Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
OPERATING ACTIVITIES:
Consolidated net income (loss)	$ 40,667	$ 151,788
Adjustments to reconcile consolidated net income to net cash provided by operating activities:
Depreciation and amortization	63,792	65,985
Amortization of debt financing costs	3,912	9,456
Impairment of intangible assets	15,678	9,368
Non-cash stock compensation expense	15,626	11,282
Non-cash interest expense	0	770
Income from available-for-sale securities	(3,032)	0
Deferred income taxes, net	(3,407)	(13,346)
Loss on sale of available-for-sale securities	199	45
Other	253	(765)
Changes in operating assets and liabilities:
Trade accounts receivable	94,520	(112,252)
Inventories, net	(7,286)	5,744
Prepaid expenses and other current assets	(21,116)	(6,349)
Trade accounts payable	(1,782)	5,698
Accrued expenses and other liabilities	11,780	(31,803)
NET CASH PROVIDED BY OPERATING ACTIVITIES	209,804	95,621
INVESTING ACTIVITIES:
Proceeds from disposal of assets	4,811	5,966
Payments for intangible assets	(200)	(3,875)
Purchases of property, plant and equipment	(77,538)	(48,884)
NET CASH USED IN INVESTING ACTIVITIES	(72,927)	(46,793)
FINANCING ACTIVITIES:
Proceeds from the exercise of stock options	7,235	8,891
Debt financing costs	0	(5,128)
Debt payments	0	(200,000)
Common stock repurchases	0	(25,000)
NET CASH PROVIDED BY(USED IN) FINANCING ACTIVITIES	7,235	(221,237)
Effect of exchange rate changes on cash and cash equivalents	496	193
INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	144,608	(172,216)
Cash and cash equivalents at beginning of period	200,772	346,266
CASH AND CASH EQUIVALENTS AT END OF PERIOD	345,380	174,050
SUPPLEMENTAL DISCLOSURES:
Amount paid for interest	33,691	33,022
Amount paid for income taxes, net	44,155	103,103
Additional capital expenditures included in accounts payable	9,734	7,514
Non-cash conversion to common shares of convertible notes	$ 0	$ 43,214