Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Current Assets
Cash and cash equivalents	$ 53,614	$ 80,900
Short-term investments	31,584	27,944
Trade accounts receivable, less allowance of $6,896 and $6,591	377,985	368,377
Other receivables, including advances to independent contractors, less allowance of $5,365 and $5,384	60,241	53,263
Deferred income taxes and other current assets	13,596	21,308
Total current assets	537,020	551,792
Operating property, less accumulated depreciation and amortization of $149,465 and $145,804	144,732	142,146
Goodwill	57,470	57,470
Other assets	72,504	57,041
Total assets	811,726	808,449
Current Liabilities
Cash overdraft	22,751	25,905
Accounts payable	165,851	163,307
Current maturities of long-term debt	15,709	17,212
Insurance claims	72,529	76,624
Other current liabilities	43,497	48,065
Total current liabilities	320,337	331,113
Long-term debt, excluding current maturities	99,524	115,130
Insurance claims	25,047	27,494
Deferred income taxes and other noncurrent liabilities	38,470	34,135
Shareholders' Equity
Common stock, $0.01 par value, authorized 160,000,000 shares, issued 66,833,233 and 66,602,486 shares	668	666
Additional paid-in capital	168,829	165,712
Retained earnings	971,429	947,156
Cost of 19,882,431 and 19,882,289 shares of common stock in treasury	(813,691)	(813,684)
Accumulated other comprehensive income	1,113	727
Total shareholders' equity	328,348	300,577
Total liabilities and shareholders' equity	$ 811,726	$ 808,449