| | | | | | | | | | | | | | | | | | | | | |
<?xml version="1.0" encoding="windows-1252"?> |
<FilingSummary> |
| <Version> 3.20.1 </Version> |
| <ProcessingTime/> |
| <ReportFormat> html </ReportFormat> |
| <ContextCount> 289 </ContextCount> |
| <ElementCount> 471 </ElementCount> |
| <EntityCount> 1 </EntityCount> |
| <FootnotesReported> true </FootnotesReported> |
| <SegmentCount> 103 </SegmentCount> |
| <ScenarioCount> 0 </ScenarioCount> |
| <TuplesReported> false </TuplesReported> |
| <UnitCount> 16 </UnitCount> |
| <MyReports> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R1.htm </HtmlFileName> |
| | | <LongName> 100000 - Document - Document and Entity Information </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DocumentDocumentAndEntityInformation </Role> |
| | | <ShortName> Document and Entity Information </ShortName> |
| | | <MenuCategory> Cover </MenuCategory> |
| | | <Position> 1 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R2.htm </HtmlFileName> |
| | | <LongName> 100010 - Statement - Consolidated Statements of Comprehensive Income (Loss) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/StatementConsolidatedStatementsOfComprehensiveIncomeLoss </Role> |
| | | <ShortName> Consolidated Statements of Comprehensive Income (Loss) </ShortName> |
| | | <MenuCategory> Statements </MenuCategory> |
| | | <Position> 2 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R3.htm </HtmlFileName> |
| | | <LongName> 100020 - Statement - Consolidated Balance Sheets </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/StatementConsolidatedBalanceSheets </Role> |
| | | <ShortName> Consolidated Balance Sheets </ShortName> |
| | | <MenuCategory> Statements </MenuCategory> |
| | | <Position> 3 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R4.htm </HtmlFileName> |
| | | <LongName> 100030 - Statement - Consolidated Balance Sheets (Parenthetical) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/StatementConsolidatedBalanceSheetsParenthetical </Role> |
| | | <ShortName> Consolidated Balance Sheets (Parenthetical) </ShortName> |
| | | <MenuCategory> Statements </MenuCategory> |
| | | <Position> 4 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R5.htm </HtmlFileName> |
| | | <LongName> 100040 - Statement - Consolidated Statements of Changes in Shareholders' Equity </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/StatementConsolidatedStatementsOfChangesInShareholdersEquity </Role> |
| | | <ShortName> Consolidated Statements of Changes in Shareholders' Equity </ShortName> |
| | | <MenuCategory> Statements </MenuCategory> |
| | | <Position> 5 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R6.htm </HtmlFileName> |
| | | <LongName> 100050 - Statement - Consolidated Statements of Changes in Shareholders' Equity (Parenthetical) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/StatementConsolidatedStatementsOfChangesInShareholdersEquityParenthetical </Role> |
| | | <ShortName> Consolidated Statements of Changes in Shareholders' Equity (Parenthetical) </ShortName> |
| | | <MenuCategory> Statements </MenuCategory> |
| | | <Position> 6 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R7.htm </HtmlFileName> |
| | | <LongName> 100060 - Statement - Consolidated Statements of Cash Flows </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows </Role> |
| | | <ShortName> Consolidated Statements of Cash Flows </ShortName> |
| | | <MenuCategory> Statements </MenuCategory> |
| | | <Position> 7 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R8.htm </HtmlFileName> |
| | | <LongName> 100070 - Disclosure - Company Information </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureCompanyInformation </Role> |
| | | <ShortName> Company Information </ShortName> |
| | | <MenuCategory> Notes </MenuCategory> |
| | | <Position> 8 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R9.htm </HtmlFileName> |
| | | <LongName> 100080 - Disclosure - Summary of Significant Accounting Policies </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureSummaryOfSignificantAccountingPolicies </Role> |
| | | <ShortName> Summary of Significant Accounting Policies </ShortName> |
| | | <MenuCategory> Notes </MenuCategory> |
| | | <Position> 9 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R10.htm </HtmlFileName> |
| | | <LongName> 100090 - Disclosure - Real Estate Properties under Development, Net </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureRealEstatePropertiesUnderDevelopmentNet </Role> |
| | | <ShortName> Real Estate Properties under Development, Net </ShortName> |
| | | <MenuCategory> Notes </MenuCategory> |
| | | <Position> 10 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R11.htm </HtmlFileName> |
| | | <LongName> 100100 - Disclosure - Property, Plant and Equipment, Net </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosurePropertyPlantAndEquipmentNet </Role> |
| | | <ShortName> Property, Plant and Equipment, Net </ShortName> |
| | | <MenuCategory> Notes </MenuCategory> |
| | | <Position> 11 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R12.htm </HtmlFileName> |
| | | <LongName> 100110 - Disclosure - Investments in Subsidiaries </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureInvestmentsInSubsidiaries </Role> |
| | | <ShortName> Investments in Subsidiaries </ShortName> |
| | | <MenuCategory> Notes </MenuCategory> |
| | | <Position> 12 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R13.htm </HtmlFileName> |
| | | <LongName> 100120 - Disclosure - Retained Earnings and Reserves </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureRetainedEarningsAndReserves </Role> |
| | | <ShortName> Retained Earnings and Reserves </ShortName> |
| | | <MenuCategory> Notes </MenuCategory> |
| | | <Position> 13 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R14.htm </HtmlFileName> |
| | | <LongName> 100130 - Disclosure - Advance from Customers </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureAdvanceFromCustomers </Role> |
| | | <ShortName> Advance from Customers </ShortName> |
| | | <MenuCategory> Notes </MenuCategory> |
| | | <Position> 14 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R15.htm </HtmlFileName> |
| | | <LongName> 100140 - Disclosure - Bank Loans and Banking Facilities </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureBankLoansAndBankingFacilities </Role> |
| | | <ShortName> Bank Loans and Banking Facilities </ShortName> |
| | | <MenuCategory> Notes </MenuCategory> |
| | | <Position> 15 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R16.htm </HtmlFileName> |
| | | <LongName> 100150 - Disclosure - Equity </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureEquity </Role> |
| | | <ShortName> Equity </ShortName> |
| | | <MenuCategory> Notes </MenuCategory> |
| | | <Position> 16 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R17.htm </HtmlFileName> |
| | | <LongName> 100160 - Disclosure - Earnings (Loss) per Share </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureEarningsLossPerShare </Role> |
| | | <ShortName> Earnings (Loss) per Share </ShortName> |
| | | <MenuCategory> Notes </MenuCategory> |
| | | <Position> 17 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R18.htm </HtmlFileName> |
| | | <LongName> 100170 - Disclosure - Staff Retirement Plans </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureStaffRetirementPlans </Role> |
| | | <ShortName> Staff Retirement Plans </ShortName> |
| | | <MenuCategory> Notes </MenuCategory> |
| | | <Position> 18 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R19.htm </HtmlFileName> |
| | | <LongName> 100180 - Disclosure - Other Income (Expenses), Net </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureOtherIncomeExpensesNet </Role> |
| | | <ShortName> Other Income (Expenses), Net </ShortName> |
| | | <MenuCategory> Notes </MenuCategory> |
| | | <Position> 19 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R20.htm </HtmlFileName> |
| | | <LongName> 100190 - Disclosure - Income Taxes </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureIncomeTaxes </Role> |
| | | <ShortName> Income Taxes </ShortName> |
| | | <MenuCategory> Notes </MenuCategory> |
| | | <Position> 20 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R21.htm </HtmlFileName> |
| | | <LongName> 100200 - Disclosure - Commitments and Contingencies </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureCommitmentsAndContingencies </Role> |
| | | <ShortName> Commitments and Contingencies </ShortName> |
| | | <MenuCategory> Notes </MenuCategory> |
| | | <Position> 21 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R22.htm </HtmlFileName> |
| | | <LongName> 100210 - Disclosure - Operating Leases </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureOperatingLeases </Role> |
| | | <ShortName> Operating Leases </ShortName> |
| | | <MenuCategory> Notes </MenuCategory> |
| | | <Position> 22 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R23.htm </HtmlFileName> |
| | | <LongName> 100220 - Disclosure - Segment Information </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureSegmentInformation </Role> |
| | | <ShortName> Segment Information </ShortName> |
| | | <MenuCategory> Notes </MenuCategory> |
| | | <Position> 23 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R24.htm </HtmlFileName> |
| | | <LongName> 100230 - Disclosure - Employee Severance Benefits </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureEmployeeSeveranceBenefits </Role> |
| | | <ShortName> Employee Severance Benefits </ShortName> |
| | | <MenuCategory> Notes </MenuCategory> |
| | | <Position> 24 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R25.htm </HtmlFileName> |
| | | <LongName> 100240 - Disclosure - Related Party Transactions </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureRelatedPartyTransactions </Role> |
| | | <ShortName> Related Party Transactions </ShortName> |
| | | <MenuCategory> Notes </MenuCategory> |
| | | <Position> 25 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R26.htm </HtmlFileName> |
| | | <LongName> 100250 - Disclosure - Subsequent Events </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureSubsequentEvents </Role> |
| | | <ShortName> Subsequent Events </ShortName> |
| | | <MenuCategory> Notes </MenuCategory> |
| | | <Position> 26 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R27.htm </HtmlFileName> |
| | | <LongName> 100260 - Disclosure - SCHEDULE 1 </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureSCHEDULE1 </Role> |
| | | <ShortName> SCHEDULE 1 </ShortName> |
| | | <MenuCategory> Notes </MenuCategory> |
| | | <Position> 27 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R28.htm </HtmlFileName> |
| | | <LongName> 100270 - Disclosure - Summary of Significant Accounting Policies (Policies) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureSummaryOfSignificantAccountingPoliciesPolicies </Role> |
| | | <ShortName> Summary of Significant Accounting Policies (Policies) </ShortName> |
| | | <MenuCategory> Policies </MenuCategory> |
| | | <ParentRole> http://www.namtai.com/20191231/taxonomy/role/DisclosureSummaryOfSignificantAccountingPolicies </ParentRole> |
| | | <Position> 28 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R29.htm </HtmlFileName> |
| | | <LongName> 100280 - Disclosure - Summary of Significant Accounting Policies (Tables) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureSummaryOfSignificantAccountingPoliciesTables </Role> |
| | | <ShortName> Summary of Significant Accounting Policies (Tables) </ShortName> |
| | | <MenuCategory> Tables </MenuCategory> |
| | | <ParentRole> http://www.namtai.com/20191231/taxonomy/role/DisclosureSummaryOfSignificantAccountingPolicies </ParentRole> |
| | | <Position> 29 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R30.htm </HtmlFileName> |
| | | <LongName> 100290 - Disclosure - Real Estate Properties under Development, Net (Tables) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureRealEstatePropertiesUnderDevelopmentNetTables </Role> |
| | | <ShortName> Real Estate Properties under Development, Net (Tables) </ShortName> |
| | | <MenuCategory> Tables </MenuCategory> |
| | | <ParentRole> http://www.namtai.com/20191231/taxonomy/role/DisclosureRealEstatePropertiesUnderDevelopmentNet </ParentRole> |
| | | <Position> 30 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R31.htm </HtmlFileName> |
| | | <LongName> 100300 - Disclosure - Property, Plant and Equipment, Net (Tables) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosurePropertyPlantAndEquipmentNetTables </Role> |
| | | <ShortName> Property, Plant and Equipment, Net (Tables) </ShortName> |
| | | <MenuCategory> Tables </MenuCategory> |
| | | <ParentRole> http://www.namtai.com/20191231/taxonomy/role/DisclosurePropertyPlantAndEquipmentNet </ParentRole> |
| | | <Position> 31 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R32.htm </HtmlFileName> |
| | | <LongName> 100310 - Disclosure - Investments in Subsidiaries (Tables) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureInvestmentsInSubsidiariesTables </Role> |
| | | <ShortName> Investments in Subsidiaries (Tables) </ShortName> |
| | | <MenuCategory> Tables </MenuCategory> |
| | | <ParentRole> http://www.namtai.com/20191231/taxonomy/role/DisclosureInvestmentsInSubsidiaries </ParentRole> |
| | | <Position> 32 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R33.htm </HtmlFileName> |
| | | <LongName> 100320 - Disclosure - Bank Loans and Banking Facilities (Tables) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureBankLoansAndBankingFacilitiesTables </Role> |
| | | <ShortName> Bank Loans and Banking Facilities (Tables) </ShortName> |
| | | <MenuCategory> Tables </MenuCategory> |
| | | <ParentRole> http://www.namtai.com/20191231/taxonomy/role/DisclosureBankLoansAndBankingFacilities </ParentRole> |
| | | <Position> 33 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R34.htm </HtmlFileName> |
| | | <LongName> 100330 - Disclosure - Equity (Tables) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureEquityTables </Role> |
| | | <ShortName> Equity (Tables) </ShortName> |
| | | <MenuCategory> Tables </MenuCategory> |
| | | <ParentRole> http://www.namtai.com/20191231/taxonomy/role/DisclosureEquity </ParentRole> |
| | | <Position> 34 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R35.htm </HtmlFileName> |
| | | <LongName> 100340 - Disclosure - Earnings (Loss) per Share (Tables) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureEarningsLossPerShareTables </Role> |
| | | <ShortName> Earnings (Loss) per Share (Tables) </ShortName> |
| | | <MenuCategory> Tables </MenuCategory> |
| | | <ParentRole> http://www.namtai.com/20191231/taxonomy/role/DisclosureEarningsLossPerShare </ParentRole> |
| | | <Position> 35 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R36.htm </HtmlFileName> |
| | | <LongName> 100350 - Disclosure - Other Income (Expenses), Net (Tables) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureOtherIncomeExpensesNetTables </Role> |
| | | <ShortName> Other Income (Expenses), Net (Tables) </ShortName> |
| | | <MenuCategory> Tables </MenuCategory> |
| | | <ParentRole> http://www.namtai.com/20191231/taxonomy/role/DisclosureOtherIncomeExpensesNet </ParentRole> |
| | | <Position> 36 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R37.htm </HtmlFileName> |
| | | <LongName> 100360 - Disclosure - Income Taxes (Tables) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureIncomeTaxesTables </Role> |
| | | <ShortName> Income Taxes (Tables) </ShortName> |
| | | <MenuCategory> Tables </MenuCategory> |
| | | <ParentRole> http://www.namtai.com/20191231/taxonomy/role/DisclosureIncomeTaxes </ParentRole> |
| | | <Position> 37 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R38.htm </HtmlFileName> |
| | | <LongName> 100370 - Disclosure - Commitments and Contingencies (Tables) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureCommitmentsAndContingenciesTables </Role> |
| | | <ShortName> Commitments and Contingencies (Tables) </ShortName> |
| | | <MenuCategory> Tables </MenuCategory> |
| | | <ParentRole> http://www.namtai.com/20191231/taxonomy/role/DisclosureCommitmentsAndContingencies </ParentRole> |
| | | <Position> 38 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R39.htm </HtmlFileName> |
| | | <LongName> 100380 - Disclosure - Operating Leases (Tables) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureOperatingLeasesTables </Role> |
| | | <ShortName> Operating Leases (Tables) </ShortName> |
| | | <MenuCategory> Tables </MenuCategory> |
| | | <ParentRole> http://www.namtai.com/20191231/taxonomy/role/DisclosureOperatingLeases </ParentRole> |
| | | <Position> 39 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R40.htm </HtmlFileName> |
| | | <LongName> 100390 - Disclosure - Segment Information (Tables) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureSegmentInformationTables </Role> |
| | | <ShortName> Segment Information (Tables) </ShortName> |
| | | <MenuCategory> Tables </MenuCategory> |
| | | <ParentRole> http://www.namtai.com/20191231/taxonomy/role/DisclosureSegmentInformation </ParentRole> |
| | | <Position> 40 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R41.htm </HtmlFileName> |
| | | <LongName> 100400 - Disclosure - Company Information - Additional Information (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureCompanyInformationAdditionalInformationDetail </Role> |
| | | <ShortName> Company Information - Additional Information (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 41 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R42.htm </HtmlFileName> |
| | | <LongName> 100410 - Disclosure - Summary of Significant Accounting Policies - Additional Information (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureSummaryOfSignificantAccountingPoliciesAdditionalInformationDetail </Role> |
| | | <ShortName> Summary of Significant Accounting Policies - Additional Information (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 42 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R43.htm </HtmlFileName> |
| | | <LongName> 100420 - Disclosure - Depreciation Expenses Using Straight-Line Method (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureDepreciationExpensesUsingStraightLineMethodDetail </Role> |
| | | <ShortName> Depreciation Expenses Using Straight-Line Method (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 43 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R44.htm </HtmlFileName> |
| | | <LongName> 100430 - Disclosure - Real Estate Properties Under Development, Net (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureRealEstatePropertiesUnderDevelopmentNetDetail </Role> |
| | | <ShortName> Real Estate Properties Under Development, Net (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 44 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R45.htm </HtmlFileName> |
| | | <LongName> 100440 - Disclosure - Real Estate Properties under Development, Net - Additional Information (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureRealEstatePropertiesUnderDevelopmentNetAdditionalInformationDetail </Role> |
| | | <ShortName> Real Estate Properties under Development, Net - Additional Information (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 45 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R46.htm </HtmlFileName> |
| | | <LongName> 100450 - Disclosure - Schedule of Lease Building to Third Parties with the Carrying Amount (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureScheduleOfLeaseBuildingToThirdPartiesWithCarryingAmountDetail </Role> |
| | | <ShortName> Schedule of Lease Building to Third Parties with the Carrying Amount (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 46 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R47.htm </HtmlFileName> |
| | | <LongName> 100460 - Disclosure - Property, Plant and Equipment, Net (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosurePropertyPlantAndEquipmentNetDetail </Role> |
| | | <ShortName> Property, Plant and Equipment, Net (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <ParentRole> http://www.namtai.com/20191231/taxonomy/role/DisclosurePropertyPlantAndEquipmentNetTables </ParentRole> |
| | | <Position> 47 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R48.htm </HtmlFileName> |
| | | <LongName> 100470 - Disclosure - Property, Plant and Equipment, Net - Additional Information (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosurePropertyPlantAndEquipmentNetAdditionalInformationDetail </Role> |
| | | <ShortName> Property, Plant and Equipment, Net - Additional Information (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 48 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R49.htm </HtmlFileName> |
| | | <LongName> 100480 - Disclosure - Schedule of Minimum Rental Payments To Be Received (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureScheduleOfMinimumRentalPaymentsToBeReceivedDetail </Role> |
| | | <ShortName> Schedule of Minimum Rental Payments To Be Received (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 49 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R50.htm </HtmlFileName> |
| | | <LongName> 100490 - Disclosure - Investments in Subsidiaries (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureInvestmentsInSubsidiariesDetail </Role> |
| | | <ShortName> Investments in Subsidiaries (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <ParentRole> http://www.namtai.com/20191231/taxonomy/role/DisclosureInvestmentsInSubsidiariesTables </ParentRole> |
| | | <Position> 50 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R51.htm </HtmlFileName> |
| | | <LongName> 100500 - Disclosure - Retained Earnings and Reserves - Additional Information (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureRetainedEarningsAndReservesAdditionalInformationDetail </Role> |
| | | <ShortName> Retained Earnings and Reserves - Additional Information (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 51 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R52.htm </HtmlFileName> |
| | | <LongName> 100510 - Disclosure - Advance from Customers - Additional Information (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureAdvanceFromCustomersAdditionalInformationDetail </Role> |
| | | <ShortName> Advance from Customers - Additional Information (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 52 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R53.htm </HtmlFileName> |
| | | <LongName> 100520 - Disclosure - Schedule of Bank Loan (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureScheduleOfBankLoanDetail </Role> |
| | | <ShortName> Schedule of Bank Loan (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 53 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R54.htm </HtmlFileName> |
| | | <LongName> 100540 - Disclosure - Schedule of Maturities of Long-Term Bank Loan (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureScheduleOfMaturitiesOfLongTermBankLoanDetail </Role> |
| | | <ShortName> Schedule of Maturities of Long-Term Bank Loan (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 54 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R55.htm </HtmlFileName> |
| | | <LongName> 100550 - Disclosure - Schedule of Bank Loans (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureScheduleOfBankLoansDetail </Role> |
| | | <ShortName> Schedule of Bank Loans (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 55 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R56.htm </HtmlFileName> |
| | | <LongName> 100560 - Disclosure - Schedule of Long-term Loans (Parenthetical) (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureScheduleOfLongTermLoansParentheticalDetail </Role> |
| | | <ShortName> Schedule of Long-term Loans (Parenthetical) (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 56 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R57.htm </HtmlFileName> |
| | | <LongName> 100570 - Disclosure - Bank Loans and Banking Facilities - Additional Information (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureBankLoansAndBankingFacilitiesAdditionalInformationDetail </Role> |
| | | <ShortName> Bank Loans and Banking Facilities - Additional Information (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 57 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R58.htm </HtmlFileName> |
| | | <LongName> 100580 - Disclosure - Equity - Additional Information (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureEquityAdditionalInformationDetail </Role> |
| | | <ShortName> Equity - Additional Information (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 58 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R59.htm </HtmlFileName> |
| | | <LongName> 100590 - Disclosure - Summary of Stock Option Activity (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureSummaryOfStockOptionActivityDetail </Role> |
| | | <ShortName> Summary of Stock Option Activity (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 59 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R60.htm </HtmlFileName> |
| | | <LongName> 100600 - Disclosure - Option Granted by Company (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureOptionGrantedByCompanyDetail </Role> |
| | | <ShortName> Option Granted by Company (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 60 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R61.htm </HtmlFileName> |
| | | <LongName> 100610 - Disclosure - Weighted Average Fair Value Options Granted, Assumptions (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureWeightedAverageFairValueOptionsGrantedAssumptionsDetail </Role> |
| | | <ShortName> Weighted Average Fair Value Options Granted, Assumptions (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 61 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R62.htm </HtmlFileName> |
| | | <LongName> 100620 - Disclosure - Computation of Basic and Diluted Earnings (Loss) Per Share (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureComputationOfBasicAndDilutedEarningsLossPerShareDetail </Role> |
| | | <ShortName> Computation of Basic and Diluted Earnings (Loss) Per Share (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 62 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R63.htm </HtmlFileName> |
| | | <LongName> 100630 - Disclosure - Staff Retirement Plans - Additional Information (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureStaffRetirementPlansAdditionalInformationDetail </Role> |
| | | <ShortName> Staff Retirement Plans - Additional Information (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 63 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R64.htm </HtmlFileName> |
| | | <LongName> 100640 - Disclosure - Components of Other Income (Expenses), Net (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureComponentsOfOtherIncomeExpensesNetDetail </Role> |
| | | <ShortName> Components of Other Income (Expenses), Net (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 64 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R65.htm </HtmlFileName> |
| | | <LongName> 100650 - Disclosure - Summary of Financial Information for Discontinued Operations (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureSummaryOfFinancialInformationForDiscontinuedOperationsDetail </Role> |
| | | <ShortName> Summary of Financial Information for Discontinued Operations (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 65 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R66.htm </HtmlFileName> |
| | | <LongName> 100660 - Disclosure - Components of Income (Loss) Before Income Tax (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureComponentsOfIncomeLossBeforeIncomeTaxDetail </Role> |
| | | <ShortName> Components of Income (Loss) Before Income Tax (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 66 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R67.htm </HtmlFileName> |
| | | <LongName> 100670 - Disclosure - Income Taxes - Additional Information (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureIncomeTaxesAdditionalInformationDetail </Role> |
| | | <ShortName> Income Taxes - Additional Information (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 67 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R68.htm </HtmlFileName> |
| | | <LongName> 100680 - Disclosure - Deferred Tax Assets (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureDeferredTaxAssetsDetail </Role> |
| | | <ShortName> Deferred Tax Assets (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 68 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R69.htm </HtmlFileName> |
| | | <LongName> 100690 - Disclosure - Movement of Deferred Tax Assets Valuation Allowance (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureMovementOfDeferredTaxAssetsValuationAllowanceDetail </Role> |
| | | <ShortName> Movement of Deferred Tax Assets Valuation Allowance (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 69 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R70.htm </HtmlFileName> |
| | | <LongName> 100700 - Disclosure - Reconciliation of Income Tax Expense to Amount Computed by Applying Current Statutory Tax Rate to Income (Loss) Before Income Taxes (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureReconciliationOfIncomeTaxExpenseToAmountComputedByApplyingCurrentStatutoryTaxRateToIncomeLossBeforeIncomeTaxesDetail </Role> |
| | | <ShortName> Reconciliation of Income Tax Expense to Amount Computed by Applying Current Statutory Tax Rate to Income (Loss) Before Income Taxes (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 70 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R71.htm </HtmlFileName> |
| | | <LongName> 100710 - Disclosure - Contractual Obligations, Including Capital Expenditures and Future Minimum Lease Payments Under Non-Cancelable Operating Lease Arrangements and Purchase Commitments (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureContractualObligationsIncludingCapitalExpendituresAndFutureMinimumLeasePaymentsUnderNonCancelableOperatingLeaseArrangementsAndPurchaseCommitmentsDetail </Role> |
| | | <ShortName> Contractual Obligations, Including Capital Expenditures and Future Minimum Lease Payments Under Non-Cancelable Operating Lease Arrangements and Purchase Commitments (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 71 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R72.htm </HtmlFileName> |
| | | <LongName> 100720 - Disclosure - Operating Leases - Additional Information (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureOperatingLeasesAdditionalInformationDetail </Role> |
| | | <ShortName> Operating Leases - Additional Information (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 72 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R73.htm </HtmlFileName> |
| | | <LongName> 100730 - Disclosure - Summary of Lease Cost and Cash Flows Arising From Operating Leases, Weighted Average Remaining Lease Term and Weighted Average Discount Rate (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureSummaryOfLeaseCostAndCashFlowsArisingFromOperatingLeasesWeightedAverageRemainingLeaseTermAndWeightedAverageDiscountRateDetail </Role> |
| | | <ShortName> Summary of Lease Cost and Cash Flows Arising From Operating Leases, Weighted Average Remaining Lease Term and Weighted Average Discount Rate (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 73 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R74.htm </HtmlFileName> |
| | | <LongName> 100740 - Disclosure - Summary of Maturities of Lease Liabilities (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureSummaryOfMaturitiesOfLeaseLiabilitiesDetail </Role> |
| | | <ShortName> Summary of Maturities of Lease Liabilities (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 74 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R75.htm </HtmlFileName> |
| | | <LongName> 100760 - Disclosure - Summary of Lease Liabilities (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureSummaryOfLeaseLiabilitiesDetail </Role> |
| | | <ShortName> Summary of Lease Liabilities (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 75 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R76.htm </HtmlFileName> |
| | | <LongName> 100770 - Disclosure - Segment Information - Additional Information (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureSegmentInformationAdditionalInformationDetail </Role> |
| | | <ShortName> Segment Information - Additional Information (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 76 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R77.htm </HtmlFileName> |
| | | <LongName> 100780 - Disclosure - Summary of Operation Income (Loss), Net by Geographical Areas (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureSummaryOfOperationIncomeLossNetByGeographicalAreasDetail </Role> |
| | | <ShortName> Summary of Operation Income (Loss), Net by Geographical Areas (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 77 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R78.htm </HtmlFileName> |
| | | <LongName> 100790 - Disclosure - Summary of Long-Lived Assets by Geographical Areas (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureSummaryOfLongLivedAssetsByGeographicalAreasDetail </Role> |
| | | <ShortName> Summary of Long-Lived Assets by Geographical Areas (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 78 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R79.htm </HtmlFileName> |
| | | <LongName> 100800 - Disclosure - Employee Severance Benefits - Additional Information (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureEmployeeSeveranceBenefitsAdditionalInformationDetail </Role> |
| | | <ShortName> Employee Severance Benefits - Additional Information (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 79 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R80.htm </HtmlFileName> |
| | | <LongName> 100810 - Disclosure - Related Party Transactions - Additional Information (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureRelatedPartyTransactionsAdditionalInformationDetail </Role> |
| | | <ShortName> Related Party Transactions - Additional Information (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 80 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R81.htm </HtmlFileName> |
| | | <LongName> 100820 - Disclosure - Subsequent Events - Additional Information (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureSubsequentEventsAdditionalInformationDetail </Role> |
| | | <ShortName> Subsequent Events - Additional Information (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 81 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R82.htm </HtmlFileName> |
| | | <LongName> 100830 - Disclosure - Statements of Comprehensive Income (Loss) (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureStatementsOfComprehensiveIncomeLossDetail </Role> |
| | | <ShortName> Statements of Comprehensive Income (Loss) (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 82 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R83.htm </HtmlFileName> |
| | | <LongName> 100840 - Disclosure - Statements of Comprehensive Income (Loss) (Parenthetical) (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureStatementsOfComprehensiveIncomeLossParentheticalDetail </Role> |
| | | <ShortName> Statements of Comprehensive Income (Loss) (Parenthetical) (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 83 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R84.htm </HtmlFileName> |
| | | <LongName> 100850 - Disclosure - Balance Sheets (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureBalanceSheetsDetail </Role> |
| | | <ShortName> Balance Sheets (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 84 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R85.htm </HtmlFileName> |
| | | <LongName> 100860 - Disclosure - Balance Sheets (Parenthetical) (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureBalanceSheetsParentheticalDetail </Role> |
| | | <ShortName> Balance Sheets (Parenthetical) (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 85 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R86.htm </HtmlFileName> |
| | | <LongName> 100870 - Disclosure - Statements of Changes In Shareholders' Equity (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureStatementsOfChangesInShareholdersEquityDetail </Role> |
| | | <ShortName> Statements of Changes In Shareholders' Equity (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 86 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R87.htm </HtmlFileName> |
| | | <LongName> 100880 - Disclosure - Statements of Changes In Shareholders' Equity (Parenthetical) (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureStatementsOfChangesInShareholdersEquityParentheticalDetail </Role> |
| | | <ShortName> Statements of Changes In Shareholders' Equity (Parenthetical) (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 87 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R88.htm </HtmlFileName> |
| | | <LongName> 100890 - Disclosure - Statements of Cash flows (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureStatementsOfCashFlowsDetail </Role> |
| | | <ShortName> Statements of Cash flows (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 88 </Position> |
| | | </Report> |
| | <Report instance="ntp-20191231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R89.htm </HtmlFileName> |
| | | <LongName> 100900 - Disclosure - Note to Schedule One - Additional Information (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.namtai.com/20191231/taxonomy/role/DisclosureNoteToScheduleOneAdditionalInformationDetail </Role> |
| | | <ShortName> Note to Schedule One - Additional Information (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 89 </Position> |
| | | </Report> |
| | <Report> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <LongName> All Reports </LongName> |
| | | <ReportType> Book </ReportType> |
| | | <ShortName> All Reports </ShortName> |
| | | </Report> |
| | </MyReports> |
| <InputFiles> |
| | <File> ntp-20191231.xml </File> |
| | <File> ntp-20191231.xsd </File> |
| | <File> ntp-20191231_cal.xml </File> |
| | <File> ntp-20191231_def.xml </File> |
| | <File> ntp-20191231_lab.xml </File> |
| | <File> ntp-20191231_pre.xml </File> |
| | </InputFiles> |
| <SupplementalFiles/> |
| <BaseTaxonomies> |
| | <BaseTaxonomy> http://xbrl.sec.gov/country/2017-01-31 </BaseTaxonomy> |
| | <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> |