CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 29, 2020	Mar. 31, 2019
Cash flows from operating activities:
Net income	$ 176,191	$ 109,138
Adjustments to reconcile net income from operations to net cash provided by operating activities:
Depreciation	18,489	16,651
Amortization	13,391	12,942
Stock-based compensation	10,460	9,474
Provision for excess and obsolete inventory	4,057	2,397
Deferred taxes	(1,825)	1,206
Contingent consideration adjustment	(10,020)	2,970
Losses (gains) on investments	4,657	(2,828)
Other	503	219
Changes in operating assets and liabilities, net of businesses acquired:
Accounts receivable	(126,779)	(41,706)
Inventories	15,818	(2,917)
Prepayments and other assets	(39,620)	(18,648)
Accounts payable and other liabilities	(35,323)	(53,323)
Deferred revenue and customer advances	(913)	6,455
Retirement plans contributions	(1,262)	(1,210)
Income taxes	15,278	(22,804)
Net cash provided by operating activities	43,102	18,016
Cash flows from investing activities:
Purchases of property, plant and equipment	(36,700)	(25,711)
Purchases of marketable securities	(187,119)	(375,184)
Proceeds from maturities of marketable securities	98,457	141,201
Proceeds from sales of marketable securities	15,005	5,440
Acquisition of businesses, net of cash acquired	149	(6,970)
Proceeds from life insurance		273
Net cash used for investing activities	(110,208)	(260,951)
Cash flows from financing activities:
Issuance of common stock under stock purchase and stock option plans	12,752	14,268
Repurchase of common stock	(79,039)	(156,468)
Dividend payments	(16,686)	(15,627)
Payments related to net settlement of employee stock compensation awards	(22,070)	(14,318)
Payments of contingent consideration	(8,852)	(27,615)
Net cash used for financing activities	(113,895)	(199,760)
Effects of exchange rate changes on cash and cash equivalents	571	(329)
Decrease in cash and cash equivalents	(180,430)	(443,024)
Cash and cash equivalents at beginning of period	773,924	926,752
Cash and cash equivalents at end of period	$ 593,494	$ 483,728