Primoris Services (PRIM) 10-Q 7 Nov 14 2014 Q3 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	9 Months Ended
	Sep. 30, 2014	Nov. 05, 2014
Document and Entity Information	'	'
Entity Registrant Name	'Primoris Services Corp	'
Entity Central Index Key	'0001361538	'
Document Type	'10-Q	'
Document Period End Date	30-Sep-14	'
Amendment Flag	'false	'
Current Fiscal Year End Date	'--12-31	'
Entity Current Reporting Status	'Yes	'
Entity Filer Category	'Large Accelerated Filer	'
Entity Common Stock, Shares Outstanding	'	51,561,396
Document Fiscal Year Focus	'2014	'
Document Fiscal Period Focus	'Q3	'

CONDENSED_CONSOLIDATED_BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Current assets:	'	'
Cash and cash equivalents	$144,150	$196,077
Short-term investments	2,080	18,686
Customer retention deposits and restricted cash	411	5,304
Accounts receivable, net	388,381	304,955
Costs and estimated earnings in excess of billings	96,150	57,146
Inventory and uninstalled contract materials	58,271	51,829
Deferred tax assets	13,133	13,133
Prepaid expenses and other current assets	11,653	12,654
Total current assets	714,229	659,784
Property and equipment, net	262,835	226,512
Intangible assets, net	42,471	45,303
Goodwill	118,626	118,626
Other long-term assets	404	468
Total assets	1,138,565	1,050,693
Current liabilities:	'	'
Accounts payable	158,118	127,302
Billings in excess of costs and estimated earnings	164,428	173,365
Accrued expenses and other current liabilities	100,052	91,079
Dividends payable	2,062	1,805
Current portion of capital leases	1,796	3,288
Current portion of long-term debt	35,024	28,475
Current portion of contingent earnout liabilities	6,136	5,000
Total current liabilities	467,616	430,314
Long-term capital leases, net of current portion	1,009	2,295
Long-term debt, net of current portion	197,857	191,051
Deferred tax liabilities	10,092	10,092
Long-term contingent earnout liabilities, net of current portion	810	4,233
Other long-term liabilities	14,543	14,260
Total liabilities	691,927	652,245
Commitments and contingencies	'	'
Stockholders' equity	'	'
Common stock-$.0001 par value; 90,000,000 shares authorized, 51,561,396 and 51,571,394 issued and outstanding at September 30, 2014 and December 31, 2013	5	5
Additional paid-in capital	159,920	159,196
Retained earnings	286,765	238,216
Noncontrolling interests	-52	1,031
Total stockholders' equity	446,638	398,448
Total liabilities and stockholders' equity	$1,138,565	$1,050,693

CONDENSED_CONSOLIDATED_BALANCE1

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $)	Sep. 30, 2014	Dec. 31, 2013
CONDENSED CONSOLIDATED BALANCE SHEETS	'	'
Common stock, par value (in dollars per share)	$0.00	$0.00
Common stock, shares authorized	90,000,000	90,000,000
Common stock, shares issued	51,561,396	51,571,394
Common stock, shares outstanding	51,561,396	51,571,394

CONDENSED_CONSOLIDATED_STATEME

CONDENSED CONSOLIDATED STATEMENTS OF INCOME (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
CONDENSED CONSOLIDATED STATEMENTS OF INCOME	'	'	'	'
Revenues	$613,237	$551,333	$1,598,602	$1,406,341
Cost of revenues	537,764	475,868	1,412,178	1,225,243
Gross profit	75,473	75,465	186,424	181,098
Selling, general and administrative expenses	36,162	36,478	99,087	96,657
Operating income	39,311	38,987	87,337	84,441
Other income (expense):	'	'	'	'
Income from non-consolidated entities	5,250	113	5,264	169
Foreign exchange gain (loss)	-101	91	74	3
Other expense	-201	-376	-642	-809
Interest income	14	32	80	95
Interest expense	-1,778	-1,579	-4,642	-4,501
Income before provision for income taxes	42,495	37,268	87,471	79,398
Provision for income taxes	-15,105	-14,075	-32,813	-30,272
Net income	27,390	23,193	54,658	49,126
Less net income attributable to noncontrolling interests	'	-1,348	-432	-1,947
Net income attributable to Primoris	$27,390	$21,845	$54,226	$47,179
Earnings per share:	'	'	'	'
Basic (in dollars per share)	$0.53	$0.42	$1.05	$0.92
Diluted (in dollars per share)	$0.53	$0.42	$1.05	$0.91
Weighted average common shares outstanding:	'	'	'	'
Basic (in shares)	51,606	51,568	51,622	51,529
Diluted (in shares)	51,759	51,671	51,759	51,595

CONDENSED_CONSOLIDATED_STATEME1

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013
Cash flows from operating activities:	'	'
Net income	$54,658	$49,126
Adjustments to reconcile net income to net cash provided by operating activities:	'	'
Depreciation	37,126	31,003
Amortization of intangible assets	5,632	5,576
Gain on sale of property and equipment	-956	-1,176
Income from non-consolidated entities	-5,264	-169
Impairment expense for non-consolidated entities	'	3,250
Non-consolidated entity distributions	'	3,186
Stock-based compensation expense	671	229
Changes in assets and liabilities:	'	'
Customer retention deposits and restricted cash	4,893	20,000
Accounts receivable	-80,658	-16,402
Costs and estimated earnings in excess of billings	-39,004	-38,733
Other current assets	-5,787	-8,665
Accounts payable	30,247	-32,551
Billings in excess of costs and estimated earnings	-8,937	-11,428
Contingent earnout liabilities	-4,358	-9,287
Accrued expenses and other current liabilities	9,301	26,626
Other long-term liabilities	283	90
Net cash provided by (used in) operating activities	-2,153	20,675
Cash flows from investing activities:	'	'
Purchase of property and equipment	-64,540	-68,749
Proceeds from sale of property and equipment	3,848	6,554
Purchase of short-term investments	-3,525	-5,620
Sale of short-term investments	20,131	5,882
Cash received for the sale of Alvah and WesPac	6,439	'
Cash paid for acquisitions	-14,595	-2,273
Net cash used in investing activities	-52,242	-64,206
Cash flows from financing activities:	'	'
Proceeds from issuance of long-term debt	39,700	97,035
Repayment of capital leases	-2,778	-3,399
Repayment of long-term debt	-26,345	-29,225
Proceeds from issuance of common stock purchased under a long-term incentive plan	1,671	1,455
Dividends paid	-5,421	-3,352
Cash distribution to non-controlling interest holder	-1,515	-2,500
Repurchase of common stock	-2,844	'
Net cash provided by financing activities	2,468	60,014
Net change in cash and cash equivalents	-51,927	16,483
Cash and cash equivalents at beginning of the period	196,077	157,551
Cash and cash equivalents at end of the period	144,150	174,034
Cash paid during the period for:	'	'
Interest	5,215	3,369
Income taxes, net of refunds received	35,484	32,379
SUPPLEMENTAL DISCLOSURES OF NONCASH INVESTING AND FINANCING ACTIVITIES	'	'
Obligations incurred for the acquisition of property and equipment	'	2,523
Dividends declared and not yet paid	$2,062	$1,805

Nature_of_Business

Nature of Business	9 Months Ended
	Sep. 30, 2014
Nature of Business	'
Nature of Business	'
	Note 1—Nature of Business
	Organization and operations  — Primoris Services Corporation is a holding company of various construction and product engineering subsidiaries. The Company’s underground and directional drilling operations install, replace and repair natural gas, petroleum, telecommunications and water pipeline systems, including large diameter pipeline systems. The Company’s industrial, civil and engineering operations build and provide maintenance services to industrial facilities including power plants, petrochemical facilities, and other processing plants; construct multi-level parking structures; and engage in the construction of highways, bridges and other environmental construction activities. The Company is incorporated in the State of Delaware, and its corporate headquarters are located at 2100 McKinney Avenue, Suite 1500, Dallas, Texas 75201.
	Reportable Operating Segments — For a number of years and through the end of the second quarter 2014, the Company segregated its business into three operating segments: the East Construction Services segment, the West Construction Services segment and the Engineering segment.  In the third quarter 2014, the Company reorganized its business segments to match the change in the Company’s internal organization and management structure.  The operating segments include:  The West Construction Services segment (“West segment”), which is unchanged from the previous segment, the East Construction Services segment (“East segment”), which is realigned from the previous East Construction Services segment and the Energy segment (“Energy segment”).  All prior period amounts related to the segment change have been retrospectively reclassified throughout these quarterly financial statements to conform to the new presentation.  See Note 20 — Reportable Operating Segments.
	The following table lists the Company’s primary operating subsidiaries and their reportable operating segment:
	Subsidiary	Operating Segment	Prior Operating Segment
	ARB, Inc. (“ARB”)	West	West
	ARB Structures, Inc.	West	West
	Q3 Contracting, Inc. (“Q3C”)	West	West
	Rockford Corporation (“Rockford”)	West	West
	Stellaris, LLC.	West	West
	Vadnais Trenchless Services, Inc. (“Vadnais”); acquired in 2014	West	West
	Silva Group (“Silva”)	East	East
	Cardinal Contractors, Inc.	East	East
	BW Primoris, LLC (“BWP”)	East	East
	James Construction Group, LLC (“JCG”):
	JCG Heavy Civil Division	East	East
	JCG Infrastructure and Maintenance Division	East	East
	JCG Industrial Division	Energy	East
	Primoris Energy Services Corporation (“PES”)	Energy	East
	OnQuest, Inc.	Energy	Engineering
	OnQuest, Canada, ULC (Born Heaters Canada, ULC prior to 2013)	Energy	Engineering
	Sprint Pipeline Services, L.P. (“Sprint”) was purchased by PES in 2012.  PES has operated using the Sprint name as a DBA during 2012 and 2013.  PES acquired two subsidiaries, The Saxon Group (“Saxon”) in 2012 and Force Specialty Services, Inc. (“FSSI”) in 2013. On January 1, 2014, the two subsidiaries were merged into PES.  Additionally, effective January 1, 2014 the Industrial division of JCG was merged into PES.  In this Quarterly Report on Form 10-Q for the three and nine months ended September 30, 2014 (the “Third Quarter 2014 Report), references to Sprint, FSSI, Saxon and James Industrial are to the divisions of PES, while the references are to the entities or divisions for periods prior to 2014.
	The Company owns 50% of the Blythe Power Constructors joint venture (“Blythe”) for the installation of a parabolic trough solar field and steam generation system in California and its operations are included as part of the West Construction Services segment.  The project has been completed and final wrap-up of the joint venture is expected in December 2014.
	In January 2014, the Company created a wholly owned subsidiary, BW Primoris, LLC, a Texas limited liability company (“BWP”) which operations are a part of the East segment. BWP’s goal is to develop water projects, primarily in Texas, that will need the Company’s construction services.  On January 22, 2014, BWP entered into an agreement to purchase the assets and business of Blaus Wasser, LLC, a Wyoming limited liability company for approximately $5 million.  During the 2014 first quarter, BWP entered into an intercompany construction contract with Cardinal Contractors, Inc. to build a small water treatment facility in West Texas; intercompany revenue and profit of the project is eliminated. At September 30, 2014, a total of $3.9 million has been capitalized as property, plant and equipment.
	In May 2014, the Company created a wholly owned subsidiary, Vadnais Trenchless Services, Inc., a California company (“Vadnais”), which is a part of the West Construction Services segment.  On June 5, 2014, the Company purchased assets, consisting of equipment, building and land, from Vadnais Corporation for $6.4 million, a general contractor specializing in micro-tunneling. In addition, the sellers were provided a contingent earnout of $0.9 million upon meeting certain operating targets through December 31, 2014. The estimated fair value of the contingent earnout on the acquisition date was $729.
	During the third quarter 2014, the Company made three small purchases totaling $8.2 million acquiring the net assets of Surber Roustabout, LLC, Ram-Fab, LLC and Williams Testing, LLC. Surber and Ram-Fab operate as divisions of PES in the Energy segment and Williams is a division of Cardinal Contractors, Inc. in the East segment.  Surber provides general oil and gas related construction activities in Texas, Ram-Fab is a fabricator of custom piping systems located in Arkansas and Williams provides construction services related to sewer pipeline maintenance, rehabilitation and integrity testing in the Florida market.  The Surber purchase provided for a contingent earnout amount of up to $1.8 million over a 3-year period, based on meeting certain operating targets, which had an estimated fair value of $1.1 million on the acquisition date.  The Ram-Fab purchase included a $0.2 million contingent earnout based on estimated earnings of a six-month operating project, with the estimated fair value of the contingency at $0.2 million.
	Unless specifically noted otherwise, as used throughout these consolidated financial statements, “Primoris”, “the Company”, “we”, “our”, “us” or “its” refers to the business, operations and financial results of the Company and its wholly-owned subsidiaries.

Basis_of_Presentation

Basis of Presentation	9 Months Ended
	Sep. 30, 2014
Basis of Presentation	'
Basis of Presentation	'
	Note 2—Basis of Presentation
	Interim consolidated financial statements  — The interim condensed consolidated financial statements for the three and nine month periods ended September 30, 2014 and 2013 have been prepared in accordance with Rule 10-01 of Regulation S-X of the Securities Exchange Act of 1934, as amended (the “Exchange Act”). As such, certain disclosures, which would substantially duplicate the disclosures contained in the Company’s Annual Report on Form 10-K, filed on March 3, 2014, which contains the Company’s audited consolidated financial statements for the year ended December 31, 2013, have been omitted.
	This Third Quarter 2014 Report should be read in concert with the Company’s most recent Annual Report on Form 10-K. In the opinion of management, the interim information includes all adjustments (consisting of normal recurring adjustments) necessary for the fair presentation of the interim financial information. The interim financial information is unaudited.
	Revenue recognition
	Fixed-price contracts — Historically, a substantial portion of the Company’s revenue has been generated under fixed-price contracts. Fixed price contracts generally provide that the Company will perform all of the work required by the contract for a stated price.  For fixed-price contracts, the Company recognizes revenues using the percentage-of-completion method, which may result in uneven and irregular results. In the percentage-of-completion method, estimated revenues and resulting contract income are calculated based on the total costs incurred to date as a percentage of total estimated costs.
	Unit-price contracts — A unit-price contract provides performance of a specific project at a specific price for each unit of output.  These contracts are commonly associated with road building.
	Unforeseen events and circumstances can alter the estimate of the costs and potential profit associated with a particular contract.  Total estimated costs, and thus contract revenues and income, can be impacted by changes in productivity, scheduling, the unit cost of labor, subcontracts, materials and equipment. Additionally, external factors such as weather, client needs, client delays in providing permits and approvals, labor availability, governmental regulation and politics may affect the progress of a project’s completion and thus the timing of revenue recognition.  To the extent that original cost estimates are modified, estimated costs to complete increase, delivery schedules are delayed, or progress under a contract is otherwise impeded, cash flow, revenue recognition and profitability from a particular contract may be adversely affected.
	Other contract forms — The Company also uses time and material and cost reimbursable plus fee contracts.  For these jobs, revenue is recognized based on contractual terms.  For example, time and material contract revenues are recognized based on purchasing and employee time records.
	For all contracts, if an estimate of total contract cost indicates a loss on a contract, the projected loss is recognized in full at the time of the estimate.  The loss amount is recognized as an “accrued loss provision” and is included in the accrued expenses and other liabilities amount on the consolidated balance sheet.  Because the full loss has been recognized, any future revenues that are generated will result in the accrued loss provision being changed and the gross profit of the contract in future periods will be zero.
	The Company considers unapproved change orders to be contract variations for which it has customer approval for a change in scope but for which it does not have an agreed upon price change.  Costs associated with unapproved change orders are included in the estimated cost to complete the contracts and are treated as project costs as incurred. The Company recognizes revenue equal to costs incurred on unapproved change orders when realization of price approval is probable.  Unapproved change orders involve the use of estimates, and it is reasonably possible that revisions to the estimated costs and recoverable amounts may be required in future reporting periods to reflect changes in estimates or final agreements with customers.
	The Company considers claims to be amounts it seeks, or will seek, to collect from customers or others for customer-caused changes in contract specifications or design, or other customer-related causes of unanticipated additional contract costs on which there is no agreement with customers on both scope and price changes. Claims are included in the calculation of revenues when realization is probable and amounts can be reliably determined. Revenues in excess of contract costs incurred on claims are recognized when the amounts have been agreed upon with the customer.  Revenue in excess of contract costs from claims is recognized when an agreement is reached with customers as to the value of the claims, which in some instances may not occur until after completion of work under the contract. Costs associated with claims are included in the estimated costs to complete the contracts and are treated as project costs when incurred.
	The caption “Costs and estimated earnings in excess of billings” in the consolidated balance sheet represents unbilled receivables which arise when revenues have been recorded but the amount will not be billed until a later date.  Balances represent:  (a) unbilled amounts arising from the use of the percentage-of-completion method of accounting which may not be billed under the terms of the contract until a later date, (b) incurred costs to be billed under cost reimbursement type contracts, (c) amounts arising from routine lags in billing, or (d) the revenue associated with unapproved change orders or claims when realization is probable and amounts can be reliably determined.  For those contracts in which billings exceed contract revenues recognized to date, the excess amounts are included in the caption “Billings in excess of costs and estimated earnings”.
	In certain contracts, primarily for highway construction for governmental agencies, the Company is allowed to purchase and bill in advance for materials that will be used on the job.   The unused amount of materials purchased and billed, but not yet installed at the balance sheet date, is included in the caption “Inventory and uninstalled contract materials.”
	In accordance with applicable terms of certain construction contracts, retainage amounts may be withheld by customers until completion and acceptance of the project.  Some payments of the retainage may not be received for a significant period after completion of our portion of a project.  In some jurisdictions, retainage amounts are deposited into an escrow account.
	Significant revision in contract estimate  — As previously discussed, revenue recognition is based on the percentage-of-completion method for firm fixed-price contracts. Under this method, the costs incurred to date as a percentage of total estimated costs are used to calculate revenue. Total estimated costs, and thus contract revenues and margin, are impacted by many factors which can cause significant changes in estimates during the life cycle of a project.
	For projects that were in process in the prior year, but are either completed or continue to be in process during the current year, there can be a difference in revenues and profits recognized to the prior year, had current year estimates of costs to complete been known in the prior year.
	Customer Concentration — The Company operates in multiple industry segments encompassing the construction of industrial and public works infrastructure assets throughout primarily the United States. Typically, the top ten customers in any one calendar year generate revenues in excess of 50% of total revenues; however in most years a different group make up the top ten customers.
	During the three and nine months ending September 30, 2014, revenues generated by the top ten customers were $309 million and $884 million, respectively, which represented 50.3% and 55.3%, respectively, of total revenues during the periods.  During these periods, TX DOT represented 7.8% and 8.6%, respectively, of total revenues and a petrochemical operating company represented 8.0% and 8.0%, respectively, of total revenues.
	During the three and nine months ending September 30, 2013, revenues generated by the top ten customers were $274 million and $717 million, respectively, which represented 49.7% and 51.0%, respectively, of total revenues during the periods.  During these periods, a large gas and electric utility represented 8.8% and 8.3%, respectively, of total revenues and a large pipeline company represented 9.7% and 6.8%, respectively, of total revenues.
	At September 30, 2014, approximately 12.4% of the Company’s accounts receivable were due from one customer, and that customer provided 8.0% of the Company’s revenues for the nine months ended September 30, 2014.  At September 30, 2013, approximately 13.1% of the Company’s accounts receivable were due from one customer, and that customer provided 7.4% of the Company’s revenues for the nine months ended September 30, 2013.
	Multiemployer Plans  — Various subsidiaries in the West Construction Services segment are signatories to collective bargaining agreements.  These agreements require that the Company participate in and contribute to a number of multiemployer benefit plans for its union employees at rates determined by the agreements.  The trustees for each multiemployer plan determine the eligibility and allocations of contributions and benefit amounts, determine the types of benefits and administer the plan.  Federal law requires that if the Company were to withdraw from an agreement, it will incur a withdrawal obligation.  The potential withdrawal obligation may be significant.  Any withdrawal liability would be recorded when it is probable that a liability exists and can be reasonably estimated, in accordance with generally accepted accounting principles (“GAAP”).  In November 2011, the Company withdrew from the Central States Southeast and Southwest Areas Pension Fund multiemployer pension plan.  The Company has no plans to withdraw from any other agreements.  See Note 19 — “Commitments and Contingencies”.
	Inventory and uninstalled contract materials — Inventory consists of expendable construction materials and small tools that will be used in construction projects and is valued at the lower of cost, using first-in, first-out method, or market.  Uninstalled contract materials include certain job specific materials not yet installed which are valued using the specific identification method relating the inventory cost to a specific project.  These materials have been purchased for specific jobs, normally highway construction jobs for state or local governmental agencies.  The Company retains responsibility for safeguarding of the materials.   At September 30, 2014, billed but not installed inventory was $51,927 compared to $44,966 at December 31, 2013.

Recent_Accounting_Pronouncemen

Recent Accounting Pronouncements	9 Months Ended
	Sep. 30, 2014
Recent Accounting Pronouncements	'
Recent Accounting Pronouncements	'
	Note 3—Recent Accounting Pronouncements
	In February 2013, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2013-04, “Liabilities (Topic 405): Obligations Resulting from Joint and Several Liability Arrangements for Which the Total Amount of the Obligation Is Fixed at the Reporting Date (a consensus of the FASB Emerging Issues Task Force)”  (“ASU 2013-04”).  ASU 2013-04 provides guidance for the recognition, measurement, and disclosure of obligations resulting from joint and several liability arrangements for which the total amount of the obligation within the scope of this guidance is fixed at the reporting date. This ASU is an update to FASB ASC Topic 405, “Liabilities”.  The Company adopted this guidance as of January 1, 2014 which did not have a material impact on the Company’s consolidated financial statements.
	In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606). The new standard is effective for reporting periods beginning after December 15, 2016 and early adoption is not permitted. The comprehensive new standard will supersede existing revenue recognition guidance and require revenue to be recognized when promised goods or services are transferred to customers in amounts that reflect the consideration to which the company expects to be entitled in exchange for those goods or services. Adoption of the new rules could affect the timing of revenue recognition for certain transactions. The guidance permits two implementation approaches, one requiring retrospective application of the new standard with restatement of prior years and one requiring prospective application of the new standard with disclosure of results under old standards. For the Company the new standard will be effective January 1, 2017 and the Company is currently evaluating the impacts of adoption and the implementation approach to be used.

Fair_Value_Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2014
Fair Value Measurements	'
Fair Value Measurements	'
	Note 4—Fair Value Measurements
	ASC Topic 820, “Fair Value Measurements and Disclosures”, defines fair value in GAAP, establishes a framework for measuring fair value and requires certain disclosures about fair value measurements.  ASC Topic 820 requires that certain financial assets and financial liabilities be re-measured and reported at fair value each reporting period while other non-financial assets and liabilities may be re-measured and reported at fair value on a non-recurring basis.
	In general, fair values determined by Level 1 inputs use quoted prices (unadjusted) in active markets for identical assets or liabilities. Fair values determined by Level 2 inputs use data points that are observable such as quoted prices, interest rates and yield curves. Fair values determined by Level 3 inputs are “unobservable data points” for the asset or liability and include situations where there is little, if any, market activity for the asset or liability.
	The following table presents, for each of the fair value hierarchy levels identified under ASC Topic 820, the Company’s financial assets and liabilities that are required to be measured at fair value at September 30, 2014 and December 31, 2013:
					Fair Value Measurements at Reporting Date
		Amount			Quoted Prices		Significant	Significant
		Recorded			in Active Markets		Other	Unobservable
		on Balance			for Identical Assets		Observable	Inputs
		Sheet			(Level 1)		Inputs	(Level 3)
							(Level 2)
	Assets as of September 30, 2014:
	Cash and cash equivalents	$	144,150		$	144,150	—	—
	Short-term investments	$	2,080		$	2,080	—	—
	Liabilities as of September 30, 2014:
	Contingent consideration	$	6,946		—		—	$	6,946
	Assets as of December 31, 2013:
	Cash and cash equivalents	$	196,077		$	196,077	—	—
	Short-term investments	$	18,686		$	18,686	—	—
	Liabilities as of December 31, 2013:
	Contingent consideration	$	9,233		—		—	$	9,233
	Short-term investments consist primarily of Certificates of Deposit (“CDs”) and U.S. Treasury bills with various financial institutions that are backed by the federal government.
	Other financial instruments of the Company not listed in the table consist of accounts receivable, accounts payable and certain accrued liabilities.  These financial instruments generally approximate fair value based on their short-term nature.  The carrying value of the Company’s long-term debt approximates fair value based on comparison with current prevailing market rates for loans of similar risks and maturities.
	The following table provides changes to the Company’s contingent consideration liability Level 3 fair value measurements during the nine months ended September 30, 2014:
	Contingent Consideration
	Balance at December 31, 2013	$	9,233
	Additions:
	Change in fair value of contingent consideration	642
	Vadnais acquisition	729
	Other acquisitions made in third quarter 2014	1,342
	Reductions:
	Payment to Q3C sellers	(5,000		)
	Balance at September 30, 2014	$	6,946
	On a quarterly basis, the Company assesses the estimated fair value of the contractual obligation to pay the contingent consideration and any changes in estimated fair value are recorded as other non-operating expense or income in the Company’s consolidated statement of income.  Fluctuations in the fair value of contingent consideration are impacted by two unobservable inputs, management’s estimate of the probability (which has ranged from 33% to 100%) of the acquired company meeting the contractual operating performance target and the estimated discount rate (a rate that approximates the Company’s cost of capital). Significant changes in either of those inputs in isolation would result in a significantly different fair value measurement.  Generally, a change in the assumption of the probability of meeting the performance target is accompanied by a directionally similar change in the fair value of contingent consideration liability, whereas a change in assumption of the estimated discount rate is accompanied by a directionally opposite change in the fair value of contingent consideration liability.

Accounts_Receivable

Accounts Receivable	9 Months Ended
	Sep. 30, 2014
Accounts Receivable	'
Accounts Receivable	'
	Note 5—Accounts Receivable
	The following is a summary of the Company’s accounts receivable:
		September 30,		December 31,
		2014		2013
	Contracts receivable, net of allowance for doubtful accounts of $525 at September 30, 2014 and $692 at December 31, 2013	$	323,387	$	257,354
	Retention receivable	64,221		47,054
		387,608		304,408
	Other accounts receivable	773		547
		$	388,381	$	304,955

Costs_and_Estimated_Earnings_o

Costs and Estimated Earnings on Uncompleted Contracts	9 Months Ended
	Sep. 30, 2014
Costs and Estimated Earnings on Uncompleted Contracts	'
Costs and Estimated Earnings on Uncompleted Contracts	'
	Note 6—Costs and Estimated Earnings on Uncompleted Contracts
	Costs and estimated earnings on uncompleted contracts consist of the following:
		September 30,			December 31,
		2014			2013
	Costs incurred on uncompleted contracts	$	4,743,681		$	4,741,249
	Gross profit recognized	559,359			582,430
		5,303,040			5,323,679
	Less: billings to date	(5,371,318		)	(5,439,898		)
		$	(68,278	)	$	(116,219	)
	This amount is included in the accompanying consolidated balance sheets under the following captions:
		September 30,			December 31,
		2014			2013
	Costs and estimated earnings in excess of billings	$	96,150		$	57,146
	Billings in excess of costs and estimated earnings	(164,428		)	(173,365		)
		$	(68,278	)	$	(116,219	)

Equity_Method_Investments

Equity Method Investments	9 Months Ended
	Sep. 30, 2014
Equity Method Investments.	'
Equity Method Investments	'
	Note 7—Equity Method Investments
	WesPac Energy LLC and WesPac Midstream LLC
	On July 1, 2010, the Company acquired a 50% membership interest in WesPac Energy LLC (“WesPac”), a Nevada limited liability company, from Kealine Holdings, LLC (“Kealine”), a Nevada limited liability company, with Kealine retaining a remaining 50% membership interest. WesPac developed pipeline and terminal projects, primarily for the oil and gas industry.
	On September 30, 2013, WesPac, Kealine and the Company entered into an agreement (the “Midstream Agreement”) with Highstar Capital IV, LP (“Highstar”), to form a new entity, WesPac Midstream LLC, a Delaware limited liability company (“Midstream”), with WesPac contributing project assets to Midstream and Highstar investing $6,082 in cash.
	The Company has accounted for the investment using the equity method of accounting and recorded its proportionate share of operating expenses.  During the fourth quarter 2013, the Company recorded non-cash impairment charges and wrote-off the total value of its equity investment.
	During the third quarter 2014, the Company entered into negotiations with the members of Midstream. In August, the Company entered into a redemption agreement for the sale of all of the Company’s ownership in both WesPac and Midstream for a total of $5,250 in cash.
	Alvah, Inc.
	As part of its acquisition of Q3C, the Company acquired a 49% membership interest in Alvah, Inc., a California corporation (“Alvah”).  Alvah is engaged in electrical contracting activities, primarily in Northern California and has worked as a subcontractor for ARB both prior to and subsequent to the Q3C acquisition.
	On February 5, 2014, the majority owner of Alvah, in accordance with the original investment agreement, elected to purchase the Company’s minority interest effective January 1, 2014 for a cash payment of $1,189.  At the time of the transaction, the Company recorded income adjustments of $14 related to the final sale in the first quarter 2014.

Business_Combinations

Business Combinations	9 Months Ended
	Sep. 30, 2014
Business Combinations	'
Business Combinations	'
	Note 8 — Business Combinations
	In May 2014, the Company created a wholly owned subsidiary, Vadnais Trenchless Services, Inc., a California company (“Vadnais”), which is a part of the West Construction Services segment.  On June 5, 2014, the Company purchased certain assets from Vadnais Corporation, a general contractor specializing in micro-tunneling.  The assets were purchased for their estimated fair value of $6.4 million in cash and included equipment, building and land.  In addition upon meeting certain operating targets through December 31, 2014, the sellers will receive a contingent earnout of $0.9 million.  The estimated fair value of the potential contingent consideration on the acquisition date was $729.  The purchase was accounted for using the acquisition method of accounting. During the third quarter of 2014, the Company finalized its estimate of fair value for the contingent consideration and intangible assets, which resulted in no change from the estimated values recorded at June 30, 2014.
	During the third quarter 2014, the Company made three small acquisitions totaling $8.2 million acquiring the net assets of Surber Roustabout, LLC, Ram-Fab, LLC and Williams Testing, LLC. Surber and Ram-Fab operate as divisions of PES in the Energy segment and Williams is a division of Cardinal Contractors, Inc. in the East segment.  Surber provides general oil and gas related construction activities in Texas, Ram-Fab is a fabricator of custom piping systems located in Arkansas and Williams provides construction services related to sewer pipeline maintenance, rehabilitation and integrity testing in the Florida market.  The Surber purchase provided for a contingent earnout amount of up to $1.8 million over a 3-year period, based on meeting certain operating targets, which had an estimated fair value of $1.1 million on the acquisition date.  The Ram-Fab purchase included a $0.2 million contingent earnout based on estimated earnings of a six-month operating project, with the estimated fair value of the contingency at $0.2 million on the acquisition date.  The purchases were accounted for using the acquisition method of accounting and, due to the short period of time between the acquisition dates and quarter end, the estimated values are preliminary and subject to change.
	Supplemental Unaudited Pro Forma Information for the three and nine months ended September 30, 2014 and 2013
	Pro forma information for the three and nine months ended September 30, 2014 and 2013 presents the results of operations of the Company as if Vadnais and the three acquisitions made in the third quarter 2014, plus the March 11, 2013 FSSI acquisition had all occurred at the beginning of 2013. The Vadnais acquisition was completed on June 5, 2014, the Surber purchase on July 28, 2014, Ram-Fab on August 29, 2014 and the Williams purchase on September 19, 2014.  The supplemental pro forma information has been adjusted to include:
		·		the pro forma impact of amortization of intangible assets and depreciation of property, plant and equipment, based on the purchase price allocations;
		·		the pro forma impact of the expense associated with the amortization of the discount for the fair value of the contingent consideration for potential earnout liabilities that may be achieved in 2013 and 2014 for the Vadnais, Surber, Ram-Fab and FSSI acquisitions;
		·		the pro forma tax effect of both the income before income taxes and the pro forma adjustments, calculated using a tax rate of 39.0% for the three and nine months ended September 30, 2014 and the same period in 2013.
	The pro forma results are presented for illustrative purposes only and are not necessarily indicative of, or intended to represent, the results that would have been achieved had the acquisitions been completed on January 1, 2013.  For example, the pro forma results do not reflect any operating efficiencies and associated cost savings that the Company might have achieved with respect to the acquisitions.
			Three months				Nine months
			ended September 30,				ended September 30,
			2014		2013		2014		2013
	Revenues		620,503		558,543		1,622,480		1,430,124
	Income before provision for income taxes		43,407		35,358		87,091		75,034
	Net income attributable to Primoris		27,946		20,680		53,994		44,517
	Weighted average common shares outstanding:
	Basic		51,606		51,568		51,622		51,529
	Diluted		51,759		51,671		51,759		51,595
	Earnings per share:
	Basic		$	0.54	$	0.40	$	1.05	$	0.86
	Diluted		$	0.54	$	0.40	$	1.04	$	0.86

Intangible_Assets

Intangible Assets	9 Months Ended
	Sep. 30, 2014
Intangible Assets	'
Intangible Assets	'
	Note 9—Intangible Assets
	At September 30, 2014 and December 31, 2013, intangible assets totaled $42,471 and $45,303, respectively, net of amortization.  The table below summarizes the intangible asset categories, amounts and the average amortization periods, as follows:
		Amortization		September 30,		December 31,
		Period		2014		2013
	Tradename	3 to 10 years		$	19,535	$	21,023
	Non-compete agreements	2 to 5 years		$	2,120	$	2,575
	Customer relationships	3 to 15 years		$	20,816	$	21,705
	Total			$	42,471	$	45,303
	Amortization expense of intangible assets, on a straight-line basis, was $1,945 and $1,891 for the three months ended September 30, 2014 and 2013, respectively, and amortization expense for the nine months ended September 30, 2014 and 2013 was $5,632 and $5,576, respectively.  Estimated future amortization expense for intangible assets is as follows:
	For the Years Ending	Estimated
	December 31,	Intangible
		Amortization
		Expense
	2014 (remaining three months)	$	2,004
	2015	7,023
	2016	6,274
	2017	5,968
	2018	5,535
	Thereafter	15,667
		$	42,471

Accounts_Payable_and_Accrued_L

Accounts Payable and Accrued Liabilities	9 Months Ended
	Sep. 30, 2014
Accounts Payable and Accrued Liabilities	'
Accounts Payable and Accrued Liabilities	'
	Note 10—Accounts Payable and Accrued Liabilities
	At September 30, 2014 and December 31, 2013, accounts payable included retention amounts of approximately $9,001 and $5,602, respectively.  These amounts are due to subcontractors but have been retained pending contract completion and customer acceptance of jobs.
	The following is a summary of accrued expenses and other current liabilities at:
		September 30,		December 31,
		2014		2013
	Payroll and related employee benefits	$	47,067	$	36,556
	Insurance, including self-insurance reserves	35,433		33,880
	Reserve for estimated losses on uncompleted contracts	3,005		1,392
	Corporate income taxes and other taxes	8,786		13,305
	Accrued overhead cost	1,314		1,165
	Other	4,447		4,781
		$	100,052	$	91,079

Credit_Arrangements

Credit Arrangements	9 Months Ended
	Sep. 30, 2014
Credit Arrangements	'
Credit Arrangements	'
	Note 11—Credit Arrangements
	Revolving Credit Facility
	As of September 30, 2014, the Company had a revolving credit facility (the “Credit Agreement”) with The PrivateBank and Trust Company, as administrative agent (the “Administrative Agent”) and co-lead arranger, The Bank of the West, as co-lead arranger, and IBERIABANK Corporation (the “Lenders”). The Credit Agreement is a $75 million revolving credit facility whereby the Lenders agree to make loans on a revolving basis from time to time and to issue letters of credit for up to the $75 million committed amount. The Credit Agreement also provides for an incremental facility of up to $50 million. The termination date of the Credit Agreement is December 28, 2017.
	The principal amount of any loans under the Credit Agreement will bear interest at either: (i) LIBOR plus an applicable margin as specified in the Credit Agreement (based on the Company’s senior debt to EBITDA ratio as that term is defined in the Credit Agreement), or (ii) the Base Rate (which is the greater of (a) the Federal Funds Rate plus 0.5% or (b) the prime rate as announced by the Administrative Agent). Quarterly non-use fees, letter of credit fees and administrative agent fees are payable at rates specified in the Credit Agreement.
	The principal amount of any loan drawn under the Credit Agreement may be prepaid in whole or in part, with a minimum prepayment of $5 million, at any time, potentially subject to make-whole provisions.
	The Credit Agreement includes customary restrictive covenants for facilities of this type, as discussed below.
	Commercial letters of credit outstanding were $4,659 at September 30, 2014 and $5,074 at December 31, 2013.  Other than commercial letters of credit, there were no borrowings under this line of credit during the nine months ended September 30, 2014, and available borrowing capacity at September 30, 2014 was $70,341.
	Senior Secured Notes and Shelf Agreement
	On December 28, 2012, the Company entered into a $50 million Senior Secured Notes purchase (“Senior Notes”) and a $25 million private shelf agreement (the “Notes Agreement”) by and among the Company, The Prudential Investment Management, Inc. and certain Prudential affiliates (the “Noteholders”).
	The Senior Notes amount was funded on December 28, 2012. The Senior Notes are due December 28, 2022 and bear interest at an annual rate of 3.65%, paid quarterly in arrears. Annual principal payments of $7.1 million are required from December 28, 2016 through December 28, 2021 with a final payment due on December 28, 2022. The principal amount may be prepaid, with a minimum prepayment of $5 million, at any time, subject to make-whole provisions.
	On July 25, 2013, the Company drew the full $25 million available under the Notes Agreement.  The notes are due July 25, 2023 and bear interest at an annual rate of 3.85% paid quarterly in arrears.  Seven annual principal payments of $3.6 million are required from July 25, 2017 with a final payment due on July 25, 2023.
	Loans made under both the Credit Agreement and the Notes Agreement are secured by our assets, including, among others, our cash, inventory, goods, equipment (excluding equipment subject to permitted liens) and accounts receivable. All of our domestic subsidiaries have issued joint and several guaranties in favor of the Lenders and Noteholders for all amounts under the Credit Agreement and Notes Agreement.
	Both the Credit Agreement and the Notes Agreement contain various restrictive and financial covenants including among others, minimum tangible net worth, senior debt/EBITDA ratio, debt service coverage requirements and a minimum balance for unencumbered net book value for fixed assets. In addition, the agreements include restrictions on investments, change of control provisions and provisions in the event the Company disposes more than 20% of its total assets.
	The Company was in compliance with the covenants for the Credit Agreement and Notes Agreement at September 30, 2014.
	Canadian Credit Facility
	The Company has a credit facility for $8,000 in Canadian dollars with a Canadian bank for purposes of issuing commercial letters of credit in Canada.  The credit facility has an annual renewal and provides for the issuance of commercial letters of credit for a term of up to five years. The facility provides for an annual fee of 1% for any issued and outstanding commercial letters of credit. Letters of credit can be denominated in either Canadian or U.S. dollars. At September 30, 2014 and December 31, 2013, letters of credit outstanding totaled $2,252 and $2,512 in Canadian dollars, respectively.  At September 30, 2014, the available borrowing capacity was $5,488 in Canadian dollars.  The credit facility contains a working capital restrictive covenant for our Canadian subsidiary, OnQuest Canada, ULC.  At September 30, 2014, OnQuest Canada, ULC was in compliance with the covenant.

Noncontrolling_Interests

Noncontrolling Interests	9 Months Ended
	Sep. 30, 2014
Noncontrolling Interests	'
Noncontrolling Interests	'
	Note 12 — Noncontrolling Interests
	The Company applies the provisions of ASC Topic 810-10-45, which establishes accounting and reporting standards for ownership interests of parties other than the Company in subsidiaries, such as joint ventures and partnerships.
	The Company determined that the Blythe joint venture was a variable interest entity (“VIE”) and that the Company was the primary beneficiary as a result of its significant influence over the joint venture operations.
	The Blythe joint venture operating activities are included in the Company’s consolidated statements of income as follows for the three and nine months ended September 30:
		Three months				Nine months
		ended September 30,				ended September 30,
		2014		2013		2014	2013
	Revenues	—		15,468		940	47,371
	Net income attributable to noncontrolling interests	—		1,348		432	1,947
	Blythe is a partnership and no tax effect was recognized for income at the partnership level.  Blythe made distributions of $1,515 to the non-controlling interests and $1,515 to the Company during the nine months ended September 30, 2014.  During the nine months ended September 30, 2013, Blythe made a total of $2,500 in distributions to the non-controlling interests and $2,500 in distributions to the Company.  There were no capital contributions made during the year ended December 31, 2013 or through the nine months ended September 30, 2014.  The project has been completed and final wrap-up of the joint venture is expected in December 2014.
	The carrying value of the assets and liabilities associated with the operations of the Blythe joint venture are included in the Company’s consolidated balance sheets as follows:
		September 30,			December 31,
		2014			2013
	Cash	$	250		$	3,025
	Accounts receivable	—			1,085
	Billings in excess of costs and estimated earnings	348			2,041
	The net assets of the joint venture are restricted for use by the project and are not available for general operations of the Company.

Contingent_Earnout_Liabilities

Contingent Earnout Liabilities	9 Months Ended
	Sep. 30, 2014
Contingent Earnout Liabilities	'
Contingent Earnout Liabilities	'
	Note 13 — Contingent Earnout Liabilities
	In March 2014, the Company paid $5,000 to the sellers of Q3C based on achievement of the 2013 operating performance targets.  The sellers will be paid an additional $3,750, contingent on meeting an EBITDA target for calendar year 2014 of at least $19 million, as defined in the purchase agreement which as of September 30, 2014, has been achieved, and an additional $1,250 will be paid if EBITDA exceeds $22 million, for a total payment of $5,000.  The estimated fair value at September 30, 2014 of the remaining contingent earnout was $4,788.
	In June 2014, the Company acquired the assets of Vadnais Company for $6,354 in cash plus an earnout of $900 in 2015, contingent upon meeting a certain performance target for the remaining calendar year 2014.  The estimated fair value of the contingent consideration on the acquisition date was $729 and on September 30, 2014 was $816.
	During the third quarter 2014, the Company made three small purchases totaling $8.2 million in cash for the net assets of Surber Roustabout, LLC, Ram-Fab, LLC and Williams Testing, LLC.  The Surber purchase provided a contingent earnout amount of up to $1.8 million over a 3-year period, based on meeting certain operating targets, which had an estimated fair value of $1.1 million on the acquisition date.  The Ram-Fab purchase included a $0.2 million contingent earnout based on estimated earnings of a six-month operating project, with the estimated fair value of the contingency at $0.2 million at the acquisition date.

Related_Party_Transactions

Related Party Transactions	9 Months Ended
	Sep. 30, 2014
Related Party Transactions	'
Related Party Transactions	'
	Note 14—Related Party Transactions
	Primoris has entered into leasing transactions with Stockdale Investment Group, Inc. (“SIGI”).  Brian Pratt, our Chief Executive Officer, President and Chairman of the Board of Directors and our largest stockholder, holds a majority interest and is the chairman, president and chief executive officer and a director of SIGI.  John M. Perisich, our Executive Vice President and General Counsel, is secretary of SIGI.
	Primoris leases properties from SIGI at the following locations:
		1	Bakersfield, California (lease expires October 2022)
		2	Pittsburg, California (lease expires April 2023)
		3	San Dimas, California (lease expires March 2019)
		4	Pasadena, Texas (lease was mutually terminated as of August 31, 2014)
	During the nine months ended September 30, 2014 and 2013, the Company paid $656 and $688, respectively, in lease payments to SIGI for the use of these properties.
	Primoris leases a property from Roger Newnham, a former owner and manager of our subsidiary, OnQuest Canada, ULC. The property is located in Calgary, Canada. During the nine months ended September 30, 2014 and 2013, Primoris paid $219 and $223, respectively, in lease payments.  The current term of the lease is through December 31, 2017.
	Primoris leases a property from Lemmie Rockford, one of the Rockford sellers, which commenced November 1, 2011.  The property is located in Toledo, Washington.  During the nine months ended September 30, 2014 and 2013, Primoris paid $68 and $68, respectively, in lease payments.  The lease expires in January 2015.
	Primoris leases a property from Quality RE Partners, owned by three of the Q3C selling shareholders, of whom two are current employees, including Jay Osborn, President of Q3C.  The property is located in Little Canada, Minnesota.  During the nine months ended September 30, 2014 and 2013, the Company paid $198 and $198, respectively, in lease payments to Quality RE Partners.  The lease expires in October 2022.
	As discussed in Note 7— “Equity Method Investments”, the Company owns several non-consolidated investments and has recognized revenues on work performed by the Company for those joint ventures.

StockBased_Compensation

Stock-Based Compensation	9 Months Ended
	Sep. 30, 2014
Stock-Based Compensation	'
Stock-Based Compensation	'
	Note 15—Stock-Based Compensation
	On May 3, 2013, the Board of Directors granted 100,000 Restricted Stock Units (“Units”) to an executive under the 2013 Long-term Incentive Equity Plan (the “Equity Plan”).  Commencing annually on May 10, 2014 and ending April 30, 2017, the Units will vest in four equal installments subject to continuing employment of the executive.  On April 30, 2014, 25,000 of these Units vested.  On March 24, 2014, the Board of Directors granted 48,512 Units to another executive under the Equity Plan.  The Units will vest 50% on September 23, 2015 and the remaining 50% on March 23, 2017 subject to continuing employment of the executive.  Vesting in both grants is also subject to earlier acceleration, termination, cancellation or forfeiture as provided in the underlying Primoris Restricted Stock Unit agreement (“RSU Award Agreement”).  Each Unit represents the right to receive one share of the Company’s common stock when vested.
	Under guidance of ASC Topic 718 “Compensation — Stock Compensation”, stock-based compensation cost is measured at the date of grant (utilizing the prior-day closing price), based on the calculated fair value of the stock-based award, and is recognized as expense over the employee’s requisite service period (generally the vesting period of the award).
	The fair value of the Units was based on the closing market price of our common stock on the day prior to the date of the grant.  Stock compensation expense for the Units is being amortized using the straight-line method over the service period.  For the three and nine months ended September 30, 2014, the Company recognized $262 and $671, respectively, in compensation expense.  At September 30, 2014, approximately $2.66 million of unrecognized compensation expense remains for the Units which will be recognized over the next 2.5 years through April 30, 2017.
	Vested Units accrue “Dividend Equivalents” (as defined in the Equity Plan) which will be accrued as additional Units.  At September 30, 2014, there were 67 Dividend Equivalent Units that were accrued on 25,000 Units that vested on April 30, 2014.

Income_Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2014
Income Taxes	'
Income Taxes	'
	Note 16—Income Taxes
	The effective tax rate on income before taxes and noncontrolling interests for the nine months ended September 30, 2014 was 37.57%.  The effective tax rate for income attributable to Primoris was 37.7%. The rate differs from the U.S. federal statutory rate of 35% due primarily to state income taxes, the “Domestic Production Activity Deduction” and nondeductible meals and incidental per diems common in the construction industry.
	To determine its quarterly provision for income taxes, the Company uses an estimated annual effective tax rate, which is based on expected annual income, statutory tax rates and tax planning opportunities available in the various jurisdictions in which the Company operates. Certain significant or unusual items are separately recognized in the quarter in which they occur and can be a source of variability in the effective tax rate from quarter to quarter.  The Company recognizes interest and penalties related to uncertain tax positions, if any, as an income tax expense.
	Income taxes are accounted for under the asset and liability method. Deferred tax assets and liabilities are recognized for the future tax consequences of temporary differences between the financial reporting basis and tax basis of the Company’s assets and liabilities. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period of enactment date.
	In the third quarter of 2013, the IRS initiated an examination of our federal income tax returns for 2011 and 2012.  The examination was settled in the third quarter of 2014 without a material impact to the Company.  The Company’s federal returns are no longer subject to examination for tax years before 2013.  The statute of limitations of state and foreign jurisdictions vary generally between 3 to 5 years.  Accordingly, the tax years 2008 through 2013 generally remain open to examination by the other taxing jurisdictions in which the Company operates.

Dividends_and_Earnings_Per_Sha

Dividends and Earnings Per Share	9 Months Ended
	Sep. 30, 2014
Dividends and Earnings Per Share	'
Dividends and Earnings Per Share	'
	Note 17—Dividends and Earnings Per Share
	The Company has paid or declared cash dividends during 2014 as follows:
		·		On October 30, 2013, the Company declared a cash dividend of $0.035 per common share, payable to stockholders of record on December 31, 2013.  The dividend, totaling $1,805, was paid on January 15, 2014.
		·		On February 26, 2014, the Company declared a cash dividend of $0.035 per common share, payable to stockholders of record on March 31, 2014.  The dividend, totaling $1,808, was paid on April 15, 2014.
		·		On May 2, 2014, the Company declared a cash dividend of $0.035 per common share, payable to stockholders of record on June 30, 2014.  The dividend, totaling $1,808, was paid on July 15, 2014.
		·		On August 5, 2014, the Company declared a cash dividend of $0.04 per common share, payable to stockholders of record on September 30, 2014.  The dividend, totaling $2,062, was paid on October 15, 2014.
	The table below presents the computation of basic and diluted earnings per share for the three and nine months ended September 30, 2014 and 2013:
			Three months				Nine months
			ended September 30,				ended September 30,
			2014		2013		2014		2013
	Numerator:
	Net income attributable to Primoris		$	27,390	$	21,845	$	54,226	$	47,179
	Denominator (shares in thousands):
	Weighted average shares for computation of basic earnings per share		51,606		51,568		51,622		51,529
	Dilutive effect of shares issued to independent directors		4		3		3		10
	Dilutive effect of unvested restricted stock units (1)		149		100		134		55
	Dilutive effect of shares to be issued Q3C sellers (2)		—		—		—		1
	Weighted average shares for computation of diluted earnings per share		51,759		51,671		51,759		51,595
	Earnings per share:
	Basic earnings per share		$	0.53	$	0.42	$	1.05	$	0.92
	Diluted earnings per share		$	0.53	$	0.42	$	1.05	$	0.91
		-1		Represents the dilutive effect of a grant for 100,000 shares of Units on May 3, 2013 and 48,512 shares of Units on March 24, 2014.
		-2		Represents the dilutive effect of 29,273 unregistered shares of common stock provided in January 2013 as part of the purchase consideration for the Q3C acquisition.

Stockholders_Equity

Stockholders' Equity	9 Months Ended
	Sep. 30, 2014
Stockholders' Equity	'
Stockholders' Equity	'
	Note 18—Stockholders’ Equity
	Common stock — In March 2014, the Company received $1,671 for 77,455 shares of common stock purchased and issued in accordance with the Company’s Long-Term Retention Plan (“LTR Plan”).  The Company’s LTR Plan for managers and executives allows participants to use a portion of their annual bonus amount to purchase Company common stock at a discount from the market price. The shares purchased in March 2014 were for bonus amounts earned in 2013 and the number of shares was calculated at 75% of the average market closing price of December 2013.  In March 2013, the Company received $1,455 for 131,989 shares of common stock issued under the LTR Plan for bonus amounts earned in the prior year.
	In February and September 2014, the Company issued 6,375 shares and 6,172 shares, respectively, of common stock as part of the quarterly compensation of the non-employee members of the Board of Directors.  Shares issued to the non-employee Directors in February and July 2013 were 12,480 shares and 9,110 shares, respectively and were issued in accordance with the LTR Plan.
	As discussed in Note 15 — “Stock Based Compensation”, the Board of Directors has granted a total of 148,512 shares of Units under the Equity Plan.
	In February 2014, the Company’s Board of Directors authorized a share repurchase program under which the Company, from time to time and depending on market conditions, share price and other factors, may acquire shares of its common stock on the open market or in privately negotiated transactions up to an aggregate purchase price of $23 million.  During the three and nine months ending September 30, 2014, the Company purchased and cancelled 100,000 shares of stock for $2.8 million at an average cost of $28.44 per share.  The share repurchase program expires December 31, 2014.

Commitments_and_Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2014
Commitments and Contingencies.	'
Commitments and Contingencies	'
	Note 19—Commitments and Contingencies
	Leases  — The Company leases certain property and equipment under non-cancellable operating leases which expire at various dates through 2022. The leases require the Company to pay all taxes, insurance, maintenance and utilities and are classified as operating leases in accordance with ASC Topic 840 “Leases”.
	Total lease expense during the three and nine months ended September 30, 2014 was $3,250 and $10,416, respectively, compared to $3,566 and $11,111 for the same periods in 2013.  The amounts for the three and nine months ended September 30, 2014 included lease payments made to related parties of $377 and $1,140, respectively, and $379 and $1,176 for the three and nine months ended September 30, 2013, respectively.
	Letters of credit  — At September 30, 2014, the Company had letters of credit outstanding of $6,911 and at December 31, 2013, the Company had letters of credit outstanding of $7,696.  The outstanding amounts include the U.S. dollar equivalents for letters of credit issued in Canadian dollars.
	Litigation — On February 7, 2012, the Company was sued in an action entitled North Texas Tollway Authority, Plaintiff v. James Construction Group, LLC, and KBR, Inc., Defendants, v. Reinforced Earth Company, Third-Party Defendant (the “Lawsuit”). In the Lawsuit, the North Texas Tollway Authority (“NTTA”) is alleging damages to a road and retaining wall that were constructed in 1999 on the George Bush Turnpike near Dallas, Texas, due to negligent construction by JCG.  The Lawsuit claims that the cost to repair the retaining wall was approximately $5,400.  The NTTA also alleges that six other walls constructed on the project by JCG could have the same potential exposure to failure.  The Company has denied any liability, has tendered the claim to its insurance carriers and has cross-complained against its engineering subcontractor for potential design liability.  The extent of insurance coverage by the carriers of the Company and its subcontractor is undetermined at this time.  The parties to the lawsuit are engaged in mediation and discussions which involve the owner, the entity performing construction management, the Company’s subcontractor and the Company.  At this time, there are no assurances that the mediation efforts will be successful and the lawsuit may proceed to trial.  However, no trial date has been set.  The Company will vigorously defend the claims.  After discussion with our legal counsel, we have recorded loss contingencies which have not been material to the financial statements, to reflect the best estimate of the Company’s portion of the NTTA claim.  At this time, management does not believe it is possible to make a reasonably probable estimate of additional loss or a range of loss.
	The Company is subject to other claims and legal proceedings arising out of its business. The Company provides for costs related to contingencies when a loss from such claims is probable and the amount is reasonably determinable. In determining whether it is possible to provide an estimate of loss, or range of possible loss, the Company reviews and evaluates its litigation and regulatory matters on a quarterly basis in light of potentially relevant factual and legal developments. If we determine an unfavorable outcome is not probable or reasonably estimable, we do not accrue for a potential litigation loss. Management is unable to ascertain the ultimate outcome of other claims and legal proceedings; however, after review and consultation with counsel and taking into consideration relevant insurance coverage and related deductibles/self-insurance retention, management believes that it has meritorious defense to the claims and believes that the reasonably possible outcome of such claims will not, individually or in the aggregate, have a materially adverse effect on the consolidated results of operations, financial condition or cash flows of the Company.
	Bonding— At September 30, 2014 and December 31, 2013, the Company had bid and completion bonds issued and outstanding totaling approximately $1,355,950 and $1,458,744, respectively.
	Withdrawal liability for multiemployer pension plan  — In November 2011, Rockford and ARB, along with other members of the Pipe Line Contractors Association (“PLCA”), withdrew from the Central States Southeast and Southwest Areas Pension Fund multiemployer pension plan (the “Plan”).  The Company withdrew from the Plan in order to mitigate its liability in connection with the Plan, which is significantly underfunded.  The Company recorded a liability of $7,500 based on information provided by the Plan. However, the Plan has asserted that the PLCA members did not affect a proper withdrawal in 2011. The Company believes that a legally effective withdrawal occurred in November 2011 and has recorded the withdrawal liability on that basis. In May 2014, the Plan asserted that the liability was $11.7 million.  Without agreeing to the amount, the Company has made monthly payments, which are being expensed, including interest, totaling $458 through September 30, 2014.
	Prior to the Company’s acquisition, Q3C had also withdrawn from the Plan.  In November 2012, Q3C estimated a withdrawal liability of $85.  In the first quarter of 2013, the Plan asserted that the liability was $119.  Without agreeing to the amount, Q3C has made monthly payments, including interest, totaling $26 through September 30, 2014.
	Contingent Consideration  — Earnouts related to acquisitions are discussed in Note 13 — “Contingent Earnout Liabilities”.

Reportable_Operating_Segments

Reportable Operating Segments	9 Months Ended
	Sep. 30, 2014
Reportable Operating Segments	'
Reportable Operating Segments	'
	Note 20—Reportable Operating Segments
	For a number of years and through the end of the second quarter 2014, the Company segregated its business into three operating segments: the East Construction Services segment, the West Construction Services segment and the Engineering segment.  In the third quarter 2014, the Company reorganized its business segments to match the change in the Company’s internal organization and management structure.  The segment changes during the quarter reflect the focus of our new chief operating officer on the services we provide to our energy related customers, primarily in the Gulf Coast area (the “Energy segment”) and a continuing geographic view for the West and East segments. The chief operating officer regularly reviews the operating and financial performance based on these revised segments.  The operating segments include:  The West Construction Services segment (“West segment”), which is unchanged from the previous segment, the East Construction Services segment (“East segment”), which is realigned from the previous East Construction Services segment and the Energy segment (which includes the previous Engineering segment).  All prior period amounts related to the segment change have been retrospectively reclassified throughout these quarterly financial statements to conform to the new presentation.  The following is a brief description of each of the Company’s reportable segments and business activities.
	The West segment includes the underground and industrial operations and construction services performed by ARB, ARB Structures, Inc., Rockford, Alaska Continental Pipeline, Inc., Q3C, Primoris Renewables, LLC, Juniper Rock Corporation, Stellaris, LLC and Vadnais, acquired in June 2014.  Most of the entities perform work primarily in California; however, Rockford operates throughout the United States and Q3C operates in Colorado and the upper Midwest United States.  The Blythe joint venture is also included as a part of the segment.  The West segment consists of businesses headquartered primarily in the western United States.
	The East segment includes the JCG Heavy Civil division, the JCG Infrastructure and Maintenance division, BW Primoris and Cardinal Contractors, Inc. construction business, located primarily in the southeastern United States and in the Gulf Coast region of the United States and includes the heavy civil construction and infrastructure and maintenance operations.
	The Energy segment businesses are located primarily in the southeastern United States and in the Gulf Coast region of the United States.  The segment includes the operations of the PES pipeline and gas facility construction and maintenance operations the JCG Industrial division and the newly acquired Surber and Ram-Fab operations.  Additionally, the segment includes the OnQuest, Inc. and OnQuest Canada, ULC operations for the design and installation of high-performance furnaces and heaters for the oil refining, petrochemical and power generation industries.
	All intersegment revenues and gross profit, which were immaterial, have been eliminated in the following tables.
	Segment Revenues
	Revenue by segment for the three months ended September 30, 2014 and 2013 were as follows:
		For the three months ended September 30,
		2014				2013
	Segment	Revenue		% of		Revenue		% of
				Segment				Segment
				Revenue				Revenue
	West	$	289,405	47.2	%	$	362,362	65.7	%
	East	135,450		22.1	%	117,537		21.3	%
	Energy	188,382		30.7	%	71,434		13.0	%
	Total	$	613,237	100.0	%	$	551,333	100.0	%
	Revenue by segment for the nine months ended September 30, 2014 and 2013 were as follows
		For the nine months ended September 30,
		2014				2013
	Segment	Revenue		% of		Revenue		% of
				Segment				Segment
				Revenue				Revenue
	West	$	747,823	46.8	%	$	828,242	58.9	%
	East	360,975		22.6	%	316,218		22.5	%
	Energy	489,804		30.6	%	261,881		18.6	%
	Total	$	1,598,602	100.0	%	$	1,406,341	100.0	%
	Segment Gross Profit
	Gross profit by segment for the three months ended September 30, 2014 and 2013 were as follows:
		For the three months ended September 30,
		2014				2013
	Segment	Gross		% of		Gross		% of
		Profit		Segment		Profit		Segment
				Revenue				Revenue
	West	$	46,240	16.0	%	$	62,520	17.3	%
	East	9,110		6.7	%	4,527		3.9	%
	Energy	20,123		10.7	%	8,418		11.8	%
	Total	$	75,473	12.3	%	$	75,465	13.7	%
	Gross profit by segment for the nine months ended September 30, 2014 and 2013 were as follows:
		For the nine months ended September 30,
		2014				2013
	Segment	Gross		% of		Gross		% of
		Profit		Segment		Profit		Segment
				Revenue				Revenue
	West	$	115,723	15.5	%	$	133,195	16.1	%
	East	24,595		6.8	%	19,575		6.2	%
	Energy	46,106		9.4	%	28,328		10.8	%
	Total	$	186,424	11.7	%	$	181,098	12.9	%
	Segment Goodwill
	The following presents the amount of goodwill recorded by segment at September 30, 2014 and at December 31, 2013.
	Segment	September 30,		December 31,
		2014		2013
	West	$	45,239	$	45,239
	East	43,267		43,267
	Energy	30,120		30,120
	Total	$	118,626	$	118,626
	Geographic Region — Revenues and Total Assets
	The majority of the Company’s revenues are derived from customers in the United States and less than 1% is generated from sources outside of the United States.

Basis_of_Presentation_Policies

Basis of Presentation (Policies)	9 Months Ended
	Sep. 30, 2014
Basis of Presentation	'
Revenue recognition	'
	Revenue recognition
	Fixed-price contracts — Historically, a substantial portion of the Company’s revenue has been generated under fixed-price contracts. Fixed price contracts generally provide that the Company will perform all of the work required by the contract for a stated price.  For fixed-price contracts, the Company recognizes revenues using the percentage-of-completion method, which may result in uneven and irregular results. In the percentage-of-completion method, estimated revenues and resulting contract income are calculated based on the total costs incurred to date as a percentage of total estimated costs.
	Unit-price contracts — A unit-price contract provides performance of a specific project at a specific price for each unit of output.  These contracts are commonly associated with road building.
	Unforeseen events and circumstances can alter the estimate of the costs and potential profit associated with a particular contract.  Total estimated costs, and thus contract revenues and income, can be impacted by changes in productivity, scheduling, the unit cost of labor, subcontracts, materials and equipment. Additionally, external factors such as weather, client needs, client delays in providing permits and approvals, labor availability, governmental regulation and politics may affect the progress of a project’s completion and thus the timing of revenue recognition.  To the extent that original cost estimates are modified, estimated costs to complete increase, delivery schedules are delayed, or progress under a contract is otherwise impeded, cash flow, revenue recognition and profitability from a particular contract may be adversely affected.
	Other contract forms — The Company also uses time and material and cost reimbursable plus fee contracts.  For these jobs, revenue is recognized based on contractual terms.  For example, time and material contract revenues are recognized based on purchasing and employee time records.
	For all contracts, if an estimate of total contract cost indicates a loss on a contract, the projected loss is recognized in full at the time of the estimate.  The loss amount is recognized as an “accrued loss provision” and is included in the accrued expenses and other liabilities amount on the consolidated balance sheet.  Because the full loss has been recognized, any future revenues that are generated will result in the accrued loss provision being changed and the gross profit of the contract in future periods will be zero.
	The Company considers unapproved change orders to be contract variations for which it has customer approval for a change in scope but for which it does not have an agreed upon price change.  Costs associated with unapproved change orders are included in the estimated cost to complete the contracts and are treated as project costs as incurred. The Company recognizes revenue equal to costs incurred on unapproved change orders when realization of price approval is probable.  Unapproved change orders involve the use of estimates, and it is reasonably possible that revisions to the estimated costs and recoverable amounts may be required in future reporting periods to reflect changes in estimates or final agreements with customers.
	The Company considers claims to be amounts it seeks, or will seek, to collect from customers or others for customer-caused changes in contract specifications or design, or other customer-related causes of unanticipated additional contract costs on which there is no agreement with customers on both scope and price changes. Claims are included in the calculation of revenues when realization is probable and amounts can be reliably determined. Revenues in excess of contract costs incurred on claims are recognized when the amounts have been agreed upon with the customer.  Revenue in excess of contract costs from claims is recognized when an agreement is reached with customers as to the value of the claims, which in some instances may not occur until after completion of work under the contract. Costs associated with claims are included in the estimated costs to complete the contracts and are treated as project costs when incurred.
	The caption “Costs and estimated earnings in excess of billings” in the consolidated balance sheet represents unbilled receivables which arise when revenues have been recorded but the amount will not be billed until a later date.  Balances represent:  (a) unbilled amounts arising from the use of the percentage-of-completion method of accounting which may not be billed under the terms of the contract until a later date, (b) incurred costs to be billed under cost reimbursement type contracts, (c) amounts arising from routine lags in billing, or (d) the revenue associated with unapproved change orders or claims when realization is probable and amounts can be reliably determined.  For those contracts in which billings exceed contract revenues recognized to date, the excess amounts are included in the caption “Billings in excess of costs and estimated earnings”.
	In certain contracts, primarily for highway construction for governmental agencies, the Company is allowed to purchase and bill in advance for materials that will be used on the job.   The unused amount of materials purchased and billed, but not yet installed at the balance sheet date, is included in the caption “Inventory and uninstalled contract materials.”
	In accordance with applicable terms of certain construction contracts, retainage amounts may be withheld by customers until completion and acceptance of the project.  Some payments of the retainage may not be received for a significant period after completion of our portion of a project.  In some jurisdictions, retainage amounts are deposited into an escrow account.
Significant revision in contract estimate	'
	Significant revision in contract estimate  — As previously discussed, revenue recognition is based on the percentage-of-completion method for firm fixed-price contracts. Under this method, the costs incurred to date as a percentage of total estimated costs are used to calculate revenue. Total estimated costs, and thus contract revenues and margin, are impacted by many factors which can cause significant changes in estimates during the life cycle of a project.
	For projects that were in process in the prior year, but are either completed or continue to be in process during the current year, there can be a difference in revenues and profits recognized to the prior year, had current year estimates of costs to complete been known in the prior year.
Customer concentration	'
	Customer Concentration — The Company operates in multiple industry segments encompassing the construction of industrial and public works infrastructure assets throughout primarily the United States. Typically, the top ten customers in any one calendar year generate revenues in excess of 50% of total revenues; however in most years a different group make up the top ten customers.
	During the three and nine months ending September 30, 2014, revenues generated by the top ten customers were $309 million and $884 million, respectively, which represented 50.3% and 55.3%, respectively, of total revenues during the periods.  During these periods, TX DOT represented 7.8% and 8.6%, respectively, of total revenues and a petrochemical operating company represented 8.0% and 8.0%, respectively, of total revenues.
	During the three and nine months ending September 30, 2013, revenues generated by the top ten customers were $274 million and $717 million, respectively, which represented 49.7% and 51.0%, respectively, of total revenues during the periods.  During these periods, a large gas and electric utility represented 8.8% and 8.3%, respectively, of total revenues and a large pipeline company represented 9.7% and 6.8%, respectively, of total revenues.
	At September 30, 2014, approximately 12.4% of the Company’s accounts receivable were due from one customer, and that customer provided 8.0% of the Company’s revenues for the nine months ended September 30, 2014.  At September 30, 2013, approximately 13.1% of the Company’s accounts receivable were due from one customer, and that customer provided 7.4% of the Company’s revenues for the nine months ended September 30, 2013.
Multiemployer plans	'
	Multiemployer Plans  — Various subsidiaries in the West Construction Services segment are signatories to collective bargaining agreements.  These agreements require that the Company participate in and contribute to a number of multiemployer benefit plans for its union employees at rates determined by the agreements.  The trustees for each multiemployer plan determine the eligibility and allocations of contributions and benefit amounts, determine the types of benefits and administer the plan.  Federal law requires that if the Company were to withdraw from an agreement, it will incur a withdrawal obligation.  The potential withdrawal obligation may be significant.  Any withdrawal liability would be recorded when it is probable that a liability exists and can be reasonably estimated, in accordance with generally accepted accounting principles (“GAAP”).  In November 2011, the Company withdrew from the Central States Southeast and Southwest Areas Pension Fund multiemployer pension plan.  The Company has no plans to withdraw from any other agreements.  See Note 19 — “Commitments and Contingencies”.
Inventory and uninstalled contract materials	'
	Inventory and uninstalled contract materials — Inventory consists of expendable construction materials and small tools that will be used in construction projects and is valued at the lower of cost, using first-in, first-out method, or market.  Uninstalled contract materials include certain job specific materials not yet installed which are valued using the specific identification method relating the inventory cost to a specific project.  These materials have been purchased for specific jobs, normally highway construction jobs for state or local governmental agencies.  The Company retains responsibility for safeguarding of the materials.   At September 30, 2014, billed but not installed inventory was $51,927 compared to $44,966 at December 31, 2013.

Nature_of_Business_Tables

Nature of Business (Tables)	9 Months Ended
	Sep. 30, 2014
Nature of Business	'
Schedule of list of primary operating subsidiaries and their reportable operating segment	'
	Subsidiary	Operating Segment	Prior Operating Segment
	ARB, Inc. (“ARB”)	West	West
	ARB Structures, Inc.	West	West
	Q3 Contracting, Inc. (“Q3C”)	West	West
	Rockford Corporation (“Rockford”)	West	West
	Stellaris, LLC.	West	West
	Vadnais Trenchless Services, Inc. (“Vadnais”); acquired in 2014	West	West
	Silva Group (“Silva”)	East	East
	Cardinal Contractors, Inc.	East	East
	BW Primoris, LLC (“BWP”)	East	East
	James Construction Group, LLC (“JCG”):
	JCG Heavy Civil Division	East	East
	JCG Infrastructure and Maintenance Division	East	East
	JCG Industrial Division	Energy	East
	Primoris Energy Services Corporation (“PES”)	Energy	East
	OnQuest, Inc.	Energy	Engineering
	OnQuest, Canada, ULC (Born Heaters Canada, ULC prior to 2013)	Energy	Engineering

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2014
Fair Value Measurements	'
Schedule of financial assets and liabilities which are required to be measured at fair value	'
					Fair Value Measurements at Reporting Date
		Amount			Quoted Prices		Significant	Significant
		Recorded			in Active Markets		Other	Unobservable
		on Balance			for Identical Assets		Observable	Inputs
		Sheet			(Level 1)		Inputs	(Level 3)
							(Level 2)
	Assets as of September 30, 2014:
	Cash and cash equivalents	$	144,150		$	144,150	—	—
	Short-term investments	$	2,080		$	2,080	—	—
	Liabilities as of September 30, 2014:
	Contingent consideration	$	6,946		—		—	$	6,946
	Assets as of December 31, 2013:
	Cash and cash equivalents	$	196,077		$	196,077	—	—
	Short-term investments	$	18,686		$	18,686	—	—
	Liabilities as of December 31, 2013:
	Contingent consideration	$	9,233		—		—	$	9,233
Schedule of changes to the Company's contingent consideration liability Level 3 fair value measurements	'
	Contingent Consideration
	Balance at December 31, 2013	$	9,233
	Additions:
	Change in fair value of contingent consideration	642
	Vadnais acquisition	729
	Other acquisitions made in third quarter 2014	1,342
	Reductions:
	Payment to Q3C sellers	(5,000		)
	Balance at September 30, 2014	$	6,946

Accounts_Receivable_Tables

Accounts Receivable (Tables)	9 Months Ended
	Sep. 30, 2014
Accounts Receivable	'
Summary of accounts receivable	'
		September 30,		December 31,
		2014		2013
	Contracts receivable, net of allowance for doubtful accounts of $525 at September 30, 2014 and $692 at December 31, 2013	$	323,387	$	257,354
	Retention receivable	64,221		47,054
		387,608		304,408
	Other accounts receivable	773		547
		$	388,381	$	304,955

Costs_and_Estimated_Earnings_o1

Costs and Estimated Earnings on Uncompleted Contracts (Tables)	9 Months Ended
	Sep. 30, 2014
Costs and Estimated Earnings on Uncompleted Contracts	'
Schedule of costs and estimated earnings on uncompleted contracts	'
		September 30,			December 31,
		2014			2013
	Costs incurred on uncompleted contracts	$	4,743,681		$	4,741,249
	Gross profit recognized	559,359			582,430
		5,303,040			5,323,679
	Less: billings to date	(5,371,318		)	(5,439,898		)
		$	(68,278	)	$	(116,219	)
Schedule of costs and estimated earnings on uncompleted contracts included in consolidated balance sheet	'
		September 30,			December 31,
		2014			2013
	Costs and estimated earnings in excess of billings	$	96,150		$	57,146
	Billings in excess of costs and estimated earnings	(164,428		)	(173,365		)
		$	(68,278	)	$	(116,219	)

Business_Combinations_Tables

Business Combinations (Tables)	9 Months Ended
	Sep. 30, 2014
Business Combinations	'
Schedule of pro forma results	'
		Three months				Nine months
		ended September 30,				ended September 30,
		2014		2013		2014		2013
	Revenues	620,503		558,543		1,622,480		1,430,124
	Income before provision for income taxes	43,407		35,358		87,091		75,034
	Net income attributable to Primoris	27,946		20,680		53,994		44,517
	Weighted average common shares outstanding:
	Basic	51,606		51,568		51,622		51,529
	Diluted	51,759		51,671		51,759		51,595
	Earnings per share:
	Basic	$	0.54	$	0.40	$	1.05	$	0.86
	Diluted	$	0.54	$	0.40	$	1.04	$	0.86

Intangible_Assets_Tables

Intangible Assets (Tables)	9 Months Ended
	Sep. 30, 2014
Intangible Assets	'
Summary of intangible asset categories, amounts and the average amortization periods	'
		Amortization		September 30,		December 31,
		Period		2014		2013
	Tradename	3 to 10 years		$	19,535	$	21,023
	Non-compete agreements	2 to 5 years		$	2,120	$	2,575
	Customer relationships	3 to 15 years		$	20,816	$	21,705
	Total			$	42,471	$	45,303
Schedule of estimated amortization expense for intangible assets	'
	For the Years Ending	Estimated
	December 31,	Intangible
		Amortization
		Expense
	2014 (remaining three months)	$	2,004
	2015	7,023
	2016	6,274
	2017	5,968
	2018	5,535
	Thereafter	15,667
		$	42,471

Accounts_Payable_and_Accrued_L1

Accounts Payable and Accrued Liabilities (Tables)	9 Months Ended
	Sep. 30, 2014
Accounts Payable and Accrued Liabilities	'
Summary of accrued expenses and other current liabilities	'
		September 30,		December 31,
		2014		2013
	Payroll and related employee benefits	$	47,067	$	36,556
	Insurance, including self-insurance reserves	35,433		33,880
	Reserve for estimated losses on uncompleted contracts	3,005		1,392
	Corporate income taxes and other taxes	8,786		13,305
	Accrued overhead cost	1,314		1,165
	Other	4,447		4,781
		$	100,052	$	91,079

Noncontrolling_Interests_Table

Noncontrolling Interests (Tables)	9 Months Ended
	Sep. 30, 2014
Noncontrolling Interests	'
Schedule of the Blythe joint venture operating activities included in the Company's consolidated statements of income	'
		Three months				Nine months
		ended September 30,				ended September 30,
		2014		2013		2014	2013
	Revenues	—		15,468		940	47,371
	Net income attributable to noncontrolling interests	—		1,348		432	1,947
Schedule of the carrying value of the assets and liabilities associated with the operations of the Blythe joint venture included in the Company's consolidated balance sheets	'
		September 30,			December 31,
		2014			2013
	Cash	$	250		$	3,025
	Accounts receivable	—			1,085
	Billings in excess of costs and estimated earnings	348			2,041

Earnings_Per_Share_Tables

Earnings Per Share (Tables)	9 Months Ended
	Sep. 30, 2014
Dividends and Earnings Per Share	'
Schedule of computation of basic and diluted earnings per share	'
			Three months				Nine months
			ended September 30,				ended September 30,
			2014		2013		2014		2013
	Numerator:
	Net income attributable to Primoris		$	27,390	$	21,845	$	54,226	$	47,179
	Denominator (shares in thousands):
	Weighted average shares for computation of basic earnings per share		51,606		51,568		51,622		51,529
	Dilutive effect of shares issued to independent directors		4		3		3		10
	Dilutive effect of unvested restricted stock units (1)		149		100		134		55
	Dilutive effect of shares to be issued Q3C sellers (2)		—		—		—		1
	Weighted average shares for computation of diluted earnings per share		51,759		51,671		51,759		51,595
	Earnings per share:
	Basic earnings per share		$	0.53	$	0.42	$	1.05	$	0.92
	Diluted earnings per share		$	0.53	$	0.42	$	1.05	$	0.91
		-1		Represents the dilutive effect of a grant for 100,000 shares of Units on May 3, 2013 and 48,512 shares of Units on March 24, 2014.
		-2		Represents the dilutive effect of 29,273 unregistered shares of common stock provided in January 2013 as part of the purchase consideration for the Q3C acquisition.

Reportable_Operating_Segments_

Reportable Operating Segments (Tables)	9 Months Ended
	Sep. 30, 2014
Reportable Operating Segments	'
Schedule of revenue by segment	'
		For the three months ended September 30,
		2014				2013
	Segment	Revenue		% of		Revenue		% of
				Segment				Segment
				Revenue				Revenue
	West	$	289,405	47.2	%	$	362,362	65.7	%
	East	135,450		22.1	%	117,537		21.3	%
	Energy	188,382		30.7	%	71,434		13.0	%
	Total	$	613,237	100.0	%	$	551,333	100.0	%
		For the nine months ended September 30,
		2014				2013
	Segment	Revenue		% of		Revenue		% of
				Segment				Segment
				Revenue				Revenue
	West	$	747,823	46.8	%	$	828,242	58.9	%
	East	360,975		22.6	%	316,218		22.5	%
	Energy	489,804		30.6	%	261,881		18.6	%
	Total	$	1,598,602	100.0	%	$	1,406,341	100.0	%
Schedule of gross profit by segment	'
		For the three months ended September 30,
		2014				2013
	Segment	Gross		% of		Gross		% of
		Profit		Segment		Profit		Segment
				Revenue				Revenue
	West	$	46,240	16.0	%	$	62,520	17.3	%
	East	9,110		6.7	%	4,527		3.9	%
	Energy	20,123		10.7	%	8,418		11.8	%
	Total	$	75,473	12.3	%	$	75,465	13.7	%
		For the nine months ended September 30,
		2014				2013
	Segment	Gross		% of		Gross		% of
		Profit		Segment		Profit		Segment
				Revenue				Revenue
	West	$	115,723	15.5	%	$	133,195	16.1	%
	East	24,595		6.8	%	19,575		6.2	%
	Energy	46,106		9.4	%	28,328		10.8	%
	Total	$	186,424	11.7	%	$	181,098	12.9	%
Schedule of amount of goodwill recorded by segment	'
	Segment	September 30,		December 31,
		2014		2013
	West	$	45,239	$	45,239
	East	43,267		43,267
	Energy	30,120		30,120
	Total	$	118,626	$	118,626

Nature_of_Business_Details

Nature of Business (Details) (USD $)

3 Months Ended

6 Months Ended

9 Months Ended

0 Months Ended

3 Months Ended

24 Months Ended

0 Months Ended

Sep. 30, 2014

Jun. 30, 2014

Sep. 30, 2014

Jun. 05, 2014

Sep. 30, 2014

Jun. 05, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Jan. 22, 2014

Sep. 30, 2014

item

segment

segment

Vadnais Corporation

Vadnais Corporation

Vadnais Corporation

Surber, RamFab and Williams

Surber

RamFab

PES

Blythe

BWP

BWP

2014 earnout target

2014 earnout target

item

item

Blaus Wasser, LLC

Blaus Wasser, LLC

Nature of Business

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of operating segments

'

3

3

'

'

'

'

'

'

'

'

'

'

Number of subsidiaries that were merged into PES

'

'

'

'

'

'

'

'

'

2

'

'

'

Ownership percentage

'

'

'

'

'

'

'

'

'

'

50.00%

'

'

Amount of purchase of assets and liabilities

'

'

'

'

'

'

$8,200,000

'

'

'

'

$5,000,000

'

Capitalized property, plant and equipment

'

'

'

'

'

'

'

'

'

'

'

'

3,900,000

Payments to Acquire Businesses, Gross

'

'

'

6,354,000

'

'

'

'

'

'

'

'

'

Potential contingent consideration

'

'

'

'

'

900,000

'

1,800,000

200,000

'

'

'

'

Estimated fair value of the potential contingent consideration

'

'

'

$729,000

$816,000

'

'

$1,100,000

$200,000

'

'

'

'

Number of small purchases made

3

'

'

'

'

'

3

'

'

'

'

'

'

Contingent earnout period (in years)

'

'

'

'

'

'

'

'3 years

'6 months

'

'

'

'

Basis_of_Presentation_Details

Basis of Presentation (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Customer concentration	'	'	'	'	'
Revenues	$613,237	$551,333	$1,598,602	$1,406,341	'
Inventory and uninstalled contract materials	'	'	'	'	'
Billed but uninstalled inventory	51,927	'	51,927	'	44,966
Revenues | Customer concentration | Top ten customers	'	'	'	'	'
Customer concentration	'	'	'	'	'
Number of top customers	10	10	10	10	'
Number of calendar years in which top customers typically generate minimum specified percentage of revenue	'	'	1	'	'
Revenues	$309,000	$274,000	$884,000	$717,000	'
Percentage of concentration risk	50.30%	49.70%	55.30%	51.00%	'
Revenues | Customer concentration | Top ten customers | Minimum	'	'	'	'	'
Customer concentration	'	'	'	'	'
Minimum percentage of revenues generated by top ten customers	'	'	50.00%	'	'
Revenues | Customer concentration | TX DOT	'	'	'	'	'
Customer concentration	'	'	'	'	'
Percentage of concentration risk	7.80%	'	8.60%	'	'
Revenues | Customer concentration | Large gas pipeline company	'	'	'	'	'
Customer concentration	'	'	'	'	'
Percentage of concentration risk	8.00%	9.70%	8.00%	6.80%	'
Revenues | Customer concentration | Large gas and electric utility	'	'	'	'	'
Customer concentration	'	'	'	'	'
Percentage of concentration risk	'	8.80%	'	8.30%	'
Revenues | Customer concentration | One customer	'	'	'	'	'
Customer concentration	'	'	'	'	'
Percentage of concentration risk	'	'	8.00%	7.40%	'
Accounts receivable. | Customer concentration | One customer	'	'	'	'	'
Customer concentration	'	'	'	'	'
Percentage of concentration risk	'	'	12.40%	13.10%	'
Number of customers	'	'	1	1	'

Fair_Value_Measurements_Detail

Fair Value Measurements (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Assets	'	'
Short-term investments	$2,080	$18,686
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)	'	'
Assets	'	'
Cash and cash equivalents	144,150	196,077
Short-term investments	2,080	18,686
Recurring | Significant Unobservable Inputs (Level 3)	'	'
Liabilities	'	'
Contingent consideration	6,946	9,233
Recurring | Amount Recorded on Balance Sheet	'	'
Assets	'	'
Cash and cash equivalents	144,150	196,077
Short-term investments	2,080	18,686
Liabilities	'	'
Contingent consideration	$6,946	$9,233

Fair_Value_Measurements_Detail1

Fair Value Measurements (Details 2) (USD $)	9 Months Ended		0 Months Ended	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Jun. 05, 2014	Sep. 30, 2014	Sep. 30, 2014	Sep. 30, 2014	Sep. 30, 2014
			Vadnais Corporation	Contingent Consideration Liability	Contingent Consideration Liability	Contingent Consideration Liability	Contingent Consideration Liability
				item	Q3 Contracting	Vadnais Corporation	Surber, RamFab and Williams
Rollforward of contingent consideration liability level three fair value measurements	'	'	'	'	'	'	'
Balance at the beginning of the period	'	'	'	$9,233	'	'	'
Change in fair value of contingent consideration	-4,358	-9,287	'	642	'	'	'
Additions on acquisition	'	'	729	'	'	729	1,342
Payments	'	'	-6,354	'	-5,000	'	'
Balance at the end of the period	'	'	'	$6,946	'	'	'
Additional information	'	'	'	'	'	'	'
Number of unobservable inputs	'	'	'	2	'	'	'
Minimum probability of acquired entity meeting contractual operating performance target (as a percent)	'	'	'	33.00%	'	'	'
Maximum probability of acquired entity meeting contractual operating performance target (as a percent)	'	'	'	100.00%	'	'	'

Accounts_Receivable_Details

Accounts Receivable (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Accounts Receivable	'	'
Contracts receivable, net of allowance for doubtful accounts	$323,387	$257,354
Retention receivable	64,221	47,054
Contracts receivable and retention	387,608	304,408
Other accounts receivable	773	547
Accounts receivable, net	388,381	304,955
Allowance for doubtful accounts	$525	$692

Costs_and_Estimated_Earnings_o2

Costs and Estimated Earnings on Uncompleted Contracts (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Costs and Estimated Earnings on Uncompleted Contracts	'	'
Costs incurred on uncompleted contracts	$4,743,681	$4,741,249
Gross profit recognized	559,359	582,430
Costs and Estimated Earnings on Uncompleted Contracts	5,303,040	5,323,679
Less: billings to date	-5,371,318	-5,439,898
Net cost and estimated earnings in excess of billings	-68,278	-116,219
Amount included in consolidated balance sheet	'	'
Costs and estimated earnings in excess of billings	96,150	57,146
Billings in excess of costs and estimated earnings	-164,428	-173,365
Net cost and estimated earnings in excess of billings	($68,278)	($116,219)

Equity_Method_Investments_Deta

Equity Method Investments (Details) (USD $)	3 Months Ended		9 Months Ended		0 Months Ended			1 Months Ended	0 Months Ended	3 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2013	Jul. 01, 2010	Jul. 01, 2010	Aug. 31, 2014	Feb. 05, 2014	Mar. 31, 2014	Nov. 17, 2012
					WPE and Kealine	WesPac	WesPac	WesPac & Midstream	Alvah, Inc.	Alvah, Inc.	Alvah, Inc.
					Highstar		Kealine
Equity method investments	'	'	'	'	'	'	'	'	'	'	'
Membership interest (as a percent)	'	'	'	'	'	50.00%	50.00%	'	'	'	49.00%
Cash proceeds from sale of projects	'	'	'	'	$6,082	'	'	$5,250	'	'	'
Cash paid by 51% owner under net asset buy-out option to the entity	'	'	6,439	'	'	'	'	'	1,189	'	'
Earnings data:	'	'	'	'	'	'	'	'	'	'	'
Company's equity in earnings	5,250	113	5,264	169	'	'	'	'	'	14	'
Share in distribution	'	'	'	$3,186	'	'	'	'	'	'	'

Business_Combinations_Details

Business Combinations (Details) (USD $)	3 Months Ended	0 Months Ended		3 Months Ended
	Sep. 30, 2014	Jun. 05, 2014	Jun. 05, 2014	Sep. 30, 2014	Sep. 30, 2014	Sep. 30, 2014
	item	Vadnais Corporation	Vadnais Corporation	Surber, RamFab and Williams	Surber	RamFab
			2014 earnout target	item
Business combinations	'	'	'	'	'	'
Fair value of consideration	'	'	'	$8,200,000	'	'
Cash payment made	'	6,354,000	'	'	'	'
Number of small purchases made	3	'	'	3	'	'
Contingent earnout period (in years)	'	'	'	'	'3 years	'6 months
Contingent consideration in cash	'	'	900,000	'	1,800,000	200,000
Estimated fair value of the potential contingent consideration	'	$729,000	'	'	$1,100,000	$200,000

Business_Combinations_Details_

Business Combinations (Details 2) (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Share data, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Pro forma results	'	'	'	'
Percentage of pro forma tax rate used in calculating taxes on income from continuing operations	39.00%	39.00%	39.00%	39.00%
Revenues	$620,503	$558,543	$1,622,480	$1,430,124
Income before provision for income taxes	43,407	35,358	87,091	75,034
Net income attributable to Primoris	$27,946	$20,680	$53,994	$44,517
Weighted average common shares outstanding:	'	'	'	'
Basic (in shares)	51,606	51,568	51,622	51,529
Diluted (in shares)	51,759	51,671	51,759	51,595
Earnings per share:	'	'	'	'
Basic (in dollars per share)	$0.54	$0.40	$1.05	$0.86
Diluted (in dollars per share)	$0.54	$0.40	$1.04	$0.86

Intangible_Assets_Details

Intangible Assets (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Intangible assets	'	'	'	'	'
Total	$42,471	'	$42,471	'	$45,303
Amortization expense of intangible assets	1,945	1,891	5,632	5,576	'
Estimated future amortization expense for intangible assets	'	'	'	'	'
2014 (remaining three months)	2,004	'	2,004	'	'
2015	7,023	'	7,023	'	'
2016	6,274	'	6,274	'	'
2017	5,968	'	5,968	'	'
2018	5,535	'	5,535	'	'
Thereafter	15,667	'	15,667	'	'
Tradename	'	'	'	'	'
Intangible assets	'	'	'	'	'
Total	19,535	'	19,535	'	21,023
Tradename | Minimum	'	'	'	'	'
Intangible assets	'	'	'	'	'
Amortization Period	'	'	'3 years	'	'
Tradename | Maximum	'	'	'	'	'
Intangible assets	'	'	'	'	'
Amortization Period	'	'	'10 years	'	'
Non-compete agreements	'	'	'	'	'
Intangible assets	'	'	'	'	'
Total	2,120	'	2,120	'	2,575
Non-compete agreements | Minimum	'	'	'	'	'
Intangible assets	'	'	'	'	'
Amortization Period	'	'	'2 years	'	'
Non-compete agreements | Maximum	'	'	'	'	'
Intangible assets	'	'	'	'	'
Amortization Period	'	'	'5 years	'	'
Customer relationship	'	'	'	'	'
Intangible assets	'	'	'	'	'
Total	$20,816	'	$20,816	'	$21,705
Customer relationship | Minimum	'	'	'	'	'
Intangible assets	'	'	'	'	'
Amortization Period	'	'	'3 years	'	'
Customer relationship | Maximum	'	'	'	'	'
Intangible assets	'	'	'	'	'
Amortization Period	'	'	'15 years	'	'

Accounts_Payable_and_Accrued_L2

Accounts Payable and Accrued Liabilities (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Accounts Payable and Accrued Liabilities	'	'
Retention amounts included in accounts payable	$9,001	$5,602
Accrued expenses and other current liabilities	'	'
Payroll and related employee benefits	47,067	36,556
Insurance, including self-insurance reserves	35,433	33,880
Reserve for estimated losses on uncompleted contracts	3,005	1,392
Corporate income taxes and other taxes	8,786	13,305
Accrued overhead cost	1,314	1,165
Other	4,447	4,781
Total accrued expenses and other current liabilities	$100,052	$91,079

Credit_Arrangements_Details

Credit Arrangements (Details)

9 Months Ended

9 Months Ended

0 Months Ended

9 Months Ended

9 Months Ended

9 Months Ended

9 Months Ended

Sep. 30, 2014

Dec. 28, 2012

Sep. 30, 2014

Jul. 25, 2013

Dec. 28, 2012

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Senior Notes

Senior Notes

Senior Notes

Notes Agreement

Notes Agreement

Notes Agreement

Credit Agreement

Credit Agreement

Credit Agreement

Credit Agreement

Credit Agreement

Credit Agreement

Canadian Credit Facility

Canadian Credit Facility

Canadian Credit Facility

USD ($)

USD ($)

Minimum

USD ($)

USD ($)

Minimum

USD ($)

Federal funds rate

Minimum

Revolving line of credit

Commercial letters of credit

Commercial letters of credit

Commercial letters of credit

Commercial letters of credit

Commercial letters of credit

USD ($)

payment

USD ($)

USD ($)

USD ($)

USD ($)

CAD

CAD

Maximum

Credit arrangements

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Maximum borrowing capacity

'

'

'

'

'

'

$75,000,000

'

'

$75,000,000

'

'

8,000,000

'

'

Incremental maximum borrowing capacity

'

'

'

'

'

'

50,000,000

'

'

'

'

'

'

'

'

Basis spread on variable rate (as a percent)

'

'

'

'

'

'

'

0.50%

'

'

'

'

'

'

'

Prepayment to be paid on debt

'

'

5,000,000

'

'

'

'

'

5,000,000

'

'

'

'

'

'

Interest rate (as a percent)

3.65%

'

'

3.85%

'

'

'

'

'

'

'

'

'

'

'

Restrictions on investments, change of control provisions and provisions as a percentage of total assets to be disposed off

'

'

'

'

'

20.00%

'

'

20.00%

'

'

'

'

'

'

Total commercial letters of credit outstanding

'

'

'

'

'

'

'

'

'

'

4,659,000

5,074,000

2,252,000

2,512,000

'

Available borrowing capacity

'

'

'

'

'

'

70,341,000

'

'

'

'

'

5,488,000

'

'

Borrowings outstanding

'

'

'

'

'

'

'

'

'

0

'

'

'

'

'

Term of credit facility

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'5 years

Annual fee (as a percent)

'

'

'

'

'

'

'

'

'

'

'

'

1.00%

'

'

Required principal payment

7,100,000

'

'

3,600,000

'

'

'

'

'

'

'

'

'

'

'

Initial principal amount

'

$50,000,000

'

$25,000,000

$25,000,000

'

'

'

'

'

'

'

'

'

'

Number of annual principal payments

'

'

'

7

'

'

'

'

'

'

'

'

'

'

'

Noncontrolling_Interests_Detai

Noncontrolling Interests (Details) (USD $)	3 Months Ended		9 Months Ended			3 Months Ended	9 Months Ended		12 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
						Blythe joint venture	Blythe joint venture	Blythe joint venture	Blythe joint venture
						Primary beneficiary	Primary beneficiary	Primary beneficiary	Primary beneficiary
Noncontrolling Interests	'	'	'	'	'	'	'	'	'
Revenues	$613,237	$551,333	$1,598,602	$1,406,341	'	$15,468	$940	$47,371	'
Net income attributable to noncontrolling interests	'	1,348	432	1,947	'	1,348	432	1,947	'
Tax effect on income recognized	15,105	14,075	32,813	30,272	'	'	0	'	'
Distributions to non-controlling interests	'	'	'	'	'	'	1,515	2,500	'
Distributions from joint venture	'	'	'	'	'	'	1,515	2,500	'
Capital contributions	'	'	'	'	'	'	0	'	0
Cash	'	'	'	'	'	'	250	'	3,025
Accounts receivable	388,381	'	388,381	'	304,955	'	'	'	1,085
Billings in excess of costs and estimated earnings	$164,428	'	$164,428	'	$173,365	'	$348	'	$2,041

Contingent_Earnout_Liabilities1

Contingent Earnout Liabilities (Details) (USD $)

3 Months Ended

1 Months Ended

1 Months Ended

0 Months Ended

3 Months Ended

Sep. 30, 2014

Mar. 31, 2014

Sep. 30, 2014

Jun. 05, 2014

Mar. 31, 2014

Mar. 31, 2014

Jun. 05, 2014

Sep. 30, 2014

Jun. 05, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

item

Q3 Contracting

Q3 Contracting

Q3 Contracting

Q3 Contracting

Q3 Contracting

Vadnais Corporation

Vadnais Corporation

Vadnais Corporation

Surber, RamFab and Williams

Surber

RamFab

2014 earnout target

2014 earnout target

2014 earnout target

2014 earnout target

2013 earnout target

2014 earnout target

2014 earnout target

item

Minimum

Contingent earnout liabilities

'

'

'

'

'

'

'

'

'

'

'

'

Cash paid

'

'

'

'

'

$5,000,000

$6,354,000

'

'

'

'

'

Minimum potential contingent consideration

'

3,750,000

'

'

'

'

'

'

'

'

'

'

EBITDA threshold for measuring financial performance

'

'

'

'

19,000,000

'

'

'

'

'

'

'

Additional potential contingent consideration

'

1,250,000

'

'

'

'

'

'

'

'

'

'

EBITDA threshold for measuring financial performance, case two

'

'

'

'

22,000,000

'

'

'

'

'

'

'

Number of small purchases made

3

'

'

'

'

'

'

'

'

3

'

'

Amount of purchase of assets and liabilities

'

'

'

'

'

'

'

'

'

8,200,000

'

'

Contingent consideration in cash

'

5,000,000

'

'

'

'

'

'

900,000

'

1,800,000

200,000

Contingent earnout period (in years)

'

'

'

'

'

'

'

'

'

'

'3 years

'6 months

Estimated fair value of the potential contingent consideration

'

'

$4,788,000

$729,000

'

'

$729,000

$816,000

'

'

$1,100,000

$200,000

Related_Party_Transactions_Det

Related Party Transactions (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Related party transactions	'	'	'	'
Lease payments to related party	$377	$379	$1,140	$1,176
SIGI	'	'	'	'
Related party transactions	'	'	'	'
Lease payments to related party	'	'	656	688
Roger Newnham	'	'	'	'
Related party transactions	'	'	'	'
Lease payments to related party	'	'	219	223
Lemmie Rockford	'	'	'	'
Related party transactions	'	'	'	'
Lease payments to related party	'	'	68	68
Quality RE Partners	'	'	'	'
Related party transactions	'	'	'	'
Lease payments to related party	'	'	$198	$198
Number of former shareholders owning leased property	'	'	3	'
Number of current employees owning leased property	'	'	2	'

StockBased_Compensation_Detail

Stock-Based Compensation (Details) (Equity Plan, Restricted Stock Units, USD $)	0 Months Ended			3 Months Ended	9 Months Ended
	Apr. 30, 2014	Mar. 24, 2014	3-May-13	Sep. 30, 2014	Sep. 30, 2014
			item
Equity Plan | Restricted Stock Units	'	'	'	'	'
Stock-based compensation	'	'	'	'	'
Shares granted	'	48,512	100,000	'	148,512
Number of equal installments to vest units over the service period	'	'	4	'	'
Shares vested	25,000	'	'	'	'
Units Vesting percentage on September 23, 2015	'	'	'	'	50.00%
Units remaining vesting percentage on March 23, 2017	'	'	'	'	50.00%
Number of shares of common stock issued for each unit when vested	'	'	1	'	'
Compensation expense recognized	'	'	'	$262,000	$671,000
Unrecognized compensation expense	'	'	'	$2,660,000	$2,660,000
Period to recognize unrecognized compensation expense	'	'	'	'	'2 years 6 months
Accrued dividend equivalent units	'	'	'	'	67

Income_Taxes_Details

Income Taxes (Details)	9 Months Ended
	Sep. 30, 2014
Income Taxes	'
Effective tax rate on income before provision for income taxes excluding income attributable to noncontrolling interests (as a percent)	37.57%
Effective tax rate for income attributable to Primoris (as a percent)	37.70%
U.S. federal statutory rate (as a percent)	35.00%
Minimum period of statute of limitations of state and foreign jurisdictions	'3 years
Maximum period of statute of limitations of state and foreign jurisdictions	'5 years

Dividends_and_Earnings_Per_Sha1

Dividends and Earnings Per Share (Details) (USD $)

0 Months Ended

3 Months Ended

9 Months Ended

In Thousands, except Per Share data, unless otherwise specified

Oct. 15, 2014

Aug. 05, 2014

Jul. 15, 2014

2-May-14

Apr. 15, 2014

Feb. 26, 2014

Jan. 15, 2014

Oct. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Dividends and Earnings Per Share

'

'

'

'

'

'

'

'

'

'

'

'

Cash dividend declared (in dollars per share)

'

$0.04

'

$0.04

'

$0.04

'

$0.04

'

'

'

'

Total dividend paid

$2,062

'

$1,808

'

$1,808

'

$1,805

'

'

'

$5,421

$3,352

Numerator:

'

'

'

'

'

'

'

'

'

'

'

'

Net income attributable to Primoris

'

'

'

'

'

'

'

'

$27,390

$21,845

$54,226

$47,179

Denominator:

'

'

'

'

'

'

'

'

'

'

'

'

Weighted average shares for computation of basic earnings per share

'

'

'

'

'

'

'

'

51,606

51,568

51,622

51,529

Dilutive effect of shares issued to independent directors

'

'

'

'

'

'

'

'

4

3

3

10

Dilutive effect of unvested restricted stock units

'

'

'

'

'

'

'

'

149

100

134

55

Dilutive effect of shares to be issued to Q3C sellers

'

'

'

'

'

'

'

'

'

'

'

1

Weighted average shares for computation of diluted earnings per share

'

'

'

'

'

'

'

'

51,759

51,671

51,759

51,595

Earnings per share:

'

'

'

'

'

'

'

'

'

'

'

'

Basic (in dollars per share)

'

'

'

'

'

'

'

'

$0.53

$0.42

$1.05

$0.92

Diluted (in dollars per share)

'

'

'

'

'

'

'

'

$0.53

$0.42

$1.05

$0.91

Dividends_and_Earnings_Per_Sha2

Dividends and Earnings Per Share (Details 2)	1 Months Ended	0 Months Ended		9 Months Ended
	Jan. 31, 2013	Mar. 24, 2014	3-May-13	Sep. 30, 2014
	Q3 Contracting	Equity Plan	Equity Plan	Equity Plan
		Restricted Stock Units	Restricted Stock Units	Restricted Stock Units
Earnings per share	'	'	'	'
Shares granted	'	48,512	100,000	148,512
Number of unregistered shares of common stock issued	29,273	'	'	'

Stockholders_Equity_Details

Stockholders' Equity (Details) (USD $)

3 Months Ended

9 Months Ended

1 Months Ended

0 Months Ended

9 Months Ended

1 Months Ended

Sep. 30, 2014

Sep. 30, 2014

Feb. 28, 2014

Sep. 30, 2014

Mar. 31, 2014

Feb. 28, 2014

Jul. 31, 2013

Mar. 31, 2013

Feb. 28, 2013

Mar. 24, 2014

3-May-13

Sep. 30, 2014

Jan. 31, 2013

LTR Plan

LTR Plan

LTR Plan

LTR Plan

LTR Plan

LTR Plan

Equity Plan

Equity Plan

Equity Plan

Q3 Contracting

Restricted Stock Units

Restricted Stock Units

Restricted Stock Units

Stockholders' equity

'

'

'

'

'

'

'

'

'

'

'

'

'

Amount received in exchange for shares of common stock under a long term incentive plan

'

'

'

'

$1,671,000

'

'

$1,455,000

'

'

'

'

'

Shares of common stock purchased under the long-term incentive plan

'

'

'

'

77,455

'

'

131,989

'

'

'

'

'

Discounted price from market price at which shares purchased by participants in LTI Plan (as a percent)

'

'

'

'

75.00%

'

'

'

'

'

'

'

'

Shares of common stock issued as a part of quarterly compensation of non-employee members of the Board of Directors

'

'

'

6,172

'

6,375

9,110

'

12,480

'

'

'

'

Stock issued to sellers (in shares)

'

'

'

'

'

'

'

'

'

'

'

'

29,273

Shares granted

'

'

'

'

'

'

'

'

'

48,512

100,000

148,512

'

Aggregate purchase price up to which shares can be acquired under share repurchase program

'

'

23,000,000

'

'

'

'

'

'

'

'

'

'

Number of shares purchased and cancelled under the share repurchase program

100,000

100,000

'

'

'

'

'

'

'

'

'

'

'

Amount paid for shares purchased and cancelled under share repurchase program

$2,800,000

$2,800,000

'

'

'

'

'

'

'

'

'

'

'

Average cost of repurchased shares of stock (in dollars per share)

$28.44

$28.44

'

'

'

'

'

'

'

'

'

'

'

Commitments_and_Contingencies_

Commitments and Contingencies (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Commitments and Contingencies.	'	'	'	'
Total lease expense	$3,250	$3,566	$10,416	$11,111
Lease payments to related party	$377	$379	$1,140	$1,176

Commitments_and_Contingencies_1

Commitments and Contingencies (Details 2) (USD $)

9 Months Ended

0 Months Ended

9 Months Ended

Sep. 30, 2014

31-May-14

Nov. 30, 2011

Feb. 07, 2012

Feb. 07, 2012

Sep. 30, 2014

Mar. 31, 2013

Nov. 30, 2012

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

James Construction Group LLC

James Construction Group LLC

Q3 Contracting

Q3 Contracting

Q3 Contracting

Letters of credit

Letters of credit

Bonding

Bonding

North Texas Tollway Authority v. James Construction Group, LLC

North Texas Tollway Authority v. James Construction Group, LLC

item

Commitments and contingencies

'

'

'

'

'

'

'

'

'

'

'

'

Total commercial letters of credit outstanding

'

'

'

'

'

'

'

'

$6,911,000

$7,696,000

'

'

Cost to repair retaining wall

'

'

'

5,400,000

'

'

'

'

'

'

'

'

Number of other walls constructed on the project, which could have potential exposure to failure

'

'

'

'

6

'

'

'

'

'

'

'

Bid and completion bonds issued and outstanding

'

'

'

'

'

'

'

'

'

'

1,355,950,000

1,458,744,000

Withdrawal liability recorded

'

'

7,500,000

'

'

'

119,000

85,000

'

'

'

'

Withdrawal liability asserted by the Plan

'

11,700,000

'

'

'

'

'

'

'

'

'

'

Monthly payments towards the liability amount

$458,000

'

'

'

'

$26,000

'

'

'

'

'

'

Reportable_Operating_Segments_1

Reportable Operating Segments (Details) (USD $)	3 Months Ended		6 Months Ended	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Jun. 30, 2014	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
			segment	segment
Reportable Operating Segments	'	'	'	'	'	'
Number of operating segments	'	'	3	3	'	'
Segment reporting information	'	'	'	'	'	'
Revenue	$613,237	$551,333	'	$1,598,602	$1,406,341	'
% of Segment Revenue	100.00%	100.00%	'	100.00%	100.00%	'
Gross Profit	75,473	75,465	'	186,424	181,098	'
% of Segment Revenue	12.30%	13.70%	'	11.70%	12.90%	'
Goodwill	118,626	'	'	118,626	'	118,626
West	'	'	'	'	'	'
Segment reporting information	'	'	'	'	'	'
Revenue	289,405	362,362	'	747,823	828,242	'
% of Segment Revenue	47.20%	65.70%	'	46.80%	58.90%	'
Gross Profit	46,240	62,520	'	115,723	133,195	'
% of Segment Revenue	16.00%	17.30%	'	15.50%	16.10%	'
Goodwill	45,239	'	'	45,239	'	45,239
East	'	'	'	'	'	'
Segment reporting information	'	'	'	'	'	'
Revenue	135,450	117,537	'	360,975	316,218	'
% of Segment Revenue	22.10%	21.30%	'	22.60%	22.50%	'
Gross Profit	9,110	4,527	'	24,595	19,575	'
% of Segment Revenue	6.70%	3.90%	'	6.80%	6.20%	'
Goodwill	43,267	'	'	43,267	'	43,267
Energy	'	'	'	'	'	'
Segment reporting information	'	'	'	'	'	'
Revenue	188,382	71,434	'	489,804	261,881	'
% of Segment Revenue	30.70%	13.00%	'	30.60%	18.60%	'
Gross Profit	20,123	8,418	'	46,106	28,328	'
% of Segment Revenue	10.70%	11.80%	'	9.40%	10.80%	'
Goodwill	$30,120	'	'	$30,120	'	$30,120

Reportable_Operating_Segments_2

Reportable Operating Segments (Details 2) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Revenues and total assets by geographic area	'	'	'	'	'
Revenue	$613,237	$551,333	$1,598,602	$1,406,341	'
% of Revenue	100.00%	100.00%	100.00%	100.00%	'
Total Assets	$1,138,565	'	$1,138,565	'	$1,050,693
Non-United States	'	'	'	'	'
Revenues and total assets by geographic area	'	'	'	'	'
% of Revenue	'	'	1.00%	'	'