<?xml version='1.0' encoding='UTF-8'?>
<FilingSummary>
  <Version>3.7.0.1</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>463</ContextCount>
  <ElementCount>592</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>true</FootnotesReported>
  <SegmentCount>131</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>24</UnitCount>
  <MyReports>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>1001 - Document - Document and Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DocumentandEntityInformation</Role>
      <ShortName>Document and Entity Information</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>1003 - Statement - Consolidated balance sheets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/StatementOfFinancialPositionClassified</Role>
      <ShortName>Consolidated balance sheets</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>1004 - Statement - Consolidated balance sheets (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/StatementOfFinancialPositionClassifiedParenthetical</Role>
      <ShortName>Consolidated balance sheets (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>1005 - Statement - Consolidated statements of operations</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/StatementOfIncomeAlternative</Role>
      <ShortName>Consolidated statements of operations</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>1006 - Statement - Consolidated statements of stockholders' equity (deficit)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/StatementOfShareholdersEquityAndOtherComprehensiveIncome</Role>
      <ShortName>Consolidated statements of stockholders' equity (deficit)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>1007 - Statement - Consolidated statements of cash flows</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/StatementOfCashFlowsIndirect</Role>
      <ShortName>Consolidated statements of cash flows</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>1008 - Disclosure - Nature of operations and summary of significant accounting policies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsOrganizationConsolidationBasisOfPresentationBusinessDescriptionAndAccountingPoliciesTextBlock</Role>
      <ShortName>Nature of operations and summary of significant accounting policies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>1009 - Disclosure - Chapter 11 Reorganization</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsReorganizationUnderChapter11OfUSBankruptcyCodeDisclosureTextBlock</Role>
      <ShortName>Chapter 11 Reorganization</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>1010 - Disclosure - Fresh start accounting</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsFreshStartAccountingTextBlock</Role>
      <ShortName>Fresh start accounting</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>1011 - Disclosure - Supplemental disclosures to the consolidated statements of cash flows</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsCashFlowSupplementalDisclosuresTextBlock</Role>
      <ShortName>Supplemental disclosures to the consolidated statements of cash flows</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>1012 - Disclosure - Debt</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsDebtDisclosureTextBlock</Role>
      <ShortName>Debt</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>1013 - Disclosure - Derivative instruments</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsDerivativeInstrumentsAndHedgingActivitiesDisclosureTextBlock</Role>
      <ShortName>Derivative instruments</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>1014 - Disclosure - Fair value measurements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsFairValueDisclosuresTextBlock</Role>
      <ShortName>Fair value measurements</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>1015 - Disclosure - Asset retirement obligations</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsAssetRetirementObligationDisclosureTextBlock</Role>
      <ShortName>Asset retirement obligations</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>1016 - Disclosure - Deferred Compensation</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock</Role>
      <ShortName>Deferred Compensation</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>1017 - Disclosure - Commitments and contingencies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsCommitmentsAndContingenciesDisclosureTextBlock</Role>
      <ShortName>Commitments and contingencies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>1018 - Disclosure - Acquisitions and divestitures</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsMergersAcquisitionsAndDispositionsDisclosuresTextBlock</Role>
      <ShortName>Acquisitions and divestitures</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>1019 - Disclosure - Property and equipment</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsPropertyPlantAndEquipmentDisclosureTextBlock</Role>
      <ShortName>Property and equipment</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>1020 - Disclosure - Income taxes</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsIncomeTaxDisclosureTextBlock</Role>
      <ShortName>Income taxes</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>1021 - Disclosure - Stockholders' equity</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsStockholdersEquityNoteDisclosureTextBlock</Role>
      <ShortName>Stockholders' equity</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>20</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>1022 - Disclosure - Retirement benefits</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsPensionAndOtherPostretirementBenefitsDisclosureTextBlock</Role>
      <ShortName>Retirement benefits</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>21</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>1023 - Disclosure - Oil and natural gas activities</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsOilAndGasPropertiesTextBlock</Role>
      <ShortName>Oil and natural gas activities</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>22</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>1024 - Disclosure - Disclosures about oil and natural gas activities (unaudited)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsOilAndGasExplorationAndProductionIndustriesDisclosuresTextBlock</Role>
      <ShortName>Disclosures about oil and natural gas activities (unaudited)</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>23</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>1025 - Disclosure - Nature of operations and summary of significant accounting policies (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsOrganizationConsolidationBasisOfPresentationBusinessDescriptionAndAccountingPoliciesTextBlockPolicies</Role>
      <ShortName>Nature of operations and summary of significant accounting policies (Policies)</ShortName>
      <MenuCategory>Policies</MenuCategory>
      <Position>24</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>1026 - Disclosure - Nature of operations and summary of significant accounting policies (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsOrganizationConsolidationBasisOfPresentationBusinessDescriptionAndAccountingPoliciesTextBlockTables</Role>
      <ShortName>Nature of operations and summary of significant accounting policies (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsOrganizationConsolidationBasisOfPresentationBusinessDescriptionAndAccountingPoliciesTextBlock</ParentRole>
      <Position>25</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>1027 - Disclosure - Oil and natural gas activities (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsOilAndGasPropertiesTextBlockTables</Role>
      <ShortName>Oil and natural gas activities (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsOilAndGasPropertiesTextBlock</ParentRole>
      <Position>26</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>1028 - Disclosure - Chapter 11 Reorganization (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsReorganizationUnderChapter11OfUSBankruptcyCodeDisclosureTextBlockTables</Role>
      <ShortName>Chapter 11 Reorganization (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsReorganizationUnderChapter11OfUSBankruptcyCodeDisclosureTextBlock</ParentRole>
      <Position>27</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>1029 - Disclosure - Fresh start accounting (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsFreshStartAccountingTextBlockTables</Role>
      <ShortName>Fresh start accounting (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsFreshStartAccountingTextBlock</ParentRole>
      <Position>28</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>1030 - Disclosure - Supplemental disclosures to the consolidated statements of cash flows (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsCashFlowSupplementalDisclosuresTextBlockTables</Role>
      <ShortName>Supplemental disclosures to the consolidated statements of cash flows (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsCashFlowSupplementalDisclosuresTextBlock</ParentRole>
      <Position>29</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>1031 - Disclosure - Debt (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsDebtDisclosureTextBlockTables</Role>
      <ShortName>Debt (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsDebtDisclosureTextBlock</ParentRole>
      <Position>30</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>1032 - Disclosure - Derivative instruments (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsDerivativeInstrumentsAndHedgingActivitiesDisclosureTextBlockTables</Role>
      <ShortName>Derivative instruments (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsDerivativeInstrumentsAndHedgingActivitiesDisclosureTextBlock</ParentRole>
      <Position>31</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>1033 - Disclosure - Fair value measurements (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsFairValueDisclosuresTextBlockTables</Role>
      <ShortName>Fair value measurements (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsFairValueDisclosuresTextBlock</ParentRole>
      <Position>32</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>1034 - Disclosure - Asset retirement obligations (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsAssetRetirementObligationDisclosureTextBlockTables</Role>
      <ShortName>Asset retirement obligations (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsAssetRetirementObligationDisclosureTextBlock</ParentRole>
      <Position>33</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>1035 - Disclosure - Deferred Compensation (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlockTables</Role>
      <ShortName>Deferred Compensation (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock</ParentRole>
      <Position>34</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>1036 - Disclosure - Property and equipment (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsPropertyPlantAndEquipmentDisclosureTextBlockTables</Role>
      <ShortName>Property and equipment (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsPropertyPlantAndEquipmentDisclosureTextBlock</ParentRole>
      <Position>35</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>1037 - Disclosure - Income taxes (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsIncomeTaxDisclosureTextBlockTables</Role>
      <ShortName>Income taxes (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsIncomeTaxDisclosureTextBlock</ParentRole>
      <Position>36</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>1038 - Disclosure - Stockholders' equity (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsStockholdersEquityNoteDisclosureTextBlockTables</Role>
      <ShortName>Stockholders' equity (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsStockholdersEquityNoteDisclosureTextBlock</ParentRole>
      <Position>37</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>1039 - Disclosure - Commitments and contingencies (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsCommitmentsAndContingenciesDisclosureTextBlockTables</Role>
      <ShortName>Commitments and contingencies (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsCommitmentsAndContingenciesDisclosureTextBlock</ParentRole>
      <Position>38</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>1040 - Disclosure - Disclosures about oil and natural gas activities (unaudited) (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsOilAndGasExplorationAndProductionIndustriesDisclosuresTextBlockTables</Role>
      <ShortName>Disclosures about oil and natural gas activities (unaudited) (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsOilAndGasExplorationAndProductionIndustriesDisclosuresTextBlock</ParentRole>
      <Position>39</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>1041 - Disclosure - Nature of operations and summary of significant accounting policies (Cash and Accounts Receivable) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureNatureOfOperationsAndSummaryOfSignificantAccountingPoliciesCashAndAccountsReceivable</Role>
      <ShortName>Nature of operations and summary of significant accounting policies (Cash and Accounts Receivable) (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsOrganizationConsolidationBasisOfPresentationBusinessDescriptionAndAccountingPoliciesTextBlockTables</ParentRole>
      <Position>40</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>1042 - Disclosure - Nature of operations and summary of significant accounting policies (Inventories) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureNatureOfOperationsAndSummaryOfSignificantAccountingPoliciesInventories</Role>
      <ShortName>Nature of operations and summary of significant accounting policies (Inventories) (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsOrganizationConsolidationBasisOfPresentationBusinessDescriptionAndAccountingPoliciesTextBlockTables</ParentRole>
      <Position>41</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>1043 - Disclosure - Nature of operations and summary of significant accounting policies (Unevaluated Oil and Natural Gas Properties) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureNatureOfOperationsAndSummaryOfSignificantAccountingPoliciesUnevaluatedOilAndNaturalGasProperties</Role>
      <ShortName>Nature of operations and summary of significant accounting policies (Unevaluated Oil and Natural Gas Properties) (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsOrganizationConsolidationBasisOfPresentationBusinessDescriptionAndAccountingPoliciesTextBlockTables</ParentRole>
      <Position>42</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>1044 - Disclosure - Nature of operations and summary of significant accounting policies (Income Taxes) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureNatureOfOperationsAndSummaryOfSignificantAccountingPoliciesIncomeTaxes</Role>
      <ShortName>Nature of operations and summary of significant accounting policies (Income Taxes) (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsOrganizationConsolidationBasisOfPresentationBusinessDescriptionAndAccountingPoliciesTextBlockTables</ParentRole>
      <Position>43</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>1045 - Disclosure - Nature of operations and summary of significant accounting policies (Cost Reduction Initiatives) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureNatureOfOperationsAndSummaryOfSignificantAccountingPoliciesCostReductionInitiatives</Role>
      <ShortName>Nature of operations and summary of significant accounting policies (Cost Reduction Initiatives) (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsOrganizationConsolidationBasisOfPresentationBusinessDescriptionAndAccountingPoliciesTextBlockTables</ParentRole>
      <Position>44</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>1046 - Disclosure - Chapter 11 Reorganization - Narrative (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureChapter11ReorganizationNarrative</Role>
      <ShortName>Chapter 11 Reorganization - Narrative (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>45</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>1047 - Disclosure - Fresh Start Accounting - Additional information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureFreshStartAccountingAdditionalInformation</Role>
      <ShortName>Fresh Start Accounting - Additional information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>46</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>1048 - Disclosure - Fresh Start Accounting - Reconciliation of Enterprise Value to Estimated Fair Value of the Successor's Common Stock (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureFreshStartAccountingReconciliationOfEnterpriseValueToEstimatedFairValueOfTheSuccessorsCommonStock</Role>
      <ShortName>Fresh Start Accounting - Reconciliation of Enterprise Value to Estimated Fair Value of the Successor's Common Stock (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>47</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>1049 - Disclosure - Fresh Start Accounting - Reconciliation of Enterprise Value to Estimated Reorganization Value of the Successor's Assets (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureFreshStartAccountingReconciliationOfEnterpriseValueToEstimatedReorganizationValueOfTheSuccessorsAssets</Role>
      <ShortName>Fresh Start Accounting - Reconciliation of Enterprise Value to Estimated Reorganization Value of the Successor's Assets (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>48</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>1050 - Disclosure - Fresh Start Accounting - Consolidated Balance Sheet (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureFreshStartAccountingConsolidatedBalanceSheet</Role>
      <ShortName>Fresh Start Accounting - Consolidated Balance Sheet (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>49</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>1051 - Disclosure - Fresh Start Accounting - Consolidated Balance Sheet (Parenthetical) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureFreshStartAccountingConsolidatedBalanceSheetParenthetical</Role>
      <ShortName>Fresh Start Accounting - Consolidated Balance Sheet (Parenthetical) (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>50</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>1052 - Disclosure - Supplemental disclosures to the consolidated statements of cash flows (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureSupplementalDisclosuresToTheConsolidatedStatementsOfCashFlows</Role>
      <ShortName>Supplemental disclosures to the consolidated statements of cash flows (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsCashFlowSupplementalDisclosuresTextBlockTables</ParentRole>
      <Position>51</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R52.htm</HtmlFileName>
      <LongName>1053 - Disclosure - Debt (Components of Debt) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureDebtComponentsOfDebt</Role>
      <ShortName>Debt (Components of Debt) (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsDebtDisclosureTextBlockTables</ParentRole>
      <Position>52</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R53.htm</HtmlFileName>
      <LongName>1054 - Disclosure - Debt (Components of Debt) (Parenthetical) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureDebtComponentsOfDebtParenthetical</Role>
      <ShortName>Debt (Components of Debt) (Parenthetical) (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsDebtDisclosureTextBlockTables</ParentRole>
      <Position>53</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R54.htm</HtmlFileName>
      <LongName>1055 - Disclosure - Debt (Unamortized Debt Issuance Costs) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureDebtUnamortizedDebtIssuanceCosts</Role>
      <ShortName>Debt (Unamortized Debt Issuance Costs) (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsDebtDisclosureTextBlockTables</ParentRole>
      <Position>54</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R55.htm</HtmlFileName>
      <LongName>1056 - Disclosure - Debt - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureDebtAdditionalInformation</Role>
      <ShortName>Debt - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>55</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R56.htm</HtmlFileName>
      <LongName>1057 - Disclosure - Debt (New Term Loan) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureDebtNewTermLoan</Role>
      <ShortName>Debt (New Term Loan) (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsDebtDisclosureTextBlockTables</ParentRole>
      <Position>56</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R57.htm</HtmlFileName>
      <LongName>1058 - Disclosure - Debt (Schedule of Mandatory Principal Payment According to Schedule of Remaining Outstanding Balance Due upon Maturity) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureDebtScheduleOfMandatoryPrincipalPaymentAccordingToScheduleOfRemainingOutstandingBalanceDueUponMaturity</Role>
      <ShortName>Debt (Schedule of Mandatory Principal Payment According to Schedule of Remaining Outstanding Balance Due upon Maturity) (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsDebtDisclosureTextBlockTables</ParentRole>
      <Position>57</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R58.htm</HtmlFileName>
      <LongName>1059 - Disclosure - Debt (New Revolver) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureDebtNewRevolver</Role>
      <ShortName>Debt (New Revolver) (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsDebtDisclosureTextBlockTables</ParentRole>
      <Position>58</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R59.htm</HtmlFileName>
      <LongName>1060 - Disclosure - Debt (Covenants) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureDebtCovenants</Role>
      <ShortName>Debt (Covenants) (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsDebtDisclosureTextBlockTables</ParentRole>
      <Position>59</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R60.htm</HtmlFileName>
      <LongName>1061 - Disclosure - Debt (Write-off of Senior Note Issuance Costs Discount and Premium) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureDebtWriteoffOfSeniorNoteIssuanceCostsDiscountAndPremium</Role>
      <ShortName>Debt (Write-off of Senior Note Issuance Costs Discount and Premium) (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsDebtDisclosureTextBlockTables</ParentRole>
      <Position>60</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R61.htm</HtmlFileName>
      <LongName>1062 - Disclosure - Debt (Premiums, Discounts and Debt Issuance Costs) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureDebtPremiumsDiscountsAndDebtIssuanceCosts</Role>
      <ShortName>Debt (Premiums, Discounts and Debt Issuance Costs) (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsDebtDisclosureTextBlockTables</ParentRole>
      <Position>61</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R62.htm</HtmlFileName>
      <LongName>1063 - Disclosure - Debt (Capital Leases) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureDebtCapitalLeases</Role>
      <ShortName>Debt (Capital Leases) (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsDebtDisclosureTextBlockTables</ParentRole>
      <Position>62</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R63.htm</HtmlFileName>
      <LongName>1064 - Disclosure - Derivative instruments - Summary of derivatives outstanding (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureDerivativeInstrumentsSummaryOfDerivativesOutstanding</Role>
      <ShortName>Derivative instruments - Summary of derivatives outstanding (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>63</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R64.htm</HtmlFileName>
      <LongName>1065 - Disclosure - Derivative Instruments (Derivative instruments recorded on the balance sheet at fair value) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureDerivativeInstrumentsDerivativeInstrumentsRecordedOnTheBalanceSheetAtFairValue</Role>
      <ShortName>Derivative Instruments (Derivative instruments recorded on the balance sheet at fair value) (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>64</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R65.htm</HtmlFileName>
      <LongName>1066 - Disclosure - Derivative Instruments (Derivative (losses) gains in the consolidated statements of operations) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureDerivativeInstrumentsDerivativelossesGainsInTheConsolidatedStatementsOfOperations</Role>
      <ShortName>Derivative Instruments (Derivative (losses) gains in the consolidated statements of operations) (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>65</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R66.htm</HtmlFileName>
      <LongName>1067 - Disclosure - Fair value measurements (Recurring Fair Value Measurements) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureFairValueMeasurementsRecurringFairValueMeasurements</Role>
      <ShortName>Fair value measurements (Recurring Fair Value Measurements) (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsFairValueDisclosuresTextBlockTables</ParentRole>
      <Position>66</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R67.htm</HtmlFileName>
      <LongName>1068 - Disclosure - Fair value measurements (Level 3 Rollforward) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureFairValueMeasurementsLevel3Rollforward</Role>
      <ShortName>Fair value measurements (Level 3 Rollforward) (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsFairValueDisclosuresTextBlockTables</ParentRole>
      <Position>67</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R68.htm</HtmlFileName>
      <LongName>1069 - Disclosure - Fair value measurements (Nonrecurring Fair Value Measurements) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureFairValueMeasurementsNonrecurringFairValueMeasurements</Role>
      <ShortName>Fair value measurements (Nonrecurring Fair Value Measurements) (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsFairValueDisclosuresTextBlockTables</ParentRole>
      <Position>68</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R69.htm</HtmlFileName>
      <LongName>1070 - Disclosure - Fair value measurements (Fair Value of Other Financial Instruments) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureFairValueMeasurementsFairValueOfOtherFinancialInstruments</Role>
      <ShortName>Fair value measurements (Fair Value of Other Financial Instruments) (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsFairValueDisclosuresTextBlockTables</ParentRole>
      <Position>69</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R70.htm</HtmlFileName>
      <LongName>1071 - Disclosure - Fair value measurements (Counterparty Credit Risk) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureFairValueMeasurementsCounterpartyCreditRisk</Role>
      <ShortName>Fair value measurements (Counterparty Credit Risk) (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsFairValueDisclosuresTextBlockTables</ParentRole>
      <Position>70</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R71.htm</HtmlFileName>
      <LongName>1072 - Disclosure - Fair value measurements (Derivatives Offset in the Consolidated Balance Sheets) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureFairValueMeasurementsDerivativesOffsetInTheConsolidatedBalanceSheets</Role>
      <ShortName>Fair value measurements (Derivatives Offset in the Consolidated Balance Sheets) (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsFairValueDisclosuresTextBlockTables</ParentRole>
      <Position>71</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R72.htm</HtmlFileName>
      <LongName>1073 - Disclosure - Asset retirement obligations (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureAssetRetirementObligations</Role>
      <ShortName>Asset retirement obligations (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsAssetRetirementObligationDisclosureTextBlockTables</ParentRole>
      <Position>72</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R73.htm</HtmlFileName>
      <LongName>1074 - Disclosure - Deferred compensation (Restricted Stock Unit Plan) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureDeferredCompensationRestrictedStockUnitPlan</Role>
      <ShortName>Deferred compensation (Restricted Stock Unit Plan) (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>73</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R74.htm</HtmlFileName>
      <LongName>1075 - Disclosure - Deferred compensation (Cash Incentive Plan) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureDeferredCompensationCashIncentivePlan</Role>
      <ShortName>Deferred compensation (Cash Incentive Plan) (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>74</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R75.htm</HtmlFileName>
      <LongName>1076 - Disclosure - Deferred compensation (2010 Equity Incentive Plan) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureDeferredCompensation2010EquityIncentivePlan</Role>
      <ShortName>Deferred compensation (2010 Equity Incentive Plan) (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>75</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R76.htm</HtmlFileName>
      <LongName>1077 - Disclosure - Deferred compensation (Stock-based compensation cost) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureDeferredCompensationStockbasedCompensationCost</Role>
      <ShortName>Deferred compensation (Stock-based compensation cost) (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>76</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R77.htm</HtmlFileName>
      <LongName>1078 - Disclosure - Commitments and Contingencies - Additional information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureCommitmentsAndContingenciesAdditionalInformation</Role>
      <ShortName>Commitments and Contingencies - Additional information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>77</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R78.htm</HtmlFileName>
      <LongName>1079 - Disclosure - Nature of operations and summary of significant accounting policies (Inventory Adjustments) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureNatureOfOperationsAndSummaryOfSignificantAccountingPoliciesInventoryAdjustments</Role>
      <ShortName>Nature of operations and summary of significant accounting policies (Inventory Adjustments) (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsOrganizationConsolidationBasisOfPresentationBusinessDescriptionAndAccountingPoliciesTextBlockTables</ParentRole>
      <Position>78</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R79.htm</HtmlFileName>
      <LongName>1080 - Disclosure - Nature of operations and summary of significant accounting policies--Property and Equipment (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureNatureOfOperationsAndSummaryOfSignificantAccountingPoliciesPropertyAndEquipment</Role>
      <ShortName>Nature of operations and summary of significant accounting policies--Property and Equipment (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>79</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R80.htm</HtmlFileName>
      <LongName>1081 - Disclosure - Nature of operations and summary of significant accounting policies (Asset Impairment) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureNatureOfOperationsAndSummaryOfSignificantAccountingPoliciesAssetImpairment</Role>
      <ShortName>Nature of operations and summary of significant accounting policies (Asset Impairment) (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsOrganizationConsolidationBasisOfPresentationBusinessDescriptionAndAccountingPoliciesTextBlockTables</ParentRole>
      <Position>80</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R81.htm</HtmlFileName>
      <LongName>1082 - Disclosure - Nature of operations and summary of significant accounting policies (Gas Balancing) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureNatureOfOperationsAndSummaryOfSignificantAccountingPoliciesGasBalancing</Role>
      <ShortName>Nature of operations and summary of significant accounting policies (Gas Balancing) (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsOrganizationConsolidationBasisOfPresentationBusinessDescriptionAndAccountingPoliciesTextBlockTables</ParentRole>
      <Position>81</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R82.htm</HtmlFileName>
      <LongName>1083 - Disclosure - Nature of operations and summary of significant accounting policies (Recently Adopted Accounting Pronouncements) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureNatureOfOperationsAndSummaryOfSignificantAccountingPoliciesRecentlyAdoptedAccountingPronouncements</Role>
      <ShortName>Nature of operations and summary of significant accounting policies (Recently Adopted Accounting Pronouncements) (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsOrganizationConsolidationBasisOfPresentationBusinessDescriptionAndAccountingPoliciesTextBlockTables</ParentRole>
      <Position>82</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R83.htm</HtmlFileName>
      <LongName>1084 - Disclosure - Acquisitions and divestitures (2015 Divestitures) - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureAcquisitionsAndDivestitures2015DivestituresAdditionalInformation</Role>
      <ShortName>Acquisitions and divestitures (2015 Divestitures) - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsMergersAcquisitionsAndDispositionsDisclosuresTextBlock</ParentRole>
      <Position>83</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R84.htm</HtmlFileName>
      <LongName>1085 - Disclosure - Acquisitions and divestitures (2014 Divestitures) - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureAcquisitionsAndDivestitures2014DivestituresAdditionalInformation</Role>
      <ShortName>Acquisitions and divestitures (2014 Divestitures) - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsMergersAcquisitionsAndDispositionsDisclosuresTextBlock</ParentRole>
      <Position>84</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R85.htm</HtmlFileName>
      <LongName>1086 - Disclosure - Property and Equipment - Components of Property and Equipment (Details) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosurePropertyAndEquipmentComponentsOfPropertyAndEquipmentDetails</Role>
      <ShortName>Property and Equipment - Components of Property and Equipment (Details) (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>85</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R86.htm</HtmlFileName>
      <LongName>1087 - Disclosure - Debt (Pre-emergence Debt) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureDebtPreemergenceDebt</Role>
      <ShortName>Debt (Pre-emergence Debt) (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsDebtDisclosureTextBlockTables</ParentRole>
      <Position>86</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R87.htm</HtmlFileName>
      <LongName>1088 - Disclosure - Debt (Initial Maturities of Debt and Capital Leases) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureDebtInitialMaturitiesOfDebtAndCapitalLeases</Role>
      <ShortName>Debt (Initial Maturities of Debt and Capital Leases) (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsDebtDisclosureTextBlockTables</ParentRole>
      <Position>87</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R88.htm</HtmlFileName>
      <LongName>1089 - Disclosure - Debt (Senior Notes) (Detail)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureDebtSeniorNotes</Role>
      <ShortName>Debt (Senior Notes) (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsDebtDisclosureTextBlockTables</ParentRole>
      <Position>88</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R89.htm</HtmlFileName>
      <LongName>1090 - Disclosure - Debt (Existing Credit Facility) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureDebtExistingCreditFacility</Role>
      <ShortName>Debt (Existing Credit Facility) (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsDebtDisclosureTextBlockTables</ParentRole>
      <Position>89</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R90.htm</HtmlFileName>
      <LongName>1091 - Disclosure - Debt (Schedule of Initial Outstanding Amounts Under New Credit Facility) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureDebtScheduleOfInitialOutstandingAmountsUnderNewCreditFacility</Role>
      <ShortName>Debt (Schedule of Initial Outstanding Amounts Under New Credit Facility) (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsDebtDisclosureTextBlockTables</ParentRole>
      <Position>90</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R91.htm</HtmlFileName>
      <LongName>1092 - Disclosure - Debt (Schedule of Initial Outstanding Amounts Under New Credit Facility) (Parenthetical) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureDebtScheduleOfInitialOutstandingAmountsUnderNewCreditFacilityParenthetical</Role>
      <ShortName>Debt (Schedule of Initial Outstanding Amounts Under New Credit Facility) (Parenthetical) (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsDebtDisclosureTextBlockTables</ParentRole>
      <Position>91</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R92.htm</HtmlFileName>
      <LongName>1093 - Disclosure - Debt (Other Provisions) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureDebtOtherProvisions</Role>
      <ShortName>Debt (Other Provisions) (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsDebtDisclosureTextBlockTables</ParentRole>
      <Position>92</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R93.htm</HtmlFileName>
      <LongName>1094 - Disclosure - Derivative instruments - Additional information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureDerivativeInstrumentsAdditionalInformation</Role>
      <ShortName>Derivative instruments - Additional information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>93</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R94.htm</HtmlFileName>
      <LongName>1095 - Disclosure - Fair value measurements - Percentages of Total Commodity Sales Excluding Effects of Hedging Activities (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureFairValueMeasurementsPercentagesOfTotalCommoditySalesExcludingEffectsOfHedgingActivities</Role>
      <ShortName>Fair value measurements - Percentages of Total Commodity Sales Excluding Effects of Hedging Activities (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>94</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R95.htm</HtmlFileName>
      <LongName>1096 - Disclosure - Income Taxes--Component of Income Tax (Benefit) Expense from Continuing Operations (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureIncomeTaxesComponentOfIncomeTaxBenefitExpenseFromContinuingOperations</Role>
      <ShortName>Income Taxes--Component of Income Tax (Benefit) Expense from Continuing Operations (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>95</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R96.htm</HtmlFileName>
      <LongName>1097 - Disclosure - Income Taxes - Rate Reconciliation (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureIncomeTaxesRateReconciliation</Role>
      <ShortName>Income Taxes - Rate Reconciliation (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>96</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R97.htm</HtmlFileName>
      <LongName>1098 - Disclosure - Income Taxes - Components of Deferred Tax Assets and Liabilities (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureIncomeTaxesComponentsOfDeferredTaxAssetsAndLiabilities</Role>
      <ShortName>Income Taxes - Components of Deferred Tax Assets and Liabilities (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>97</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R98.htm</HtmlFileName>
      <LongName>1099 - Disclosure - Income Taxes - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureIncomeTaxesAdditionalInformation</Role>
      <ShortName>Income Taxes - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>98</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R99.htm</HtmlFileName>
      <LongName>1100 - Disclosure - Deferred compensation (Phantom Stock Plan and Restricted Stock Unit Plan) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureDeferredCompensationPhantomStockPlanAndRestrictedStockUnitPlan</Role>
      <ShortName>Deferred compensation (Phantom Stock Plan and Restricted Stock Unit Plan) (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>99</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R100.htm</HtmlFileName>
      <LongName>1101 - Disclosure - Deferred compensation--Variables and Assumptions Used to Value Restricted Stock Awards (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureDeferredCompensationVariablesAndAssumptionsUsedToValueRestrictedStockAwards</Role>
      <ShortName>Deferred compensation--Variables and Assumptions Used to Value Restricted Stock Awards (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>100</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R101.htm</HtmlFileName>
      <LongName>1102 - Disclosure - Stockholders' equity (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureStockholdersEquity</Role>
      <ShortName>Stockholders' equity (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsStockholdersEquityNoteDisclosureTextBlockTables</ParentRole>
      <Position>101</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R102.htm</HtmlFileName>
      <LongName>1103 - Disclosure - Stockholders' equity - Summary of Changes in Common Shares Outstanding (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureStockholdersEquitySummaryOfChangesInCommonSharesOutstanding</Role>
      <ShortName>Stockholders' equity - Summary of Changes in Common Shares Outstanding (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>102</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R103.htm</HtmlFileName>
      <LongName>1104 - Disclosure - Retirement Benefits - Additional information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureRetirementBenefitsAdditionalInformation</Role>
      <ShortName>Retirement Benefits - Additional information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>103</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R104.htm</HtmlFileName>
      <LongName>1105 - Disclosure - Commitments and Contingencies - Minimum Purchase Obligations (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureCommitmentsAndContingenciesMinimumPurchaseObligations</Role>
      <ShortName>Commitments and Contingencies - Minimum Purchase Obligations (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>104</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R105.htm</HtmlFileName>
      <LongName>1106 - Disclosure - Commitments and Contingencies - Operating Lease Schedule (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureCommitmentsAndContingenciesOperatingLeaseSchedule</Role>
      <ShortName>Commitments and Contingencies - Operating Lease Schedule (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>105</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R106.htm</HtmlFileName>
      <LongName>1107 - Disclosure - Oil and Natural Gas Activities - Costs Incurred (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureOilAndNaturalGasActivitiesCostsIncurred</Role>
      <ShortName>Oil and Natural Gas Activities - Costs Incurred (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>106</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R107.htm</HtmlFileName>
      <LongName>1108 - Disclosure - Oil and Natural Gas Activities - Depreciation, Depletion and Amortization Expense of Oil and Natural Gas Properties (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureOilAndNaturalGasActivitiesDepreciationDepletionAndAmortizationExpenseOfOilAndNaturalGasProperties</Role>
      <ShortName>Oil and Natural Gas Activities - Depreciation, Depletion and Amortization Expense of Oil and Natural Gas Properties (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>107</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R108.htm</HtmlFileName>
      <LongName>1109 - Disclosure - Oil and Natural Gas Activities - Oil and Natural Gas Properties not Subject to Amortization (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureOilAndNaturalGasActivitiesOilAndNaturalGasPropertiesNotSubjectToAmortization</Role>
      <ShortName>Oil and Natural Gas Activities - Oil and Natural Gas Properties not Subject to Amortization (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>108</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R109.htm</HtmlFileName>
      <LongName>1110 - Disclosure - Oil and Natural Gas Activities - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureOilAndNaturalGasActivitiesAdditionalInformation</Role>
      <ShortName>Oil and Natural Gas Activities - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>109</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R110.htm</HtmlFileName>
      <LongName>1111 - Disclosure - Disclosures about Oil and Natural Gas Activities (Unaudited) - Summary of Changes in Quantities of Proved Reserves (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureDisclosuresAboutOilAndNaturalGasActivitiesUnauditedSummaryOfChangesInQuantitiesOfProvedReserves</Role>
      <ShortName>Disclosures about Oil and Natural Gas Activities (Unaudited) - Summary of Changes in Quantities of Proved Reserves (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>110</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R111.htm</HtmlFileName>
      <LongName>1112 - Disclosure - Disclosures about Oil and Natural Gas Activities (Unaudited) - Standardized Measure of Discounted Future Net Cash Flows (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureDisclosuresAboutOilAndNaturalGasActivitiesUnauditedStandardizedMeasureOfDiscountedFutureNetCashFlows</Role>
      <ShortName>Disclosures about Oil and Natural Gas Activities (Unaudited) - Standardized Measure of Discounted Future Net Cash Flows (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>111</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R112.htm</HtmlFileName>
      <LongName>1113 - Disclosure - Disclosures about Oil and Natural Gas Activities (Unaudited) - Changes in Standardized Measure of Discounted Future Net Cash Flows (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureDisclosuresAboutOilAndNaturalGasActivitiesUnauditedChangesInStandardizedMeasureOfDiscountedFutureNetCashFlows</Role>
      <ShortName>Disclosures about Oil and Natural Gas Activities (Unaudited) - Changes in Standardized Measure of Discounted Future Net Cash Flows (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>112</Position>
    </Report>
    <Report instance="chpe-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R113.htm</HtmlFileName>
      <LongName>1114 - Disclosure - Disclosures about Oil and Natural Gas Activities (Unaudited) - Prices Used in Determining Future Net Revenues (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://imetrix.edgar-online.com/taxonomy/role/DisclosureDisclosuresAboutOilAndNaturalGasActivitiesUnauditedPricesUsedInDeterminingFutureNetRevenues</Role>
      <ShortName>Disclosures about Oil and Natural Gas Activities (Unaudited) - Prices Used in Determining Future Net Revenues (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>113</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <InputFiles>
    <File>chpe-20170331.xml</File>
    <File>chpe-20170331.xsd</File>
    <File>chpe-20170331_cal.xml</File>
    <File>chpe-20170331_def.xml</File>
    <File>chpe-20170331_lab.xml</File>
    <File>chpe-20170331_pre.xml</File>
  </InputFiles>
  <SupplementalFiles/>
  <BaseTaxonomies/>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
