<?xml version='1.0' encoding='UTF-8'?>
<FilingSummary>
  <Version>3.5.0.2</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>113</ContextCount>
  <ElementCount>177</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>true</FootnotesReported>
  <SegmentCount>50</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>7</UnitCount>
  <MyReports>
    <Report instance="glf-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>000 - Document - Document And Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gulfmark.com/20160630/role/statement-document-and-entity-information</Role>
      <ShortName>Document And Entity Information</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="glf-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>001 - Statement - Current Period Unaudited Condensed Consolidated Balance Sheets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gulfmark.com/20160630/role/statement-current-period-unaudited-condensed-consolidated-balance-sheets</Role>
      <ShortName>Current Period Unaudited Condensed Consolidated Balance Sheets</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="glf-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>002 - Statement - Current Period Unaudited Condensed Consolidated Balance Sheets (Parentheticals)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gulfmark.com/20160630/role/statement-current-period-unaudited-condensed-consolidated-balance-sheets-parentheticals</Role>
      <ShortName>Current Period Unaudited Condensed Consolidated Balance Sheets (Parentheticals)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="glf-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>003 - Statement - Unaudited Condensed Consolidated Statements of Operations</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gulfmark.com/20160630/role/statement-unaudited-condensed-consolidated-statements-of-operations</Role>
      <ShortName>Unaudited Condensed Consolidated Statements of Operations</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="glf-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>004 - Statement - Unaudited Condensed Consolidated Statements of Comprehensive Income (Loss)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gulfmark.com/20160630/role/statement-unaudited-condensed-consolidated-statements-of-comprehensive-income-loss</Role>
      <ShortName>Unaudited Condensed Consolidated Statements of Comprehensive Income (Loss)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="glf-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>005 - Statement - Unaudited Condensed Consolidated Statement of Stockholders' Equity</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gulfmark.com/20160630/role/statement-unaudited-condensed-consolidated-statement-of-stockholders-equity</Role>
      <ShortName>Unaudited Condensed Consolidated Statement of Stockholders' Equity</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="glf-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>006 - Statement - Unaudited Condensed Consolidated Statements of Cash Flows</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gulfmark.com/20160630/role/statement-unaudited-condensed-consolidated-statements-of-cash-flows</Role>
      <ShortName>Unaudited Condensed Consolidated Statements of Cash Flows</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="glf-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>007 - Disclosure - Note 1 - General Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gulfmark.com/20160630/role/statement-note-1-general-information</Role>
      <ShortName>Note 1 - General Information</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="glf-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>008 - Disclosure - Note 2 - Impairment Charges</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gulfmark.com/20160630/role/statement-note-2-impairment-charges</Role>
      <ShortName>Note 2 - Impairment Charges</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="glf-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>009 - Disclosure - Note 3 - Vessel Acquisitions and Dispositions</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gulfmark.com/20160630/role/statement-note-3-vessel-acquisitions-and-dispositions</Role>
      <ShortName>Note 3 - Vessel Acquisitions and Dispositions</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="glf-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>010 - Disclosure - Note 4 - Long-term Debt</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gulfmark.com/20160630/role/statement-note-4-longterm-debt</Role>
      <ShortName>Note 4 - Long-term Debt</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="glf-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>011 - Disclosure - Note 5 - Income Taxes</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gulfmark.com/20160630/role/statement-note-5-income-taxes</Role>
      <ShortName>Note 5 - Income Taxes</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="glf-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>012 - Disclosure - Note 6 - Commitments and Contingencies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gulfmark.com/20160630/role/statement-note-6-commitments-and-contingencies</Role>
      <ShortName>Note 6 - Commitments and Contingencies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="glf-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>013 - Document - Note 7 - New Accounting Pronouncements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gulfmark.com/20160630/role/statement-note-7-new-accounting-pronouncements-</Role>
      <ShortName>Note 7 - New Accounting Pronouncements</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="glf-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>014 - Disclosure - Note 8 - Operating Segment Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gulfmark.com/20160630/role/statement-note-8-operating-segment-information</Role>
      <ShortName>Note 8 - Operating Segment Information</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="glf-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>015 - Disclosure - Significant Accounting Policies (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gulfmark.com/20160630/role/statement-significant-accounting-policies-policies</Role>
      <ShortName>Significant Accounting Policies (Policies)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="glf-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>016 - Disclosure - Note 3 - Vessel Acquisitions and Dispositions (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gulfmark.com/20160630/role/statement-note-3-vessel-acquisitions-and-dispositions-tables</Role>
      <ShortName>Note 3 - Vessel Acquisitions and Dispositions (Tables)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="glf-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>017 - Disclosure - Note 4 - Long-term Debt (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gulfmark.com/20160630/role/statement-note-4-longterm-debt-tables</Role>
      <ShortName>Note 4 - Long-term Debt (Tables)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="glf-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>018 - Disclosure - Note 8 - Operating Segment Information (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gulfmark.com/20160630/role/statement-note-8-operating-segment-information-tables</Role>
      <ShortName>Note 8 - Operating Segment Information (Tables)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report instance="glf-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>019 - Disclosure - Note 2 - Impairment Charges (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gulfmark.com/20160630/role/statement-note-2-impairment-charges-details-textual</Role>
      <ShortName>Note 2 - Impairment Charges (Details Textual)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>20</Position>
    </Report>
    <Report instance="glf-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>020 - Disclosure - Note 3 - Vessel Acquisitions and Dispositions (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gulfmark.com/20160630/role/statement-note-3-vessel-acquisitions-and-dispositions-details-textual</Role>
      <ShortName>Note 3 - Vessel Acquisitions and Dispositions (Details Textual)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>21</Position>
    </Report>
    <Report instance="glf-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>021 - Disclosure - Note 3 - Vessel Acquisitions and Dispositions - Vessels Under Construction (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gulfmark.com/20160630/role/statement-note-3-vessel-acquisitions-and-dispositions-vessels-under-construction-details</Role>
      <ShortName>Note 3 - Vessel Acquisitions and Dispositions - Vessels Under Construction (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>22</Position>
    </Report>
    <Report instance="glf-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>022 - Disclosure - Note 3 - Vessel Acquisitions and Dispositions - Vessels Additions (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gulfmark.com/20160630/role/statement-note-3-vessel-acquisitions-and-dispositions-vessels-additions-details</Role>
      <ShortName>Note 3 - Vessel Acquisitions and Dispositions - Vessels Additions (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>23</Position>
    </Report>
    <Report instance="glf-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>023 - Disclosure - Note 3 - Vessel Acquisitions and Dispositions - Vessels Disposed (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gulfmark.com/20160630/role/statement-note-3-vessel-acquisitions-and-dispositions-vessels-disposed-details</Role>
      <ShortName>Note 3 - Vessel Acquisitions and Dispositions - Vessels Disposed (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>24</Position>
    </Report>
    <Report instance="glf-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>024 - Disclosure - Note 4 - Long-term Debt (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gulfmark.com/20160630/role/statement-note-4-longterm-debt-details-textual</Role>
      <ShortName>Note 4 - Long-term Debt (Details Textual)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>25</Position>
    </Report>
    <Report instance="glf-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>025 - Disclosure - Note 4 - Long-term Debt - Long-term Debt (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gulfmark.com/20160630/role/statement-note-4-longterm-debt-longterm-debt-details</Role>
      <ShortName>Note 4 - Long-term Debt - Long-term Debt (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>26</Position>
    </Report>
    <Report instance="glf-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>026 - Disclosure - Note 4 - Long-term Debt - Maturities of Long-term Debt (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gulfmark.com/20160630/role/statement-note-4-longterm-debt-maturities-of-longterm-debt-details</Role>
      <ShortName>Note 4 - Long-term Debt - Maturities of Long-term Debt (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>27</Position>
    </Report>
    <Report instance="glf-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>027 - Disclosure - Note 5 - Income Taxes (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gulfmark.com/20160630/role/statement-note-5-income-taxes-details-textual</Role>
      <ShortName>Note 5 - Income Taxes (Details Textual)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>28</Position>
    </Report>
    <Report instance="glf-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>028 - Disclosure - Note 6 - Commitments and Contingencies (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gulfmark.com/20160630/role/statement-note-6-commitments-and-contingencies-details-textual</Role>
      <ShortName>Note 6 - Commitments and Contingencies (Details Textual)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>29</Position>
    </Report>
    <Report instance="glf-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>029 - Disclosure - Note 8 - Operating Segment Information (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gulfmark.com/20160630/role/statement-note-8-operating-segment-information-details-textual</Role>
      <ShortName>Note 8 - Operating Segment Information (Details Textual)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>30</Position>
    </Report>
    <Report instance="glf-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>030 - Disclosure - Note 8 - Operating Segment Information - Operating Income (Loss) by Operating Segment (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gulfmark.com/20160630/role/statement-note-8-operating-segment-information-operating-income-loss-by-operating-segment-details</Role>
      <ShortName>Note 8 - Operating Segment Information - Operating Income (Loss) by Operating Segment (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>31</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <InputFiles>
    <File>glf-20160630.xml</File>
    <File>glf-20160630.xsd</File>
    <File>glf-20160630_cal.xml</File>
    <File>glf-20160630_def.xml</File>
    <File>glf-20160630_lab.xml</File>
    <File>glf-20160630_pre.xml</File>
  </InputFiles>
  <SupplementalFiles/>
  <BaseTaxonomies/>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
