Dividends and Earnings Per Share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	0 Months Ended				3 Months Ended		6 Months Ended
	Jul. 15, 2013	May 03, 2013	Apr. 15, 2013	Mar. 05, 2013	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Dividends and Earnings Per Share
Cash dividend declared (in dollars per share)		$ 0.035		$ 0.03
Total dividend paid	$ 1,805		$ 1,547				$ 1,547	$ 3,069
Numerator:
Net income attributable to Primoris					$ 15,564	$ 11,733	$ 25,334	$ 22,219
Denominator:
Weighted average shares for computation of basic earnings per share					51,562	51,435	51,510	51,386
Dilutive effect of shares issued to independent directors							4
Dilutive effect of shares issued as part of Q3C acquisition							1
Dilutive effect of unvested restricted stock units					64		32
Weighted average shares for computation of diluted earnings per share					51,626	51,435	51,547	51,386
Earnings per share:
Basic earnings per share (in dollars per share)					$ 0.30	$ 0.23	$ 0.49	$ 0.43
Diluted earnings per share (in dollars per share)					$ 0.30	$ 0.23	$ 0.49	$ 0.43