<?xml version="1.0" encoding="utf-8"?>
<FilingSummary xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <Version>2.4.0.8</Version>
  <ProcessingTime />
  <ReportFormat>Html</ReportFormat>
  <ContextCount>37</ContextCount>
  <ElementCount>133</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>false</FootnotesReported>
  <SegmentCount>9</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>6</UnitCount>
  <MyReports>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>101 - Document - Document and Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://pwrr.com/taxonomy/role/DocumentandEntityInformation</Role>
      <ShortName>Document and Entity Information</ShortName>
    </Report>
    <Report>
      <IsDefault>true</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>103 - Statement - Condensed Balance Sheets (Unaudited)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://pwrr.com/taxonomy/role/StatementOfFinancialPositionClassified</Role>
      <ShortName>Condensed Balance Sheets (Unaudited)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>104 - Statement - Condensed Balance Sheets (Unaudited) (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://pwrr.com/taxonomy/role/StatementOfFinancialPositionClassifiedParenthetical</Role>
      <ShortName>Condensed Balance Sheets (Unaudited) (Parenthetical)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>105 - Statement - Condensed Statements of Operations (Unaudited)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://pwrr.com/taxonomy/role/StatementOfIncomeAlternative</Role>
      <ShortName>Condensed Statements of Operations (Unaudited)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>106 - Statement - Condensed Statements of Cash Flows (Unaudited)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://pwrr.com/taxonomy/role/StatementOfCashFlowsIndirect</Role>
      <ShortName>Condensed Statements of Cash Flows (Unaudited)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>107 - Disclosure - Basis of Presentation</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://pwrr.com/taxonomy/role/NotesToFinancialStatementsOrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureTextBlock</Role>
      <ShortName>Basis of Presentation</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>108 - Disclosure - Recent Accounting Pronouncements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://pwrr.com/taxonomy/role/NotesToFinancialStatementsNewAccountingPronouncementsAndChangesInAccountingPrinciplesTextBlock</Role>
      <ShortName>Recent Accounting Pronouncements</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>109 - Disclosure - Changes in Shareholders' Equity</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://pwrr.com/taxonomy/role/NotesToFinancialStatementsStockholdersEquityNoteDisclosureTextBlock</Role>
      <ShortName>Changes in Shareholders' Equity</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>110 - Disclosure - Debt</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://pwrr.com/taxonomy/role/NotesToFinancialStatementsDebtDisclosureTextBlock</Role>
      <ShortName>Debt</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>111 - Disclosure - Income (Loss) per Common Share</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://pwrr.com/taxonomy/role/NotesToFinancialStatementsEarningsPerShareTextBlock</Role>
      <ShortName>Income (Loss) per Common Share</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>112 - Disclosure - Commitments and Contingent Liabilities</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://pwrr.com/taxonomy/role/NotesToFinancialStatementsCommitmentsAndContingenciesDisclosureTextBlock</Role>
      <ShortName>Commitments and Contingent Liabilities</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>113 - Disclosure - Amtrak Agreement</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://pwrr.com/taxonomy/role/NotesToFinancialStatementsAgreementWithRelatedPartyTextBlock</Role>
      <ShortName>Amtrak Agreement</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>114 - Disclosure - Open-Top Hoppers</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://pwrr.com/taxonomy/role/NotesToFinancialStatementsBusinessCombinationDisclosureTextBlock</Role>
      <ShortName>Open-Top Hoppers</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>115 - Disclosure - Subsequent event and dividends</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://pwrr.com/taxonomy/role/NotesToFinancialStatementsSubsequentEventsTextBlock</Role>
      <ShortName>Subsequent event and dividends</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>116 - Disclosure - Changes in Shareholders' Equity (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://pwrr.com/taxonomy/role/NotesToFinancialStatementsStockholdersEquityNoteDisclosureTextBlockTables</Role>
      <ShortName>Changes in Shareholders' Equity (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>117 - Disclosure - Income (Loss) per Common Share (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://pwrr.com/taxonomy/role/NotesToFinancialStatementsEarningsPerShareTextBlockTables</Role>
      <ShortName>Income (Loss) per Common Share (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>118 - Disclosure - Amtrak Agreement (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://pwrr.com/taxonomy/role/NotesToFinancialStatementsAgreementWithRelatedPartyTextBlockTables</Role>
      <ShortName>Amtrak Agreement (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>119 - Disclosure - Changes in Shareholders' Equity - Changes in Shareholders' Equity (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://pwrr.com/taxonomy/role/DisclosureChangesInShareholdersEquityChangesInShareholdersEquity</Role>
      <ShortName>Changes in Shareholders' Equity - Changes in Shareholders' Equity (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>120 - Disclosure - Changes in Shareholders' Equity - Changes in Shareholders' Equity (Parenthetical) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://pwrr.com/taxonomy/role/DisclosureChangesInShareholdersEquityChangesInShareholdersEquityParenthetical</Role>
      <ShortName>Changes in Shareholders' Equity - Changes in Shareholders' Equity (Parenthetical) (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>121 - Disclosure - Debt - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://pwrr.com/taxonomy/role/DisclosureDebtAdditionalInformation</Role>
      <ShortName>Debt - Additional Information (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>122 - Disclosure - Income (Loss) per Common Share - Reconciliation of Weighted-Average Shares Used for the Basic Computation and that Used for the Diluted Computation (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://pwrr.com/taxonomy/role/DisclosureIncomeLossPerCommonShareReconciliationOfWeightedAverageSharesUsedForTheBasicComputationAndThatUsedForTheDilutedComputation</Role>
      <ShortName>Income (Loss) per Common Share - Reconciliation of Weighted-Average Shares Used for the Basic Computation and that Used for the Diluted Computation (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>123 - Disclosure - Income (Loss) Per Common Share - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://pwrr.com/taxonomy/role/DisclosureIncomeLossPerCommonShareAdditionalInformation</Role>
      <ShortName>Income (Loss) Per Common Share - Additional Information (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>124 - Disclosure - Commitments and Contingent Liabilities - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://pwrr.com/taxonomy/role/DisclosureCommitmentsAndContingentLiabilitiesAdditionalInformation</Role>
      <ShortName>Commitments and Contingent Liabilities - Additional Information (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>125 - Disclosure - Amtrak Agreement - Schedule of Remaining Track Mileage Credit (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://pwrr.com/taxonomy/role/DisclosureAmtrakAgreementScheduleOfRemainingTrackMileageCredit</Role>
      <ShortName>Amtrak Agreement - Schedule of Remaining Track Mileage Credit (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>126 - Disclosure - Open-Top Hoppers - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://pwrr.com/taxonomy/role/DisclosureOpenTopHoppersAdditionalInformation</Role>
      <ShortName>Open-Top Hoppers - Additional Information (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>127 - Disclosure - Subsequent Event and Dividends - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://pwrr.com/taxonomy/role/DisclosureSubsequentEventAndDividendsAdditionalInformation</Role>
      <ShortName>Subsequent Event and Dividends - Additional Information (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <Logs>
    <Log type="Info">'Monetary' elements on report '124 - Disclosure - Commitments and Contingent Liabilities - Additional Information (Detail)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">Process Flow-Through: 103 - Statement - Condensed Balance Sheets (Unaudited)</Log>
    <Log type="Info">	Process Flow-Through: Removing column 'Sep. 30, 2013'</Log>
    <Log type="Info">	Process Flow-Through: Removing column 'Dec. 31, 2012'</Log>
    <Log type="Info">Process Flow-Through: 104 - Statement - Condensed Balance Sheets (Unaudited) (Parenthetical)</Log>
    <Log type="Info">Process Flow-Through: 105 - Statement - Condensed Statements of Operations (Unaudited)</Log>
    <Log type="Info">Process Flow-Through: 106 - Statement - Condensed Statements of Cash Flows (Unaudited)</Log>
  </Logs>
  <InputFiles>
    <File>pwx-20140930.xml</File>
    <File>pwx-20140930.xsd</File>
    <File>pwx-20140930_cal.xml</File>
    <File>pwx-20140930_def.xml</File>
    <File>pwx-20140930_lab.xml</File>
    <File>pwx-20140930_pre.xml</File>
  </InputFiles>
  <SupplementalFiles />
  <BaseTaxonomies />
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
