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Stockholders' Equity (Details) (USD $)
1 Months Ended 0 Months Ended 11 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Mar. 24, 2014
May 03, 2013
Mar. 24, 2014
Feb. 28, 2014
Common Stock            
Aggregate purchase price up to which shares can be acquired under share repurchase program           $ 23,000,000us-gaap_StockRepurchaseProgramAuthorizedAmount1
LTR Plan            
Common Stock            
Amount received in exchange for shares of common stock under a long term incentive plan $ 1,621,000us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan
/ us-gaap_PlanNameAxis
= prim_LongTermRetentionPlanMember
$ 1,671,000us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan
/ us-gaap_PlanNameAxis
= prim_LongTermRetentionPlanMember
       
Shares of common stock purchased under the long-term incentive plan 96,257us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans
/ us-gaap_PlanNameAxis
= prim_LongTermRetentionPlanMember
77,455us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans
/ us-gaap_PlanNameAxis
= prim_LongTermRetentionPlanMember
       
Discounted price from market price at which shares purchased by participants in LTR Plan (as a percent) 75.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardDiscountFromMarketPricePurchaseDate
/ us-gaap_PlanNameAxis
= prim_LongTermRetentionPlanMember
         
Shares of common stock issued as a part of quarterly compensation of non-employee members of the Board of Directors 8,168us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation
/ us-gaap_PlanNameAxis
= prim_LongTermRetentionPlanMember
6,375us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation
/ us-gaap_PlanNameAxis
= prim_LongTermRetentionPlanMember
       
Equity Plan | Restricted Stock Units            
Common Stock            
Shares granted     48,512us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
/ us-gaap_PlanNameAxis
= prim_EquityIncentivePlan2013Member
100,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
/ us-gaap_PlanNameAxis
= prim_EquityIncentivePlan2013Member
148,512us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
/ us-gaap_PlanNameAxis
= prim_EquityIncentivePlan2013Member