<?xml version='1.0' encoding='UTF-8'?>
<FilingSummary>
  <Version>3.8.0.1</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>294</ContextCount>
  <ElementCount>331</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>true</FootnotesReported>
  <SegmentCount>83</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>4</UnitCount>
  <MyReports>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>000 - Document - Document And Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-document-and-entity-information</Role>
      <ShortName>Document And Entity Information</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>001 - Statement - Consolidated Statements of Comprehensive Income</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-consolidated-statements-of-comprehensive-income</Role>
      <ShortName>Consolidated Statements of Comprehensive Income</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>002 - Statement - Consolidated Statements of Comprehensive Income (Parentheticals)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-consolidated-statements-of-comprehensive-income-parentheticals</Role>
      <ShortName>Consolidated Statements of Comprehensive Income (Parentheticals)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>003 - Statement - Consolidated Balance Sheets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-consolidated-balance-sheets</Role>
      <ShortName>Consolidated Balance Sheets</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>004 - Statement - Consolidated Balance Sheets (Parentheticals)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-consolidated-balance-sheets-parentheticals</Role>
      <ShortName>Consolidated Balance Sheets (Parentheticals)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>005 - Statement - Consolidated Statements of Cash Flows</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-consolidated-statements-of-cash-flows</Role>
      <ShortName>Consolidated Statements of Cash Flows</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>006 - Statement - Consolidated Statements of Stockholders' Equity</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-consolidated-statements-of-stockholders-equity</Role>
      <ShortName>Consolidated Statements of Stockholders' Equity</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>007 - Statement - Consolidated Statements of Stockholders' Equity (Parentheticals)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-consolidated-statements-of-stockholders-equity-parentheticals</Role>
      <ShortName>Consolidated Statements of Stockholders' Equity (Parentheticals)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>008 - Disclosure - Note 1 - Summary of Significant Accounting Policies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-note-1-summary-of-significant-accounting-policies</Role>
      <ShortName>Note 1 - Summary of Significant Accounting Policies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>009 - Disclosure - Note 2 - Accounts Receivable</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-note-2-accounts-receivable</Role>
      <ShortName>Note 2 - Accounts Receivable</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>010 - Disclosure - Note 3 - Inventories</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-note-3-inventories</Role>
      <ShortName>Note 3 - Inventories</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>011 - Disclosure - Note 4 - Property and Equipment</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-note-4-property-and-equipment</Role>
      <ShortName>Note 4 - Property and Equipment</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>012 - Disclosure - Note 5 - Intangible Assets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-note-5-intangible-assets</Role>
      <ShortName>Note 5 - Intangible Assets</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>013 - Disclosure - Note 6 - Debt</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-note-6-debt</Role>
      <ShortName>Note 6 - Debt</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>014 - Disclosure - Note 7 - Derivative Instruments</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-note-7-derivative-instruments</Role>
      <ShortName>Note 7 - Derivative Instruments</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>015 - Disclosure - Note 8 - Fair Value of Assets and Liabilities</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-note-8-fair-value-of-assets-and-liabilities</Role>
      <ShortName>Note 8 - Fair Value of Assets and Liabilities</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>016 - Disclosure - Note 9 - Accumulated Other Comprehensive Loss</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-note-9-accumulated-other-comprehensive-loss</Role>
      <ShortName>Note 9 - Accumulated Other Comprehensive Loss</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>017 - Disclosure - Note 10 - Equity Plans</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-note-10-equity-plans</Role>
      <ShortName>Note 10 - Equity Plans</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>018 - Disclosure - Note 11 - Commitments and Contingencies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-note-11-commitments-and-contingencies</Role>
      <ShortName>Note 11 - Commitments and Contingencies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>019 - Disclosure - Note 12 - Income Taxes</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-note-12-income-taxes</Role>
      <ShortName>Note 12 - Income Taxes</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>20</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>020 - Disclosure - Note 13 - Shares Outstanding and Earnings Per Share</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-note-13-shares-outstanding-and-earnings-per-share</Role>
      <ShortName>Note 13 - Shares Outstanding and Earnings Per Share</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>21</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>021 - Disclosure - Note 14 - Stock Repurchase Program</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-note-14-stock-repurchase-program</Role>
      <ShortName>Note 14 - Stock Repurchase Program</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>22</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>022 - Disclosure - Note 15 - Segment Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-note-15-segment-information</Role>
      <ShortName>Note 15 - Segment Information</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>23</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>023 - Disclosure - Note 16 - Retirement Plans</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-note-16-retirement-plans</Role>
      <ShortName>Note 16 - Retirement Plans</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>24</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>024 - Disclosure - Note 17 - Related-party Transactions</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-note-17-relatedparty-transactions</Role>
      <ShortName>Note 17 - Related-party Transactions</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>25</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>025 - Document - Schedule II - Valuation and Qualifying Accounts</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-schedule-ii-valuation-and-qualifying-accounts</Role>
      <ShortName>Schedule II - Valuation and Qualifying Accounts</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>26</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>026 - Disclosure - Schedule III - Supplemental Financial Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-schedule-iii-supplemental-financial-information</Role>
      <ShortName>Schedule III - Supplemental Financial Information</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>27</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>027 - Disclosure - Significant Accounting Policies (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-significant-accounting-policies-policies</Role>
      <ShortName>Significant Accounting Policies (Policies)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>28</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>028 - Disclosure - Note 3 - Inventories (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-note-3-inventories-tables</Role>
      <ShortName>Note 3 - Inventories (Tables)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>29</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>029 - Disclosure - Note 4 - Property and Equipment (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-note-4-property-and-equipment-tables</Role>
      <ShortName>Note 4 - Property and Equipment (Tables)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>30</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>030 - Disclosure - Note 5 - Intangible Assets (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-note-5-intangible-assets-tables</Role>
      <ShortName>Note 5 - Intangible Assets (Tables)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>31</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>031 - Disclosure - Note 6 - Debt (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-note-6-debt-tables</Role>
      <ShortName>Note 6 - Debt (Tables)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>32</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>032 - Disclosure - Note 7 - Derivative Instruments (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-note-7-derivative-instruments-tables</Role>
      <ShortName>Note 7 - Derivative Instruments (Tables)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>33</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>033 - Disclosure - Note 8 - Fair Value of Assets and Liabilities (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-note-8-fair-value-of-assets-and-liabilities-tables</Role>
      <ShortName>Note 8 - Fair Value of Assets and Liabilities (Tables)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>34</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>034 - Disclosure - Note 10 - Equity Plans (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-note-10-equity-plans-tables</Role>
      <ShortName>Note 10 - Equity Plans (Tables)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>35</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>035 - Disclosure - Note 11 - Commitments and Contingencies (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-note-11-commitments-and-contingencies-tables</Role>
      <ShortName>Note 11 - Commitments and Contingencies (Tables)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>36</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>036 - Disclosure - Note 12 - Income Taxes (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-note-12-income-taxes-tables</Role>
      <ShortName>Note 12 - Income Taxes (Tables)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>37</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>037 - Disclosure - Note 13 - Shares Outstanding and Earnings Per Share (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-note-13-shares-outstanding-and-earnings-per-share-tables</Role>
      <ShortName>Note 13 - Shares Outstanding and Earnings Per Share (Tables)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>38</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>038 - Disclosure - Note 15 - Segment Information (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-note-15-segment-information-tables</Role>
      <ShortName>Note 15 - Segment Information (Tables)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>39</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>039 - Disclosure - Schedule II - Valuation and Qualifying Accounts (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-schedule-ii-valuation-and-qualifying-accounts-tables</Role>
      <ShortName>Schedule II - Valuation and Qualifying Accounts (Tables)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>40</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>040 - Disclosure - Schedule III - Supplemental Financial Information (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-schedule-iii-supplemental-financial-information-tables</Role>
      <ShortName>Schedule III - Supplemental Financial Information (Tables)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>41</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>041 - Disclosure - Note 1 - Summary of Significant Accounting Policies (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-note-1-summary-of-significant-accounting-policies-details-textual</Role>
      <ShortName>Note 1 - Summary of Significant Accounting Policies (Details Textual)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>42</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>042 - Disclosure - Note 2 - Accounts Receivable (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-note-2-accounts-receivable-details-textual</Role>
      <ShortName>Note 2 - Accounts Receivable (Details Textual)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>43</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>043 - Disclosure - Note 3 - Inventories (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-note-3-inventories-details-textual</Role>
      <ShortName>Note 3 - Inventories (Details Textual)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>44</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>044 - Disclosure - Note 3 - Inventories - Steel Inventories (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-note-3-inventories-steel-inventories-details</Role>
      <ShortName>Note 3 - Inventories - Steel Inventories (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>45</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>045 - Disclosure - Note 4 - Property and Equipment (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-note-4-property-and-equipment-details-textual</Role>
      <ShortName>Note 4 - Property and Equipment (Details Textual)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>46</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>046 - Disclosure - Note 4 - Property and Equipment - Property and Equipment (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-note-4-property-and-equipment-property-and-equipment-details</Role>
      <ShortName>Note 4 - Property and Equipment - Property and Equipment (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>47</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>047 - Disclosure - Note 5 - Intangible Assets (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-note-5-intangible-assets-details-textual</Role>
      <ShortName>Note 5 - Intangible Assets (Details Textual)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>48</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>048 - Disclosure - Note 5 - Intangible Assets - Intangible Assets, Net (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-note-5-intangible-assets-intangible-assets-net-details</Role>
      <ShortName>Note 5 - Intangible Assets - Intangible Assets, Net (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>49</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>049 - Disclosure - Note 6 - Debt (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-note-6-debt-details-textual</Role>
      <ShortName>Note 6 - Debt (Details Textual)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>50</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>050 - Disclosure - Note 6 - Debt - Summary of Debt (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-note-6-debt-summary-of-debt-details</Role>
      <ShortName>Note 6 - Debt - Summary of Debt (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>51</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R52.htm</HtmlFileName>
      <LongName>051 - Disclosure - Note 6 - Debt - Principal Payments Over the Next 5 Years and Thereafter (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-note-6-debt-principal-payments-over-the-next-5-years-and-thereafter-details</Role>
      <ShortName>Note 6 - Debt - Principal Payments Over the Next 5 Years and Thereafter (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>52</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R53.htm</HtmlFileName>
      <LongName>052 - Disclosure - Note 7 - Derivative Instruments (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-note-7-derivative-instruments-details-textual</Role>
      <ShortName>Note 7 - Derivative Instruments (Details Textual)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>53</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R54.htm</HtmlFileName>
      <LongName>053 - Disclosure - Note 7 - Derivative Instruments - Impact from Derivatives on Consolidated Statements of Comprehensive Income (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-note-7-derivative-instruments-impact-from-derivatives-on-consolidated-statements-of-comprehensive-income-details</Role>
      <ShortName>Note 7 - Derivative Instruments - Impact from Derivatives on Consolidated Statements of Comprehensive Income (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>54</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R55.htm</HtmlFileName>
      <LongName>054 - Disclosure - Note 8 - Fair Value of Assets and Liabilities (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-note-8-fair-value-of-assets-and-liabilities-details-textual</Role>
      <ShortName>Note 8 - Fair Value of Assets and Liabilities (Details Textual)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>55</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R56.htm</HtmlFileName>
      <LongName>055 - Disclosure - Note 8 - Fair Value of Assets and Liabilities - Fair Value Measurements, Recorded (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-note-8-fair-value-of-assets-and-liabilities-fair-value-measurements-recorded-details</Role>
      <ShortName>Note 8 - Fair Value of Assets and Liabilities - Fair Value Measurements, Recorded (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>56</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R57.htm</HtmlFileName>
      <LongName>056 - Disclosure - Note 8 - Fair Value of Financial Instruments - Fair Value Measurements, Not Recorded (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-note-8-fair-value-of-financial-instruments-fair-value-measurements-not-recorded-details</Role>
      <ShortName>Note 8 - Fair Value of Financial Instruments - Fair Value Measurements, Not Recorded (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>57</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R58.htm</HtmlFileName>
      <LongName>057 - Disclosure - Note 9 - Accumulated Other Comprehensive Loss (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-note-9-accumulated-other-comprehensive-loss-details-textual</Role>
      <ShortName>Note 9 - Accumulated Other Comprehensive Loss (Details Textual)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>58</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R59.htm</HtmlFileName>
      <LongName>058 - Disclosure - Note 10 - Equity Plans (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-note-10-equity-plans-details-textual</Role>
      <ShortName>Note 10 - Equity Plans (Details Textual)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>59</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R60.htm</HtmlFileName>
      <LongName>059 - Disclosure - Note 10 - Equity Plans - Stock-based Compensation Expense Recognized on Restricted Stock Units (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-note-10-equity-plans-stockbased-compensation-expense-recognized-on-restricted-stock-units-details</Role>
      <ShortName>Note 10 - Equity Plans - Stock-based Compensation Expense Recognized on Restricted Stock Units (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>60</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R61.htm</HtmlFileName>
      <LongName>060 - Disclosure - Note 10 - Equity Plans - Restricted Stock Unit Activity (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-note-10-equity-plans-restricted-stock-unit-activity-details</Role>
      <ShortName>Note 10 - Equity Plans - Restricted Stock Unit Activity (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>61</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R62.htm</HtmlFileName>
      <LongName>061 - Disclosure - Note 11 - Commitments and Contingencies (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-note-11-commitments-and-contingencies-details-textual</Role>
      <ShortName>Note 11 - Commitments and Contingencies (Details Textual)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>62</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R63.htm</HtmlFileName>
      <LongName>062 - Disclosure - Note 11 - Commitments and Contingencies - Future Minimum Lease Payments (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-note-11-commitments-and-contingencies-future-minimum-lease-payments-details</Role>
      <ShortName>Note 11 - Commitments and Contingencies - Future Minimum Lease Payments (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>63</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R64.htm</HtmlFileName>
      <LongName>063 - Disclosure - Note 12 - Income Taxes (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-note-12-income-taxes-details-textual</Role>
      <ShortName>Note 12 - Income Taxes (Details Textual)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>64</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R65.htm</HtmlFileName>
      <LongName>064 - Disclosure - Note 12 - Income Taxes - Provision (Benefit) for Income Taxes (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-note-12-income-taxes-provision-benefit-for-income-taxes-details</Role>
      <ShortName>Note 12 - Income Taxes - Provision (Benefit) for Income Taxes (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>65</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R66.htm</HtmlFileName>
      <LongName>065 - Disclosure - Note 12 - Income Taxes - Deferred Income Taxes (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-note-12-income-taxes-deferred-income-taxes-details</Role>
      <ShortName>Note 12 - Income Taxes - Deferred Income Taxes (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>66</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R67.htm</HtmlFileName>
      <LongName>066 - Disclosure - Note 12 - Income Taxes - Unrecognized Tax Benefits Activity (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-note-12-income-taxes-unrecognized-tax-benefits-activity-details</Role>
      <ShortName>Note 12 - Income Taxes - Unrecognized Tax Benefits Activity (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>67</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R68.htm</HtmlFileName>
      <LongName>067 - Disclosure - Note 12 - Income Taxes - Tax Rate Reconciliation (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-note-12-income-taxes-tax-rate-reconciliation-details</Role>
      <ShortName>Note 12 - Income Taxes - Tax Rate Reconciliation (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>68</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R69.htm</HtmlFileName>
      <LongName>068 - Disclosure - Note 13 - Shares Outstanding and Earnings Per Share - Earnings Per Share (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-note-13-shares-outstanding-and-earnings-per-share-earnings-per-share-details</Role>
      <ShortName>Note 13 - Shares Outstanding and Earnings Per Share - Earnings Per Share (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>69</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R70.htm</HtmlFileName>
      <LongName>069 - Disclosure - Note 14 - Stock Repurchase Program (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-note-14-stock-repurchase-program-details-textual</Role>
      <ShortName>Note 14 - Stock Repurchase Program (Details Textual)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>70</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R71.htm</HtmlFileName>
      <LongName>070 - Disclosure - Note 15 - Segment Information (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-note-15-segment-information-details-textual</Role>
      <ShortName>Note 15 - Segment Information (Details Textual)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>71</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R72.htm</HtmlFileName>
      <LongName>071 - Disclosure - Note 15 - Segment Information - Segment Reporting Information by Revenue (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-note-15-segment-information-segment-reporting-information-by-revenue-details</Role>
      <ShortName>Note 15 - Segment Information - Segment Reporting Information by Revenue (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>72</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R73.htm</HtmlFileName>
      <LongName>072 - Disclosure - Note 15 - Segment Information - Segment Reporting Information by Capital Expenditures (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-note-15-segment-information-segment-reporting-information-by-capital-expenditures-details</Role>
      <ShortName>Note 15 - Segment Information - Segment Reporting Information by Capital Expenditures (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>73</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R74.htm</HtmlFileName>
      <LongName>073 - Disclosure - Note 16 - Retirement Plans (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-note-16-retirement-plans-details-textual</Role>
      <ShortName>Note 16 - Retirement Plans (Details Textual)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>74</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R75.htm</HtmlFileName>
      <LongName>074 - Disclosure - Note 17 - Related-party Transactions (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-note-17-relatedparty-transactions-details-textual</Role>
      <ShortName>Note 17 - Related-party Transactions (Details Textual)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>75</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R76.htm</HtmlFileName>
      <LongName>075 - Disclosure - Schedule II - Valuation and Qualifying Accounts - Summary of Valuation and Qualifying Accounts (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-schedule-ii-valuation-and-qualifying-accounts-summary-of-valuation-and-qualifying-accounts-details</Role>
      <ShortName>Schedule II - Valuation and Qualifying Accounts - Summary of Valuation and Qualifying Accounts (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>76</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R77.htm</HtmlFileName>
      <LongName>076 - Disclosure - Schedule III - Supplemental Financial Information (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-schedule-iii-supplemental-financial-information-details-textual</Role>
      <ShortName>Schedule III - Supplemental Financial Information (Details Textual)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>77</Position>
    </Report>
    <Report instance="zeus-20171231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R78.htm</HtmlFileName>
      <LongName>077 - Disclosure - Schedule III - Supplemental Financial Information - Quarterly Results of Operations (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://olysteel.com/20171231/role/statement-schedule-iii-supplemental-financial-information-quarterly-results-of-operations-details</Role>
      <ShortName>Schedule III - Supplemental Financial Information - Quarterly Results of Operations (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>78</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <InputFiles>
    <File>zeus-20171231.xml</File>
    <File>zeus-20171231.xsd</File>
    <File>zeus-20171231_cal.xml</File>
    <File>zeus-20171231_def.xml</File>
    <File>zeus-20171231_lab.xml</File>
    <File>zeus-20171231_pre.xml</File>
  </InputFiles>
  <SupplementalFiles/>
  <BaseTaxonomies>
    <BaseTaxonomy>http://fasb.org/us-gaap/2017-01-31</BaseTaxonomy>
    <BaseTaxonomy>http://xbrl.sec.gov/dei/2014-01-31</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
