Consolidated Statements of Income - USD ($)
shares in Thousands, $ in Thousands
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Income Statement [Abstract]      
Revenue $ 1,114,788 $ 1,190,519 $ 1,180,684
Cost of revenue 1,012,840 1,083,607 1,075,035
Selling, general and administrative expenses 60,728 64,086 65,687
Operating income 41,220 42,826 39,962
Interest (expense) income, net (4,640) (5,639) (6,531)
Income from operations before income taxes 36,580 37,187 33,431
Income tax (benefit) expense (22,917) 13,532 2,458
Net income $ 59,497 $ 23,655 $ 30,973
Earnings Per Share      
Basic (in dollars per share) $ 5.40 $ 2.21 $ 2.94
Diluted (in dollars per share) $ 5.31 $ 2.16 $ 2.86
Weighted average common shares outstanding - basic (in shares) 11,021 10,714 10,551
Weighted average common shares outstanding - diluted (in shares) 11,209 10,974 10,825