Name:	prim_DebtInstrumentAnnualPrincipalPaymentPercentage
Namespace Prefix:	prim_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

The period of time specific payments are to be made per the agreement.

No definition available.

Name:	prim_DebtInstrumentPaymentPeriodicTerm
Namespace Prefix:	prim_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Amount of the required periodic payments applied to principal as a percentage of the original principal amount.

No definition available.

Name:	prim_DebtInstrumentPeriodicPaymentPrincipalPercentage
Namespace Prefix:	prim_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

The amount that the debt instrument can increase per the accordian feature.

No definition available.

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

Aggregate dividends declared during the period for each share of common stock outstanding.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

Name:	us-gaap_CommonStockDividendsPerShareDeclared
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Balance Type:	na
Period Type:	duration

Face (par) amount of debt instrument at time of issuance.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

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

- References

No definition available.

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- References

No definition available.

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

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_CreditFacilityAxis=prim_CreditFacilityWithPrivateBankBankOfWestAndIBERIABANKCorporationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_CreditFacilityAxis=us-gaap_LoansPayableMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_StatementScenarioAxis=prim_FirstPaymentPeriodMember
Namespace Prefix:
Data Type:	na
Balance Type:
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