Label Element Value
Prospectus [Line Items] rr_ProspectusLineItems  
Document Type dei_DocumentType 485BPOS
Document Period End Date dei_DocumentPeriodEndDate Dec. 31, 2021
Entity Registrant Name dei_EntityRegistrantName Putnam Tax Exempt Income Fund
Entity Central Index Key dei_EntityCentralIndexKey 0000205802
Entity Inv Company Type dei_EntityInvCompanyType N-1A
Amendment Flag dei_AmendmentFlag false
Putnam Tax Exempt Income  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return [Heading] rr_RiskReturnHeading Fund summary
Objective [Heading] rr_ObjectiveHeading Goal
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock

Putnam Tax Exempt Income Fund seeks as high a level of current income exempt from federal income tax as we believe to be consistent with preservation of capital.

Expense [Heading] rr_ExpenseHeading Fees and expenses
Expense Narrative [Text Block] rr_ExpenseNarrativeTextBlock

The following tables describe the fees and expenses you may pay if you buy, hold and sell shares of the fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $100,000 in class A shares of Putnam funds. More information about these and other discounts is available from your financial professional and in How do I buy fund shares? beginning on page 15 of the fund’s prospectus, in the Appendix to the fund’s prospectus, and in How to buy shares beginning on page II-1 of the fund’s statement of additional information (SAI).

Shareholder Fees Caption [Text] rr_ShareholderFeesCaption Shareholder fees (fees paid directly from your investment)
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (expenses you pay each year as a percentage of the value of your investment)
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock

The fund pays transaction-related costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher turnover rate may indicate higher transaction costs and may result in higher taxes when the fund’s shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or the above example, affect fund performance. The fund’s turnover rate in the most recent fiscal year was 34%.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 34.00%
Expense Breakpoint Discounts [Text] rr_ExpenseBreakpointDiscounts You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $100,000 in class A shares of Putnam funds.
Expense Breakpoint, Minimum Investment Required [Amount] rr_ExpenseBreakpointMinimumInvestmentRequiredAmount $ 100,000
Expense Example [Heading] rr_ExpenseExampleHeading Example
Expense Example Narrative [Text Block] rr_ExpenseExampleNarrativeTextBlock

The following hypothetical example is intended to help you compare the cost of investing in the fund with the cost of investing in other funds. It assumes that you invest $10,000 in the fund for the time periods indicated and then, except as indicated, redeem all your shares at the end of those periods. It assumes a 5% return on your investment each year and that the fund’s operating expenses remain the same. Your actual costs may be higher or lower.

Strategy [Heading] rr_StrategyHeading Investments, risks, and performance
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock

Investments

We invest mainly in bonds that pay interest that is exempt from federal income tax (but that may be subject to federal alternative minimum tax (AMT)), are investment-grade in quality, and have intermediate- to long-term maturities (i.e., three years or longer). Under normal circumstances, we invest at least 80% of the fund’s net assets in tax-exempt investments, which for purposes of this policy exclude investments paying interest subject to the federal AMT for individuals. This investment policy cannot be changed without the approval of the fund’s shareholders. We may consider, among other factors, credit, interest rate and prepayment risks, as well as general market conditions, when deciding whether to buy or sell investments.

Risk [Heading] rr_RiskHeading Risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock

It is important to understand that you can lose money by investing in the fund.

The value of investments in the fund’s portfolio may fall or fail to rise over extended periods of time for a variety of reasons, including general economic, political or financial market conditions, investor sentiment and market perceptions, government actions, geopolitical events or changes, and factors related to a specific issuer, geography, industry or sector. These and other factors may lead to increased volatility



 



and reduced liquidity in the fund’s portfolio holdings. The novel coronavirus (COVID-19) pandemic and efforts to contain its spread are likely to negatively affect the value, volatility, and liquidity of the securities and other assets in which the fund invests and exacerbate other risks that apply to the fund. These effects could negatively impact the fund’s performance and lead to losses on your investment in the fund.

The risks associated with bond investments include interest rate risk, which is the risk that the value of the fund’s investments is likely to fall if interest rates rise. Bond investments also are subject to credit risk, which is the risk that the issuers of the fund’s investments may default on payment of interest or principal. Bond investments may be more susceptible to downgrades or defaults during economic downturns or other periods of economic stress. Interest rate risk is generally greater for longer-term bonds, and credit risk is generally greater for below-investment-grade bonds, which can be more sensitive to changes in markets, credit conditions, and interest rates and may be considered speculative. Since the fund invests in tax-exempt bonds, which, to be treated as tax-exempt under the Internal Revenue Code, may be issued only by limited types of issuers for limited types of projects, the fund’s investments may be focused in certain market segments. Consequently, the fund may be more vulnerable to fluctuations in the values of the securities it holds than a fund that invests more broadly. Interest the fund receives might be taxable.

There is no guarantee that the investment techniques, analyses, or judgments that we apply in making investment decisions for the fund will produce the intended outcome or that the investments we select for the fund will perform as well as other securities that were not selected for the fund. We, or the fund’s other service providers, may experience disruptions or operating errors that could negatively impact the fund.

The fund may not achieve its goal, and it is not intended to be a complete investment program. An investment in the fund is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Risk Lose Money [Text] rr_RiskLoseMoney It is important to understand that you can lose money by investing in the fund.
Risk Not Insured Depository Institution [Text] rr_RiskNotInsuredDepositoryInstitution An investment in the fund is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock

The performance information below gives some indication of the risks associated with an investment in the fund by showing the fund’s performance year to year and over time. The bar chart does not reflect the impact of sales charges. If it did, performance would be lower. Please remember that past performance is not necessarily an indication of future results. Monthly performance figures for the fund are available at putnam.com.



 
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The performance information below gives some indication of the risks associated with an investment in the fund by showing the fund’s performance year to year and over time.
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress putnam.com
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture Please remember that past performance is not necessarily an indication of future results.
Bar Chart [Heading] rr_BarChartHeading Annual total returns for class A shares before sales charges
Bar Chart Does Not Reflect Sales Loads [Text] rr_BarChartDoesNotReflectSalesLoads The bar chart does not reflect the impact of sales charges. If it did, performance would be lower.
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best calendar quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Mar. 31, 2014
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 3.53%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst calendar quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2016
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (3.55%)
Performance Table Heading rr_PerformanceTableHeading Average annual total returns after sales charges (for periods ended 12/31/21)
Performance Table Uses Highest Federal Rate rr_PerformanceTableUsesHighestFederalRate After-tax returns reflect the historical highest individual federal marginal income tax rates and do not reflect state and local taxes.
Performance Table Not Relevant to Tax Deferred rr_PerformanceTableNotRelevantToTaxDeferred Actual after-tax returns depend on an investor’s tax situation and may differ from those shown.
Performance Table One Class of after Tax Shown [Text] rr_PerformanceTableOneClassOfAfterTaxShown After-tax returns are shown for class A shares only and will vary for other classes.
Performance Table Closing [Text Block] rr_PerformanceTableClosingTextBlock
BLOOMBERG® is a trademark and service mark of Bloomberg Finance L.P. and its affiliates (collectively “Bloomberg”). Bloomberg or Bloomberg’s licensors, own all proprietary rights in the Bloomberg Indices. Neither Bloomberg nor Bloomberg’s licensors approve or endorse this material, or guarantees the accuracy or completeness of any information herein, or makes any warranty, express or implied, as to the results to be obtained therefrom, and to the maximum extent allowed by law, neither shall have any liability or responsibility for injury or damages arising in connection therewith.
After-tax returns reflect the historical highest individual federal marginal income tax rates and do not reflect state and local taxes. Actual after-tax returns depend on an investor’s tax situation and may differ from those shown. After-tax returns are shown for class A shares only and will vary for other classes. These after-tax returns do not apply if you hold your fund shares through a 401(k) plan, an IRA, or another tax-advantaged arrangement.
Class B and C share performance reflects conversion to class A shares after eight years.



 
Putnam Tax Exempt Income | Bloomberg Municipal Bond Index (no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
1 Year rr_AverageAnnualReturnYear01 1.52% [1]
5 Years rr_AverageAnnualReturnYear05 4.17% [1]
10 Years rr_AverageAnnualReturnYear10 3.72% [1]
Putnam Tax Exempt Income | Class A  
Prospectus [Line Items] rr_ProspectusLineItems  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 4.00%
Maximum Deferred Sales Charge (as a percentage) rr_MaximumDeferredSalesChargeOverOther 1.00% [2]
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.42%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.13%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.80%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 478
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 645
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 826
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,350
Annual Return 2012 rr_AnnualReturn2012 8.80%
Annual Return 2013 rr_AnnualReturn2013 (4.10%)
Annual Return 2014 rr_AnnualReturn2014 9.93%
Annual Return 2015 rr_AnnualReturn2015 2.65%
Annual Return 2016 rr_AnnualReturn2016 0.38%
Annual Return 2017 rr_AnnualReturn2017 5.88%
Annual Return 2018 rr_AnnualReturn2018 0.70%
Annual Return 2019 rr_AnnualReturn2019 8.15%
Annual Return 2020 rr_AnnualReturn2020 4.48%
Annual Return 2021 rr_AnnualReturn2021 2.13%
1 Year rr_AverageAnnualReturnYear01 (1.96%)
5 Years rr_AverageAnnualReturnYear05 3.38%
10 Years rr_AverageAnnualReturnYear10 3.39%
Putnam Tax Exempt Income | Class A | After Taxes on Distributions  
Prospectus [Line Items] rr_ProspectusLineItems  
1 Year rr_AverageAnnualReturnYear01 (2.41%)
5 Years rr_AverageAnnualReturnYear05 3.10%
10 Years rr_AverageAnnualReturnYear10 3.23%
Putnam Tax Exempt Income | Class A | After Taxes on Distributions and Sales  
Prospectus [Line Items] rr_ProspectusLineItems  
1 Year rr_AverageAnnualReturnYear01 (0.05%)
5 Years rr_AverageAnnualReturnYear05 3.15%
10 Years rr_AverageAnnualReturnYear10 3.30%
Putnam Tax Exempt Income | Class B  
Prospectus [Line Items] rr_ProspectusLineItems  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage) rr_MaximumDeferredSalesChargeOverOther 5.00% [3]
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.42%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.85%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.13%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.40%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 643
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 743
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 966
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 1,516
Expense Example, No Redemption, 1 Year rr_ExpenseExampleNoRedemptionYear01 143
Expense Example, No Redemption, 3 Years rr_ExpenseExampleNoRedemptionYear03 443
Expense Example, No Redemption, 5 Years rr_ExpenseExampleNoRedemptionYear05 766
Expense Example, No Redemption, 10 Years rr_ExpenseExampleNoRedemptionYear10 $ 1,516
1 Year rr_AverageAnnualReturnYear01 (3.40%)
5 Years rr_AverageAnnualReturnYear05 3.25%
10 Years rr_AverageAnnualReturnYear10 3.29%
Putnam Tax Exempt Income | Class C  
Prospectus [Line Items] rr_ProspectusLineItems  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage) rr_MaximumDeferredSalesChargeOverOther 1.00% [4]
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.42%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 1.00%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.13%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.55%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 258
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 490
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 845
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 1,643
Expense Example, No Redemption, 1 Year rr_ExpenseExampleNoRedemptionYear01 158
Expense Example, No Redemption, 3 Years rr_ExpenseExampleNoRedemptionYear03 490
Expense Example, No Redemption, 5 Years rr_ExpenseExampleNoRedemptionYear05 845
Expense Example, No Redemption, 10 Years rr_ExpenseExampleNoRedemptionYear10 $ 1,643
1 Year rr_AverageAnnualReturnYear01 0.38%
5 Years rr_AverageAnnualReturnYear05 3.44%
10 Years rr_AverageAnnualReturnYear10 3.17%
Putnam Tax Exempt Income | Class R6  
Prospectus [Line Items] rr_ProspectusLineItems  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage) rr_MaximumDeferredSalesChargeOverOther none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.42%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.12%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.54%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 55
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 173
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 302
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 677
1 Year rr_AverageAnnualReturnYear01 2.41% [5]
5 Years rr_AverageAnnualReturnYear05 4.48% [5]
10 Years rr_AverageAnnualReturnYear10 4.06% [5]
Putnam Tax Exempt Income | Class Y  
Prospectus [Line Items] rr_ProspectusLineItems  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage) rr_MaximumDeferredSalesChargeOverOther none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.42%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.13%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.55%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 56
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 176
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 307
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 689
1 Year rr_AverageAnnualReturnYear01 2.39%
5 Years rr_AverageAnnualReturnYear05 4.48%
10 Years rr_AverageAnnualReturnYear10 4.06%
[1] Source: Bloomberg Index Services Limited.
[2] Applies only to certain redemptions of shares bought with no initial sales charge.
[3] This charge is phased out over six years.
[4] This charge is eliminated after one year.
[5] Performance for R6 shares prior to their inception (5/22/18) is derived from the historical performance of class Y shares and has not been adjusted for the lower investor servicing fees applicable to class R6 shares; had it, returns would have been higher.