Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
OPERATING ACTIVITIES:
Net income	$ 10,378	$ 18,203
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	29,011	23,753
Bad debt expense	354	432
Sale leaseback deferred gain amortization	(131)	(168)
Stock compensation-net of excess tax benefits	251	218
Deferred	6,233	10,268
Reclassification of unrealized loss on marketable equity securities	709	579
Recognized (gain) loss on marketable equity securities	(1,003)	73
Gain on sale or disposal of equipment	(3,951)	(4,611)
Changes in operating assets and liabilities:
Accounts receivable	(10,354)	(5,853)
Prepaid expenses, deposits, inventories, and other assets	100	2,987
Income taxes refundable	2,308	(1,319)
Trade accounts payable	10,195	20,628
Accrued expenses and other liabilities	(1,917)	1,751
Net cash provided by operating activities	42,183	66,941
INVESTING ACTIVITIES:
Purchases of property and equipment	(55,948)	(106,230)
Proceeds from disposition of equipment	24,479	29,888
Change in restricted cash	(5,461)	8,019
Sales of marketable equity securities	1,550	18
Purchases of marketable equity securities, net of return of capital	(836)	(2,372)
Net cash used in investing activities	(36,216)	(70,677)
FINANCING ACTIVITIES:
Borrowings under line of credit	375,930	407,317
Repayments under line of credit	(379,043)	(406,860)
Borrowings of long-term debt	52,224	64,752
Repayments of long-term debt	(33,092)	(41,723)
Borrowings under margin account	1,040	2,546
Repayments under margin account	(2,392)	(989)
Repurchases of common stock	(20,726)	(48,021)
Exercise of stock options	74	236
Net cash used in financing activities	(5,985)	(22,742)
NET DECREASE IN CASH AND CASH EQUIVALENTS	(18)	(26,478)
CASH AND CASH EQUIVALENTS-Beginning of period	157	27,649
CASH AND CASH EQUIVALENTS-End of period	139	1,171
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION-
Interest	2,643	2,009
Income taxes	260	2,495
NONCASH INVESTING AND FINANCING ACTIVITIES-
Purchases of property and equipment included in accounts payable	$ 2,788	$ 336