Condensed Consolidated Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Statement [Abstract]
Revenues	$ 202,763	$ 235,329	$ 630,648	$ 698,884
Cost of revenues	169,429	194,730	522,338	569,665
Selling, general and administrative expenses	27,017	29,820	85,796	85,482
Other operating (income) loss, net	29	725	(367)	702
Operating income	6,288	10,054	22,881	43,035
Foreign currency exchange (gain) loss	828	(89)	756	594
Interest expense, net	3,628	3,668	10,807	10,659
Income before income taxes	1,832	6,475	11,318	31,782
Provision for income taxes	3,273	2,831	7,171	10,070
Net income (loss)	$ (1,441)	$ 3,644	$ 4,147	$ 21,712
Net income (loss) per common share - basic (in dollars per share)	$ (0.02)	$ 0.04	$ 0.05	$ 0.24
Net income (loss) per common share - diluted (in dollars per share)	$ (0.02)	$ 0.04	$ 0.05	$ 0.23