false
497 2023-09-30 N-1A 2024-02-01 2024-01-31 0000816153
~ http://thornburg.com/role/ShareholderFeesData
column dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000012859Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/OperatingExpensesData
column dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000012859Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ExpenseExample column
dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000012859Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~
http://thornburg.com/role/ExpenseExampleNoRedemption column
dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000012859Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/BarChartData column
dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000012859Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/PerformanceTableData
column dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000012859Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ShareholderFeesData
column dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000011849Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/OperatingExpensesData
column dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000011849Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ExpenseExample column
dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000011849Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~
http://thornburg.com/role/ExpenseExampleNoRedemption column
dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000011849Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/BarChartData column
dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000011849Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/PerformanceTableData
column dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000011849Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ShareholderFeesData
column dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000050704Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/OperatingExpensesData
column dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000050704Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ExpenseExample column
dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000050704Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~
http://thornburg.com/role/ExpenseExampleNoRedemption column
dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000050704Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/BarChartData column
dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000050704Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/PerformanceTableData
column dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000050704Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ShareholderFeesData
column dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000015648Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/OperatingExpensesData
column dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000015648Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ExpenseExample column
dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000015648Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~
http://thornburg.com/role/ExpenseExampleNoRedemption column
dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000015648Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/BarChartData column
dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000015648Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/PerformanceTableData
column dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000015648Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ShareholderFeesData
column dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000027135Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/OperatingExpensesData
column dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000027135Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ExpenseExample column
dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000027135Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~
http://thornburg.com/role/ExpenseExampleNoRedemption column
dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000027135Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/BarChartData column
dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000027135Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/PerformanceTableData
column dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000027135Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ShareholderFeesData
column dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000011846Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/OperatingExpensesData
column dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000011846Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ExpenseExample column
dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000011846Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~
http://thornburg.com/role/ExpenseExampleNoRedemption column
dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000011846Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/BarChartData column
dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000011846Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/PerformanceTableData
column dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000011846Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ShareholderFeesData
column dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000011850Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/OperatingExpensesData
column dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000011850Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ExpenseExample column
dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000011850Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~
http://thornburg.com/role/ExpenseExampleNoRedemption column
dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000011850Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/BarChartData column
dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000011850Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/PerformanceTableData
column dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000011850Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ShareholderFeesData
column dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000011851Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/OperatingExpensesData
column dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000011851Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ExpenseExample column
dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000011851Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~
http://thornburg.com/role/ExpenseExampleNoRedemption column
dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000011851Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/BarChartData column
dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000011851Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/PerformanceTableData
column dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000011851Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ShareholderFeesData
column dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000064930Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/OperatingExpensesData
column dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000064930Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ExpenseExample column
dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000064930Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/BarChartData column
dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000064930Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/PerformanceTableData
column dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000064930Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ShareholderFeesData
column dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000043670Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/OperatingExpensesData
column dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000043670Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ExpenseExample column
dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000043670Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/BarChartData column
dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000043670Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/PerformanceTableData
column dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000043670Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ShareholderFeesData
column dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000011842Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/OperatingExpensesData
column dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000011842Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ExpenseExample column
dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000011842Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~
http://thornburg.com/role/ExpenseExampleNoRedemption column
dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000011842Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/BarChartData column
dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000011842Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/PerformanceTableData
column dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000011842Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ShareholderFeesData
column dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000011845Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/OperatingExpensesData
column dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000011845Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ExpenseExample column
dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000011845Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~
http://thornburg.com/role/ExpenseExampleNoRedemption column
dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000011845Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/BarChartData column
dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000011845Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/PerformanceTableData
column dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000011845Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ShareholderFeesData
column dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000082059Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/OperatingExpensesData
column dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000082059Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ExpenseExample column
dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000082059Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~
http://thornburg.com/role/ExpenseExampleNoRedemption column
dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000082059Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ShareholderFeesData
column dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000020097Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/OperatingExpensesData
column dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000020097Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ExpenseExample column
dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000020097Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~
http://thornburg.com/role/ExpenseExampleNoRedemption column
dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000020097Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/BarChartData column
dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000020097Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/PerformanceTableData
column dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000020097Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ShareholderFeesData
column dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000043669Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/OperatingExpensesData
column dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000043669Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ExpenseExample column
dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000043669Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/BarChartData column
dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000043669Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/PerformanceTableData
column dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000043669Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ShareholderFeesData
column dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000000540Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/OperatingExpensesData
column dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000000540Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ExpenseExample column
dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000000540Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~
http://thornburg.com/role/ExpenseExampleNoRedemption column
dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000000540Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/BarChartData column
dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000000540Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/PerformanceTableData
column dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000000540Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ShareholderFeesData
column dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000011844Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/OperatingExpensesData
column dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000011844Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ExpenseExample column
dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000011844Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~
http://thornburg.com/role/ExpenseExampleNoRedemption column
dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000011844Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/BarChartData column
dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000011844Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/PerformanceTableData
column dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000011844Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ShareholderFeesData
column dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000025152Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/OperatingExpensesData
column dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000025152Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ExpenseExample column
dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000025152Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~
http://thornburg.com/role/ExpenseExampleNoRedemption column
dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000025152Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/BarChartData column
dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000025152Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/PerformanceTableData
column dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000025152Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ShareholderFeesData
column dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000011841Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/OperatingExpensesData
column dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000011841Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ExpenseExample column
dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000011841Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~
http://thornburg.com/role/ExpenseExampleNoRedemption column
dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000011841Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/BarChartData column
dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000011841Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/PerformanceTableData
column dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000011841Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ShareholderFeesData
column dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000011843Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/OperatingExpensesData
column dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000011843Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ExpenseExample column
dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000011843Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/BarChartData column
dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000011843Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/PerformanceTableData
column dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000011843Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ShareholderFeesData
column dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000011848Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/OperatingExpensesData
column dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000011848Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ExpenseExample column
dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000011848Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/BarChartData column
dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000011848Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/PerformanceTableData
column dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000011848Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ShareholderFeesData
column dei_DocumentInformationDocumentAxis compact tbit_RetailMember column
dei_LegalEntityAxis compact tbit_S000011848Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ShareholderFeesData
column dei_DocumentInformationDocumentAxis compact tbit_RetirementMember column
dei_LegalEntityAxis compact tbit_S000012859Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/OperatingExpensesData
column dei_DocumentInformationDocumentAxis compact tbit_RetirementMember column
dei_LegalEntityAxis compact tbit_S000012859Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ExpenseExample column
dei_DocumentInformationDocumentAxis compact tbit_RetirementMember column
dei_LegalEntityAxis compact tbit_S000012859Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/BarChartData column
dei_DocumentInformationDocumentAxis compact tbit_RetirementMember column
dei_LegalEntityAxis compact tbit_S000012859Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/PerformanceTableData
column dei_DocumentInformationDocumentAxis compact tbit_RetirementMember column
dei_LegalEntityAxis compact tbit_S000012859Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ShareholderFeesData
column dei_DocumentInformationDocumentAxis compact tbit_RetirementMember column
dei_LegalEntityAxis compact tbit_S000011849Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/OperatingExpensesData
column dei_DocumentInformationDocumentAxis compact tbit_RetirementMember column
dei_LegalEntityAxis compact tbit_S000011849Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ExpenseExample column
dei_DocumentInformationDocumentAxis compact tbit_RetirementMember column
dei_LegalEntityAxis compact tbit_S000011849Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/BarChartData column
dei_DocumentInformationDocumentAxis compact tbit_RetirementMember column
dei_LegalEntityAxis compact tbit_S000011849Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/PerformanceTableData
column dei_DocumentInformationDocumentAxis compact tbit_RetirementMember column
dei_LegalEntityAxis compact tbit_S000011849Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ShareholderFeesData
column dei_DocumentInformationDocumentAxis compact tbit_RetirementMember column
dei_LegalEntityAxis compact tbit_S000015648Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/OperatingExpensesData
column dei_DocumentInformationDocumentAxis compact tbit_RetirementMember column
dei_LegalEntityAxis compact tbit_S000015648Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ExpenseExample column
dei_DocumentInformationDocumentAxis compact tbit_RetirementMember column
dei_LegalEntityAxis compact tbit_S000015648Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/BarChartData column
dei_DocumentInformationDocumentAxis compact tbit_RetirementMember column
dei_LegalEntityAxis compact tbit_S000015648Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/PerformanceTableData
column dei_DocumentInformationDocumentAxis compact tbit_RetirementMember column
dei_LegalEntityAxis compact tbit_S000015648Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ShareholderFeesData
column dei_DocumentInformationDocumentAxis compact tbit_RetirementMember column
dei_LegalEntityAxis compact tbit_S000027135Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/OperatingExpensesData
column dei_DocumentInformationDocumentAxis compact tbit_RetirementMember column
dei_LegalEntityAxis compact tbit_S000027135Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ExpenseExample column
dei_DocumentInformationDocumentAxis compact tbit_RetirementMember column
dei_LegalEntityAxis compact tbit_S000027135Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/BarChartData column
dei_DocumentInformationDocumentAxis compact tbit_RetirementMember column
dei_LegalEntityAxis compact tbit_S000027135Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/PerformanceTableData
column dei_DocumentInformationDocumentAxis compact tbit_RetirementMember column
dei_LegalEntityAxis compact tbit_S000027135Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ShareholderFeesData
column dei_DocumentInformationDocumentAxis compact tbit_RetirementMember column
dei_LegalEntityAxis compact tbit_S000011846Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/OperatingExpensesData
column dei_DocumentInformationDocumentAxis compact tbit_RetirementMember column
dei_LegalEntityAxis compact tbit_S000011846Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ExpenseExample column
dei_DocumentInformationDocumentAxis compact tbit_RetirementMember column
dei_LegalEntityAxis compact tbit_S000011846Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/BarChartData column
dei_DocumentInformationDocumentAxis compact tbit_RetirementMember column
dei_LegalEntityAxis compact tbit_S000011846Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/PerformanceTableData
column dei_DocumentInformationDocumentAxis compact tbit_RetirementMember column
dei_LegalEntityAxis compact tbit_S000011846Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ShareholderFeesData
column dei_DocumentInformationDocumentAxis compact tbit_RetirementMember column
dei_LegalEntityAxis compact tbit_S000011850Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/OperatingExpensesData
column dei_DocumentInformationDocumentAxis compact tbit_RetirementMember column
dei_LegalEntityAxis compact tbit_S000011850Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ExpenseExample column
dei_DocumentInformationDocumentAxis compact tbit_RetirementMember column
dei_LegalEntityAxis compact tbit_S000011850Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/BarChartData column
dei_DocumentInformationDocumentAxis compact tbit_RetirementMember column
dei_LegalEntityAxis compact tbit_S000011850Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/PerformanceTableData
column dei_DocumentInformationDocumentAxis compact tbit_RetirementMember column
dei_LegalEntityAxis compact tbit_S000011850Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ShareholderFeesData
column dei_DocumentInformationDocumentAxis compact tbit_RetirementMember column
dei_LegalEntityAxis compact tbit_S000011851Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/OperatingExpensesData
column dei_DocumentInformationDocumentAxis compact tbit_RetirementMember column
dei_LegalEntityAxis compact tbit_S000011851Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ExpenseExample column
dei_DocumentInformationDocumentAxis compact tbit_RetirementMember column
dei_LegalEntityAxis compact tbit_S000011851Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/BarChartData column
dei_DocumentInformationDocumentAxis compact tbit_RetirementMember column
dei_LegalEntityAxis compact tbit_S000011851Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/PerformanceTableData
column dei_DocumentInformationDocumentAxis compact tbit_RetirementMember column
dei_LegalEntityAxis compact tbit_S000011851Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ShareholderFeesData
column dei_DocumentInformationDocumentAxis compact tbit_RetirementMember column
dei_LegalEntityAxis compact tbit_S000011842Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/OperatingExpensesData
column dei_DocumentInformationDocumentAxis compact tbit_RetirementMember column
dei_LegalEntityAxis compact tbit_S000011842Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ExpenseExample column
dei_DocumentInformationDocumentAxis compact tbit_RetirementMember column
dei_LegalEntityAxis compact tbit_S000011842Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/BarChartData column
dei_DocumentInformationDocumentAxis compact tbit_RetirementMember column
dei_LegalEntityAxis compact tbit_S000011842Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/PerformanceTableData
column dei_DocumentInformationDocumentAxis compact tbit_RetirementMember column
dei_LegalEntityAxis compact tbit_S000011842Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ShareholderFeesData
column dei_DocumentInformationDocumentAxis compact tbit_RetirementMember column
dei_LegalEntityAxis compact tbit_S000011845Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/OperatingExpensesData
column dei_DocumentInformationDocumentAxis compact tbit_RetirementMember column
dei_LegalEntityAxis compact tbit_S000011845Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ExpenseExample column
dei_DocumentInformationDocumentAxis compact tbit_RetirementMember column
dei_LegalEntityAxis compact tbit_S000011845Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/BarChartData column
dei_DocumentInformationDocumentAxis compact tbit_RetirementMember column
dei_LegalEntityAxis compact tbit_S000011845Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/PerformanceTableData
column dei_DocumentInformationDocumentAxis compact tbit_RetirementMember column
dei_LegalEntityAxis compact tbit_S000011845Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ShareholderFeesData
column dei_DocumentInformationDocumentAxis compact tbit_RetirementMember column
dei_LegalEntityAxis compact tbit_S000082059Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/OperatingExpensesData
column dei_DocumentInformationDocumentAxis compact tbit_RetirementMember column
dei_LegalEntityAxis compact tbit_S000082059Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ExpenseExample column
dei_DocumentInformationDocumentAxis compact tbit_RetirementMember column
dei_LegalEntityAxis compact tbit_S000082059Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ShareholderFeesData
column dei_DocumentInformationDocumentAxis compact tbit_RetirementMember column
dei_LegalEntityAxis compact tbit_S000020097Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/OperatingExpensesData
column dei_DocumentInformationDocumentAxis compact tbit_RetirementMember column
dei_LegalEntityAxis compact tbit_S000020097Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/ExpenseExample column
dei_DocumentInformationDocumentAxis compact tbit_RetirementMember column
dei_LegalEntityAxis compact tbit_S000020097Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/BarChartData column
dei_DocumentInformationDocumentAxis compact tbit_RetirementMember column
dei_LegalEntityAxis compact tbit_S000020097Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~
~ http://thornburg.com/role/PerformanceTableData
column dei_DocumentInformationDocumentAxis compact tbit_RetirementMember column
dei_LegalEntityAxis compact tbit_S000020097Member column
rr_ProspectusShareClassAxis compact * row primary compact *
~