<?xml version='1.0' encoding='UTF-8'?>
<FilingSummary>
  <Version>3.7.0.1</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>141</ContextCount>
  <ElementCount>215</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>false</FootnotesReported>
  <SegmentCount>70</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>7</UnitCount>
  <MyReports>
    <Report instance="ryi-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>100000 - Document - Document and Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ryerson.com/20170331/taxonomy/role/DocumentDocumentAndEntityInformation</Role>
      <ShortName>Document and Entity Information</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="ryi-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>100010 - Statement - Condensed Consolidated Statements of Comprehensive Income (Unaudited)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ryerson.com/20170331/taxonomy/role/StatementCondensedConsolidatedStatementsOfComprehensiveIncomeUnaudited</Role>
      <ShortName>Condensed Consolidated Statements of Comprehensive Income (Unaudited)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="ryi-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>100020 - Statement - Condensed Consolidated Statements of Cash Flows (Unaudited)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ryerson.com/20170331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited</Role>
      <ShortName>Condensed Consolidated Statements of Cash Flows (Unaudited)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="ryi-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>100030 - Statement - Condensed Consolidated Balance Sheets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ryerson.com/20170331/taxonomy/role/StatementCondensedConsolidatedBalanceSheets</Role>
      <ShortName>Condensed Consolidated Balance Sheets</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="ryi-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>100040 - Statement - Condensed Consolidated Balance Sheets (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ryerson.com/20170331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsParenthetical</Role>
      <ShortName>Condensed Consolidated Balance Sheets (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="ryi-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>100050 - Disclosure - Financial Statements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ryerson.com/20170331/taxonomy/role/DisclosureFinancialStatements</Role>
      <ShortName>Financial Statements</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="ryi-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>100060 - Disclosure - Recent Accounting Pronouncements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ryerson.com/20170331/taxonomy/role/DisclosureRecentAccountingPronouncements</Role>
      <ShortName>Recent Accounting Pronouncements</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="ryi-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>100070 - Disclosure - Inventories</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ryerson.com/20170331/taxonomy/role/DisclosureInventories</Role>
      <ShortName>Inventories</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="ryi-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>100080 - Disclosure - Goodwill and Other Intangible Assets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ryerson.com/20170331/taxonomy/role/DisclosureGoodwillAndOtherIntangibleAssets</Role>
      <ShortName>Goodwill and Other Intangible Assets</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="ryi-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>100090 - Disclosure - Acquisitions</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ryerson.com/20170331/taxonomy/role/DisclosureAcquisitions</Role>
      <ShortName>Acquisitions</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="ryi-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>100100 - Disclosure - Long-Term Debt</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ryerson.com/20170331/taxonomy/role/DisclosureLongTermDebt</Role>
      <ShortName>Long-Term Debt</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="ryi-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>100110 - Disclosure - Employee Benefits</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ryerson.com/20170331/taxonomy/role/DisclosureEmployeeBenefits</Role>
      <ShortName>Employee Benefits</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="ryi-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>100120 - Disclosure - Commitments and Contingencies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ryerson.com/20170331/taxonomy/role/DisclosureCommitmentsAndContingencies</Role>
      <ShortName>Commitments and Contingencies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="ryi-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>100130 - Disclosure - Derivatives and Fair Value Measurements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ryerson.com/20170331/taxonomy/role/DisclosureDerivativesAndFairValueMeasurements</Role>
      <ShortName>Derivatives and Fair Value Measurements</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="ryi-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>100140 - Disclosure - Stockholders' Equity (Deficit), Accumulated Other Comprehensive Income (Loss) and Redeemable Noncontrolling Interest</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ryerson.com/20170331/taxonomy/role/DisclosureStockholdersEquityDeficitAccumulatedOtherComprehensiveIncomeLossAndRedeemableNoncontrollingInterest</Role>
      <ShortName>Stockholders' Equity (Deficit), Accumulated Other Comprehensive Income (Loss) and Redeemable Noncontrolling Interest</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="ryi-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>100150 - Disclosure - Income Taxes</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ryerson.com/20170331/taxonomy/role/DisclosureIncomeTaxes</Role>
      <ShortName>Income Taxes</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="ryi-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>100160 - Disclosure - Earnings Per Share</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ryerson.com/20170331/taxonomy/role/DisclosureEarningsPerShare</Role>
      <ShortName>Earnings Per Share</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="ryi-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>100170 - Disclosure - Financial Statements (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ryerson.com/20170331/taxonomy/role/DisclosureFinancialStatementsTables</Role>
      <ShortName>Financial Statements (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.ryerson.com/20170331/taxonomy/role/DisclosureFinancialStatements</ParentRole>
      <Position>18</Position>
    </Report>
    <Report instance="ryi-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>100180 - Disclosure - Inventories (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ryerson.com/20170331/taxonomy/role/DisclosureInventoriesTables</Role>
      <ShortName>Inventories (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.ryerson.com/20170331/taxonomy/role/DisclosureInventories</ParentRole>
      <Position>19</Position>
    </Report>
    <Report instance="ryi-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>100190 - Disclosure - Long-Term Debt (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ryerson.com/20170331/taxonomy/role/DisclosureLongTermDebtTables</Role>
      <ShortName>Long-Term Debt (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.ryerson.com/20170331/taxonomy/role/DisclosureLongTermDebt</ParentRole>
      <Position>20</Position>
    </Report>
    <Report instance="ryi-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>100200 - Disclosure - Employee Benefits (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ryerson.com/20170331/taxonomy/role/DisclosureEmployeeBenefitsTables</Role>
      <ShortName>Employee Benefits (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.ryerson.com/20170331/taxonomy/role/DisclosureEmployeeBenefits</ParentRole>
      <Position>21</Position>
    </Report>
    <Report instance="ryi-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>100210 - Disclosure - Derivatives and Fair Value Measurements (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ryerson.com/20170331/taxonomy/role/DisclosureDerivativesAndFairValueMeasurementsTables</Role>
      <ShortName>Derivatives and Fair Value Measurements (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.ryerson.com/20170331/taxonomy/role/DisclosureDerivativesAndFairValueMeasurements</ParentRole>
      <Position>22</Position>
    </Report>
    <Report instance="ryi-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>100220 - Disclosure - Stockholders' Equity (Deficit), Accumulated Other Comprehensive Income (Loss) and Redeemable Noncontrolling Interest (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ryerson.com/20170331/taxonomy/role/DisclosureStockholdersEquityDeficitAccumulatedOtherComprehensiveIncomeLossAndRedeemableNoncontrollingInterestTables</Role>
      <ShortName>Stockholders' Equity (Deficit), Accumulated Other Comprehensive Income (Loss) and Redeemable Noncontrolling Interest (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.ryerson.com/20170331/taxonomy/role/DisclosureStockholdersEquityDeficitAccumulatedOtherComprehensiveIncomeLossAndRedeemableNoncontrollingInterest</ParentRole>
      <Position>23</Position>
    </Report>
    <Report instance="ryi-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>100230 - Disclosure - Earnings Per Share (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ryerson.com/20170331/taxonomy/role/DisclosureEarningsPerShareTables</Role>
      <ShortName>Earnings Per Share (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.ryerson.com/20170331/taxonomy/role/DisclosureEarningsPerShare</ParentRole>
      <Position>24</Position>
    </Report>
    <Report instance="ryi-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>100240 - Disclosure - Financial Statements - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ryerson.com/20170331/taxonomy/role/DisclosureFinancialStatementsAdditionalInformationDetail</Role>
      <ShortName>Financial Statements - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>25</Position>
    </Report>
    <Report instance="ryi-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>100250 - Disclosure - Financial Statements - Percentage of Sales by Major Product Line (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ryerson.com/20170331/taxonomy/role/DisclosureFinancialStatementsPercentageOfSalesByMajorProductLineDetail</Role>
      <ShortName>Financial Statements - Percentage of Sales by Major Product Line (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>26</Position>
    </Report>
    <Report instance="ryi-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>100260 - Disclosure - Inventories - Schedule of Inventories (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ryerson.com/20170331/taxonomy/role/DisclosureInventoriesScheduleOfInventoriesDetail</Role>
      <ShortName>Inventories - Schedule of Inventories (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>27</Position>
    </Report>
    <Report instance="ryi-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>100270 - Disclosure - Inventories - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ryerson.com/20170331/taxonomy/role/DisclosureInventoriesAdditionalInformationDetail</Role>
      <ShortName>Inventories - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>28</Position>
    </Report>
    <Report instance="ryi-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>100280 - Disclosure - Goodwill and Other Intangible Assets - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ryerson.com/20170331/taxonomy/role/DisclosureGoodwillAndOtherIntangibleAssetsAdditionalInformationDetail</Role>
      <ShortName>Goodwill and Other Intangible Assets - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>29</Position>
    </Report>
    <Report instance="ryi-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>100290 - Disclosure - Acquisitions - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ryerson.com/20170331/taxonomy/role/DisclosureAcquisitionsAdditionalInformationDetail</Role>
      <ShortName>Acquisitions - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>30</Position>
    </Report>
    <Report instance="ryi-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>100300 - Disclosure - Long-Term Debt - Long-Term Debt (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ryerson.com/20170331/taxonomy/role/DisclosureLongTermDebtLongTermDebtDetail</Role>
      <ShortName>Long-Term Debt - Long-Term Debt (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>31</Position>
    </Report>
    <Report instance="ryi-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>100320 - Disclosure - Long-Term Debt - Ryerson Credit Facility - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ryerson.com/20170331/taxonomy/role/DisclosureLongTermDebtRyersonCreditFacilityAdditionalInformationDetail</Role>
      <ShortName>Long-Term Debt - Ryerson Credit Facility - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>32</Position>
    </Report>
    <Report instance="ryi-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>100330 - Disclosure - Long-Term Debt - 2022 Notes - Additional Information (Detail)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.ryerson.com/20170331/taxonomy/role/DisclosureLongTermDebt2022NotesAdditionalInformationDetail</Role>
      <ShortName>Long-Term Debt - 2022 Notes - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>33</Position>
    </Report>
    <Report instance="ryi-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>100340 - Disclosure - Long-Term Debt - Foreign Debt - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ryerson.com/20170331/taxonomy/role/DisclosureLongTermDebtForeignDebtAdditionalInformationDetail</Role>
      <ShortName>Long-Term Debt - Foreign Debt - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>34</Position>
    </Report>
    <Report instance="ryi-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>100350 - Disclosure - Employee Benefits - Components of Net Periodic Benefit (Credit) Cost (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ryerson.com/20170331/taxonomy/role/DisclosureEmployeeBenefitsComponentsOfNetPeriodicBenefitCreditCostDetail</Role>
      <ShortName>Employee Benefits - Components of Net Periodic Benefit (Credit) Cost (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>35</Position>
    </Report>
    <Report instance="ryi-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>100360 - Disclosure - Employee Benefits - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ryerson.com/20170331/taxonomy/role/DisclosureEmployeeBenefitsAdditionalInformationDetail</Role>
      <ShortName>Employee Benefits - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>36</Position>
    </Report>
    <Report instance="ryi-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>100370 - Disclosure - Commitments and Contingencies - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ryerson.com/20170331/taxonomy/role/DisclosureCommitmentsAndContingenciesAdditionalInformationDetail</Role>
      <ShortName>Commitments and Contingencies - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>37</Position>
    </Report>
    <Report instance="ryi-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>100380 - Disclosure - Derivatives and Fair Value Measurements - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ryerson.com/20170331/taxonomy/role/DisclosureDerivativesAndFairValueMeasurementsAdditionalInformationDetail</Role>
      <ShortName>Derivatives and Fair Value Measurements - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>38</Position>
    </Report>
    <Report instance="ryi-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>100390 - Disclosure - Derivatives and Fair Value Measurements - Location and Fair Value Amount of Derivative Instruments (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ryerson.com/20170331/taxonomy/role/DisclosureDerivativesAndFairValueMeasurementsLocationAndFairValueAmountOfDerivativeInstrumentsDetail</Role>
      <ShortName>Derivatives and Fair Value Measurements - Location and Fair Value Amount of Derivative Instruments (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>39</Position>
    </Report>
    <Report instance="ryi-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>100400 - Disclosure - Derivatives and Fair Value Measurements - Location and Amount of Gains and Losses Reported in Condensed Consolidated Statements of Comprehensive Income (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ryerson.com/20170331/taxonomy/role/DisclosureDerivativesAndFairValueMeasurementsLocationAndAmountOfGainsAndLossesReportedInCondensedConsolidatedStatementsOfComprehensiveIncomeDetail</Role>
      <ShortName>Derivatives and Fair Value Measurements - Location and Amount of Gains and Losses Reported in Condensed Consolidated Statements of Comprehensive Income (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>40</Position>
    </Report>
    <Report instance="ryi-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>100410 - Disclosure - Derivatives and Fair Value Measurements - Assets and Liabilities Measured and Recorded at Fair Value (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ryerson.com/20170331/taxonomy/role/DisclosureDerivativesAndFairValueMeasurementsAssetsAndLiabilitiesMeasuredAndRecordedAtFairValueDetail</Role>
      <ShortName>Derivatives and Fair Value Measurements - Assets and Liabilities Measured and Recorded at Fair Value (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>41</Position>
    </Report>
    <Report instance="ryi-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>100420 - Disclosure - Derivatives and Fair Value Measurements - Carrying and Estimated Fair Values Financial Instruments (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ryerson.com/20170331/taxonomy/role/DisclosureDerivativesAndFairValueMeasurementsCarryingAndEstimatedFairValuesFinancialInstrumentsDetail</Role>
      <ShortName>Derivatives and Fair Value Measurements - Carrying and Estimated Fair Values Financial Instruments (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>42</Position>
    </Report>
    <Report instance="ryi-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>100430 - Disclosure - Derivatives and Fair Value Measurements - Assets and Liabilities Measured and Recorded at Fair Value on Non Recurring Basis (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ryerson.com/20170331/taxonomy/role/DisclosureDerivativesAndFairValueMeasurementsAssetsAndLiabilitiesMeasuredAndRecordedAtFairValueOnNonRecurringBasisDetail</Role>
      <ShortName>Derivatives and Fair Value Measurements - Assets and Liabilities Measured and Recorded at Fair Value on Non Recurring Basis (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>43</Position>
    </Report>
    <Report instance="ryi-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>100440 - Disclosure - Derivatives and Fair Value Measurements - Available-for-Sale Securities (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ryerson.com/20170331/taxonomy/role/DisclosureDerivativesAndFairValueMeasurementsAvailableForSaleSecuritiesDetail</Role>
      <ShortName>Derivatives and Fair Value Measurements - Available-for-Sale Securities (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>44</Position>
    </Report>
    <Report instance="ryi-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>100450 - Disclosure - Stockholders' Equity (Deficit), Accumulated Other Comprehensive Income (Loss) and Redeemable Noncontrolling Interest - Change in Stockholders' Equity (Deficit) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ryerson.com/20170331/taxonomy/role/DisclosureStockholdersEquityDeficitAccumulatedOtherComprehensiveIncomeLossAndRedeemableNoncontrollingInterestChangeInStockholdersEquityDeficitDetail</Role>
      <ShortName>Stockholders' Equity (Deficit), Accumulated Other Comprehensive Income (Loss) and Redeemable Noncontrolling Interest - Change in Stockholders' Equity (Deficit) (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.ryerson.com/20170331/taxonomy/role/DisclosureStockholdersEquityDeficitAccumulatedOtherComprehensiveIncomeLossAndRedeemableNoncontrollingInterestTables</ParentRole>
      <Position>45</Position>
    </Report>
    <Report instance="ryi-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>100460 - Disclosure - Stockholders' Equity (Deficit), Accumulated Other Comprehensive Income (Loss) and Redeemable Noncontrolling Interest - Change in Stockholders' Equity (Deficit) (Parenthetical) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ryerson.com/20170331/taxonomy/role/DisclosureStockholdersEquityDeficitAccumulatedOtherComprehensiveIncomeLossAndRedeemableNoncontrollingInterestChangeInStockholdersEquityDeficitParentheticalDetail</Role>
      <ShortName>Stockholders' Equity (Deficit), Accumulated Other Comprehensive Income (Loss) and Redeemable Noncontrolling Interest - Change in Stockholders' Equity (Deficit) (Parenthetical) (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.ryerson.com/20170331/taxonomy/role/DisclosureStockholdersEquityDeficitAccumulatedOtherComprehensiveIncomeLossAndRedeemableNoncontrollingInterestTables</ParentRole>
      <Position>46</Position>
    </Report>
    <Report instance="ryi-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>100470 - Disclosure - Stockholders' Equity (Deficit), Accumulated Other Comprehensive Income (Loss) and Redeemable Noncontrolling Interest - Changes in Accumulated Other Comprehensive Income/(Loss) by Component (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ryerson.com/20170331/taxonomy/role/DisclosureStockholdersEquityDeficitAccumulatedOtherComprehensiveIncomeLossAndRedeemableNoncontrollingInterestChangesInAccumulatedOtherComprehensiveIncomeLossByComponentDetail</Role>
      <ShortName>Stockholders' Equity (Deficit), Accumulated Other Comprehensive Income (Loss) and Redeemable Noncontrolling Interest - Changes in Accumulated Other Comprehensive Income/(Loss) by Component (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.ryerson.com/20170331/taxonomy/role/DisclosureStockholdersEquityDeficitAccumulatedOtherComprehensiveIncomeLossAndRedeemableNoncontrollingInterestTables</ParentRole>
      <Position>47</Position>
    </Report>
    <Report instance="ryi-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>100480 - Disclosure - Stockholders' Equity (Deficit), Accumulated Other Comprehensive Income (Loss) and Redeemable Noncontrolling Interest - Reclassifications Out of Accumulated Other Comprehensive Income (Loss) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ryerson.com/20170331/taxonomy/role/DisclosureStockholdersEquityDeficitAccumulatedOtherComprehensiveIncomeLossAndRedeemableNoncontrollingInterestReclassificationsOutOfAccumulatedOtherComprehensiveIncomeLossDetail</Role>
      <ShortName>Stockholders' Equity (Deficit), Accumulated Other Comprehensive Income (Loss) and Redeemable Noncontrolling Interest - Reclassifications Out of Accumulated Other Comprehensive Income (Loss) (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.ryerson.com/20170331/taxonomy/role/DisclosureStockholdersEquityDeficitAccumulatedOtherComprehensiveIncomeLossAndRedeemableNoncontrollingInterestTables</ParentRole>
      <Position>48</Position>
    </Report>
    <Report instance="ryi-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>100490 - Disclosure - Income Taxes - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ryerson.com/20170331/taxonomy/role/DisclosureIncomeTaxesAdditionalInformationDetail</Role>
      <ShortName>Income Taxes - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>49</Position>
    </Report>
    <Report instance="ryi-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>100500 - Disclosure - Earnings Per Share - Calculation of Basic and Diluted Earnings Per Share (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ryerson.com/20170331/taxonomy/role/DisclosureEarningsPerShareCalculationOfBasicAndDilutedEarningsPerShareDetail</Role>
      <ShortName>Earnings Per Share - Calculation of Basic and Diluted Earnings Per Share (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>50</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <InputFiles>
    <File>ryi-20170331.xml</File>
    <File>ryi-20170331.xsd</File>
    <File>ryi-20170331_cal.xml</File>
    <File>ryi-20170331_def.xml</File>
    <File>ryi-20170331_lab.xml</File>
    <File>ryi-20170331_pre.xml</File>
  </InputFiles>
  <SupplementalFiles/>
  <BaseTaxonomies/>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
