Selected Quarterly Financial Information (Unaudited) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended												12 Months Ended
	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
Selected Quarterly Financial Information
Revenues	$ 601,863	$ 507,828	$ 456,811	$ 430,446	$ 497,145	$ 555,945	$ 483,545	$ 392,780	$ 487,592	$ 613,237	$ 515,291	$ 470,074	$ 1,996,948	$ 1,929,415	$ 2,086,194
Gross Profit	68,616	50,129	43,285	39,277	63,725	71,647	46,496	38,005	49,616	75,473	61,194	49,757	201,307	219,873	236,040
Impairment of goodwill					401								2,716	401
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 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
Earnings per share:
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
Weighted average common shares outstanding:
Basic (in shares)	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
Diluted (in shares)	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