CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities:
Net income	$ 467,468	$ 451,779	$ 257,692
Adjustments to reconcile net income from operations to net cash provided by operating activities:
Depreciation	70,834	67,415	66,122
Amortization	49,821	45,809	41,953
Stock-based compensation	37,897	33,577	34,097
Deferred taxes	(9,456)	28,340	37,105
Provision for excess and obsolete inventory	15,244	11,242	8,844
Investment impairment	15,000
Contingent consideration fair value adjustment	(19,257)	987	7,820
(Gains) losses on investments	(6,033)	3,494	(878)
Retirement plans actuarial losses (gains)	8,176	(3,316)	(6,624)
Property insurance recovery, net			(4,309)
Other	766	1,083	1,585
Changes in operating assets and liabilities, net of businesses acquired:
Accounts receivable	(70,440)	(17,938)	(80,584)
Inventories	(27,408)	(29,498)	44,960
Prepayments and other assets	(23,784)	(58,402)	2,254
Accounts payable and other liabilities	49,279	13,693	43,574
Deferred revenue and customer advances	39,313	13,379	4,984
Retirement plans contributions	(5,086)	(4,334)	(5,902)
Income taxes	(13,584)	(80,429)	173,802
Net cash provided by operating activities	578,750	476,881	626,495
Cash flows from investing activities:
Purchases of property, plant and equipment	(134,642)	(114,379)	(105,375)
Proceeds from government subsidy for property, plant and equipment		7,920
Purchases of marketable securities	(662,701)	(918,744)	(1,391,917)
Proceeds from maturities of marketable securities	611,927	1,270,439	701,681
Proceeds from sales of marketable securities	105,586	846,122	527,746
Proceeds from insurance	2,912	1,126	5,064
Purchase of investment and acquisition of businesses, net of cash acquired	(79,742)	(169,474)
Net cash (used for) provided by investing activities	(156,660)	923,010	(262,801)
Cash flows from financing activities:
Issuance of common stock under stock purchase and stock option plans	29,312	20,973	24,493
Repurchase of common stock	(500,000)	(823,478)	(200,304)
Dividend payments	(61,305)	(67,322)	(55,447)
Payments related to net settlement of employee stock compensation awards	(14,741)	(20,023)	(12,881)
Payments of contingent consideration	(27,615)	(13,571)	(1,050)
Net cash used for financing activities	(574,349)	(903,421)	(245,189)
Effects of exchange rate changes on cash and cash equivalents	(569)	439	3,454
(Decrease) Increase in cash and cash equivalents	(152,828)	496,909	121,959
Cash and cash equivalents at beginning of year	926,752	429,843	307,884
Cash and cash equivalents at end of year	773,924	926,752	429,843
Cash paid for:
Interest	5,996	6,205	6,446
Income taxes	$ 81,410	$ 72,811	$ 53,775