Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Operating activities:
Net loss	$ (21,798)	$ (9,622)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization	50,593	53,054
Deferred income taxes	(9,416)	(6,775)
Loss (gain) on asset dispositions	3	(3,854)
Equity in loss of unconsolidated affiliate, net	1,556	274
Inventory valuation reserves	(3)	3,766
Changes in operating assets and liabilities	(22,803)	(43,991)
Net cash (used in) provided by operating activities	(1,868)	(7,148)
Investing activities:
Purchase of property and equipment	(49,227)	(74,950)
Proceeds from asset dispositions	21	13,233
Purchase of short-term investments	(268,525)	(263,204)
Proceeds from sale of short-term investments	354,250	259,322
Payment of deposits on aircraft	0	(197)
Loan to unconsolidated affiliate	0	(1,200)
Net cash provided by (used in) investing activities	36,519	(66,996)
Financing activities:
Proceeds from line of credit	99,150	213,900
Payments on line of credit	(133,150)	(139,000)
Repurchase of common stock	(256)	(524)
Net cash (used in) provided by financing activities	(34,256)	74,376
Decrease in cash	395	232
Cash, beginning of period	2,596	2,407
Cash, end of period	2,991	2,639
Cash paid during the period for:
Interest	29,536	28,258
Income taxes	1,213	2,856
Noncash investing activities:
Other current liabilities and accrued payables related to purchase of property and equipment	$ 21	$ 3,717