Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating Income (Loss) [Abstract]
Revenues	$ 471,496	$ 676,865	$ 1,118,416
Cost of revenues	437,836	599,013	876,999
Selling, general and administrative expenses	88,473	101,032	112,648
Other operating income, net	(4,345)	(2,426)	(1,827)
Impairments and other charges	6,745	78,345	0
Operating income (loss)	(57,213)	(99,099)	130,596
Foreign currency exchange (gain) loss	(710)	4,016	108
Interest expense, net	9,866	9,111	10,431
Gain on extinguishment of debt	(1,615)	0	0
Income (loss) from continuing operations before income taxes	(64,754)	(112,226)	120,057
Provision (benefit) for income taxes	(24,042)	(21,398)	41,048
Income (loss) from continuing operations	(40,712)	(90,828)	79,009
Income from discontinued operations, net of tax	0	0	1,152
Gain from disposal of discontinued operations, net of tax	0	0	22,117
Net income (loss)	$ (40,712)	$ (90,828)	$ 102,278
Income (loss) per common share - basic:
Income (loss) from continuing operations (in dollars per share)	$ (0.49)	$ (1.10)	$ 0.95
Income from discontinued operations (in dollars per share)	0.00	0.00	0.28
Net income (loss) (in dollars per share)	(0.49)	(1.10)	1.23
Income (loss) per common share - diluted:
Income (loss) from continuing operations (in dollars per share)	(0.49)	(1.10)	0.84
Income from discontinued operations (in dollars per share)	0.00	0.00	0.23
Net income (loss) (in dollars per share)	$ (0.49)	$ (1.10)	$ 1.07