Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
OPERATING ACTIVITIES:
Net income (loss)	$ 48,625	$ 3,874
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	41,426	41,936
Bad debt expense	837	329
Stock compensation-net of excess tax benefits	347	430
Provision for deferred income taxes	14,984	763
Recognized (gain) / loss on marketable equity securities	(5,382)	7,484
Gain on disposition of equipment	(962)	(71)
Changes in operating assets and liabilities:
Accounts receivable	(27,584)	(8,409)
Prepaid expenses, deposits, inventories, and other assets	1,781	1,064
Income taxes payable	455	(52)
Trade accounts payable	1,929	22,112
Accrued expenses and other liabilities	(2,500)	(16,354)
Net cash provided by operating activities	73,956	53,106
INVESTING ACTIVITIES:
Purchases of property and equipment	(15,297)	(39,763)
Proceeds from disposition of equipment	28,047	13,502
Sales of marketable equity securities	1,496	860
Purchases of marketable equity securities, net of return of capital	(4,302)	(3,982)
Net cash provided by (used in) investing activities	9,944	(29,383)
FINANCING ACTIVITIES:
Borrowings under line of credit	450,222	365,263
Repayments under line of credit	(468,469)	(371,182)
Borrowings of long-term debt	6,594	17,640
Repayments of long-term debt	(42,032)	(38,872)
Borrowings under margin account	4,387	7,037
Repayments under margin account	(2,536)	(1,806)
Repurchases of common stock	(10,828)	(1,793)
Net cash used in financing activities	(62,662)	(23,713)
NET INCREASE IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH	21,238	10
CASH, CASH EQUIVALENTS AND RESTRICTED CASH -Beginning of period	337	318
CASH, CASH EQUIVALENTS AND RESTRICTED CASH -End of period	21,575	328
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION:
Interest	6,425	6,544
Income taxes	2,581	159
NONCASH INVESTING AND FINANCING ACTIVITIES:
Purchases of property and equipment included in accounts payable	$ 2,282	$ 3,944