Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Registrant Name

dei_EntityRegistrantName

THORNBURG INVESTMENT TRUST

Prospectus Date

rr_ProspectusDate

Feb. 01, 2015

Thornburg International Value Fund | A B C I

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

FUND SUMMARY

International Value Fund

Objective [Heading]

rr_ObjectiveHeading

Investment Goal

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

International Value Fund seeks long-term capital appreciation by investing in equity and debt securities of all types.

Objective, Secondary [Text Block]

rr_ObjectiveSecondaryTextBlock

The secondary, non-fundamental goal of the Fund is to seek some current income.

Expense [Heading]

rr_ExpenseHeading

Fees and Expenses of the Fund

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. You may qualify for discounts from the sales charges applicable to Class A shares if you or other qualifying account holders invest, or agree to invest in the future, at least $50,000 in the Thornburg Funds. More information about these and other discounts is available from your financial professional and in “Opening Your Account – Buying Fund Shares” on page 82 of this Prospectus.

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 that 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 costs, such as commissions, when it buys and sells securities (or “turns over”) its portfolio. A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Annual Fund Operating Expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 37.25% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

37.25%

Expense Breakpoint Discounts [Text]

rr_ExpenseBreakpointDiscounts

You may qualify for discounts from the sales charges applicable to Class A shares if you or other qualifying account holders invest, or agree to invest in the future, at least $50,000 in the Thornburg Funds. More information about these and other discounts is available from your financial professional and in “Opening Your Account – Buying Fund Shares” on page 82 of this Prospectus.

Expense Breakpoint, Minimum Investment Required [Amount]

rr_ExpenseBreakpointMinimumInvestmentRequiredAmount

50,000

Expense Example [Heading]

rr_ExpenseExampleHeading

Example.

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.

The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year, dividends and distributions are reinvested, and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example, No Redemption, By Year, Caption [Text]

rr_ExpenseExampleNoRedemptionByYearCaption

You would pay the following expenses if you did not redeem your Class B or C shares:

Strategy [Heading]

rr_StrategyHeading

Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund invests primarily in foreign securities or depository receipts of foreign securities. The Fund may invest in developing countries, but under normal conditions those investments are expected to comprise a smaller proportion of the Fund than investments in developed countries.

The Fund’s investment advisor, Thornburg Investment Management, Inc. (“Thornburg”), intends to invest on an opportunistic basis where the Fund’s portfolio managers believe intrinsic value is not recognized by the marketplace. The Fund seeks to identify value in a broad or different context by investing in a diversified portfolio of stocks classified as basic values, consistent earners, and emerging franchises, when the portfolio managers believe these issues are value priced. The relative proportions of securities invested in each of those categories will vary over time. The Fund seeks to invest in promising companies, and may invest in stocks that reflect unfavorable market perceptions of the company or industry fundamentals. The Fund may invest in companies of any size, but invests primarily in the large and middle capitalization range of publicly traded companies.

Thornburg primarily uses individual issuer and industry analysis to make investment decisions. Value, for purposes of the Fund’s selection criteria, may consider both current and projected measures. Among the specific factors considered by Thornburg in identifying securities for inclusion in the Fund are:

■	profitability	■	undervalued assets
■	price/earnings ratio	■	earnings growth potential
■	price/book value ratio	■	industry growth characteristics
■	price/cash flow ratio	■	industry leadership
■	debt/capital ratio	■	franchise value
■	dividend characteristics	■	potential for favorable developments
■	security and consistency of revenues	■	EBIT (earnings before interest and taxes)/interest expense ratio
■	EV (enterprise value)/ EBITDA (earnings before interest, taxes, depreciation and amortization) ratio

The Fund classifies its equity investments in the following three categories:

Basic Value: Companies which, in Thornburg’s opinion, are financially sound with well established businesses selling at low valuations relative to the companies’ net assets or potential earning power.

Consistent Earner: Companies which normally exhibit steady earnings growth, cash flow characteristics and/or dividend growth. These companies may have above average profitability measures and normally sell at above average valuations.

Emerging Franchise: Companies which, in Thornburg’s opinion, are in the process of establishing a leading position in a product, service or market with the potential to grow at an above average rate. Under normal conditions, the proportion of the Fund invested in this category will be lower than the other categories.

Debt obligations may be considered for investment if Thornburg believes them to be more attractive than equity alternatives, or to manage risk. The Fund may purchase debt obligations of any maturity and of any credit quality, including “high yield” or “junk” bonds. There is no minimum credit quality or rating of debt obligation the Fund may purchase.

Risk [Heading]

rr_RiskHeading

Principal Investment Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

An investment in the Fund is not a deposit in any bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency. Accordingly, the loss of money is a risk of investing in the Fund. The value of the Fund’s shares varies from day to day and over time, and when you sell your shares they may be worth less than what you paid for them. The following is a summary of the principal risks of investing in the Fund.

Management Risk – The Fund is an actively managed portfolio, and the value of the Fund may be reduced if Thornburg pursues unsuccessful investments or fails to correctly identify risks affecting the broad economy or specific issuers in which the Fund invests.

Market and Economic Risk – The value of the Fund’s investments may decline and its share value may be reduced due to changes in general economic and market conditions. The value of a security may change in response to developments affecting entire economies, markets or industries, including changes in interest rates, political and legal developments, and general market volatility.

Risks Affecting Specific Issuers – The value of an equity security or debt obligation may decline in response to developments affecting the specific issuer of the security or obligation, even if the overall industry or economy is unaffected. These developments may include a variety of factors, including but not limited to management issues or other corporate disruption, a decline in revenues or profitability, an increase in costs, or an adverse effect on the issuer’s competitive position.

Foreign Investment Risk – Investments in securities of foreign issuers may involve risks including adverse fluctuations in currency exchange rates, political instability, confiscations, taxes or restrictions on currency exchange, difficulty in selling foreign investments, and reduced legal protection.

Developing Country Risk – The risks which may affect investments in foreign issuers (see “Foreign Investment Risk,” above) may be more pronounced for investments in developing countries because the economies of those countries are usually less diversified, communications, transportation and economic infrastructures are less developed, and developing countries ordinarily have less established legal, political, business and social frameworks. At times the prices of equity securities or debt obligations of a developing country issuer may be extremely volatile. An issuer domiciled in a developed country may be similarly affected by these developing country risks to the extent that the issuer conducts a significant percentage of its business in developing countries.

Small and Mid-Cap Company Risk – Investments in small-capitalization companies and mid-capitalization companies may involve additional risks, which may be relatively higher with smaller companies. These additional risks may result from limited product lines, more limited access to markets and financial resources, greater vulnerability to competition and changes in markets, lack of management depth, increased volatility in share price, and possible difficulties in valuing or selling these investments.

Credit Risk – If debt obligations held by the Fund are downgraded by ratings agencies or go into default, or if management action, legislation or other government action reduces the ability of issuers to pay principal and interest when due, the value of those debt obligations may decline and the Fund’s share value and any dividends paid by the Fund may be reduced. Because the ability of an issuer of a lower-rated or unrated debt obligation to pay principal and interest when due is typically less certain than for an issuer of a higher-rated debt obligation, lower-rated and unrated debt obligations are generally more vulnerable than higher-rated debt obligations to default, to ratings downgrades, and to liquidity risk.

Interest Rate Risk – When interest rates increase, the value of the Fund’s investments in debt obligations may decline and the Fund’s share value may be reduced. This effect is typically more pronounced for intermediate and longer-term debt obligations. Decreases in market interest rates may result in prepayments of debt obligations the Fund acquires, requiring the Fund to reinvest at lower interest rates.

Liquidity Risk – Due to a lack of demand in the marketplace or other factors, the Fund may not be able to sell some or all of the investments promptly, or may only be able to sell investments at less than desired prices.

Additional information about Fund investments, investment strategies, and risks of investing in the Fund appears below beginning on page 74.

Risk Lose Money [Text]

rr_RiskLoseMoney

Accordingly, the loss of money is a risk of investing in the Fund.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the Fund is not a deposit in any bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Past Performance of the Fund

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following information provides some indication of the risks of investing in International Value Fund by showing how the Fund’s investment results vary from year to year. The bar chart shows how the annual total returns for Class A shares have been different in each full year shown. The average annual total return figures compare Class A, Class B, Class C and Class I share performance to the Morgan Stanley Capital International (MSCI) Europe, Australasia and Far East (EAFE) Index and the MSCI All Country (AC) World ex-U.S. Index, each of which is a broad measure of market performance. Past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future. The performance information shown below is as of the calendar year ended December 31, 2014. Updated performance information may be obtained on the Thornburg website at www.thornburg.com or by calling 1-800-847-0200.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following information provides some indication of the risks of investing in International Value Fund by showing how the Fund’s investment results vary from year to year.

Performance Additional Market Index [Text]

rr_PerformanceAdditionalMarketIndex

The average annual total return figures compare Class A, Class B, Class C and Class I share performance to the Morgan Stanley Capital International (MSCI) Europe, Australasia and Far East (EAFE) Index and the MSCI All Country (AC) World ex-U.S. Index, each of which is a broad measure of market performance.

Performance Availability Phone [Text]

rr_PerformanceAvailabilityPhone

1-800-847-0200

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.thornburg.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

Past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

Annual Total Returns – Class A Shares

Bar Chart Does Not Reflect Sales Loads [Text]

rr_BarChartDoesNotReflectSalesLoads

The sales charge for Class A shares is not reflected in the returns shown in the bar chart above, and the returns would be less if the charge was taken into account.

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Highest quarterly results for time period shown: 22.74%
(quarter ended 6-30-09).

Lowest quarterly results for time period shown: -20.94%
(quarter ended 9-30-11).

The sales charge for Class A shares is not reflected in the returns shown in the bar chart above, and the returns would be less if the charge was taken into account.

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Total Returns (periods ended 12-31-14)

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the highest historical individual federal marginal income tax rates, and do not reflect state or local income taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

Actual after-tax returns depend on an investor’s own tax situation and may differ from the returns shown, and after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

Performance Table One Class of after Tax Shown [Text]

rr_PerformanceTableOneClassOfAfterTaxShown

The after-tax returns shown relate only to Class A shares, and after-tax returns will vary for Class B, Class C and Class I shares because the returns of the classes are different.

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

After-tax returns are calculated using the highest historical individual federal marginal income tax rates, and do not reflect state or local income taxes. Actual after-tax returns depend on an investor’s own tax situation and may differ from the returns shown, and after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts. The after-tax returns shown relate only to Class A shares, and after-tax returns will vary for Class B, Class C and Class I shares because the returns of the classes are different.

Thornburg International Value Fund | A B C I | Class A

Risk/Return:

rr_RiskReturnAbstract

Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

4.50%

Maximum Deferred Sales Charge (Load) (as a percentage of redemption proceeds or original purchase price, whichever is lower)

rr_MaximumDeferredSalesChargeOverOther

none

^[1]

Management Fees

rr_ManagementFeesOverAssets

0.68%

Distribution and Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other Expenses

rr_OtherExpensesOverAssets

0.33%

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

1.26%

Expenses Deferred Charges [Text Block]

rr_ExpensesDeferredChargesTextBlock

A 1.00% contingent deferred sales charge (CDSC) is imposed on redemptions of any part or all of a purchase of $1 million or more within 12 months of purchase.

1 Year

rr_ExpenseExampleYear01

573

3 Years

rr_ExpenseExampleYear03

832

5 Years

rr_ExpenseExampleYear05

1,110

10 Years

rr_ExpenseExampleYear10

1,904

2005

rr_AnnualReturn2005

17.70%

2006

rr_AnnualReturn2006

25.62%

2007

rr_AnnualReturn2007

27.71%

2008

rr_AnnualReturn2008

(41.89%)

2009

rr_AnnualReturn2009

31.43%

2010

rr_AnnualReturn2010

13.70%

2011

rr_AnnualReturn2011

(13.24%)

2012

rr_AnnualReturn2012

15.33%

2013

rr_AnnualReturn2013

15.35%

2014

rr_AnnualReturn2014

(5.90%)

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Highest quarterly results

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

22.74%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Lowest quarterly results

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2011

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(20.94%)

1 Year

rr_AverageAnnualReturnYear01

(10.14%)

5 Years

rr_AverageAnnualReturnYear05

3.35%

10 Years

rr_AverageAnnualReturnYear10

5.45%

Thornburg International Value Fund | A B C I | Class B

Risk/Return:

rr_RiskReturnAbstract

Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

^[2]

Maximum Deferred Sales Charge (Load) (as a percentage of redemption proceeds or original purchase price, whichever is lower)

rr_MaximumDeferredSalesChargeOverOther

5.00%

^[2],[3]

Management Fees

rr_ManagementFeesOverAssets

0.68%

^[2]

Distribution and Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

1.00%

^[2]

Other Expenses

rr_OtherExpensesOverAssets

0.45%

^[2]

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

2.13%

^[2]

Expenses Deferred Charges [Text Block]

rr_ExpensesDeferredChargesTextBlock

Class B shares are subject to a contingent deferred sales charge (CDSC) if shares are redeemed within seven years of purchase. The CDSC decreases over time.

1 Year

rr_ExpenseExampleYear01

716

3 Years

rr_ExpenseExampleYear03

1,017

5 Years

rr_ExpenseExampleYear05

1,344

10 Years

rr_ExpenseExampleYear10

2,238

^[4]

1 Year

rr_ExpenseExampleNoRedemptionYear01

216

3 Years

rr_ExpenseExampleNoRedemptionYear03

667

5 Years

rr_ExpenseExampleNoRedemptionYear05

1,144

10 Years

rr_ExpenseExampleNoRedemptionYear10

2,238

^[4]

1 Year

rr_AverageAnnualReturnYear01

(10.95%)

5 Years

rr_AverageAnnualReturnYear05

3.09%

10 Years

rr_AverageAnnualReturnYear10

5.27%

Thornburg International Value Fund | A B C I | Class C

Risk/Return:

rr_RiskReturnAbstract

Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum Deferred Sales Charge (Load) (as a percentage of redemption proceeds or original purchase price, whichever is lower)

rr_MaximumDeferredSalesChargeOverOther

1.00%

^[5]

Management Fees

rr_ManagementFeesOverAssets

0.68%

Distribution and Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

1.00%

Other Expenses

rr_OtherExpensesOverAssets

0.31%

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

1.99%

Expenses Deferred Charges [Text Block]

rr_ExpensesDeferredChargesTextBlock

Imposed only on redemptions of Class C shares within 12 months of purchase.

1 Year

rr_ExpenseExampleYear01

302

3 Years

rr_ExpenseExampleYear03

624

5 Years

rr_ExpenseExampleYear05

1,073

10 Years

rr_ExpenseExampleYear10

2,317

1 Year

rr_ExpenseExampleNoRedemptionYear01

202

3 Years

rr_ExpenseExampleNoRedemptionYear03

624

5 Years

rr_ExpenseExampleNoRedemptionYear05

1,073

10 Years

rr_ExpenseExampleNoRedemptionYear10

2,317

1 Year

rr_AverageAnnualReturnYear01

(7.40%)

5 Years

rr_AverageAnnualReturnYear05

3.53%

10 Years

rr_AverageAnnualReturnYear10

5.17%

Thornburg International Value Fund | A B C I | Class I

Risk/Return:

rr_RiskReturnAbstract

Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum Deferred Sales Charge (Load) (as a percentage of redemption proceeds or original purchase price, whichever is lower)

rr_MaximumDeferredSalesChargeOverOther

none

Management Fees

rr_ManagementFeesOverAssets

0.68%

Distribution and Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

none

Other Expenses

rr_OtherExpensesOverAssets

0.20%

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

0.88%

1 Year

rr_ExpenseExampleYear01

90

3 Years

rr_ExpenseExampleYear03

281

5 Years

rr_ExpenseExampleYear05

488

10 Years

rr_ExpenseExampleYear10

1,084

1 Year

rr_AverageAnnualReturnYear01

(5.55%)

5 Years

rr_AverageAnnualReturnYear05

4.71%

10 Years

rr_AverageAnnualReturnYear10

6.36%

Thornburg International Value Fund | A B C I | Return After Taxes on Distributions | Class A

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(12.25%)

5 Years

rr_AverageAnnualReturnYear05

2.59%

10 Years

rr_AverageAnnualReturnYear10

4.63%

Thornburg International Value Fund | A B C I | Return After Taxes on Distributions and Sale of Fund Shares | Class A

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(4.19%)

5 Years

rr_AverageAnnualReturnYear05

2.45%

10 Years

rr_AverageAnnualReturnYear10

4.24%

Thornburg International Value Fund | A B C I | EAFE Index (reflects no deduction for fees, expenses, or taxes) | Class A

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(4.90%)

5 Years

rr_AverageAnnualReturnYear05

5.33%

10 Years

rr_AverageAnnualReturnYear10

4.43%

Thornburg International Value Fund | A B C I | EAFE Index (reflects no deduction for fees, expenses, or taxes) | Class B

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(4.90%)

5 Years

rr_AverageAnnualReturnYear05

5.33%

10 Years

rr_AverageAnnualReturnYear10

4.43%

Thornburg International Value Fund | A B C I | EAFE Index (reflects no deduction for fees, expenses, or taxes) | Class C

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(4.90%)

5 Years

rr_AverageAnnualReturnYear05

5.33%

10 Years

rr_AverageAnnualReturnYear10

4.43%

Thornburg International Value Fund | A B C I | EAFE Index (reflects no deduction for fees, expenses, or taxes) | Class I

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(4.90%)

5 Years

rr_AverageAnnualReturnYear05

5.33%

10 Years

rr_AverageAnnualReturnYear10

4.43%

Thornburg International Value Fund | A B C I | MSCI AC World ex-U.S. Index (reflects no deduction for fees, expenses, or taxes) | Class A

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(3.43%)

5 Years

rr_AverageAnnualReturnYear05

4.89%

10 Years

rr_AverageAnnualReturnYear10

5.59%

Thornburg International Value Fund | A B C I | MSCI AC World ex-U.S. Index (reflects no deduction for fees, expenses, or taxes) | Class B

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(3.43%)

5 Years

rr_AverageAnnualReturnYear05

4.89%

10 Years

rr_AverageAnnualReturnYear10

5.59%

Thornburg International Value Fund | A B C I | MSCI AC World ex-U.S. Index (reflects no deduction for fees, expenses, or taxes) | Class C

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(3.43%)

5 Years

rr_AverageAnnualReturnYear05

4.89%

10 Years

rr_AverageAnnualReturnYear10

5.59%

Thornburg International Value Fund | A B C I | MSCI AC World ex-U.S. Index (reflects no deduction for fees, expenses, or taxes) | Class I

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

(3.43%)

5 Years

rr_AverageAnnualReturnYear05

4.89%

10 Years

rr_AverageAnnualReturnYear10

5.59%

[1] A 1.00% contingent deferred sales charge (CDSC) is imposed on redemptions of any part or all of a purchase of $1 million or more within 12 months of purchase.

[2] The Fund no longer sells Class B shares. See "Buying and Selling Class B Shares" for additional information.

[3] Class B shares are subject to a contingent deferred sales charge (CDSC) if shares are redeemed within seven years of purchase. The CDSC decreases over time.

[4] Reflects the conversion to Class A Shares at the end of eight years.

[5] Imposed only on redemptions of Class C shares within 12 months of purchase.