CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Oct. 01, 2017
Cash flows from operating activities:
Net income	$ 307,991	$ 363,616
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	49,930	49,243
Amortization	32,909	32,313
Stock-based compensation	25,327	25,620
Deferred taxes	24,442	(679)
Provision for excess and obsolete inventory	9,522	7,154
Contingent consideration adjustment	(9,236)	1,847
Retirement plan actuarial losses (gains)	196	(2,504)
Property insurance recovery		(4,309)
Other	516	429
Changes in operating assets and liabilities, net of businesses acquired:
Accounts receivable	(77,807)	(75,623)
Inventories	(34,117)	23,770
Prepayments and other assets	(28,719)	7,362
Accounts payable and other accrued expenses	16,124	5,298
Deferred revenue and customer advances	9,823	34,535
Retirement plans contributions	(3,244)	(4,858)
Income taxes	(33,152)	15,808
Net cash provided by operating activities	290,505	479,022
Cash flows from investing activities:
Purchases of property, plant and equipment	(88,269)	(73,247)
Proceeds from government subsidy for property, plant and equipment	7,920
Purchases of marketable securities	(809,521)	(1,036,523)
Proceeds from sales of marketable securities	843,164	443,169
Proceeds from maturities of marketable securities	934,100	473,255
Proceeds from life insurance	1,126
Proceeds from property insurance		5,064
Acquisition of businesses, net of cash acquired	(169,474)
Net cash provided by (used for) investing activities	719,046	(188,282)
Cash flows from financing activities:
Issuance of common stock under stock purchase and stock option plans	20,959	24,462
Repurchase of common stock	(562,263)	(151,821)
Dividend payments	(51,320)	(41,730)
Payments related to net settlement of employee stock compensation awards	(19,841)	(12,584)
Payments of contingent consideration	(13,571)	(1,050)
Net cash used for financing activities	(626,036)	(182,723)
Effects of exchange rate changes on cash and cash equivalents	661	2,776
Increase in cash and cash equivalents	384,176	110,793
Cash and cash equivalents at beginning of period	429,843	307,884
Cash and cash equivalents at end of period	$ 814,019	$ 418,677