Name:	prim_MultiemployerPlansAnnualContributedNumberOfPensionPlans
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Represents the number of pension plans in which annual contribution was made by the entity during the last three years.

No definition available.

Name:	prim_MultiemployerPlansAnnualContributionsNumberOfPensionPlans
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Data Type:	xbrli:integerItemType
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Represents the amount of contributions made to the specified 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.

No definition available.

Name:	prim_MultiemployerPlansContributedSpecifiedPlans
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Represents the amount of contributions made to the other 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.

No definition available.

Name:	prim_MultiemployerPlansContributionsOtherPlans
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Data Type:	xbrli:monetaryItemType
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Represents the amount of contributions made to the significant 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.

No definition available.

Name:	prim_MultiemployerPlansContributionsSignificantPlans
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

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

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.

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

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Name:	us-gaap_MultiemployerPlanNameAxis=prim_ConstructionLaborersPensionTrustForSouthernCaliforniaMember
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Name:	us-gaap_MultiemployerPlanNameAxis=prim_LaborersPensionTrustFundForNorthernCaliforniaMember
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Name:	us-gaap_MultiemployerPlanNameAxis=prim_LIUNANationalIndustrialPensionFundMember
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Name:	us-gaap_MultiemployerPlanNameAxis=prim_PipelineIndustryBenefitFundMember
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