Consolidated Condensed Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 22,610	$ 16,962
Accounts receivable, trade, less allowance of $8,434 and $9,183, respectively	250,402	261,372
Other receivables	15,654	15,168
Inventories and supplies	11,589	12,768
Prepaid taxes, licenses and permits	7,365	15,374
Income taxes receivable	8,468	21,497
Other current assets	30,979	29,987
Total current assets	347,067	373,128
Property and equipment	2,077,051	2,109,991
Less – accumulated depreciation	746,822	747,353
Property and equipment, net	1,330,229	1,362,638
Other non-current assets	54,159	57,237
Total assets	1,731,455	1,793,003
Current liabilities:
Accounts payable	70,717	66,618
Current portion of long-term debt	0	20,000
Insurance and claims accruals	75,001	83,404
Accrued payroll	30,885	26,189
Other current liabilities	22,309	18,650
Total current liabilities	198,912	214,861
Long-term debt, net of current portion	75,000	160,000
Other long-term liabilities	15,321	16,711
Insurance and claims accruals, net of current portion	110,610	113,875
Deferred income taxes	300,082	292,769
Commitments and contingencies
Stockholders’ equity:
Common stock, $0.01 par value, 200,000,000 shares authorized; 80,533,536 shares issued; 72,249,924 and 72,166,969 shares outstanding, respectively	805	805
Paid-in capital	102,553	101,035
Retained earnings	1,114,351	1,084,796
Accumulated other comprehensive loss	(12,851)	(16,917)
Treasury stock, at cost; 8,283,612 and 8,366,567 shares, respectively	(173,328)	(174,932)
Total stockholders’ equity	1,031,530	994,787
Total liabilities and stockholders’ equity	$ 1,731,455	$ 1,793,003