Consolidated Condensed Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 30,804	$ 16,962
Accounts receivable, trade, less allowance of $9,301 and $9,183, respectively	247,035	261,372
Other receivables	15,604	15,168
Inventories and supplies	12,314	12,768
Prepaid taxes, licenses and permits	11,499	15,374
Income taxes receivable	15,300	21,497
Other current assets	37,261	29,987
Total current assets	369,817	373,128
Property and equipment	2,067,555	2,109,991
Less – accumulated depreciation	744,181	747,353
Property and equipment, net	1,323,374	1,362,638
Other non-current assets	52,477	57,237
Total assets	1,745,668	1,793,003
Current liabilities:
Accounts payable	63,546	66,618
Current portion of long-term debt	25,000	20,000
Insurance and claims accruals	74,483	83,404
Accrued payroll	27,034	26,189
Other current liabilities	17,000	18,650
Total current liabilities	207,063	214,861
Long-term debt, net of current portion	105,000	160,000
Other long-term liabilities	16,064	16,711
Insurance and claims accruals, net of current portion	110,960	113,875
Deferred income taxes	296,197	292,769
Commitments and contingencies
Stockholders’ equity:
Common stock, $0.01 par value, 200,000,000 shares authorized; 80,533,536 shares issued; 72,219,768 and 72,166,969 shares outstanding, respectively	805	805
Paid-in capital	101,587	101,035
Retained earnings	1,096,190	1,084,796
Accumulated other comprehensive loss	(14,256)	(16,917)
Treasury stock, at cost; 8,313,768 and 8,366,567 shares, respectively	(173,942)	(174,932)
Total stockholders’ equity	1,010,384	994,787
Total liabilities and stockholders’ equity	$ 1,745,668	$ 1,793,003