<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.20.1</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>253</ContextCount>
  <ElementCount>462</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>false</FootnotesReported>
  <SegmentCount>90</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>12</UnitCount>
  <MyReports>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>00090 - Document - Document and Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/DocumentDocumentAndEntityInformation</Role>
      <ShortName>Document and Entity Information</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>00100 - Statement - CONSOLIDATED BALANCE SHEETS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/StatementConsolidatedBalanceSheets</Role>
      <ShortName>CONSOLIDATED BALANCE SHEETS</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>00105 - Statement - CONSOLIDATED BALANCE SHEETS (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/StatementConsolidatedBalanceSheetsParenthetical</Role>
      <ShortName>CONSOLIDATED BALANCE SHEETS (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>00200 - Statement - CONSOLIDATED STATEMENTS OF OPERATIONS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/StatementConsolidatedStatementsOfOperations</Role>
      <ShortName>CONSOLIDATED STATEMENTS OF OPERATIONS</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>00300 - Statement - CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/StatementConsolidatedStatementsOfComprehensiveLoss</Role>
      <ShortName>CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>00400 - Statement - CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (DEFICIT)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/StatementConsolidatedStatementsOfStockholdersEquityDeficit</Role>
      <ShortName>CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (DEFICIT)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>00500 - Statement - CONSOLIDATED STATEMENTS OF CASH FLOWS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/StatementConsolidatedStatementsOfCashFlows</Role>
      <ShortName>CONSOLIDATED STATEMENTS OF CASH FLOWS</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>10101 - Disclosure - Organization and nature of operations</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/DisclosureOrganizationAndNatureOfOperations</Role>
      <ShortName>Organization and nature of operations</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>10201 - Disclosure - Summary of significant accounting policies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/DisclosureSummaryOfSignificantAccountingPolicies</Role>
      <ShortName>Summary of significant accounting policies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>10301 - Disclosure - Net loss per share</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/DisclosureNetLossPerShare</Role>
      <ShortName>Net loss per share</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>10401 - Disclosure - Fair value of financial instruments</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/DisclosureFairValueOfFinancialInstruments</Role>
      <ShortName>Fair value of financial instruments</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>10501 - Disclosure - Inventories</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/DisclosureInventories</Role>
      <ShortName>Inventories</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>10601 - Disclosure - Accrued expenses</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/DisclosureAccruedExpenses</Role>
      <ShortName>Accrued expenses</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>10701 - Disclosure - Debt</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/DisclosureDebt</Role>
      <ShortName>Debt</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>10801 - Disclosure - Leases</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/DisclosureLeases</Role>
      <ShortName>Leases</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>10901 - Disclosure - Common stock</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/DisclosureCommonStock</Role>
      <ShortName>Common stock</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>11001 - Disclosure - Share-based Compensation</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/DisclosureShareBasedCompensation</Role>
      <ShortName>Share-based Compensation</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>11101 - Disclosure - Treasury stock</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/DisclosureTreasuryStock</Role>
      <ShortName>Treasury stock</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>11201 - Disclosure - Commitments and contingencies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/DisclosureCommitmentsAndContingencies</Role>
      <ShortName>Commitments and contingencies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>11301 - Disclosure - License agreements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/DisclosureLicenseAgreements</Role>
      <ShortName>License agreements</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>20</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>11401 - Disclosure - Related party transactions</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/DisclosureRelatedPartyTransactions</Role>
      <ShortName>Related party transactions</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>21</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>11501 - Disclosure - Subsequent event</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/DisclosureSubsequentEvent</Role>
      <ShortName>Subsequent event</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>22</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>20202 - Disclosure - Summary of significant accounting policies (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/DisclosureSummaryOfSignificantAccountingPoliciesPolicies</Role>
      <ShortName>Summary of significant accounting policies (Policies)</ShortName>
      <MenuCategory>Policies</MenuCategory>
      <Position>23</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>30203 - Disclosure - Summary of significant accounting policies (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/DisclosureSummaryOfSignificantAccountingPoliciesTables</Role>
      <ShortName>Summary of significant accounting policies (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.neostx.com/role/DisclosureSummaryOfSignificantAccountingPolicies</ParentRole>
      <Position>24</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>30303 - Disclosure - Net loss per share (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/DisclosureNetLossPerShareTables</Role>
      <ShortName>Net loss per share (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.neostx.com/role/DisclosureNetLossPerShare</ParentRole>
      <Position>25</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>30403 - Disclosure - Fair value of financial instruments (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/DisclosureFairValueOfFinancialInstrumentsTables</Role>
      <ShortName>Fair value of financial instruments (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.neostx.com/role/DisclosureFairValueOfFinancialInstruments</ParentRole>
      <Position>26</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>30503 - Disclosure - Inventories (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/DisclosureInventoriesTables</Role>
      <ShortName>Inventories (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.neostx.com/role/DisclosureInventories</ParentRole>
      <Position>27</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>30603 - Disclosure - Accrued expenses (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/DisclosureAccruedExpensesTables</Role>
      <ShortName>Accrued expenses (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.neostx.com/role/DisclosureAccruedExpenses</ParentRole>
      <Position>28</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>30703 - Disclosure - Debt (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/DisclosureDebtTables</Role>
      <ShortName>Debt (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.neostx.com/role/DisclosureDebt</ParentRole>
      <Position>29</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>30803 - Disclosure - Leases (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/DisclosureLeasesTables</Role>
      <ShortName>Leases (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.neostx.com/role/DisclosureLeases</ParentRole>
      <Position>30</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>31003 - Disclosure - Share-based Compensation (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/DisclosureShareBasedCompensationTables</Role>
      <ShortName>Share-based Compensation (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.neostx.com/role/DisclosureShareBasedCompensation</ParentRole>
      <Position>31</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>40101 - Disclosure - Organization and nature of operations (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/DisclosureOrganizationAndNatureOfOperationsDetails</Role>
      <ShortName>Organization and nature of operations (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.neostx.com/role/DisclosureOrganizationAndNatureOfOperations</ParentRole>
      <Position>32</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>40201 - Disclosure - Summary of significant accounting policies (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/DisclosureSummaryOfSignificantAccountingPoliciesDetails</Role>
      <ShortName>Summary of significant accounting policies (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.neostx.com/role/DisclosureSummaryOfSignificantAccountingPoliciesTables</ParentRole>
      <Position>33</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>40203 - Disclosure - Summary of significant accounting policies - Liquidity (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/DisclosureSummaryOfSignificantAccountingPoliciesLiquidityDetails</Role>
      <ShortName>Summary of significant accounting policies - Liquidity (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>34</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>40301 - Disclosure - Net loss per share (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/DisclosureNetLossPerShareDetails</Role>
      <ShortName>Net loss per share (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.neostx.com/role/DisclosureNetLossPerShareTables</ParentRole>
      <Position>35</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>40401 - Disclosure - Fair value of financial instruments - Hierarchy (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/DisclosureFairValueOfFinancialInstrumentsHierarchyDetails</Role>
      <ShortName>Fair value of financial instruments - Hierarchy (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>36</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>40402 - Disclosure - Fair value of financial instruments - Cash and cash equivalents and short-term investments (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/DisclosureFairValueOfFinancialInstrumentsCashAndCashEquivalentsAndShortTermInvestmentsDetails</Role>
      <ShortName>Fair value of financial instruments - Cash and cash equivalents and short-term investments (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>37</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>40404 - Disclosure - Fair value of financial instruments - Derivative liability (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/DisclosureFairValueOfFinancialInstrumentsDerivativeLiabilityDetails</Role>
      <ShortName>Fair value of financial instruments - Derivative liability (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>38</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>40405 - Disclosure - Fair value of financial instruments - Changes in Level 3 (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/DisclosureFairValueOfFinancialInstrumentsChangesInLevel3Details</Role>
      <ShortName>Fair value of financial instruments - Changes in Level 3 (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>39</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>40501 - Disclosure - Inventories (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/DisclosureInventoriesDetails</Role>
      <ShortName>Inventories (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.neostx.com/role/DisclosureInventoriesTables</ParentRole>
      <Position>40</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>40601 - Disclosure - Accrued expenses (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/DisclosureAccruedExpensesDetails</Role>
      <ShortName>Accrued expenses (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.neostx.com/role/DisclosureAccruedExpensesTables</ParentRole>
      <Position>41</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>40701 - Disclosure - Debt - Short-term line of credit (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/DisclosureDebtShortTermLineOfCreditDetails</Role>
      <ShortName>Debt - Short-term line of credit (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>42</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>40702 - Disclosure - Debt - Summary (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/DisclosureDebtSummaryDetails</Role>
      <ShortName>Debt - Summary (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>43</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>40703 - Disclosure - Debt - Senior Secured Credit facility (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/DisclosureDebtSeniorSecuredCreditFacilityDetails</Role>
      <ShortName>Debt - Senior Secured Credit facility (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>44</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>40704 - Disclosure - Debt - Financing and Capital Lease Obligations (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/DisclosureDebtFinancingAndCapitalLeaseObligationsDetails</Role>
      <ShortName>Debt - Financing and Capital Lease Obligations (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>45</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>40705 - Disclosure - Debt - Future Principal Payments (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/DisclosureDebtFuturePrincipalPaymentsDetails</Role>
      <ShortName>Debt - Future Principal Payments (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>46</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>40801 - Disclosure - Leases (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/DisclosureLeasesDetails</Role>
      <ShortName>Leases (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.neostx.com/role/DisclosureLeasesTables</ParentRole>
      <Position>47</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>40802 - Disclosure - Leases - Lease expense (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/DisclosureLeasesLeaseExpenseDetails</Role>
      <ShortName>Leases - Lease expense (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>48</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>40803 - Disclosure - Leases - Consolidated balance sheet information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/DisclosureLeasesConsolidatedBalanceSheetInformationDetails</Role>
      <ShortName>Leases - Consolidated balance sheet information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>49</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>40804 - Disclosure - Leases - Schedule of Weighted Average Remaining Lease Term and Discount Rate Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/DisclosureLeasesScheduleOfWeightedAverageRemainingLeaseTermAndDiscountRateInformationDetails</Role>
      <ShortName>Leases - Schedule of Weighted Average Remaining Lease Term and Discount Rate Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>50</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>40805 - Disclosure - Leases - Supplemental cash flow information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/DisclosureLeasesSupplementalCashFlowInformationDetails</Role>
      <ShortName>Leases - Supplemental cash flow information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>51</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R52.htm</HtmlFileName>
      <LongName>40806 - Disclosure - Leases - Future minimum rental payments (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/DisclosureLeasesFutureMinimumRentalPaymentsDetails</Role>
      <ShortName>Leases - Future minimum rental payments (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>52</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R53.htm</HtmlFileName>
      <LongName>40901 - Disclosure - Common stock - Shelf Registration Statement and Public Offerings (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/DisclosureCommonStockShelfRegistrationStatementAndPublicOfferingsDetails</Role>
      <ShortName>Common stock - Shelf Registration Statement and Public Offerings (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>53</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R54.htm</HtmlFileName>
      <LongName>40902 - Disclosure - Common stock - Offer under sales agreement (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/DisclosureCommonStockOfferUnderSalesAgreementDetails</Role>
      <ShortName>Common stock - Offer under sales agreement (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>54</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R55.htm</HtmlFileName>
      <LongName>41001 - Disclosure - Share-based Compensation - Plan Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/DisclosureShareBasedCompensationPlanInformationDetails</Role>
      <ShortName>Share-based Compensation - Plan Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>55</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R56.htm</HtmlFileName>
      <LongName>41002 - Disclosure - Share-based Compensation - Expense Allocation (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/DisclosureShareBasedCompensationExpenseAllocationDetails</Role>
      <ShortName>Share-based Compensation - Expense Allocation (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>56</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R57.htm</HtmlFileName>
      <LongName>41003 - Disclosure - Share-based Compensation - Expense Other (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/DisclosureShareBasedCompensationExpenseOtherDetails</Role>
      <ShortName>Share-based Compensation - Expense Other (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>57</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R58.htm</HtmlFileName>
      <LongName>41004 - Disclosure - Share-based Compensation - Assumptions Used in Determining Fair Value of Options (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/DisclosureShareBasedCompensationAssumptionsUsedInDeterminingFairValueOfOptionsDetails</Role>
      <ShortName>Share-based Compensation - Assumptions Used in Determining Fair Value of Options (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>58</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R59.htm</HtmlFileName>
      <LongName>41005 - Disclosure - Share-based Compensation - Options (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/DisclosureShareBasedCompensationOptionsDetails</Role>
      <ShortName>Share-based Compensation - Options (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>59</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R60.htm</HtmlFileName>
      <LongName>41006 - Disclosure - Share-based Compensation ??? Restricted Stock Units (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/DisclosureShareBasedCompensationRestrictedStockUnitsDetails</Role>
      <ShortName>Share-based Compensation ??? Restricted Stock Units (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>60</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R61.htm</HtmlFileName>
      <LongName>41007 - Disclosure - Share-based Compensation - Summary of Outstanding RSUs (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/DisclosureShareBasedCompensationSummaryOfOutstandingRsusDetails</Role>
      <ShortName>Share-based Compensation - Summary of Outstanding RSUs (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>61</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R62.htm</HtmlFileName>
      <LongName>41008 - Disclosure - Share-based Compensation - Restricted Stock (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/DisclosureShareBasedCompensationRestrictedStockDetails</Role>
      <ShortName>Share-based Compensation - Restricted Stock (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>62</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R63.htm</HtmlFileName>
      <LongName>41101 - Disclosure - Treasury stock (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/DisclosureTreasuryStockDetails</Role>
      <ShortName>Treasury stock (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.neostx.com/role/DisclosureTreasuryStock</ParentRole>
      <Position>63</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R64.htm</HtmlFileName>
      <LongName>41201 - Disclosure - Commitments and contingencies - Registration Payment Arrangement (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/DisclosureCommitmentsAndContingenciesRegistrationPaymentArrangementDetails</Role>
      <ShortName>Commitments and contingencies - Registration Payment Arrangement (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>64</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R65.htm</HtmlFileName>
      <LongName>41203 - Disclosure - Commitments and contingencies - Operating Lease, Cash Incentive Bonus Plan, Inducement Option Grant (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/DisclosureCommitmentsAndContingenciesOperatingLeaseCashIncentiveBonusPlanInducementOptionGrantDetails</Role>
      <ShortName>Commitments and contingencies - Operating Lease, Cash Incentive Bonus Plan, Inducement Option Grant (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>65</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R66.htm</HtmlFileName>
      <LongName>41301 - Disclosure - License agreements (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/DisclosureLicenseAgreementsDetails</Role>
      <ShortName>License agreements (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.neostx.com/role/DisclosureLicenseAgreements</ParentRole>
      <Position>66</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R67.htm</HtmlFileName>
      <LongName>41401 - Disclosure - Related party transactions (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/DisclosureRelatedPartyTransactionsDetails</Role>
      <ShortName>Related party transactions (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.neostx.com/role/DisclosureRelatedPartyTransactions</ParentRole>
      <Position>67</Position>
    </Report>
    <Report instance="neos-20200331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R68.htm</HtmlFileName>
      <LongName>41501 - Disclosure - Subsequent events (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.neostx.com/role/DisclosureSubsequentEventsDetails</Role>
      <ShortName>Subsequent events (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.neostx.com/role/DisclosureSubsequentEvent</ParentRole>
      <Position>68</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <InputFiles>
    <File>neos-20200331.xml</File>
    <File>neos-20200331.xsd</File>
    <File>neos-20200331_cal.xml</File>
    <File>neos-20200331_def.xml</File>
    <File>neos-20200331_lab.xml</File>
    <File>neos-20200331_pre.xml</File>
  </InputFiles>
  <SupplementalFiles/>
  <BaseTaxonomies>
    <BaseTaxonomy>http://fasb.org/us-gaap/2019-01-31</BaseTaxonomy>
    <BaseTaxonomy>http://xbrl.sec.gov/dei/2019-01-31</BaseTaxonomy>
    <BaseTaxonomy>http://fasb.org/srt/2019-01-31</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
