Consolidated Condensed Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 15,237	$ 31,833
Accounts receivable, trade, less allowance of $8,970 and $10,298, respectively	239,108	251,023
Other receivables	20,947	17,241
Inventories and supplies	14,823	16,415
Prepaid taxes, licenses and permits	7,620	15,657
Income taxes receivable	23,321	20,052
Other current assets	27,532	27,281
Total current assets	348,588	379,502
Property and equipment	2,057,986	1,908,600
Less – accumulated depreciation	743,768	754,130
Property and equipment, net	1,314,218	1,154,470
Other non-current assets	64,061	51,675
Total assets	1,726,867	1,585,647
Current liabilities:
Checks issued in excess of cash balances	6,941	0
Accounts payable	85,547	70,643
Insurance and claims accruals	72,992	64,106
Accrued payroll	28,447	25,233
Other current liabilities	18,006	23,720
Total current liabilities	211,933	183,702
Long-term debt, net of current portion	145,000	75,000
Other long-term liabilities	21,061	19,832
Insurance and claims accruals, net of current portion	116,725	125,195
Deferred income taxes	269,012	246,264
Commitments and contingencies
Stockholders’ equity:
Common stock, $0.01 par value, 200,000,000 shares authorized; 80,533,536 shares issued; 72,050,173 and 71,998,750 shares outstanding, respectively	805	805
Paid-in capital	102,489	102,734
Retained earnings	1,052,718	1,022,966
Accumulated other comprehensive loss	(15,954)	(13,063)
Treasury stock, at cost; 8,483,363 and 8,534,786 shares, respectively	(176,922)	(177,788)
Total stockholders’ equity	963,136	935,654
Total liabilities and stockholders’ equity	$ 1,726,867	$ 1,585,647