Consolidated Condensed Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 38,789	$ 13,626
Accounts receivable, trade, less allowance of $8,436 and $8,250, respectively	301,967	304,174
Other receivables	17,076	26,491
Inventories and supplies	10,620	11,694
Prepaid taxes, licenses and permits	11,991	15,972
Other current assets	30,824	28,272
Total current assets	411,267	400,229
Property and equipment	2,126,307	2,114,337
Less – accumulated depreciation	776,125	767,474
Property and equipment, net	1,350,182	1,346,863
Other non-current assets	60,596	60,899
Total assets	1,822,045	1,807,991
Current liabilities:
Checks issued in excess of cash balances	0	21,539
Accounts payable	83,295	73,802
Insurance and claims accruals	73,674	79,674
Accrued payroll	30,733	32,520
Other current liabilities	24,095	24,642
Total current liabilities	211,797	232,177
Long-term debt, net of current portion	75,000	75,000
Other long-term liabilities	12,045	12,575
Insurance and claims accruals, net of current portion	108,560	108,270
Deferred income taxes	201,539	195,187
Commitments and contingencies
Stockholders’ equity:
Common stock, $0.01 par value, 200,000,000 shares authorized; 80,533,536 shares issued; 72,454,202 and 72,409,222 shares outstanding, respectively	805	805
Paid-in capital	102,904	102,563
Retained earnings	1,292,618	1,267,871
Accumulated other comprehensive loss	(13,232)	(15,835)
Treasury stock, at cost; 8,079,334 and 8,124,314 shares, respectively	(169,991)	(170,622)
Total stockholders’ equity	1,213,104	1,184,782
Total liabilities and stockholders’ equity	$ 1,822,045	$ 1,807,991