Consolidated Condensed Balance Sheets (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Current assets:
Cash and cash equivalents	$ 18,037	$ 12,412
Accounts receivable, trade, less allowance of $10,530 and $10,154, respectively	217,758	218,712
Other receivables	9,957	9,213
Inventories and supplies	25,172	30,212
Prepaid taxes, licenses and permits	6,568	15,094
Current deferred income taxes	27,420	25,805
Other current assets	23,768	29,883
Total current assets	328,680	341,331
Property and equipment	1,689,927	1,625,008
Less – accumulated depreciation	691,418	682,872
Property and equipment, net	998,509	942,136
Other non-current assets	19,143	18,949
Total assets	1,346,332	1,302,416
Current liabilities:
Checks issued in excess of cash balances	0	6,671
Accounts payable	74,216	93,486
Insurance and claims accruals	56,798	62,681
Accrued payroll	26,512	19,483
Other current liabilities	19,902	16,504
Total current liabilities	177,428	198,825
Other long-term liabilities	15,306	14,194
Insurance and claims accruals, net of current portion	121,200	121,250
Deferred income taxes	236,232	243,000
Commitments and contingencies
Stockholders' equity:
Common stock, $0.01 par value, 200,000,000 shares authorized; 80,533,536 shares issued; 72,883,336 and 72,847,576 shares outstanding, respectively	805	805
Paid-in capital	97,404	94,396
Retained earnings	846,116	779,994
Accumulated other comprehensive loss	(3,902)	(5,170)
Treasury stock, at cost; 7,650,200 and 7,685,960 shares, respectively	(144,257)	(144,878)
Total stockholders' equity	796,166	725,147
Total liabilities and stockholders' equity	$ 1,346,332	$ 1,302,416