Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Apr. 01, 2017
OPERATING ACTIVITIES
Net income	$ 57,473	$ 32,383
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization of operating property and intangible assets	10,997	9,934
Non-cash interest charges	63	64
Provisions for losses on trade and other accounts receivable	2,735	1,857
Gains on sales/disposals of operating property	(852)	(463)
Deferred income taxes, net	(757)	(709)
Stock-based compensation	3,710	994
Changes in operating assets and liabilities:
Decrease in trade and other accounts receivable	2,901	16,427
Decrease (increase) in other assets	4,311	(174)
Decrease in accounts payable	(9,127)	(15,424)
(Decrease) increase in other liabilities	(191)	13,357
Increase in insurance claims	739	3,702
NET CASH PROVIDED BY OPERATING ACTIVITIES	72,002	61,948
INVESTING ACTIVITIES
Sales and maturities of investments	12,698	23,155
Purchases of investments	(13,399)	(23,678)
Purchases of operating property	(3,814)	(4,978)
Proceeds from sales of operating property	2,285	1,665
NET CASH USED BY INVESTING ACTIVITIES	(2,230)	(3,836)
FINANCING ACTIVITIES
Decrease in cash overdraft	(5,922)	(6,878)
Dividends paid	(69,293)	(3,770)
Proceeds from exercises of stock options	979	1,717
Taxes paid in lieu of shares issued related to stock-based compensation plans	(2,704)	(339)
Purchases of common stock	(1,508)
Principal payments on capital lease obligations	(11,832)	(12,408)
Payment of contingent consideration	(985)
NET CASH USED BY FINANCING ACTIVITIES	(91,265)	(21,678)
Effect of exchange rate changes on cash and cash equivalents	(318)	137
(Decrease) increase in cash and cash equivalents	(21,811)	36,571
Cash and cash equivalents at beginning of period	242,416	178,897
Cash and cash equivalents at end of period	$ 220,605	$ 215,468