Business Combinations (Details 5) (USD $) In Thousands, except Share data, unless otherwise specified	9 Months Ended		0 Months Ended		1 Months Ended	9 Months Ended			0 Months Ended			0 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Jan. 07, 2013 Q3C	Nov. 17, 2012 Q3C	Aug. 31, 2013 Q3C	Sep. 30, 2013 Q3C	Dec. 31, 2012 Q3C	Nov. 17, 2012 Q3C Earnout target period from November 18, 2012 through December 31, 2013	Nov. 17, 2012 Q3C Earnout target period from November 18, 2012 through December 31, 2013 Minimum	Nov. 17, 2012 Q3C Earnout target period from November 18, 2012 through December 31, 2013 Maximum	Nov. 17, 2012 Q3C 2014 earnout target	Nov. 17, 2012 Q3C 2014 earnout target Minimum	Nov. 17, 2012 Q3C 2014 earnout target Maximum	Sep. 30, 2013 Q3C 2014 earnout target Maximum
2012 Acquisition - Q3 Contracting
Total consideration				$ 56,592
Cash paid for acquisitions	2,273	38,110		48,116	598	598
Contingent consideration				7,448		8,536	7,490
Company common stock as a part of consideration				430
Pretax income threshold for measuring financial performance									17,700			19,000
Contingent consideration in cash								3,750			3,750
Additional potential contingent consideration									1,250	5,000		1,250	5,000	5,000
EBITDA threshold for measuring financial performance, case two									$ 19,000			$ 22,000
Unregistered shares of common stock issued with an acquisition			29,273			29,273