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
Income Statement [Abstract]
Revenue	$ 501,867	$ 436,689	$ 401,572
Cost of revenue	412,292	360,424	329,601
Gross profit	89,575	76,265	71,971
Selling, general and administrative expenses	47,108	39,589	35,500
Gain (loss) on change in fair value of contingent consideration, net	1,392	1,676	(789)
Operating income	43,859	38,352	35,682
Interest expense	833	366	269
Other income (expense) (including interest income of $112 in 2014, $56 in 2013 and $29 in 2012)	(203)	502	389
Income before income taxes	42,823	38,488	35,802
Income tax expense	15,725	14,732	13,114
Net income	$ 27,098	$ 23,756	$ 22,688
Basic weighted average shares outstanding (in shares)	18,641	19,103	18,956
Diluted weighted average shares outstanding (in shares)	18,887	19,362	19,275
Per common share data:
Basic earnings per share (in dollars per share)	$ 1.45	$ 1.24	$ 1.20
Diluted earnings per share (in dollars per share)	$ 1.43	$ 1.23	$ 1.18