CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Current Assets
Cash and cash equivalents	$ 64,395	$ 80,900
Short-term investments	36,601	27,944
Trade accounts receivable, less allowance of $7,379 and $6,591	423,059	368,377
Other receivables, including advances to independent contractors, less allowance of $4,727 and $5,384	54,938	53,263
Deferred income taxes and other current assets	23,089	21,308
Total current assets	602,082	551,792
Operating property, less accumulated depreciation and amortization of $150,687 and $145,804	152,059	142,146
Goodwill	57,470	57,470
Other assets	71,687	57,041
Total assets	883,298	808,449
Current Liabilities
Cash overdraft	24,072	25,905
Accounts payable	203,919	163,307
Current maturities of long-term debt	16,937	17,212
Insurance claims	69,156	76,624
Other current liabilities	46,984	48,065
Total current liabilities	361,068	331,113
Long-term debt, excluding current maturities	108,617	115,130
Insurance claims	25,297	27,494
Deferred income taxes and other noncurrent liabilities	40,557	34,135
Shareholders' Equity
Common stock, $0.01 par value, authorized 160,000,000 shares, issued 66,851,672 and 66,602,486 shares	669	666
Additional paid-in capital	170,921	165,712
Retained earnings	1,004,701	947,156
Cost of 20,202,662 and 19,882,289 shares of common stock in treasury	(829,443)	(813,684)
Accumulated other comprehensive income	911	727
Total shareholders' equity	347,759	300,577
Total liabilities and shareholders' equity	$ 883,298	$ 808,449