Consolidated Condensed Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 9,650	$ 13,626
Accounts receivable, trade, less allowance of $8,750 and $8,250, respectively	324,911	304,174
Other receivables	27,559	26,491
Inventories and supplies	11,805	11,694
Prepaid taxes, licenses and permits	7,327	15,972
Other current assets	38,595	28,272
Total current assets	419,847	400,229
Property and equipment	2,249,911	2,114,337
Less – accumulated depreciation	781,262	767,474
Property and equipment, net	1,468,649	1,346,863
Other non-current assets	144,640	60,899
Total assets	2,033,136	1,807,991
Current liabilities:
Checks issued in excess of cash balances	3,299	21,539
Accounts payable	90,013	73,802
Current portion of long-term debt	75,000	0
Insurance and claims accruals	65,021	79,674
Accrued payroll	37,787	32,520
Other current liabilities	26,757	24,642
Total current liabilities	297,877	232,177
Long-term debt, net of current portion	50,000	75,000
Other long-term liabilities	11,646	12,575
Insurance and claims accruals, net of current portion	208,560	108,270
Deferred income taxes	221,552	195,187
Commitments and contingencies
Stockholders’ equity:
Common stock, $0.01 par value, 200,000,000 shares authorized; 80,533,536 shares issued; 71,194,303 and 72,409,222 shares outstanding, respectively	805	805
Paid-in capital	106,904	102,563
Retained earnings	1,365,523	1,267,871
Accumulated other comprehensive loss	(13,659)	(15,835)
Treasury stock, at cost; 9,339,233 and 8,124,314 shares, respectively	(216,072)	(170,622)
Total stockholders’ equity	1,243,501	1,184,782
Total liabilities and stockholders’ equity	$ 2,033,136	$ 1,807,991