v3.26.1
Shareholder Report
6 Months Ended
Jan. 31, 2026
USD ($)
Holding
Shareholder Report [Line Items]  
Document Type N-CSRS
Amendment Flag false
Registrant Name American High-Income Municipal Bond Fund
Entity Central Index Key 0000925950
Entity Investment Company Type N-1A
Document Period End Date Jan. 31, 2026
American High-Income Municipal Bond Fund® - Class A  
Shareholder Report [Line Items]  
Fund Name American High-Income Municipal Bond Fund®
Class Name Class A
Trading Symbol AMHIX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about American High-Income Municipal Bond Fund
 
(the "fund") for the period from August 1, 2025 to January 31, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at
capitalgroup.com/mutual-fund-literature-A
. You can also request this information by contacting us at
(800) 421-4225
.
Additional Information Phone Number (800) 421-4225
Additional Information Website capitalgroup.com/mutual-fund-literature-A
Expenses [Text Block]
What were the fund costs for the last six months?
(based on a
hypothetical
$
10,000
investment
)
Share class
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
Class A
$
35
0.68
%
*
*Annualized.
Expenses Paid, Amount $ 35
Expense Ratio, Percent 0.68% [1]
Net Assets $ 13,906,000,000
Holdings Count | Holding 3,764
Investment Company, Portfolio Turnover 17.00%
Additional Fund Statistics [Text Block]
Key fund statistics
Fund net assets (in millions)
$
13,906
Total number of portfolio holdings3,764
Portfolio turnover rate17
%
Holdings [Text Block]
Portfolio quality summary
*
(percent of net assets)
Graphical Representation - Allocation 1 Chart
*
Bond ratings, which typically range from AAA/Aaa (highest) to D (lowest), are assigned by credit rating agencies such as Standard & Poor’s, Moody’s and/or Fitch as an indication of an issuer’s creditworthiness. In assigning a credit rating to a security, the fund looks specifically to the ratings assigned to the issuer of the security by Standard & Poor’s, Moody’s and/or Fitch. If agency ratings differ, the security will be considered to have received the lowest of those ratings, consistent with the fund’s investment policies. Securities in the “unrated“ category (above) have not been rated by a rating agency; however, the investment adviser performs its own credit analysis and assigns comparable ratings that are used for compliance with the fund’s investment policies.
Includes derivatives.
American High-Income Municipal Bond Fund® - Class C  
Shareholder Report [Line Items]  
Fund Name American High-Income Municipal Bond Fund®
Class Name Class C
Trading Symbol AHICX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about American High-Income Municipal Bond Fund (the "fund") for the period from August 1, 2025 to January 31, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at
capitalgroup.com/mutual-fund-literature-C
. You can also request this information by contacting us at
(800) 421-4225
.
Additional Information Phone Number (800) 421-4225
Additional Information Website capitalgroup.com/mutual-fund-literature-C
Expenses [Text Block]
What were the fund costs for the last six
months
?
(based on a hypothetical $10,000 investment)
Share classCosts of a $10,000 investmentCosts paid as a percentage of a $10,000 investment
Class C
$
72
1.38
%
*
*Annualized.
Expenses Paid, Amount $ 72
Expense Ratio, Percent 1.38% [1]
Net Assets $ 13,906,000,000
Holdings Count | Holding 3,764
Investment Company, Portfolio Turnover 17.00%
Additional Fund Statistics [Text Block]
Key fund statistics
Fund net assets (in millions)
$
13,906
Total number of portfolio holdings3,764
Portfolio turnover rate17
%
Holdings [Text Block]
Portfolio quality summary
*
(percent of net assets)
Graphical Representation - Allocation 1 Chart
*
Bond ratings, which typically range from AAA/Aaa (highest) to D (lowest), are assigned by credit rating agencies such as Standard & Poor’s, Moody’s and/or Fitch as an indication of an issuer’s creditworthiness. In assigning a credit rating to a security, the fund looks specifically to the ratings assigned to the issuer of the security by Standard & Poor’s, Moody’s and/or Fitch. If agency ratings differ, the security will be considered to have received the lowest of those ratings, consistent with the fund’s investment policies. Securities in the “unrated“ category (above) have not been rated by a rating agency; however, the investment adviser performs its own credit analysis and assigns comparable ratings that are used for compliance with the fund’s investment policies.
Includes derivatives.
American High-Income Municipal Bond Fund® - Class T  
Shareholder Report [Line Items]  
Fund Name American High-Income Municipal Bond Fund®
Class Name Class T
Trading Symbol TAHHX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about American High-Income Municipal Bond Fund (the "fund") for the period from August 1, 2025 to January 31, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at
capitalgroup.com/mutual-fund-literature
. You can also request this information by contacting us at
(800) 421-4225
.
Additional Information Phone Number (800) 421-4225
Additional Information Website capitalgroup.com/mutual-fund-literature
Expenses [Text Block]
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Share classCosts of a $10,000 investmentCosts paid as a percentage of a $10,000 investment
Class T
$
19
0.37
%
*
*Annualized.
Expenses Paid, Amount $ 19
Expense Ratio, Percent 0.37% [1]
Net Assets $ 13,906,000,000
Holdings Count | Holding 3,764
Investment Company, Portfolio Turnover 17.00%
Additional Fund Statistics [Text Block]
Key fund statistics
Fund net assets (in millions)
$
13,906
Total number of portfolio holdings3,764
Portfolio turnover rate17
%
Holdings [Text Block]
Portfolio quality summary
*
(percent of net assets)
Graphical Representation - Allocation 1 Chart
*
Bond ratings, which typically range from AAA/Aaa (highest) to D (lowest), are assigned by credit rating agencies such as Standard & Poor’s, Moody’s and/or Fitch as an indication of an issuer’s creditworthiness. In assigning a credit rating to a security, the fund looks specifically to the ratings assigned to the issuer of the security by Standard & Poor’s, Moody’s and/or Fitch. If agency ratings differ, the security will be considered to have received the lowest of those ratings, consistent with the fund’s investment policies. Securities in the “unrated“ category (above) have not been rated by a rating agency; however, the investment adviser performs its own credit analysis and assigns comparable ratings that are used for compliance with the fund’s investment policies.
Includes derivatives.
American High-Income Municipal Bond Fund® - Class F-1  
Shareholder Report [Line Items]  
Fund Name American High-Income Municipal Bond Fund®
Class Name Class F-1
Trading Symbol ABHFX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about American High-Income Municipal Bond Fund (the "fund") for the period from August 1, 2025 to January 31, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at
capitalgroup.com/mutual-fund-literature-F1
. You can also request this information by contacting us at
(800) 421-4225
.
Additional Information Phone Number (800) 421-4225
Additional Information Website capitalgroup.com/mutual-fund-literature-F1
Expenses [Text Block]
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Share classCosts of a $10,000 investmentCosts paid as a percentage of a $10,000 investment
Class F-1
$
37
0.71
%
*
*Annualized.
Expenses Paid, Amount $ 37
Expense Ratio, Percent 0.71% [1]
Net Assets $ 13,906,000,000
Holdings Count | Holding 3,764
Investment Company, Portfolio Turnover 17.00%
Additional Fund Statistics [Text Block]
Key fund statistics
Fund net assets (in millions)
$
13,906
Total number of portfolio holdings3,764
Portfolio turnover rate17
%
Holdings [Text Block]
Portfolio quality summary
*
(percent of net assets)
Graphical Representation - Allocation 1 Chart
*
Bond ratings, which typically range from AAA/Aaa (highest) to D (lowest), are assigned by credit rating agencies such as Standard & Poor’s, Moody’s and/or Fitch as an indication of an issuer’s creditworthiness. In assigning a credit rating to a security, the fund looks specifically to the ratings assigned to the issuer of the security by Standard & Poor’s, Moody’s and/or Fitch. If agency ratings differ, the security will be considered to have received the lowest of those ratings, consistent with the fund’s investment policies. Securities in the “unrated“ category (above) have not been rated by a rating agency; however, the investment adviser performs its own credit analysis and assigns comparable ratings that are used for compliance with the fund’s investment policies.
Includes derivatives.
American High-Income Municipal Bond Fund® - Class F-2  
Shareholder Report [Line Items]  
Fund Name American High-Income Municipal Bond Fund®
Class Name Class F-2
Trading Symbol AHMFX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about American High-Income Municipal Bond Fund
 
(the "fund") for the period from August 1, 2025 to January 31, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at
capitalgroup.com/mutual-fund-literature-F2
. You can also request this information by contacting us at
(800) 421-4225
.
Additional Information Phone Number (800) 421-4225
Additional Information Website capitalgroup.com/mutual-fund-literature-F2
Expenses [Text Block]
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Share classCosts of a $10,000 investmentCosts paid as a percentage of a $10,000 investment
Class F-2
$
23
0.45
%
*
*Annualized.
Expenses Paid, Amount $ 23
Expense Ratio, Percent 0.45% [1]
Net Assets $ 13,906,000,000
Holdings Count | Holding 3,764
Investment Company, Portfolio Turnover 17.00%
Additional Fund Statistics [Text Block]
Key fund statistics
Fund net assets (in millions)
$
13,906
Total number of portfolio holdings3,764
Portfolio turnover rate17
%
Holdings [Text Block]
Portfolio quality summary
*
(percent of net assets)
Graphical Representation - Allocation 1 Chart
*
Bond ratings, which typically range from AAA/Aaa (highest) to D (lowest), are assigned by credit rating agencies such as Standard & Poor’s, Moody’s and/or Fitch as an indication of an issuer’s creditworthiness. In assigning a credit rating to a security, the fund looks specifically to the ratings assigned to the issuer of the security by Standard & Poor’s, Moody’s and/or Fitch. If agency ratings differ, the security will be considered to have received the lowest of those ratings, consistent with the fund’s investment policies. Securities in the “unrated“ category (above) have not been rated by a rating agency; however, the investment adviser performs its own credit analysis and assigns comparable ratings that are used for compliance with the fund’s investment policies.
Includes derivatives.
American High-Income Municipal Bond Fund® - Class F-3  
Shareholder Report [Line Items]  
Fund Name American High-Income Municipal Bond Fund®
Class Name Class F-3
Trading Symbol HIMFX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about American High-Income Municipal Bond Fund (the "fund") for the period from August 1, 2025 to January 31, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at
capitalgroup.com/mutual-fund-literature-F3
. You can also request this information by contacting us at
(800) 421-4225
.
Additional Information Phone Number (800) 421-4225
Additional Information Website capitalgroup.com/mutual-fund-literature-F3
Expenses [Text Block]
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Share classCosts of a $10,000 investmentCosts paid as a percentage of a $10,000 investment
Class F-3
$
17
0.33
%
*
*Annualized.
Expenses Paid, Amount $ 17
Expense Ratio, Percent 0.33% [1]
Net Assets $ 13,906,000,000
Holdings Count | Holding 3,764
Investment Company, Portfolio Turnover 17.00%
Additional Fund Statistics [Text Block]
Key fund statistics
Fund net assets (in millions)
$
13,906
Total number of portfolio holdings3,764
Portfolio turnover rate17
%
Holdings [Text Block]
Portfolio quality summary
*
(percent of net assets)
Graphical Representation - Allocation 1 Chart
*
Bond ratings, which typically range from AAA/Aaa (highest) to D (lowest), are assigned by credit rating agencies such as Standard & Poor’s, Moody’s and/or Fitch as an indication of an issuer’s creditworthiness. In assigning a credit rating to a security, the fund looks specifically to the ratings assigned to the issuer of the security by Standard & Poor’s, Moody’s and/or Fitch. If agency ratings differ, the security will be considered to have received the lowest of those ratings, consistent with the fund’s investment policies. Securities in the “unrated“ category (above) have not been rated by a rating agency; however, the investment adviser performs its own credit analysis and assigns comparable ratings that are used for compliance with the fund’s investment policies.
Includes derivatives.
American High-Income Municipal Bond Fund® - Class R-6  
Shareholder Report [Line Items]  
Fund Name American High-Income Municipal Bond Fund®
Class Name Class R-6
No Trading Symbol Flag true
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about American High-Income Municipal Bond Fund (the "fund") for the period from August 1, 2025 to January 31, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at
capitalgroup.com/mutual-fund-literature-R6
. You can also request this information by contacting us at
(800) 421-4225
.
Additional Information Phone Number (800) 421-4225
Additional Information Website capitalgroup.com/mutual-fund-literature-R6
Expenses [Text Block]
What were the fund costs for the last six months?
(based on a hypothetical $10,000
investment
)
Share classCosts of a $10,000 investmentCosts paid as a percentage of a $10,000 investment
Class R-6
$
16
0.31
%
*
*Annualized.
Expenses Paid, Amount $ 16
Expense Ratio, Percent 0.31% [1]
Net Assets $ 13,906,000,000
Holdings Count | Holding 3,764
Investment Company, Portfolio Turnover 17.00%
Additional Fund Statistics [Text Block]
Key fund statistics
Fund net assets (in millions)
$
13,906
Total number of portfolio holdings3,764
Portfolio turnover rate17
%
Holdings [Text Block]
Portfolio quality summary
*
(percent of net assets)
Graphical Representation - Allocation 1 Chart
*
Bond ratings, which typically range from AAA/Aaa (highest) to D (lowest), are assigned by credit rating agencies such as Standard & Poor’s, Moody’s and/or Fitch as an indication of an issuer’s creditworthiness. In assigning a credit rating to a security, the fund looks specifically to the ratings assigned to the issuer of the security by Standard & Poor’s, Moody’s and/or Fitch. If agency ratings differ, the security will be considered to have received the lowest of those ratings, consistent with the fund’s investment policies. Securities in the “unrated“ category (above) have not been rated by a rating agency; however, the investment adviser performs its own credit analysis and assigns comparable ratings that are used for compliance with the fund’s investment policies.
Includes derivatives.
[1] Annualized.