Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 27, 2021	Mar. 28, 2020
OPERATING ACTIVITIES
Net income	$ 77,240	$ 40,895
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization of operating property and intangible assets	12,101	11,505
Non-cash interest charges	112	63
Provisions for losses on trade and other accounts receivable	547	4,122
Gains on sales/disposals of operating property	(24)	(858)
Deferred income taxes, net	(1,110)	797
Stock-based compensation	4,029	631
Changes in operating assets and liabilities:
Decrease in trade and other accounts receivable	33,440	21,369
Decrease in other assets	6,175	9,987
Increase in accounts payable	33,935	179
Increase in other liabilities	13,008	4,404
(Decrease) increase in insurance claims	(109,562)	6,122
NET CASH PROVIDED BY OPERATING ACTIVITIES	69,891	99,216
INVESTING ACTIVITIES
Net changes in other short-term investments		131
Sales and maturities of investments	7,957	7,963
Purchases of investments	(8,716)	(8,830)
Purchases of operating property	(4,076)	(5,799)
Proceeds from sales of operating property	500	2,081
NET CASH USED BY INVESTING ACTIVITIES	(4,335)	(4,454)
FINANCING ACTIVITIES
Increase (decrease) in cash overdraft	6	(17,876)
Dividends paid	(84,837)	(86,283)
Proceeds from exercises of stock options	77	575
Taxes paid in lieu of shares issued related to stock-based compensation plans	(1,241)	(2,994)
Purchases of common stock		(115,962)
Principal payments on finance lease obligations	(9,778)	(10,923)
NET CASH USED BY FINANCING ACTIVITIES	(95,773)	(233,463)
Effect of exchange rate changes on cash and cash equivalents	252	(3,590)
Decrease in cash and cash equivalents	(29,965)	(142,291)
Cash and cash equivalents at beginning of period	249,354	319,515
Cash and cash equivalents at end of period	$ 219,389	$ 177,224