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  <Logs>
    <Log type="Info">'Monetary' elements on report '4110 - Disclosure - Credit Arrangements (Details)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">Process Flow-Through: 0010 - Statement - CONDENSED CONSOLIDATED BALANCE SHEETS</Log>
    <Log type="Info">	Process Flow-Through: Removing column 'Mar. 31, 2012'</Log>
    <Log type="Info">	Process Flow-Through: Removing column 'Dec. 31, 2011'</Log>
    <Log type="Info">Process Flow-Through: 0015 - Statement - CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical)</Log>
    <Log type="Info">Process Flow-Through: 0020 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF INCOME</Log>
    <Log type="Info">Process Flow-Through: 0030 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS</Log>
    <Log type="Info">	Process Flow-Through: Removing column '12 Months Ended
Dec. 31, 2012'</Log>
  </Logs>
  <InputFiles>
    <File>prim-20130331.xml</File>
    <File>prim-20130331.xsd</File>
    <File>prim-20130331_cal.xml</File>
    <File>prim-20130331_def.xml</File>
    <File>prim-20130331_lab.xml</File>
    <File>prim-20130331_pre.xml</File>
  </InputFiles>
  <SupplementalFiles />
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</FilingSummary>
