CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
CURRENT ASSETS:
Cash and cash equivalents	$ 246,021	$ 124,506
Accounts receivable trade, net	533,198	518,975
Other receivables	4,283	1,265
Prepaid taxes	1,731	1,336
Prepaid expenses and other current assets	14,483	26,753
TOTAL CURRENT ASSETS	799,716	672,835
Restricted investments	23,305	23,353
Property and equipment, net	632,236	671,101
Right-of-use assets - operating leases	42,191	43,573
Right-of-use assets - financing leases	2,337	3,557
Other intangibles, net	146,724	163,953
Goodwill, net	522,360	508,555
Other assets	17,350	18,469
TOTAL ASSETS	2,186,219	2,105,396
CURRENT LIABILITIES:
Accounts payable trade	331,836	285,320
Accounts payable other	37,478	12,680
Accrued payroll	35,492	23,044
Accrued other	87,934	102,613
Lease liability - operating leases	10,400	10,093
Lease liability - financing leases	2,222	1,793
Current portion of long-term debt	86,868	93,562
TOTAL CURRENT LIABILITIES	592,230	529,105
Long-term debt	143,101	176,797
Non-current liabilities	42,805	42,910
Lease liability - operating leases	33,898	36,328
Lease liability - financing leases	187	8
Deferred taxes	166,922	162,325
STOCKHOLDERS' EQUITY:
Preferred stock, $.01 par value; 2,000,000 shares authorized; no shares issued or outstanding in 2021 and 2020
Additional paid-in capital	186,210	186,058
Purchase price in excess of predecessor basis, net of tax benefit of $10,306	(15,458)	(15,458)
Retained earnings	1,296,982	1,253,160
Accumulated other comprehensive loss	(176)	(191)
Treasury stock; at cost, 7,519,741 shares in 2021 and 7,675,084 shares in 2020	(260,901)	(266,065)
TOTAL STOCKHOLDERS' EQUITY	1,207,076	1,157,923
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	2,186,219	2,105,396
Class A Common Stock [Member]
STOCKHOLDERS' EQUITY:
Common stock	412	412
Class B Common Stock [Member]
STOCKHOLDERS' EQUITY:
Common stock	$ 7	$ 7