Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 28, 2013	Sep. 29, 2012
OPERATING ACTIVITIES
Net income	$ 86,452	$ 95,803
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization of operating property and intangible assets	22,833	20,476
Non-cash interest charges	164	164
Provisions for losses on trade and other accounts receivable	2,455	3,436
Gains on sales/disposals of operating property	(2,894)	(2,728)
Deferred income taxes, net	4,730	6,223
Stock-based compensation	4,133	4,613
Changes in operating assets and liabilities:
Increase in trade and other accounts receivable	(10,355)	(63,246)
Decrease (increase) in other assets	(2,328)	603
Increase in accounts payable	5,153	49,346
Decrease in other liabilities	(5,127)	(1,083)
Increase (decrease) in insurance claims	26,591	(10,322)
NET CASH PROVIDED BY OPERATING ACTIVITIES	131,807	103,285
INVESTING ACTIVITIES
Net change in other short-term investments	(4,091)
Sales and maturities of investments	33,265	20,889
Purchases of investments	(44,596)	(44,261)
Purchases of operating property	(4,866)	(4,428)
Proceeds from sales of operating property	8,662	8,997
NET CASH USED BY INVESTING ACTIVITIES	(11,626)	(18,803)
FINANCING ACTIVITIES
Increase (decrease) in cash overdraft	(6,753)	814
Dividends paid		(7,956)
Proceeds from exercises of stock options	2,253	4,310
Taxes paid in lieu of shares issued related to stock-based compensation plans	(1,767)	(3,023)
Excess tax effect on stock option exercises	343	839
Borrowings on revolving credit facility		60,000
Purchases of common stock	(46,603)	(24,582)
Principal payments on long-term debt and capital lease obligations	(44,002)	(116,180)
NET CASH USED BY FINANCING ACTIVITIES	(96,529)	(85,778)
Effect of exchange rate changes on cash and cash equivalents	(384)	357
Increase (decrease) in cash and cash equivalents	23,268	(939)
Cash and cash equivalents at beginning of period	74,284	80,900
Cash and cash equivalents at end of period	$ 97,552	$ 79,961