Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
OPERATING ACTIVITIES:
Consolidated net (loss) income	$ (28,747)	$ 41,027
Adjustments to reconcile consolidated net income to net cash (used in) provided by operating activities:
Depreciation and amortization	20,278	20,914
Amortization of debt financing costs	1,304	1,304
Impairment of intangible assets	18,815	225
Non-cash stock compensation expense	5,508	4,709
Deferred income taxes, net	(7,833)	(1,174)
Other	218	31
Changes in operating assets and liabilities:
Trade accounts receivable	(35,508)	49,563
Inventories, net	(9,292)	2,708
Prepaid expenses and other current assets	12,034	3,266
Trade accounts payable	11,318	(4,286)
Accrued expenses and other liabilities	(19,686)	8,296
NET CASH (USED IN) PROVIDED BY OPERATING ACTIVITIES	(31,591)	126,583
INVESTING ACTIVITIES:
Proceeds from disposal of assets	1	152
Purchases of property, plant and equipment	(22,341)	(22,483)
NET CASH USED IN INVESTING ACTIVITIES	(22,340)	(22,331)
FINANCING ACTIVITIES:
Proceeds from the exercise of stock options	546	1,115
Payment of contingent acquisition liabilities	(4,793)	0
Lease payments	(3)	0
NET CASH (USED IN) PROVIDED BY FINANCING ACTIVITIES	(4,250)	1,115
Effect of exchange rate changes on cash and cash equivalents	41	529
(DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS	(58,140)	105,896
Cash and cash equivalents, and restricted at beginning of period	369,889	204,034
CASH, CASH EQUIVALENTS, AND RESTRICTED CASH AT END OF PERIOD	311,749	309,930
SUPPLEMENTAL DISCLOSURES:
Amount paid for interest	12,262	11,041
Amount paid for income taxes, net	8,205	(42)
Additional capital expenditures included in accounts payable	$ 8,227	$ 7,571