Noncontrolling Interests (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017 USD ($) item	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) item	Sep. 30, 2016 USD ($)	Dec. 31, 2016 USD ($)
Noncontrolling Interests
Number of joint ventures | item	2		2
Revenue	$ 608,311	$ 507,828	$ 1,800,978	$ 1,395,085
Net income attributable to noncontrolling interests	1,537	252	3,209	706
Tax effect on income recognized	9,952	4,078	28,644	9,244
Cash	143,235		143,235		$ 135,823
Accounts receivable	356,851		356,851		388,000
Costs and estimated earnings in excess of billings	177,662		177,662		138,618
Billings in excess of costs and estimated earnings	159,120		159,120		112,606
Other current liabilities	505,415		505,415		449,938
Accounts payable	153,677		153,677		168,110
Carlsbad
Noncontrolling Interests
Revenue	28,722	608	65,725	7,276
Net income attributable to noncontrolling interests	550	41	930	327
Tax effect on income recognized			0
Distributions to partners			0
Capital contributions			0
Cash	51,869		51,869		4,630
Accounts receivable	10,832		10,832
Costs and estimated earnings in excess of billings					124
Billings in excess of costs and estimated earnings	42,964		42,964		3,426
Accounts payable	16,882		16,882		286
Due to Primoris					46
Wilmington
Noncontrolling Interests
Revenue	5,143	6,140	29,742	11,057
Net income attributable to noncontrolling interests	987	$ 211	2,279	$ 379
Tax effect on income recognized			0
Distributions to partners			0
Capital contributions			0
Cash	15,165		15,165		2,415
Accounts receivable	239		239		4,242
Billings in excess of costs and estimated earnings	1,822		1,822		2,572
Accounts payable	2,766		2,766		602
Due to Primoris	4,809		4,809		2,035
Carlsbad and Wilmington
Noncontrolling Interests
Cash	67,034		67,034		7,045
Accounts receivable	11,071		11,071		4,242
Costs and estimated earnings in excess of billings					124
Billings in excess of costs and estimated earnings	44,786		44,786		5,998
Accounts payable	$ 19,648		$ 19,648		$ 888