Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($)	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
OPERATING ACTIVITIES:
Net income	$ 18,203,000	$ 11,359,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	23,753,000	27,329,000
Bad debt expense	432,000	506,000
Sale leaseback deferred gain amortization	(168,000)	(149,000)
Stock compensation-net of excess tax benefits	218,000	146,000
Deferred	10,268,000	6,228,000
Reclassification of unrealized loss on marketable equity securities	579,000	1,000
Recognized loss (gain) on marketable equity securities	73,000	(364,000)
Gain on sale or disposal of equipment	(4,611,000)	(3,414,000)
Changes in operating assets and liabilities:
Accounts receivable	(5,853,000)	(3,515,000)
Prepaid expenses, deposits, inventories, and other assets	2,987,000	(315,000)
Income taxes refundable	$ (1,319,000)	230,000
Income taxes payable		27,000
Trade accounts payable	$ 20,628,000	1,256,000
Accrued expenses and other liabilities	1,751,000	4,149,000
Net cash provided by operating activities	66,941,000	43,474,000
INVESTING ACTIVITIES:
Purchases of property and equipment	(106,230,000)	(22,901,000)
Proceeds from disposition of equipment	29,888,000	28,403,000
Change in restricted cash	8,019,000	(2,275,000)
Sales of marketable equity securities	18,000	439,000
Purchases of marketable equity securities, net of return of capital	(2,372,000)	(931,000)
Net cash (used in) provided by investing activities	(70,677,000)	2,735,000
FINANCING ACTIVITIES:
Borrowings under line of credit	407,317,000	365,015,000
Repayments under line of credit	(406,860,000)	(362,140,000)
Borrowings of long-term debt	64,752,000	19,299,000
Repayments of long-term debt	(41,723,000)	(51,821,000)
Borrowings under margin account	2,546,000	1,030,000
Repayments under margin account	(989,000)	(1,117,000)
Repurchases of common stock	(48,021,000)	(16,006,000)
Exercise of stock options	236,000	841,000
Net cash used in financing activities	(22,742,000)	(44,899,000)
NET (DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS	(26,478,000)	1,310,000
CASH AND CASH EQUIVALENTS-Beginning of period	27,649,000	1,172,000
CASH AND CASH EQUIVALENTS-End of period	1,171,000	2,482,000
Cash paid during the period for:
Interest	2,009,000	2,256,000
Income taxes	2,495,000	927,000
NONCASH INVESTING AND FINANCING ACTIVITIES-
Purchases of property and equipment included in accounts payable	$ 336,000	$ 387,000