Represents the amount of bonds issued and outstanding.

No definition available.

Name:	prim_BondsIssuedAndOutstanding
Namespace Prefix:	prim_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of the obligation, asserted by the Plan, by withdrawing from a pension or postretirement benefit plan to which two or more unrelated employers contribute where assets contributed by one participating employer may be used to provide benefits to employees of other participating employers

+ References

No definition available.

+ Details

Name:	prim_MultiemployerPlansWithdrawalAssertedObligation
Namespace Prefix:	prim_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents the number of construction projects completed by the company.

+ References

No definition available.

+ Details

Name:	prim_NumberOfCompletedProjects
Namespace Prefix:	prim_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Liability attributable to (i) billings in excess of costs under the percentage of completion contract accounting method representing the difference between contractually invoiced amounts (billings) and revenue recognized based, for example, on costs incurred to estimated total costs at period end or (ii) contractually invoiced amounts (billings) in excess of costs incurred and accumulated under the completed contract accounting method that are expected to be realized within one year or one operating cycle, whichever is longer, from the reporting date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 605

-SubTopic 35

-Section 45

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=6802688&loc=d3e57788-111642

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 605

-SubTopic 35

-Section 45

-Paragraph 5

-URI http://asc.fasb.org/extlink&oid=6802688&loc=d3e57807-111642

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 605

-SubTopic 35

-Section 45

-Paragraph 4

-URI http://asc.fasb.org/extlink&oid=6802688&loc=d3e57795-111642

+ Details

Name:	us-gaap_BillingsInExcessOfCostCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

No definition available.

+ Details

Name:	us-gaap_LettersOfCreditOutstandingAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of judgment or settlement awarded to (against) the entity in respect of litigation.

+ References

No definition available.

+ Details

Name:	us-gaap_LitigationSettlementAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	us-gaap_LossContingenciesLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of receivable related to a loss contingency accrual. For example, an insurance recovery receivable.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 460

-SubTopic 10

-Section 50

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=6851643&loc=d3e12053-110248

+ Details

Name:	us-gaap_LossContingencyReceivable
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of collections of receivables pertaining to a loss contingency.

+ References

No definition available.

+ Details

Name:	us-gaap_LossContingencyRelatedReceivableCarryingValueReceipts
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of contributions made to the multiemployer plan by all employers who participate in the plan. A multiemployer plan is a pension or postretirement benefit plan to which two or more unrelated employers contribute where assets contributed by one participating employer may be used to provide benefits to employees of other participating employers.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 80

-Section 50

-Paragraph 7

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=35742057&loc=SL14450678-114947

+ Details

Name:	us-gaap_MultiemployerPlansPlanContributions
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of the obligation recognized by withdrawing from a pension or postretirement benefit plan to which two or more unrelated employers contribute where assets contributed by one participating employer may be used to provide benefits to employees of other participating employers.

+ References

No definition available.

+ Details

Name:	us-gaap_MultiemployerPlansWithdrawalObligation
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	dei_LegalEntityAxis=prim_Q3ContractingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=prim_JamesConstructionGroupLLCMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LitigationCaseAxis=prim_ConstructionProjectLitigationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LitigationCaseAxis=prim_ConstructionProjectLitigationProjectOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LitigationCaseAxis=prim_ConstructionProjectLitigationProjectTwoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LossContingenciesByNatureOfContingencyAxis=us-gaap_StandbyLettersOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LossContingenciesByNatureOfContingencyAxis=us-gaap_SuretyBondMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Commitments and Contingencies (Details 2) (USD $)	41 Months Ended	1 Months Ended	0 Months Ended	3 Months Ended
Commitments and Contingencies (Details 2) (USD $)	Mar. 31, 2015	Apr. 30, 2015	Feb. 25, 2015	Mar. 31, 2015	Dec. 31, 2014	May 31, 2014	Nov. 30, 2011	Mar. 31, 2013	Nov. 30, 2012
Commitments and contingencies
Billings in excess of costs and estimated earnings	$ 145,982,000us-gaap_BillingsInExcessOfCostCurrent			$ 145,982,000us-gaap_BillingsInExcessOfCostCurrent	$ 158,595,000us-gaap_BillingsInExcessOfCostCurrent
Withdrawal liability recorded							7,500,000
Withdrawal liability asserted by the Plan						11,700,000
Monthly payments towards the liability amount	1,008,000
Construction Projects
Commitments and contingencies
Number of projects under litigation	2			2
Billings in excess of costs and estimated earnings	29,000,000			29,000,000
Construction Project One
Commitments and contingencies
Receivable recorded relating to the project	32,900,000			32,900,000
Construction Project Two
Commitments and contingencies
Receivable recorded relating to the project	29,700,000			29,700,000
Amount due received relating to the project		11,200,000
James Construction Group LLC \| North Texas Tollway Authority v. James Construction Group, LLC
Commitments and contingencies
Expected cost on settlement			9,000,000
Q3 Contracting
Commitments and contingencies
Withdrawal liability recorded								119,000	85,000
Monthly payments towards the liability amount				34,000
Letters of credit
Commitments and contingencies
Total commercial letters of credit outstanding	5,601,000			5,601,000	6,864,000
Bonding
Commitments and contingencies
Bid and completion bonds issued and outstanding	$ 1,423,744,000			$ 1,423,744,000	$ 1,518,018,000