Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 29, 2013	Jun. 30, 2012
OPERATING ACTIVITIES
Net income	$ 57,206	$ 62,702
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization of operating property and intangible assets	14,993	13,404
Non-cash interest charges	109	109
Provisions for losses on trade and other accounts receivable	1,565	1,830
Gains on sales/disposals of operating property	(2,320)	(2,008)
Deferred income taxes, net	6,071	6,901
Stock-based compensation	2,992	3,186
Changes in operating assets and liabilities:
Decrease (increase) in trade and other accounts receivable	14,568	(58,187)
Increase in other assets	(6,900)	(4,619)
Increase (decrease) in accounts payable	(452)	40,612
Increase (decrease) in other liabilities	(4,592)	545
Increase (decrease) in insurance claims	1,525	(9,665)
NET CASH PROVIDED BY OPERATING ACTIVITIES	84,765	54,810
INVESTING ACTIVITIES
Sales and maturities of investments	24,296	13,277
Purchases of investments	(35,157)	(36,233)
Purchases of operating property	(2,749)	(2,982)
Proceeds from sales of operating property	6,826	6,250
NET CASH USED BY INVESTING ACTIVITIES	(6,784)	(19,688)
FINANCING ACTIVITIES
Decrease in cash overdraft	(6,622)	(1,833)
Dividends paid		(5,157)
Proceeds from exercises of stock options	1,885	4,155
Taxes paid in lieu of shares issued related to stock-based compensation plans	(1,633)	(3,022)
Excess tax effect on stock option exercises	252	886
Borrowings on revolving credit facility		60,000
Purchases of common stock	(46,603)	(15,752)
Principal payments on long-term debt and capital lease obligations	(31,560)	(90,840)
NET CASH USED BY FINANCING ACTIVITIES	(84,281)	(51,563)
Effect of exchange rate changes on cash and cash equivalents	(510)	(64)
Decrease in cash and cash equivalents	(6,810)	(16,505)
Cash and cash equivalents at beginning of period	74,284	80,900
Cash and cash equivalents at end of period	$ 67,474	$ 64,395