CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jul. 01, 2018	Jul. 02, 2017
Cash flows from operating activities:
Net income	$ 188,010	$ 260,197
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	33,156	32,474
Amortization	20,177	22,412
Stock-based compensation	17,625	17,312
Deferred taxes	17,312	(3,563)
Provision for excess and obsolete inventory	6,175	5,295
Contingent consideration adjustment	(8,468)	2,133
Retirement plan actuarial gains	(71)	(2,504)
Other	1,168	1,153
Changes in operating assets and liabilities, net of businesses acquired:
Accounts receivable	(179,403)	(214,189)
Inventories	(21,283)	(8,149)
Prepayments and other assets	1,641	4,425
Accounts payable and other accrued expenses	(8,155)	34,504
Deferred revenue and customer advances	10,518	5,312
Retirement plans contributions	(2,173)	(1,983)
Income taxes	(26,308)	14,363
Net cash provided by operating activities	49,921	169,192
Cash flows from investing activities:
Purchases of property, plant and equipment	(62,663)	(45,967)
Purchases of marketable securities	(647,071)	(334,819)
Proceeds from sales of marketable securities	829,053	313,254
Proceeds from maturities of marketable securities	469,862	307,607
Acquisition of businesses, net of cash acquired	(170,632)
Net cash provided by investing activities	418,549	240,075
Cash flows from financing activities:
Issuance of common stock under stock purchase and stock option plans	10,681	15,215
Repurchase of common stock	(360,795)	(94,328)
Dividend payments	(34,682)	(27,925)
Payments related to net settlement of employee stock compensation awards	(19,751)	(12,438)
Payments of contingent consideration	(13,571)	(1,050)
Net cash used for financing activities	(418,118)	(120,526)
Effects of exchange rate changes on cash and cash equivalents	189	1,724
Increase in cash and cash equivalents	50,541	290,465
Cash and cash equivalents at beginning of period	429,843	307,884
Cash and cash equivalents at end of period	$ 480,384	$ 598,349