Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Operating activities:
Net (loss) earnings	$ (9,622)	$ 24,486
Adjustments to reconcile net earnings to net cash provided by operating activities:
Depreciation and amortization	53,054	54,312
Deferred income taxes	(6,775)	15,983
Loss (gain) on disposal of assets	(3,854)	(238)
Equity in loss of unconsolidated affiliate	274	249
Inventory valuation reserves	3,766	1,576
Changes in operating assets and liabilities	(43,991)	11,787
Net cash (used in) provided by operating activities	(7,148)	108,155
Investing activities:
Purchase of property and equipment	(74,950)	(48,244)
Proceeds from asset dispositions	13,233	3,469
Purchase of short-term investments	(263,204)	(560,148)
Proceeds from sale of short-term investments	259,322	458,468
Refund of deposits on aircraft		6,010
Payment of deposits on aircraft	(197)	(1,207)
Loan to unconsolidated affiliate	(1,200)
Net cash used in investing activities	(66,996)	(141,652)
Financing activities:
Proceeds from line of credit	213,900	206,660
Payments on line of credit	(139,000)	(171,440)
Repurchase of common stock	(524)	(2,441)
Net cash provided by (used in) financing activities	74,376	32,779
Increase (decrease) in cash	232	(718)
Cash, beginning of period	2,407	6,270
Cash, end of period	2,639	5,552
Cash paid during the period for:
Interest	28,258	27,161
Income taxes	2,856	3,061
Noncash investing activities:
Other current liabilities and accrued payables related to purchase of property and equipment	$ 3,717	$ 45