<?xml version="1.0" encoding="utf-8"?>
<FilingSummary xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  <Version>2.4.0.6</Version>
  <ProcessingTime />
  <ReportFormat>Html</ReportFormat>
  <ContextCount>84</ContextCount>
  <ElementCount>55</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>false</FootnotesReported>
  <SegmentCount>7</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>4</UnitCount>
  <MyReports>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>001 - Document - DOCUMENT AND ENTITY INFORMATION</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bostoncapital.com/role/DocumentAndEntityInformation</Role>
      <ShortName>DOCUMENT AND ENTITY INFORMATION</ShortName>
    </Report>
    <Report>
      <IsDefault>true</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>002 - Statement - CONDENSED BALANCE SHEETS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bostoncapital.com/role/StatementOfFinancialPositionUnclassified-RealEstateOperations</Role>
      <ShortName>CONDENSED BALANCE SHEETS</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>003 - Statement - CONDENSED BALANCE SHEETS [Parenthetical]</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bostoncapital.com/role/BalanceSheetParenthetical</Role>
      <ShortName>CONDENSED BALANCE SHEETS [Parenthetical]</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>004 - Statement - CONDENSED STATEMENTS OF OPERATIONS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bostoncapital.com/role/StatementOfIncomeRealEstateExcludingREITs</Role>
      <ShortName>CONDENSED STATEMENTS OF OPERATIONS</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>005 - Statement - CONDENSED STATEMENTS OF CHANGES IN PARTNERS' CAPITAL (DEFICIT)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bostoncapital.com/role/StatementOfPartnersCapital</Role>
      <ShortName>CONDENSED STATEMENTS OF CHANGES IN PARTNERS' CAPITAL (DEFICIT)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>006 - Statement - CONDENSED STATEMENTS OF CASH FLOWS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bostoncapital.com/role/StatementOfCashFlowsIndirectRealEstate</Role>
      <ShortName>CONDENSED STATEMENTS OF CASH FLOWS</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>007 - Disclosure - ORGANIZATION</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bostoncapital.com/role/ORGANIZATION</Role>
      <ShortName>ORGANIZATION</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>008 - Disclosure - ACCOUNTING AND FINANCIAL REPORTING POLICIES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bostoncapital.com/role/ACCOUNTINGANDFINANCIALREPORTINGPOLICIES</Role>
      <ShortName>ACCOUNTING AND FINANCIAL REPORTING POLICIES</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>009 - Disclosure - RELATED PARTY TRANSACTIONS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bostoncapital.com/role/RELATEDPARTYTRANSACTIONS</Role>
      <ShortName>RELATED PARTY TRANSACTIONS</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>010 - Disclosure - INVESTMENTS IN OPERATING PARTNERSHIPS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bostoncapital.com/role/INVESTMENTSINOPERATINGLIMITEDPARTNERSHIPS</Role>
      <ShortName>INVESTMENTS IN OPERATING PARTNERSHIPS</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>011 - Disclosure - TAXABLE LOSS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bostoncapital.com/role/TAXABLELOSS</Role>
      <ShortName>TAXABLE LOSS</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>012 - Disclosure - INCOME TAXES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bostoncapital.com/role/INCOMETAXES</Role>
      <ShortName>INCOME TAXES</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>013 - Disclosure - SUBSEQUENT EVENTS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bostoncapital.com/role/SUBSEQUENTEVENTS</Role>
      <ShortName>SUBSEQUENT EVENTS</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <Logs>
    <Log type="Info">Process Flow-Through: 002 - Statement - CONDENSED BALANCE SHEETS</Log>
    <Log type="Info">	Process Flow-Through: Removing column 'Dec. 31, 2010'</Log>
    <Log type="Info">	Process Flow-Through: Removing column 'Mar. 31, 2010'</Log>
    <Log type="Info">Process Flow-Through: 003 - Statement - CONDENSED BALANCE SHEETS [Parenthetical]</Log>
    <Log type="Info">Process Flow-Through: 004 - Statement - CONDENSED STATEMENTS OF OPERATIONS</Log>
    <Log type="Info">Process Flow-Through: 006 - Statement - CONDENSED STATEMENTS OF CASH FLOWS</Log>
  </Logs>
  <InputFiles>
    <File>bctciii-20111231.xml</File>
    <File>bctciii-20111231.xsd</File>
    <File>bctciii-20111231_cal.xml</File>
    <File>bctciii-20111231_def.xml</File>
    <File>bctciii-20111231_lab.xml</File>
    <File>bctciii-20111231_pre.xml</File>
  </InputFiles>
  <SupplementalFiles />
  <BaseTaxonomies />
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
