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

Amount of obligation before accrued loss provision on transfer good or service to customer for which consideration has been received or is receivable, classified as current.

No definition available.

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

Amount of increase (decrease) in contract with customers liability current.

No definition available.

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

Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable, classified as current.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=82913815&loc=SL49130532-203044

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=82913815&loc=SL49130531-203044

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 8
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130549-203045

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

Amount of revenue recognized that was previously included in balance of obligation to transfer good or service to customer for which consideration from customer has been received or is due.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 8
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130549-203045