Condensed Consolidated Statements of Income (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 29, 2019	Mar. 30, 2018
Income Statement [Abstract]
Revenue	$ 325,928	$ 320,516
Cost of revenue	295,596	294,050
Selling, general and administrative expenses	19,919	17,795
Operating income	10,413	8,671
Interest expense, net	(1,575)	(1,164)
Income from operations before income taxes	8,838	7,507
Income tax expense	1,747	1,396
Net income	$ 7,091	$ 6,111
Earnings per share
Basic (in dollars per share)	$ 0.63	$ 0.55
Diluted (in dollars per share)	$ 0.62	$ 0.54
Weighted average common shares outstanding - basic (in shares)	11,292	11,146
Diluted weighted average common shares outstanding - diluted (in shares)	11,399	11,338