Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues [Abstract]
Product sales	$ 628,401	$ 390,306	$ 569,290
Rental and services	119,362	81,190	107,575
Total Revenues	747,763	471,496	676,865
Cost of revenues
Cost of product sales	539,243	386,085	533,040
Cost of rental and services	68,656	51,751	65,973
Total Cost of revenues	607,899	437,836	599,013
Selling, general and administrative expenses	108,838	88,473	101,032
Other operating income, net	(410)	(4,345)	(2,426)
Impairments and other charges	0	6,745	78,345
Operating income (loss)	31,436	(57,213)	(99,099)
Foreign currency exchange (gain) loss	2,051	(710)	4,016
Interest expense, net	13,273	9,866	9,111
Gain on extinguishment of debt	0	(1,615)	0
Income (loss) from continuing operations before income taxes	16,112	(64,754)	(112,226)
Provision (benefit) for income taxes	4,893	(24,042)	(21,398)
Income (loss) from continuing operations	11,219	(40,712)	(90,828)
Loss from disposal of discontinued operations, net of tax	17,367	0	0
Net loss	$ (6,148)	$ (40,712)	$ (90,828)
Income (loss) per common share - basic:
Income (loss) from continuing operations, basic (in dollars per share)	$ 0.13	$ (0.49)	$ (1.10)
Income from discontinued operations, basic (in dollars per share)	(0.20)	0.00	0.00
Net income (loss), basic (in dollars per share)	(0.07)	(0.49)	(1.10)
Income (loss) per common share - diluted:
Income (loss) from continuing operations, diluted (in dollars per share)	0.13	(0.49)	(1.10)
Income from discontinued operations, diluted (in dollars per share)	(0.20)	0.00	0.00
Net income (loss), diluted (in dollars per share)	$ (0.07)	$ (0.49)	$ (1.10)