Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Dec. 27, 2014	Dec. 28, 2013
Current Assets
Cash and cash equivalents	$ 163,944	$ 180,302
Short-term investments	37,007	34,939
Trade accounts receivable, less allowance of $4,338 and $3,773	492,642	378,732
Other receivables, including advances to independent contractors, less allowance of $4,189 and $4,253	15,132	73,903
Deferred income taxes and other current assets	23,603	14,592
Total current assets	732,328	682,468
Operating property, less accumulated depreciation and amortization of $160,681 and $157,985	202,203	177,329
Goodwill	31,134	31,134
Other assets	78,547	79,765
Total assets	1,044,212	970,696
Current Liabilities
Cash overdraft	34,629	27,780
Accounts payable	220,077	157,796
Current maturities of long-term debt	35,064	27,567
Insurance claims	24,233	92,280
Dividends payable	44,794	15,921
Other current liabilities	51,654	54,316
Total current liabilities	410,451	375,660
Long-term debt, excluding current maturities	76,257	73,938
Insurance claims	21,769	24,171
Deferred income taxes and other noncurrent liabilities	47,474	42,446
Shareholders' Equity
Common stock, $0.01 par value, authorized 160,000,000 shares, issued 67,268,817 and 67,017,858 shares	673	670
Additional paid-in capital	189,012	179,807
Retained earnings	1,255,374	1,173,044
Cost of 22,474,331 and 21,528,693 shares of common stock in treasury	(955,613)	(899,028)
Accumulated other comprehensive loss	(1,185)	(12)
Total shareholders' equity	488,261	454,481
Total liabilities and shareholders' equity	$ 1,044,212	$ 970,696