Noncontrolling Interests (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017 USD ($) item	Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($) item	Jun. 30, 2016 USD ($)	Dec. 31, 2016 USD ($)
Noncontrolling Interests
Number of joint ventures | item	2		2
Revenue	$ 631,165	$ 456,811	$ 1,192,667	$ 887,257
Net income attributable to noncontrolling interests	851	231	1,672	454
Tax effect on income recognized	14,175	3,333	18,692	5,166
Cash	111,676		111,676		$ 135,823
Accounts receivable	355,231		355,231		388,000
Costs and estimated earnings in excess of billings	158,741		158,741		138,618
Billings in excess of costs and estimated earnings	158,698		158,698		112,606
Accounts payable	$ 134,091		$ 134,091		168,110
Carlsbad
Noncontrolling Interests
Ownership percentage	50.00%		50.00%
Carlsbad | Primary beneficiary
Noncontrolling Interests
Revenue	$ 26,203	3,150	$ 37,003	6,668
Net income attributable to noncontrolling interests	12	131	380	286
Tax effect on income recognized			0
Distributions to partners			0
Capital contributions			0
Cash	39,222		39,222		4,630
Accounts receivable	6,703		6,703
Costs and estimated earnings in excess of billings	124		124		124
Billings in excess of costs and estimated earnings	33,452		33,452		3,426
Accounts payable	6,288		6,288		286
Due to Primoris	$ 4,553		$ 4,553		46
Wilmington
Noncontrolling Interests
Ownership percentage	50.00%		50.00%
Wilmington | Primary beneficiary
Noncontrolling Interests
Revenue	$ 12,289	2,958	$ 24,599	4,917
Net income attributable to noncontrolling interests	839	$ 100	1,292	$ 168
Tax effect on income recognized			0
Distributions to partners			0
Capital contributions			0
Cash	8,872		8,872		2,415
Accounts receivable	6,406		6,406		4,242
Billings in excess of costs and estimated earnings	2,334		2,334		2,572
Accounts payable	7,467		7,467		602
Due to Primoris	1,446		1,446		2,035
Carlsbad and Wilmington | Primary beneficiary
Noncontrolling Interests
Cash	48,094		48,094		7,045
Accounts receivable	13,109		13,109		4,242
Costs and estimated earnings in excess of billings	124		124		124
Billings in excess of costs and estimated earnings	35,786		35,786		5,998
Accounts payable	$ 13,755		$ 13,755		$ 888