Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 30, 2019	Mar. 31, 2018
Operating activities
Net earnings	$ 75,641	$ 62,545
Adjustments to reconcile net earnings to net cash provided by operating activities:
Depreciation and amortization	40,428	40,558
(Gain) loss on disposal of property and equipment	(173)	(176)
Accretion of interest on convertible debt instruments	3,490	1,309
Inventory write-offs for obsolescence	6,967	5,457
Deferred income taxes	(2,614)	7,014
Loss on extinguishment of debt	1,307	0
Other	(1,744)	2,908
Net change in operating assets and liabilities, net of effects of businesses acquired	(43,784)	(72,756)
Net cash provided by operating activities	79,518	46,859
Investing activities
Capital expenditures	(36,367)	(28,273)
Proceeds from sale of property and equipment	395	184
Purchase of businesses, net of cash received	(11,862)	(12,072)
Purchase of short-term investments	(1,920)	(39,243)
Maturity of short-term investments	71,455	93,194
Other investing activities	2,893	(935)
Net cash provided by (used in) investing activities	24,594	12,855
Financing activities
Repurchase of convertible debentures	(22,695)	0
Net proceeds (payments) on revolving credit lines	0	34,000
Net changes in short-term borrowings	0	52
Cash withholding taxes paid when shares withheld for vested equity awards	(2,659)	(2,297)
Net cash provided by (used in) financing activities	(37,631)	22,020
Effect of exchange rate changes on cash and cash equivalents	(3,087)	9,825
Net increase in cash and cash equivalents	63,394	91,559
Cash and cash equivalents at beginning of period	686,032	748,032
Cash and cash equivalents at end of period	749,426	839,591
Common Stock [Member]
Operating activities
Net earnings	0	0
Financing activities
Dividends paid to common stockholders	(11,249)	(8,918)
Class B Convertible Common Stock [Member]
Operating activities
Net earnings	0	0
Financing activities
Dividends paid to common stockholders	$ (1,028)	$ (817)