Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
CURRENT ASSETS
Cash and cash equivalents	$ 139,770	$ 121,120
Short-term investments	0	8,300
Trade receivables, net	44,198	41,619
Prepaid tires	12,820	6,570
Other current assets	1,932	1,725
Income tax receivable	314	2,052
Deferred income taxes, net	14,401	12,400
Total current assets	213,435	193,786
PROPERTY AND EQUIPMENT
Land and land improvements	17,451	17,442
Buildings	26,761	26,761
Furniture and fixtures	2,269	2,269
Shop and service equipment	7,324	6,462
Revenue equipment	355,905	333,254
Property, Plant and Equipment, Gross	409,710	386,188
Less accumulated depreciation	161,269	165,736
Property and equipment, net	248,441	220,452
LONG-TERM INVESTMENTS	50,569	80,394
GOODWILL	4,815	4,815
OTHER ASSETS	8,406	6,588
Assets	525,666	506,035
CURRENT LIABILITIES
Accounts payable and accrued liabilities	9,088	10,972
Compensation and benefits	15,493	14,823
Insurance accruals	13,997	16,341
Other accruals	7,085	6,764
Total current liabilities	45,663	48,900
LONG-TERM LIABILITIES
Income taxes payable	24,077	27,313
Deferred income taxes, net	57,661	40,917
Insurance accruals less current portion	57,494	54,718
Total long-term liabilities	139,232	122,948
COMMITMENTS AND CONTINGENCIES (Note 9)
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 2011 and 2010, outstanding, 86,475 and 90,689 in 2011 and 2010, respectively	907	907
Additional paid-in capital	589	439
Retained earnings	398,706	335,922
Treasury stock, at cost; 4,214 shares in 2011	(56,350)	0
Accumulated other comprehensive loss	(3,081)	(3,081)
Stockholders' Equity Attributable to Parent	340,771	334,187
Liabilities and Stockholders' Equity	$ 525,666	$ 506,035