Consolidated Condensed Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 47,491	$ 22,604
Accounts receivable, trade, less allowance of $9,616 and $10,017, respectively	258,823	266,727
Other receivables	21,283	20,316
Inventories and supplies	16,756	17,824
Prepaid taxes, licenses and permits	7,374	14,914
Current deferred income taxes	34,568	34,066
Income taxes receivable	2,950	23,435
Other current assets	26,827	26,458
Total current assets	416,072	426,344
Property and equipment	1,850,826	1,786,229
Less – accumulated depreciation	766,340	772,447
Property and equipment, net	1,084,486	1,013,782
Other non-current assets	42,857	40,336
Total assets	1,543,415	1,480,462
Current liabilities:
Accounts payable	87,981	64,827
Insurance and claims accruals	62,067	73,814
Accrued payroll	32,286	28,121
Other current liabilities	21,445	19,768
Total current liabilities	203,779	186,530
Long-term debt, net of current portion	75,000	75,000
Other long-term liabilities	17,940	20,021
Insurance and claims accruals, net of current portion	130,545	123,445
Deferred income taxes	$ 237,911	$ 241,606
Commitments and contingencies
Stockholders’ equity:
Common stock, $0.01 par value, 200,000,000 shares authorized; 80,533,536 shares issued; 71,882,822 and 72,038,368 shares outstanding, respectively	$ 805	$ 805
Paid-in capital	104,909	101,803
Retained earnings	962,876	915,085
Accumulated other comprehensive loss	(10,672)	(9,375)
Treasury stock, at cost; 8,650,714 and 8,495,168 shares, respectively	(179,678)	(174,458)
Total stockholders’ equity	878,240	833,860
Total liabilities and stockholders’ equity	$ 1,543,415	$ 1,480,462