Name:	prim_MultiemployerPlansAnnualContributedNumberOfPensionPlans
Namespace Prefix:	prim_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

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
Namespace Prefix:	prim_
Data Type:	xbrli:integerItemType
Balance Type:	na
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
Namespace Prefix:	prim_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

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
Namespace Prefix:	prim_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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

Amount of contributions made to multiemployer plan by all employers who participate in plan.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 80
-Section 50
-Paragraph 7
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=65877416&loc=SL14450678-114947

Name:	us-gaap_MultiemployerPlansPlanContributions1
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Data Type:	xbrli:monetaryItemType
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Period Type:	duration

Name:	us-gaap_MultiemployerPlanNameAxis=prim_CentralPensionFundMember
Namespace Prefix:
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Name:	us-gaap_MultiemployerPlanNameAxis=prim_SouthernCaliforniaPipetradesTrustFundsMember
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Data Type:	na
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Name:	us-gaap_MultiemployerPlanNameAxis=prim_LIUNANationalIndustrialPensionFundMember
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Name:	us-gaap_MultiemployerPlanNameAxis=prim_LaborersPensionTrustFundForNorthernCaliforniaMember
Namespace Prefix:
Data Type:	na
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Name:	us-gaap_MultiemployerPlanNameAxis=prim_PlumbersAndPipefittersNationalPensionFundMember
Namespace Prefix:
Data Type:	na
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Name:	us-gaap_MultiemployerPlanNameAxis=prim_ConstructionLaborersPensionTrustForSouthernCaliforniaMember
Namespace Prefix:
Data Type:	na
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Name:	us-gaap_MultiemployerPlanNameAxis=prim_MinnesotaLaborersPensionFundMember
Namespace Prefix:
Data Type:	na
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Name:	us-gaap_MultiemployerPlanNameAxis=prim_OperatingEngineerTrustFundsMember
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Data Type:	na
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