Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 30, 2019	Mar. 31, 2018
OPERATING ACTIVITIES
Net income	$ 63,300	$ 57,473
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization of operating property and intangible assets	11,316	10,997
Non-cash interest charges	63	63
Provisions for losses on trade and other accounts receivable	2,150	2,735
Gains on sales/disposals of operating property	(876)	(852)
Deferred income taxes, net	2,079	(757)
Stock-based compensation	1,938	3,710
Changes in operating assets and liabilities:
Decrease in trade and other accounts receivable	84,505	2,901
Decrease in other assets	2,229	4,311
Decrease in accounts payable	(40,953)	(9,127)
Decrease in other liabilities	(3,776)	(191)
(Decrease) increase in insurance claims	(559)	739
NET CASH PROVIDED BY OPERATING ACTIVITIES	121,416	72,002
INVESTING ACTIVITIES
Sales and maturities of investments	25,739	12,698
Purchases of investments	(26,707)	(13,399)
Purchases of operating property	(4,576)	(3,814)
Proceeds from sales of operating property	2,130	2,285
NET CASH USED BY INVESTING ACTIVITIES	(3,414)	(2,230)
FINANCING ACTIVITIES
Decrease in cash overdraft	(13,820)	(5,922)
Dividends paid	(6,629)	(69,293)
Proceeds from exercises of stock options	319	979
Taxes paid in lieu of shares issued related to stock-based compensation plans	(7,923)	(2,704)
Purchases of common stock	(12,977)	(1,508)
Principal payments on finance lease obligations	(11,995)	(11,832)
Purchase of noncontrolling interest	(600)
Payment of contingent consideration		(985)
NET CASH USED BY FINANCING ACTIVITIES	(53,625)	(91,265)
Effect of exchange rate changes on cash and cash equivalents	512	(318)
Increase (decrease) in cash and cash equivalents	64,889	(21,811)
Cash and cash equivalents at beginning of period	199,736	242,416
Cash and cash equivalents at end of period	$ 264,625	$ 220,605