Dividends and Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands									3 Months Ended												12 Months Ended
	Nov. 02, 2016	Aug. 03, 2016	May 02, 2016	Feb. 22, 2016	Nov. 03, 2015	Aug. 04, 2015	May 01, 2015	Feb. 24, 2015	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Earnings Per Share
Cash dividend declared (in dollars per share)	$ 0.055	$ 0.055	$ 0.055	$ 0.055	$ 0.055	$ 0.055	$ 0.055	$ 0.040													$ 0.22	$ 0.205	$ 0.15
Total dividend paid																					$ 11,384	$ 9,809	$ 7,483
Numerator:
Net income									$ 14,766	$ 4,756	$ 5,287	$ 2,916	$ 12,708	$ 19,079	$ 3,692	$ 1,672	$ 9,024	$ 27,390	$ 16,003	$ 11,265	27,725	37,151	63,682
Net income attributable to noncontrolling interests																					(1,002)	(279)	(526)
Net income attributable to Primoris									$ 14,470	$ 4,504	$ 5,056	$ 2,693	$ 12,555	$ 19,007	$ 3,638	$ 1,672	$ 8,930	$ 27,390	$ 16,003	$ 10,833	$ 26,723	$ 36,872	$ 63,156
Denominator (shares in thousands):
Weighted average shares for computation of basic earnings per share									51,771	51,780	51,772	51,725	51,676	51,672	51,666	51,572	51,561	51,606	51,655	51,610	51,762	51,647	51,607
Dilutive effect of shares issued to independent directors																					3	2	2
Dilutive effect of restricted stock units																					224	149	138
Weighted average shares for computation of diluted earnings per share									52,021	52,034	52,022	51,881	51,825	51,824	51,815	51,726	51,710	51,759	51,804	51,714	51,989	51,798	51,747
Earnings per share attributable to Primoris:
Basic earnings per share (in dollars per share)									$ 0.28	$ 0.09	$ 0.10	$ 0.05	$ 0.24	$ 0.37	$ 0.07	$ 0.03	$ 0.17	$ 0.53	$ 0.31	$ 0.21	$ 0.52	$ 0.71	$ 1.22
Diluted earnings per share (in dollars per share)									$ 0.28	$ 0.09	$ 0.10	$ 0.05	$ 0.24	$ 0.37	$ 0.07	$ 0.03	$ 0.17	$ 0.53	$ 0.31	$ 0.21	$ 0.51	$ 0.71	$ 1.22