Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
CURRENT ASSETS
Cash and cash equivalents	$ 141,554	$ 119,838
Trade receivables, net	49,602	46,555
Prepaid tires	4,811	6,603
Other current assets	6,695	2,281
Income tax receivable	1,424	2,351
Deferred income taxes, net	12,584	13,797
Total current assets	216,670	191,425
PROPERTY AND EQUIPMENT
Land and land improvements	17,451	17,451
Buildings	27,559	26,761
Furniture and fixtures	2,269	2,269
Shop and service equipment	7,257	7,266
Revenue equipment	385,853	378,583
Property, Plant and Equipment, Gross	440,389	432,330
Less accumulated depreciation	174,253	189,959
Property and equipment, net	266,136	242,371
LONG-TERM INVESTMENTS	10,791	20,016
GOODWILL	4,815	4,815
OTHER ASSETS	9,099	9,110
Assets	507,511	467,737
CURRENT LIABILITIES
Accounts payable and accrued liabilities	8,818	7,583
Compensation and benefits	17,463	16,409
Insurance accruals	12,596	13,924
Other accruals	8,159	7,439
Total current liabilities	47,036	45,355
LONG-TERM LIABILITIES
Income taxes payable	21,146	23,122
Deferred income taxes, net	54,803	51,306
Insurance accruals less current portion	57,468	57,590
Total long-term liabilities	133,417	132,018
COMMITMENTS AND CONTINGENCIES (Note 11)
STOCKHOLDERS' EQUITY
Preferred stock, par value $.01; authorized 5,000 shares; none issued	0	0
Capital stock, common, $.01 par value; authorized 395,000 shares; issued 90,689 in 2013 and 2012; outstanding, 84,837 in 2013 and 84,770 in 2012	907	907
Additional paid-in capital	3,590	2,968
Retained earnings	403,785	368,313
Treasury stock, at cost; 5,852 shares in 2013 and 5,919 shares in 2012	(80,540)	(80,540)
Accumulated other comprehensive loss	(684)	(1,284)
Stockholders' Equity Attributable to Parent	327,058	290,364
Liabilities and Stockholders' Equity	$ 507,511	$ 467,737