Consolidated Statements of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenues	$ 1,118,416	$ 1,042,356	$ 983,953
Cost of revenues	876,999	858,467	811,048
Selling, general and administrative expenses	112,648	93,657	81,500
Other operating income, net	(1,827)	(4,213)	(870)
Operating income	130,596	94,445	92,275
Foreign currency exchange loss	108	1,819	749
Interest expense, net	10,431	11,279	9,727
Income from continuing operations before income taxes	120,057	81,347	81,799
Provision for income taxes	41,048	28,725	31,346
Income from continuing operations	79,009	52,622	50,453
Income from discontinued operations, net of tax	1,152	12,701	9,579
Gain from disposal of discontinued operations, net of tax	22,117
Net income	$ 102,278	$ 65,323	$ 60,032
Income per common share -basic:
Income from continuing operations (in Dollars per share)	$ 0.95	$ 0.62	$ 0.58
Income from discontinued operations (in Dollars per share)	$ 0.28	$ 0.15	$ 0.11
Net income (in Dollars per share)	$ 1.23	$ 0.77	$ 0.69
Income per common share -diluted:
Income from continuing operations (in Dollars per share)	$ 0.84	$ 0.56	$ 0.53
Income from discontinued operations (in Dollars per share)	$ 0.23	$ 0.13	$ 0.09
Net income (in Dollars per share)	$ 1.07	$ 0.69	$ 0.62