Consolidated Condensed Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 192,128	$ 29,334
Accounts receivable, trade, less allowance of $8,988 and $8,686, respectively	391,082	341,104
Other receivables	25,120	23,491
Inventories and supplies	11,899	12,062
Prepaid taxes, licenses and permits	7,970	17,231
Other current assets	38,312	33,694
Total current assets	666,511	456,916
Property and equipment	2,428,268	2,405,335
Less – accumulated depreciation	893,453	862,077
Property and equipment, net	1,534,815	1,543,258
Other non-current assets	181,541	156,502
Total assets	2,382,867	2,156,676
Current liabilities:
Accounts payable	94,367	83,263
Current portion of long-term debt	5,000	25,000
Insurance and claims accruals	65,321	76,917
Accrued payroll	48,420	35,594
Accrued expenses	25,972	25,032
Other current liabilities	20,107	28,208
Total current liabilities	259,187	274,014
Long-term debt, net of current portion	295,000	175,000
Other long-term liabilities	42,568	43,114
Insurance and claims accruals, net of current portion	236,270	231,638
Deferred income taxes	253,259	237,870
Commitments and contingencies
Stockholders’ equity:
Common stock, $0.01 par value, 200,000,000 shares authorized; 80,533,536 shares issued; 67,931,873 and 67,931,726 shares outstanding, respectively	805	805
Paid-in capital	117,069	116,039
Retained earnings	1,542,497	1,438,916
Accumulated other comprehensive loss	(20,873)	(22,833)
Treasury stock, at cost; 12,601,663 and 12,601,810 shares, respectively	(342,915)	(337,887)
Total stockholders’ equity	1,296,583	1,195,040
Total liabilities and stockholders’ equity	$ 2,382,867	$ 2,156,676