86,131)	(39,620)
Accounts payable and other liabilities	(10,571)	(35,323)
Deferred revenue and customer advances	7,952	(913)
Retirement plans contributions	(1,925)	(1,262)
Income taxes	4,941	15,278
Net cash provided by operating activities	38,139	43,102
Cash flows from investing activities:
Purchases of property, plant and equipment	(39,250)	(36,700)
Purchases of marketable securities	(211,604)	(187,119)
Proceeds from maturities of marketable securities	194,228	98,457
Proceeds from sales of marketable securities	61,293	15,005
Acquisition of businesses, net of cash acquired		149
Net cash provided by (used for) investing activities	4,667	(110,208)
Cash flows from financing activities:
Issuance of common stock under stock purchase and stock option plans	17,144	12,752
Payments of convertible debt principal	(51,275)
Repurchase of common stock	(45,188)	(79,039)
Dividend payments	(16,667)	(16,686)
Payments related to net settlement of employee stock compensation awards	(30,675)	(22,070)
Payments of contingent consideration		(8,852)
Net cash used for financing activities	(126,661)	(113,895)
Effects of exchange rate changes on cash and cash equivalents	883	571
Decrease in cash and cash equivalents	(82,972)	(180,430)
Cash and cash equivalents at beginning of period	914,121	773,924
Cash and cash equivalents at end of period	831,149	593,494
Non-cash investing activities:
Capital expenditures incurred but not yet paid	$ 3,840	$ 5,357