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Label Element Value
Prospectus: rr_ProspectusTable  
Document Type dei_DocumentType 485BPOS
Document Period End Date dei_DocumentPeriodEndDate Sep. 30, 2015
Entity Registrant Name dei_EntityRegistrantName Calvert Fund
Central Index Key dei_EntityCentralIndexKey 0000701039
Amendment Flag dei_AmendmentFlag false
Document Creation Date dei_DocumentCreationDate Feb. 01, 2016
Document Effective Date dei_DocumentEffectiveDate Feb. 01, 2016
Prospectus Date rr_ProspectusDate Feb. 01, 2016
Class A, C and Y | Calvert Income Fund  
Prospectus: rr_ProspectusTable  
Risk/Return [Heading] rr_RiskReturnHeading CALVERT INCOME FUND Class (Ticker):A (CFICX)C (CIFCX)Y (CIFYX)
Objective [Heading] rr_ObjectiveHeading INVESTMENT OBJECTIVE
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
The Fund seeks to maximize income, to the extent consistent with preservation of capital, through investment in bonds and income-producing securities.
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 sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in Calvert mutual funds. More information about these and other discounts is available from your financial professional and under “Choosing a Share Class” on page 47 and “Reduced Sales Charges” on page 50 of this Prospectus, and under “Method of Distribution” on page 40 of the Fund’s Statement of Additional Information.
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 % 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 (“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 236% of its portfolio’s average value.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 236.00%
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 $50,000 in Calvert mutual funds.
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 either redeem or hold your shares at the end of those periods;
•
your investment has a 5% return each year; and
•
the Fund’s operating expenses remain the same.
Although your actual costs may be higher or lower, under these assumptions your costs would be:
Strategy [Heading] rr_StrategyHeading INVESTMENTS, RISKS AND PERFORMANCE Principal Investment Strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
The Fund typically invests at least 65% of its net assets in investment grade, U.S. dollar-denominated debt securities, as assessed at the time of purchase. A debt security is considered investment grade when assigned a credit quality rating of BBB- or higher by Standard & Poor’s Ratings Services (“Standard & Poor’s”) or an equivalent rating by another nationally recognized statistical rating organization (“NRSRO”), including Moody’s Investors Service or Fitch Ratings, or if unrated, considered to be of comparable credit quality by the Fund’s Advisor.
The Fund invests principally in bonds issued by U.S. corporations, the U.S. Government or its agencies, and U.S. government-sponsored enterprises (“GSEs”) such as the Federal National Mortgage Association (“FNMA”) and the Federal Home Loan Mortgage Corporation (“FHLMC”). The Fund also may invest in trust preferred securities, taxable municipal securities, leveraged loans and asset-backed securities (“ABS”), including commercial mortgage-backed securities.
The Fund may invest in securities that represent interests in pools of mortgage loans or other assets assembled for sale to investors by various U.S. governmental agencies, government-related organizations and private issuers. These investments may include securities such as collateralized mortgage obligations (“CMOs”) and ABS.
The Fund may invest up to 35% of its net assets in below-investment grade, high-yield debt securities (commonly known as “junk bonds”), including distressed securities that are in default. A debt security is considered below investment grade when assigned a credit quality rating below BBB- by Standard & Poor’s or an equivalent rating by another NRSRO, or if unrated, considered to be of comparable credit quality by the Fund’s Advisor.
The Fund may also invest up to 25% of its net assets in foreign debt securities. Foreign debt securities include American Depositary Receipts (“ADRs”).
The Fund is “non-diversified,” which means it may hold securities of a smaller number of issuers and invest a greater percentage of its assets in a particular issuer than a “diversified” fund.
The Fund uses an active trading strategy, seeking relative value to earn incremental income.
The Fund uses a hedging technique that includes the purchase and sale of U.S. Treasury securities and related futures contracts to manage the duration of the Fund and hedge interest rate risk.
Responsible Investing. In conjunction with Calvert’s financial analysis, Calvert’s comprehensive responsible investment principles guide our investment research processes and decision-making. The principles, which include the Advisor’s proprietary assessment of critical environmental, social and governance (“ESG”) issues, are applied across industries and to specific companies in order to inform our view of risk and opportunity factors that may affect investment performance.
Risk [Heading] rr_RiskHeading Principal Risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
You could lose money on your investment in the Fund, or the Fund could underperform, because of the risks described below. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Non-Diversification Risk. Because the Fund may hold securities of a smaller number of issuers or invest a greater percentage of its assets in a particular issuer than a diversified fund, the gains or losses on a single bond may have greater impact on the Fund than on a diversified fund.
Bond Market Risk. The market prices of bonds held by the Fund may fall.
Credit Risk. The credit quality of fixed-income securities may deteriorate, which could lead to default or bankruptcy of the issuer where the issuer becomes unable to pay its obligations when due.
Mortgage-Backed and Asset-Backed Securities Risk. The value of investments in mortgage-backed and asset-backed securities is subject to interest rate risk and credit risk. These securities are also subject to the risk that borrowers will prepay the principal on their loans more quickly than expected (prepayment risk) or more slowly than expected (extension risk), which will affect the yield, average life and price of the securities. In addition, faster than expected prepayments may cause the Fund to invest the prepaid principal in lower yielding securities and slower than expected prepayments may reduce the potential for the Fund to invest in higher yielding securities.
Mortgage-Backed Security Risk (Government-Sponsored Enterprises).  Debt and mortgage-backed securities issued by GSEs such as FNMA and FHLMC are neither insured nor guaranteed by the U.S. Treasury and are not backed by the full faith and credit of the U.S. government. Such securities are only supported by the credit of the applicable GSE. The U.S. government has provided financial support to FNMA and FHLMC, but there can be no assurance that it will support these or other GSEs in the future.
Leveraged Loan Risk. Leveraged loans are subject to the risks typically associated with debt securities, such as credit risk discussed above. The loans in which the Fund will invest are expected to be below-investment-grade quality and to bear interest at a floating rate that resets periodically. In addition, leveraged loans, which typically hold a senior position in the capital structure of a borrower, are subject to the risk that a court could subordinate such loans to presently existing or future indebtedness or take other action detrimental to the holders of leveraged loans. Leveraged loans are also subject to the risk that the value of the collateral, if any, securing a loan may decline, be insufficient to meet the obligations of the borrower, or be difficult to liquidate. Some leveraged loans are not as easily purchased or sold as publicly-traded securities and others are illiquid, which may make it more difficult for the Fund to value them or dispose of them at an acceptable price. Leveraged loans are usually more credit sensitive than investment-grade securities.
Management Risk. Individual investments of the Fund may not perform as expected, and the Fund’s portfolio management practices may not achieve the desired result.
Interest Rate Risk. A change in interest rates may adversely affect the value of fixed-income securities. When interest rates rise, the value of fixed-income securities will generally fall. Longer-term securities are subject to greater interest rate risk.
Portfolio Duration Risk. Duration is a measure of the expected life of a fixed-income security and its sensitivity to changes in interest rates. The longer a fund’s average portfolio duration, the more sensitive the fund will be to changes in interest rates.
Liquidity Risk. Liquidity risk exists when particular investments are difficult to sell. The Fund may be unable to sell illiquid securities at an advantageous time or price or achieve its desired level of exposure to a certain sector. Liquidity risk may result from the lack of an active market, reduced number and capacity of traditional market participants to make a market in fixed-income securities, and may be magnified in a rising interest rate environment or other circumstances where investor redemptions from fixed-income mutual funds may be higher than normal, causing increased supply in the market due to selling activity. Illiquid securities also may be difficult to value.
Junk Bond Risk. Investments in junk bonds can involve a substantial risk of loss. Junk bonds are considered to be speculative with respect to the issuer’s ability to pay interest and principal. These securities, which are rated below investment grade, have a higher risk of issuer default, are subject to greater price volatility than investment grade securities and may be illiquid.
Defaulted Bonds Risk. For bonds in default (those rated “D” by Standard & Poor’s or the equivalent by another NRSRO), there is a significant risk that these bonds will not achieve their original value.
Unrated Security Risk. Unrated securities may be less liquid than rated securities determined to be of comparable credit quality by the Advisor. When the Fund purchases unrated securities, it will depend on the Advisor’s analysis of credit risk without the assessment of an NRSRO.
Taxable Municipal Bond Risk. Taxable municipal bonds are subject to credit risk, interest rate risk and certain additional risks. The Fund may be more sensitive to adverse economic, business or political developments if it invests a substantial portion of its assets in the bonds of similar projects or industrial development bonds.
Trust Preferred Securities Risk. Trust preferred securities are preferred stocks issued by a special purpose trust subsidiary backed by subordinated debt of the corporate parent. Trust preferred securities are subject to unique risks, which include the fact that dividend payments will only be paid if interest payments on the underlying obligations are made, which interest payments are dependent on the financial condition of the parent corporation. There is also the risk that the underlying obligations, and thus the trust preferred securities, may be prepaid after a stated call date or as a result of certain tax or regulatory events, resulting in a lower yield to maturity.
Collateralized Mortgage Obligation and Structured Asset-Backed Securities Risk. A CMO is a multiclass bond that is backed by a pool of mortgage loans or mortgage-backed securities. A structured ABS is a multiclass bond that is typically backed by a pool of auto loans, credit card receivables, home equity loans or student loans. A CMO or structured ABS is subject to interest rate risk, credit risk, prepayment risk and extension risk. In addition, if the Fund holds a class of a CMO or a structured ABS that is subordinated to other classes backed by the same pool of collateral, the likelihood that the Fund will receive payments of principal may be substantially limited.
Foreign Securities Risk. Investing in foreign securities involves additional risks relating to political, social, and economic developments abroad. Other risks result from the differences between the regulations to which U.S. and foreign issuers and markets are subject, and the potential for foreign markets to be less liquid and more volatile than U.S. markets. Foreign securities include ADRs. Unsponsored ADRs involve additional risks because U.S. reporting requirements do not apply and the issuing bank will recover shareholder distribution costs from movement of share prices and payment of dividends.
Foreign Currency Risk. Securities that trade or are denominated in currencies other than the U.S. dollar may be adversely affected by fluctuations in currency exchange rates. When the U.S. dollar strengthens relative to a foreign currency, the U.S. dollar value of an investment denominated in that currency will typically fall. ADRs indirectly bear currency risk because they represent an interest in securities that are not denominated in U.S. dollars.
Active Trading Strategy Risk. The Fund employs an active style that seeks to position the Fund with securities that offer the greatest price appreciation while minimizing risk. This style can result in higher turnover (exceeding 100%), may translate to higher transaction costs and may increase your tax liability.
Responsible Investing Risk. Investing primarily in responsible investments carries the risk that, under certain market conditions, the Fund may underperform funds that do not utilize a responsible investment strategy. The application of responsible investment principles may affect the Fund’s exposure to certain sectors or types of investments and may impact the Fund’s relative investment performance depending on whether such sectors or investments are in or out of favor in the market. A company’s ESG performance or the Advisor’s assessment of a company’s ESG performance may change over time, which could cause the Fund to temporarily hold securities that do not comply with the Fund’s responsible investment principles. In evaluating a company, the Advisor is dependent upon information and data that may be incomplete, inaccurate or unavailable, which could cause the Advisor to incorrectly assess a company’s ESG performance. Successful application of the Fund’s responsible investment strategy will depend on the Advisor’s skill in properly identifying and analyzing material ESG issues.
Futures Contracts Risk. The value of a futures contract tends to increase and decrease in tandem with the value of the underlying instrument. The price of futures can be highly volatile; using them could lower total return, and the potential loss from futures can exceed the Fund’s initial investment in such contracts. Futures contracts may not provide an effective hedge of the underlying securities or indexes because changes in the prices of futures contracts may not track those of the securities or indexes that they are intended to hedge.
Risk Lose Money [Text] rr_RiskLoseMoney You could lose money on your investment in the Fund, or the Fund could underperform, because of the risks described below.
Risk Nondiversified Status [Text] rr_RiskNondiversifiedStatus Non-Diversification Risk. Because the Fund may hold securities of a smaller number of issuers or invest a greater percentage of its assets in a particular issuer than a diversified fund, the gains or losses on a single bond may have greater impact on the Fund than on a diversified fund.
Risk Not Insured Depository Institution [Text] rr_RiskNotInsuredDepositoryInstitution An investment in the Fund is not a bank deposit and 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 following bar chart and table show the Fund’s annual returns and its long-term performance, which give some indication of the risks of investing in the Fund. The bar chart shows how the performance of the Class A shares has varied from year to year. The table compares the Fund’s performance over time with that of a benchmark and a performance average of similar mutual funds. The performance reflected in the bar chart and table assumes the reinvestment of dividends and capital gains distributions, if any.
The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. For updated performance information, visit www.calvert.com.
Performance results for Class Y shares prior to February 29, 2008 (the Class Y shares’ inception date) reflect the performance of Class A shares at net asset value. Actual Class Y share performance would have been higher than Class A share performance because Class Y has lower class-specific expenses than Class A.
The return for each of the Fund’s other Classes of shares will differ from the Class A returns shown in the bar chart, depending upon the expenses of that Class. The bar chart does not reflect any sales charge that you may be required to pay upon purchase or redemption of the Fund’s shares. Any sales charge will reduce your return.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following bar chart and table show the Fund’s annual returns and its long-term performance, which give some indication of the risks of investing in the Fund. The bar chart shows how the performance of the Class A shares has varied from year to year. The table compares the Fund’s performance over time with that of a benchmark and a performance average of similar mutual funds.
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress www.calvert.com
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar Year Total Returns for Class A at NAV
Bar Chart Does Not Reflect Sales Loads [Text] rr_BarChartDoesNotReflectSalesLoads The bar chart does not reflect any sales charge that you may be required to pay upon purchase or redemption of the Fund’s shares. Any sales charge will reduce your return.
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
 
Quarter
Ended
 
Total
Return
Best Quarter (of periods shown)
6/30/09
 
7.78%
Worst Quarter (of periods shown)
12/31/08
 
-7.72%
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns (as of 12-31-15) (with maximum sales charge deducted, if any)
Performance Table Does Reflect Sales Loads rr_PerformanceTableDoesReflectSalesLoads The average total return table shows the Fund’s returns with the maximum sales charge deducted, and no sales charge has been applied to the indices used for comparison in the table.
Performance Table Uses Highest Federal Rate rr_PerformanceTableUsesHighestFederalRate After-tax returns are calculated using the historical highest individual federal marginal income tax rates, and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred rr_PerformanceTableNotRelevantToTaxDeferred The after-tax returns shown are not relevant to you if you hold your Fund shares through a tax-deferred arrangement such as a 401(k) plan or individual retirement account.
Performance Table One Class of after Tax Shown [Text] rr_PerformanceTableOneClassOfAfterTaxShown After-tax returns are shown only for Class A shares; after-tax returns for other Classes will vary.
Performance Table Explanation after Tax Higher rr_PerformanceTableExplanationAfterTaxHigher The return after taxes on distributions and sale of Fund shares may be higher than the return before taxes because the calculation assumes that shareholders receive a tax benefit for capital losses incurred on the sale of their shares.
Performance Table Narrative rr_PerformanceTableNarrativeTextBlock
The average total return table shows the Fund’s returns with the maximum sales charge deducted, and no sales charge has been applied to the indices used for comparison in the table.
After-tax returns are calculated using the historical highest individual federal marginal income tax rates, and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. The after-tax returns shown are not relevant to you if you hold your Fund shares through a tax-deferred arrangement such as a 401(k) plan or individual retirement account. The return after taxes on distributions and sale of Fund shares may be higher than the return before taxes because the calculation assumes that shareholders receive a tax benefit for capital losses incurred on the sale of their shares. After-tax returns are shown only for Class A shares; after-tax returns for other Classes will vary.
Class A, C and Y | Calvert Income Fund | Barclays U.S. Credit Index (reflects no deduction for fees, expenses or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (0.77%)
5 Years rr_AverageAnnualReturnYear05 4.38%
10 Years rr_AverageAnnualReturnYear10 5.18%
Class A, C and Y | Calvert Income Fund | Lipper Corporate Debt Funds BBB Rated Avg. (reflects no deduction for taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (1.71%)
5 Years rr_AverageAnnualReturnYear05 4.11%
10 Years rr_AverageAnnualReturnYear10 4.91%
Class A, C and Y | Calvert Income Fund | Class A  
Prospectus: rr_ProspectusTable  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 4.75%
Maximum Deferred Sales Charge (as a percentage) rr_MaximumDeferredSalesChargeOverOther none [1]
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.52% [2]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.29%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.06%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 578
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 796
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,032
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,708
Annual Return 2006 rr_AnnualReturn2006 4.82%
Annual Return 2007 rr_AnnualReturn2007 5.08%
Annual Return 2008 rr_AnnualReturn2008 (12.00%)
Annual Return 2009 rr_AnnualReturn2009 16.42%
Annual Return 2010 rr_AnnualReturn2010 6.45%
Annual Return 2011 rr_AnnualReturn2011 2.63%
Annual Return 2012 rr_AnnualReturn2012 8.63%
Annual Return 2013 rr_AnnualReturn2013 (0.75%)
Annual Return 2014 rr_AnnualReturn2014 4.88%
Annual Return 2015 rr_AnnualReturn2015 (1.20%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best Quarter (of periods shown)
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2009
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 7.78%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst Quarter (of periods shown)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (7.72%)
1 Year rr_AverageAnnualReturnYear01 (4.92%)
5 Years rr_AverageAnnualReturnYear05 1.99%
10 Years rr_AverageAnnualReturnYear10 2.86%
Class A, C and Y | Calvert Income Fund | Class A | After Taxes on Distributions  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (6.07%)
5 Years rr_AverageAnnualReturnYear05 0.78%
10 Years rr_AverageAnnualReturnYear10 1.43%
Class A, C and Y | Calvert Income Fund | Class A | After Taxes on Distributions and Sales  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (2.80%)
5 Years rr_AverageAnnualReturnYear05 1.02%
10 Years rr_AverageAnnualReturnYear10 1.64%
Class A, C and Y | Calvert Income Fund | Class C  
Prospectus: rr_ProspectusTable  
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% [3]
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.52% [2]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 1.00%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.23%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.75%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 278
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 551
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 949
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 2,062
Expense Example, No Redemption, 1 Year rr_ExpenseExampleNoRedemptionYear01 178
Expense Example, No Redemption, 3 Years rr_ExpenseExampleNoRedemptionYear03 551
Expense Example, No Redemption, 5 Years rr_ExpenseExampleNoRedemptionYear05 949
Expense Example, No Redemption, 10 Years rr_ExpenseExampleNoRedemptionYear10 $ 2,062
1 Year rr_AverageAnnualReturnYear01 (2.89%)
5 Years rr_AverageAnnualReturnYear05 2.06%
10 Years rr_AverageAnnualReturnYear10 2.53%
Class A, C and Y | Calvert Income Fund | Class Y  
Prospectus: rr_ProspectusTable  
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 0.52% [2]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.21%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.73%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 75
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 233
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 406
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 906
1 Year rr_AverageAnnualReturnYear01 (0.88%)
5 Years rr_AverageAnnualReturnYear05 3.14%
10 Years rr_AverageAnnualReturnYear10 3.55%
Class A, C and Y | Calvert Short Duration Income Fund  
Prospectus: rr_ProspectusTable  
Risk/Return [Heading] rr_RiskReturnHeading CALVERT SHORT DURATION INCOME FUND Class (Ticker):A (CSDAX)C (CDICX)Y (CSDYX)
Objective [Heading] rr_ObjectiveHeading INVESTMENT OBJECTIVE
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
The Fund seeks to maximize income, to the extent consistent with preservation of capital, through investment in short-term bonds and income-producing securities.
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 sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in
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 % 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 (“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 206% of its portfolio’s average value.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 206.00%
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 $50,000 in
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 either redeem or hold your shares at the end of those periods;
•
your investment has a 5% return each year; and
•
the Fund’s operating expenses remain the same;
Strategy [Heading] rr_StrategyHeading INVESTMENTS, RISKS AND PERFORMANCE Principal Investment Strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
The Fund typically invests at least 65% of its net assets in investment grade, U.S. dollar-denominated debt securities, as assessed at the time of purchase. A debt security is considered investment grade when assigned a credit quality rating of BBB- or higher by Standard & Poor’s Ratings Services (“Standard & Poor’s”) or an equivalent rating by another nationally recognized statistical rating organization (“NRSRO”), including Moody’s Investors Service or Fitch Ratings, or if unrated, considered to be of comparable credit quality by the Fund’s Advisor.
The Fund invests principally in bonds issued by U.S. corporations, the U.S. Government or its agencies, and U.S. government-sponsored enterprises (“GSEs”) such as the Federal National Mortgage Association (“FNMA”) and the Federal Home Loan Mortgage Corporation (“FHLMC”). The Fund also may invest in trust preferred securities, taxable municipal securities, leveraged loans and asset-backed securities (“ABS”), including commercial mortgage-backed securities.
The Fund may invest in securities that represent interests in pools of mortgage loans or other assets assembled for sale to investors by various U.S. governmental agencies, government-related organizations and private issuers. These investments may include securities such as collateralized mortgage obligations (“CMOs”) and ABS.
The Fund may invest up to 35% of its net assets in below-investment grade, high-yield debt securities (commonly known as “junk bonds”), including distressed securities that are in default. A debt security is considered below investment grade when assigned a credit quality rating below BBB- by Standard & Poor’s or an equivalent rating by another NRSRO, or if unrated, considered to be of comparable credit quality by the Fund’s Advisor.
The Fund may also invest up to 25% of its net assets in foreign debt securities. Foreign debt securities include American Depositary Receipts (“ADRs”).
The Fund is “non-diversified,” which means it may hold securities of a smaller number of issuers and invest a greater percentage of its assets in a particular issuer than a “diversified” fund.
Under normal circumstances, the Fund’s average portfolio duration will range from one to three years.
The Fund uses an active trading strategy, seeking relative value to earn incremental income.
The Fund uses a hedging technique that includes the purchase and sale of U.S. Treasury securities and related futures contracts to manage the duration of the Fund and hedge interest rate risk.
Responsible Investing. In conjunction with Calvert’s financial analysis, Calvert’s comprehensive responsible investment principles guide our investment research processes and decision-making. The principles, which include the Advisor’s proprietary assessment of critical environmental, social and governance (“ESG”) issues, are applied across industries and to specific companies in order to inform our view of risk and opportunity factors that may affect investment performance.
Risk [Heading] rr_RiskHeading Principal Risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
You could lose money on your investment in the Fund, or the Fund could underperform, because of the risks described below. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Non-Diversification Risk. Because the Fund may hold securities of a smaller number of issuers or invest a greater percentage of its assets in a particular issuer than a diversified fund, the gains or losses on a single bond may have greater impact on the Fund than on a diversified fund.
Bond Market Risk. The market prices of bonds held by the Fund may fall.
Credit Risk. The credit quality of fixed-income securities may deteriorate, which could lead to default or bankruptcy of the issuer where the issuer becomes unable to pay its obligations when due.
Mortgage-Backed and Asset-Backed Securities Risk. The value of investments in mortgage-backed and asset-backed securities is subject to interest rate risk and credit risk. These securities are also subject to the risk that borrowers will prepay the principal on their loans more quickly than expected (prepayment risk) or more slowly than expected (extension risk), which will affect the yield, average life and price of the securities. In addition, faster than expected prepayments may cause the Fund to invest the prepaid principal in lower yielding securities and slower than expected prepayments may reduce the potential for the Fund to invest in higher yielding securities.
Mortgage-Backed Security Risk (Government-Sponsored Enterprises).  Debt and mortgage-backed securities issued by GSEs such as FNMA and FHLMC are neither insured nor guaranteed by the U.S. Treasury and are not backed by the full faith and credit of the U.S. government. Such securities are only supported by the credit of the applicable GSE. The U.S. government has provided financial support to FNMA and FHLMC, but there can be no assurance that it will support these or other GSEs in the future.
Leveraged Loan Risk. Leveraged loans are subject to the risks typically associated with debt securities, such as credit risk discussed above. The loans in which the Fund will invest are expected to be below-investment-grade quality and to bear interest at a floating rate that resets periodically. In addition, leveraged loans, which typically hold a senior position in the capital structure of a borrower, are subject to the risk that a court could subordinate such loans to presently existing or future indebtedness or take other action detrimental to the holders of leveraged loans. Leveraged loans are also subject to the risk that the value of the collateral, if any, securing a loan may decline, be insufficient to meet the obligations of the borrower, or be difficult to liquidate. Some leveraged loans are not as easily purchased or sold as publicly-traded securities and others are illiquid, which may make it more difficult for the Fund to value them or dispose of them at an acceptable price. Leveraged loans are usually more credit sensitive than investment-grade securities.
Management Risk. Individual investments of the Fund may not perform as expected, and the Fund’s portfolio management practices may not achieve the desired result.
Interest Rate Risk. A change in interest rates may adversely affect the value of fixed-income securities. When interest rates rise, the value of fixed-income securities will generally fall. Longer-term securities are subject to greater interest rate risk.
Portfolio Duration Risk. Duration is a measure of the expected life of a fixed-income security and its sensitivity to changes in interest rates. The longer a fund’s average portfolio duration, the more sensitive the fund will be to changes in interest rates.
Liquidity Risk. Liquidity risk exists when particular investments are difficult to sell. The Fund may be unable to sell illiquid securities at an advantageous time or price or achieve its desired level of exposure to a certain sector. Liquidity risk may result from the lack of an active market, reduced number and capacity of traditional market participants to make a market in fixed-income securities, and may be magnified in a rising interest rate environment or other circumstances where investor redemptions from fixed-income mutual funds may be higher than normal, causing increased supply in the market due to selling activity. Illiquid securities also may be difficult to value.
Junk Bond Risk. Investments in junk bonds can involve a substantial risk of loss. Junk bonds are considered to be speculative with respect to the issuer’s ability to pay interest and principal. These securities, which are rated below investment grade, have a higher risk of issuer default, are subject to greater price volatility than investment grade securities and may be illiquid.
Defaulted Bonds Risk. For bonds in default (those rated “D” by Standard & Poor’s or the equivalent by another NRSRO), there is a significant risk that these bonds will not achieve their original value.
Unrated Security Risk. Unrated securities may be less liquid than rated securities determined to be of comparable credit quality by the Advisor. When the Fund purchases unrated securities, it will depend on the Advisor’s analysis of credit risk without the assessment of an NRSRO.
Taxable Municipal Bond Risk. Taxable municipal bonds are subject to credit risk, interest rate risk and certain additional risks. The Fund may be more sensitive to adverse economic, business or political developments if it invests a substantial portion of its assets in the bonds of similar projects or industrial development bonds.
Trust Preferred Securities Risk. Trust preferred securities are preferred stocks issued by a special purpose trust subsidiary backed by subordinated debt of the corporate parent. Trust preferred securities are subject to unique risks, which include the fact that dividend payments will only be paid if interest payments on the underlying obligations are made, which interest payments are dependent on the financial condition of the parent corporation. There is also the risk that the underlying obligations, and thus the trust preferred securities, may be prepaid after a stated call date or as a result of certain tax or regulatory events, resulting in a lower yield to maturity.
Collateralized Mortgage Obligation and Structured Asset-Backed Securities Risk. A CMO is a multiclass bond that is backed by a pool of mortgage loans or mortgage-backed securities. A structured ABS is a multiclass bond that is typically backed by a pool of auto loans, credit card receivables, home equity loans or student loans. A CMO or structured ABS is subject to interest rate risk, credit risk, prepayment risk and extension risk. In addition, if the Fund holds a class of a CMO or a structured ABS that is subordinated to other classes backed by the same pool of collateral, the likelihood that the Fund will receive payments of principal may be substantially limited.
Foreign Securities Risk. Investing in foreign securities involves additional risks relating to political, social, and economic developments abroad. Other risks result from the differences between the regulations to which U.S. and foreign issuers and markets are subject, and the potential for foreign markets to be less liquid and more volatile than U.S. markets. Foreign securities include ADRs. Unsponsored ADRs involve additional risks because U.S. reporting requirements do not apply and the issuing bank will recover shareholder distribution costs from movement of share prices and payment of dividends.
Foreign Currency Risk. Securities that trade or are denominated in currencies other than the U.S. dollar may be adversely affected by fluctuations in currency exchange rates. When the U.S. dollar strengthens relative to a foreign currency, the U.S. dollar value of an investment denominated in that currency will typically fall. ADRs indirectly bear currency risk because they represent an interest in securities that are not denominated in U.S. dollars.
Active Trading Strategy Risk. The Fund employs an active style that seeks to position the Fund with securities that offer the greatest price appreciation while minimizing risk. This style can result in higher turnover (exceeding 100%), may translate to higher transaction costs and may increase your tax liability.
Responsible Investing Risk. Investing primarily in responsible investments carries the risk that, under certain market conditions, the Fund may underperform funds that do not utilize a responsible investment strategy. The application of responsible investment principles may affect the Fund’s exposure to certain sectors or types of investments and may impact the Fund’s relative investment performance depending on whether such sectors or investments are in or out of favor in the market. A company’s ESG performance or the Advisor’s assessment of a company’s ESG performance may change over time, which could cause the Fund to temporarily hold securities that do not comply with the Fund’s responsible investment principles. In evaluating a company, the Advisor is dependent upon information and data that may be incomplete, inaccurate or unavailable, which could cause the Advisor to incorrectly assess a company’s ESG performance. Successful application of the Fund’s responsible investment strategy will depend on the Advisor’s skill in properly identifying and analyzing material ESG issues.
Futures Contracts Risk. The value of a futures contract tends to increase and decrease in tandem with the value of the underlying instrument. The price of futures can be highly volatile; using them could lower total return, and the potential loss from futures can exceed the Fund’s initial investment in such contracts. Futures contracts may not provide an effective hedge of the underlying securities or indexes because changes in the prices of futures contracts may not track those of the securities or indexes that they are intended to hedge.
Risk Lose Money [Text] rr_RiskLoseMoney You could lose money on your investment in the Fund, or the Fund could underperform, because of the risks described below.
Risk Nondiversified Status [Text] rr_RiskNondiversifiedStatus Non-Diversification Risk. Because the Fund may hold securities of a smaller number of issuers or invest a greater percentage of its assets in a particular issuer than a diversified fund, the gains or losses on a single bond may have greater impact on the Fund than on a diversified fund.
Risk Not Insured Depository Institution [Text] rr_RiskNotInsuredDepositoryInstitution An investment in the Fund is not a bank deposit and 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 following bar chart and table show the Fund’s annual returns and its long-term performance, which give some indication of the risks of investing in the Fund. The bar chart shows how the performance of the Class A shares has varied from year to year. The table compares the Fund’s performance over time with that of a benchmark and a performance average of similar mutual funds. The performance reflected in the bar chart and table assumes the reinvestment of dividends and capital gains distributions, if any.
The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. For updated performance information, visit www.calvert.com.
Performance results for Class Y shares prior to February 29, 2008 (the Class Y shares’ inception date) reflect the performance of Class A shares at net asset value. Actual Class Y share performance would have been higher than Class A share performance because Class Y has lower class-specific expenses than Class A.
The return for each of the Fund’s other Classes of shares will differ from the Class A returns shown in the bar chart, depending upon the expenses of that Class. The bar chart does not reflect any sales charge that you may be required to pay upon purchase or redemption of the Fund’s shares. Any sales charge will reduce your return.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following bar chart and table show the Fund’s annual returns and its long-term performance, which give some indication of the risks of investing in the Fund.
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress www.calvert.com
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar Year Total Returns for Class A at NAV
Bar Chart Does Not Reflect Sales Loads [Text] rr_BarChartDoesNotReflectSalesLoads The bar chart does not reflect any sales charge that you may be required to pay upon purchase or redemption of the Fund’s shares. Any sales charge will reduce your return.
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
 
Quarter
Ended
 
Total
Return
Best Quarter (of periods shown)
6/30/09
 
5.03%
Worst Quarter (of periods shown)
12/31/08
 
-1.60%
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns (as of 12-31-15) (with maximum sales charge deducted, if any)
Performance Table Does Reflect Sales Loads rr_PerformanceTableDoesReflectSalesLoads The average total return table shows the Fund’s returns with the maximum sales charge deducted, and no sales charge has been applied to the indices used for comparison in the table.
Performance Table Uses Highest Federal Rate rr_PerformanceTableUsesHighestFederalRate After-tax returns are calculated using the historical highest individual federal marginal income tax rates, and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred rr_PerformanceTableNotRelevantToTaxDeferred The after-tax returns shown are not relevant to you if you hold your Fund shares through a tax-deferred arrangement such as a 401(k) plan or individual retirement account.
Performance Table One Class of after Tax Shown [Text] rr_PerformanceTableOneClassOfAfterTaxShown After-tax returns are shown only for Class A shares; after-tax returns for other Classes will vary.
Performance Table Explanation after Tax Higher rr_PerformanceTableExplanationAfterTaxHigher The return after taxes on distributions and sale of Fund shares may be higher than the return before taxes because the calculation assumes that shareholders receive a tax benefit for capital losses incurred on the sale of their shares.
Performance Table Narrative rr_PerformanceTableNarrativeTextBlock
The average total return table shows the Fund’s returns with the maximum sales charge deducted, and no sales charge has been applied to the indices used for comparison in the table.
After-tax returns are calculated using the historical highest individual federal marginal income tax rates, and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. The after-tax returns shown are not relevant to you if you hold your Fund shares through a tax-deferred arrangement such as a 401(k) plan or individual retirement account. The return after taxes on distributions and sale of Fund shares may be higher than the return before taxes because the calculation assumes that shareholders receive a tax benefit for capital losses incurred on the sale of their shares. After-tax returns are shown only for Class A shares; after-tax returns for other Classes will vary.
Class A, C and Y | Calvert Short Duration Income Fund | Barclays 1-5 Year U.S. Credit Index (reflects no deduction for fees, expenses or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 1.06%
5 Years rr_AverageAnnualReturnYear05 2.55%
10 Years rr_AverageAnnualReturnYear10 4.07%
Class A, C and Y | Calvert Short Duration Income Fund | Lipper Short Investment Grade Debt Funds Avg. (reflects no deduction for taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 0.24%
5 Years rr_AverageAnnualReturnYear05 1.33%
10 Years rr_AverageAnnualReturnYear10 2.52%
Class A, C and Y | Calvert Short Duration Income Fund | Class A  
Prospectus: rr_ProspectusTable  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 2.75%
Maximum Deferred Sales Charge (as a percentage) rr_MaximumDeferredSalesChargeOverOther none [4]
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.45% [5]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.25%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.95%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination 1/30/2017
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 369
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 569
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 786
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,409
Annual Return 2006 rr_AnnualReturn2006 5.25%
Annual Return 2007 rr_AnnualReturn2007 5.69%
Annual Return 2008 rr_AnnualReturn2008 (0.95%)
Annual Return 2009 rr_AnnualReturn2009 12.13%
Annual Return 2010 rr_AnnualReturn2010 3.72%
Annual Return 2011 rr_AnnualReturn2011 0.38%
Annual Return 2012 rr_AnnualReturn2012 6.47%
Annual Return 2013 rr_AnnualReturn2013 0.67%
Annual Return 2014 rr_AnnualReturn2014 0.67%
Annual Return 2015 rr_AnnualReturn2015 0.24%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best Quarter (of periods shown)
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2009
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 5.03%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst Quarter (of periods shown)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (1.60%)
1 Year rr_AverageAnnualReturnYear01 (2.49%)
5 Years rr_AverageAnnualReturnYear05 1.10%
10 Years rr_AverageAnnualReturnYear10 3.07%
Class A, C and Y | Calvert Short Duration Income Fund | Class A | After Taxes on Distributions  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (3.25%)
5 Years rr_AverageAnnualReturnYear05 0.22%
10 Years rr_AverageAnnualReturnYear10 1.83%
Class A, C and Y | Calvert Short Duration Income Fund | Class A | After Taxes on Distributions and Sales  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (1.41%)
5 Years rr_AverageAnnualReturnYear05 0.53%
10 Years rr_AverageAnnualReturnYear10 1.92%
Class A, C and Y | Calvert Short Duration Income Fund | Class C  
Prospectus: rr_ProspectusTable  
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% [6]
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.45% [5]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 1.00%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.18%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.63%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination January 31, 2017
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 266
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 514
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 887
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 1,933
Expense Example, No Redemption, 1 Year rr_ExpenseExampleNoRedemptionYear01 166
Expense Example, No Redemption, 3 Years rr_ExpenseExampleNoRedemptionYear03 514
Expense Example, No Redemption, 5 Years rr_ExpenseExampleNoRedemptionYear05 887
Expense Example, No Redemption, 10 Years rr_ExpenseExampleNoRedemptionYear10 $ 1,933
1 Year rr_AverageAnnualReturnYear01 (1.55%)
5 Years rr_AverageAnnualReturnYear05 0.91%
10 Years rr_AverageAnnualReturnYear10 2.58%
Class A, C and Y | Calvert Short Duration Income Fund | Class Y  
Prospectus: rr_ProspectusTable  
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 0.45% [5]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.17%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.62%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination January 31, 2017
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 63
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 199
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 346
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 774
1 Year rr_AverageAnnualReturnYear01 0.45%
5 Years rr_AverageAnnualReturnYear05 1.96%
10 Years rr_AverageAnnualReturnYear10 3.58%
Class A, C and Y | Calvert High Yield Bond Fund  
Prospectus: rr_ProspectusTable  
Risk/Return [Heading] rr_RiskReturnHeading CALVERT HIGH YIELD BOND FUND Class (Ticker):A (CYBAX)C (CHBCX)Y (CYBYX)
Objective [Heading] rr_ObjectiveHeading INVESTMENT OBJECTIVE
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
The Fund seeks high current income and capital appreciation, secondarily.
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 sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in Calvert mutual funds. More information about these and other discounts is available from your financial professional and under “Choosing a Share Class” on page 47 and “Reduced Sales Charges” on page 50 of this Prospectus, and under “Method of Distribution” on page 40 of the Fund’s Statement of Additional Information.
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 % 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 (“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 198% of its portfolio’s average value.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 198.00%
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 $50,000 in Calvert mutual funds.
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 either redeem or hold your shares at the end of those periods;
•
your investment has a 5% return each year;
•
the Fund’s operating expenses remain the same; and
•
any Calvert expense limitation is in effect for the period indicated in the fee table above.
Strategy [Heading] rr_StrategyHeading INVESTMENTS, RISKS AND PERFORMANCE Principal Investment Strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
The Fund invests primarily in high-yield, high-risk bonds, with varying maturities, including distressed securities that are in default. The Fund’s duration and maturity will be managed tactically based on the Advisor’s outlook for the fixed-income markets. For its investments, the Fund seeks to identify high yield bonds of companies that have the ability to make timely payments of principal and interest. Using fundamental credit analysis of companies, the Fund seeks to invest in companies whose financial condition gives them greater value relative to other companies in the high-yield market, providing the further potential for capital appreciation. Consequently, capital appreciation is a secondary objective of the Fund. Under normal circumstances, the Fund will invest at least 80% of its net assets (including borrowings for investment purposes) in high yield, high risk bonds, also known as “junk” bonds. The Fund will provide shareholders with at least 60 days’ notice before changing this 80% policy.
The Advisor will actively manage the Fund to take advantage of relative values of various sectors of the high yield market in order to seek high current income and secondarily, capital appreciation. The Fund will buy and sell securities based on its overall objective of achieving the highest possible total return.
The Fund also may invest in trust preferred securities, taxable municipal securities, leveraged loans and asset-backed securities (“ABS”), including commercial mortgage-backed securities. In addition, the Fund may invest in foreign debt securities.
The Fund may invest in securities that represent interests in pools of mortgage loans or other assets assembled for sale to investors by various U.S. governmental agencies, government-related organizations and private issuers. These investments may include securities such as collateralized mortgage obligations (“CMOs”) and ABS.
Under certain market conditions, the Fund may opportunistically use a hedging technique that includes the purchase and sale of U.S. Treasury securities and related futures contracts to manage the duration of the Fund and hedge interest rate risk.
The Fund is “non-diversified,” which means it may hold securities of a smaller number of issuers and invest a greater percentage of its assets in a particular issuer than a “diversified” fund.
When a corporation issues a bond, it generally submits the security to one or more nationally recognized statistical rating organizations (“NRSROs”) such as Moody’s Investors Service (“Moody’s”) or Standard & Poor’s Ratings Services (“Standard & Poor’s”). These services evaluate the creditworthiness of the issuer and assign a rating, based on their evaluation of the issuer’s ability to repay the bond. Bonds with ratings below Baa3 (Moody’s) or BBB- (Standard & Poor’s) are considered below investment grade and are commonly referred to as junk bonds. Some bonds are not rated at all. The Advisor determines the comparable rating quality of bonds that are not rated.
Responsible Investing. In conjunction with Calvert’s financial analysis, Calvert’s comprehensive responsible investment principles guide our investment research processes and decision-making. The principles, which include the Advisor’s proprietary assessment of critical environmental, social and governance (“ESG”) issues, are applied across industries and to specific companies in order to inform our view of risk and opportunity factors that may affect investment performance.
Risk [Heading] rr_RiskHeading Principal Risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
You could lose money on your investment in the Fund, or the Fund could underperform, because of the risks described below. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Non-Diversification Risk. Because the Fund may hold securities of a smaller number of issuers or invest a greater percentage of its assets in a particular issuer than a diversified fund, the gains or losses on a single bond may have greater impact on the Fund than on a diversified fund.

Bond Market Risk. The market prices of bonds held by the Fund may fall.
Credit Risk. The credit quality of fixed-income securities may deteriorate, which could lead to default or bankruptcy of the issuer where the issuer becomes unable to pay its obligations when due.
Liquidity Risk. Liquidity risk exists when particular investments are difficult to sell. The Fund may be unable to sell illiquid securities at an advantageous time or price or achieve its desired level of exposure to a certain sector. Liquidity risk may result from the lack of an active market, reduced number and capacity of traditional market participants to make a market in fixed-income securities, and may be magnified in a rising interest rate environment or other circumstances where investor redemptions from fixed-income mutual funds may be higher than normal, causing increased supply in the market due to selling activity. Illiquid securities also may be difficult to value.
Junk Bond Risk. Investments in junk bonds can involve a substantial risk of loss. Junk bonds are considered to be speculative with respect to the issuer’s ability to pay interest and principal. These securities, which are rated below investment grade, have a higher risk of issuer default, are subject to greater price volatility than investment grade securities and may be illiquid.
Mortgage-Backed and Asset-Backed Securities Risk. The value of investments in mortgage-backed and asset-backed securities is subject to interest rate risk and credit risk. These securities are also subject to the risk that borrowers will prepay the principal on their loans more quickly than expected (prepayment risk) or more slowly than expected (extension risk), which will affect the yield, average life and price of the securities. In addition, faster than expected prepayments may cause the Fund to invest the prepaid principal in lower yielding securities and slower than expected prepayments may reduce the potential for the Fund to invest in higher yielding securities.
Mortgage-Backed Security Risk (Government-Sponsored Enterprises). Debt and mortgage-backed securities issued by government-sponsored enterprises (“GSEs”) such as the Federal National Mortgage Association (“FNMA”) and the Federal Home Loan Mortgage Corporation (“FHLMC”) are neither insured nor guaranteed by the U.S. Treasury and are not backed by the full faith and credit of the U.S. government. Such securities are only supported by the credit of the applicable GSE. The U.S. government has provided financial support to FNMA and FHLMC, but there can be no assurance that it will support these or other GSEs in the future.
Leveraged Loan Risk. Leveraged loans are subject to the risks typically associated with debt securities, such as credit risk discussed above. The loans in which the Fund will invest are expected to be below-investment-grade quality and to bear interest at a floating rate that resets periodically. In addition, leveraged loans, which typically hold a senior position in the capital structure of a borrower, are subject to the risk that a court could subordinate such loans to presently existing or future indebtedness or take other action detrimental to the holders of leveraged loans. Leveraged loans are also subject to the risk that the value of the collateral, if any, securing a loan may decline, be insufficient to meet the obligations of the borrower, or be difficult to liquidate. Some leveraged loans are not as easily purchased or sold as publicly-traded securities and others are illiquid, which may make it more difficult for the Fund to value them or dispose of them at an acceptable price. Leveraged loans are usually more credit sensitive than investment-grade securities.
Management Risk. The individual investments of the Fund may not perform as expected, and the Fund’s portfolio management practices may not achieve the desired result.
Interest Rate Risk. A change in interest rates may adversely affect the value of fixed-income securities. When interest rates rise, the value of fixed-income securities will generally fall. Longer-term securities are subject to greater interest rate risk.
Portfolio Duration Risk. Duration is a measure of the expected life of a fixed-income security and its sensitivity to changes in interest rates. The longer a fund’s average portfolio duration, the more sensitive the fund will be to changes in interest rates.
Defaulted Bonds Risk. For bonds in default (rated “D” by Standard & Poor’s or the equivalent by another NRSRO), there is a significant risk that these bonds will not achieve their original value.
Unrated Security Risk. Unrated securities may be less liquid than rated securities determined to be of comparable credit quality by the Advisor. When the Fund purchases unrated securities, it will depend on the Advisor’s analysis of credit risk without the assessment of an NRSRO.
Taxable Municipal Bond Risk. Taxable municipal bonds are subject to credit risk, interest rate risk and certain additional risks. The Fund may be more sensitive to adverse economic, business or political developments if it invests a substantial portion of its assets in the bonds of similar projects or industrial development bonds.
Trust Preferred Securities Risk. Trust preferred securities are preferred stocks issued by a special purpose trust subsidiary backed by subordinated debt of the corporate parent. Trust preferred securities are subject to unique risks, which include the fact that dividend payments will only be paid if interest payments on the underlying obligations are made, which interest payments are dependent on the financial condition of the parent corporation. There is also the risk that the underlying obligations, and thus the trust preferred securities, may be prepaid after a stated call date or as a result of certain tax or regulatory events, resulting in a lower yield to maturity.
Collateralized Mortgage Obligation and Structured Asset-Backed Securities Risk. A CMO is a multiclass bond that is backed by a pool of mortgage loans or mortgage-backed securities. A structured ABS is a multiclass bond that is typically backed by a pool of auto loans, credit card receivables, home equity loans or student loans. A CMO or structured ABS is subject to interest rate risk, credit risk, prepayment risk and extension risk. In addition, if the Fund holds a class of a CMO or a structured ABS that is subordinated to other classes backed by the same pool of collateral, the likelihood that the Fund will receive payments of principal may be substantially limited.
Foreign Securities Risk. Investing in foreign securities involves additional risks relating to political, social, and economic developments abroad. Other risks result from the differences between the regulations to which U.S. and foreign issuers and markets are subject, and the potential for foreign markets to be less liquid and more volatile than U.S. markets. Foreign securities include ADRs. Unsponsored ADRs involve additional risks because U.S. reporting requirements do not apply and the issuing bank will recover shareholder distribution costs from movement of share prices and payment of dividends.
Foreign Currency Risk. Securities that trade or are denominated in currencies other than the U.S. dollar may be adversely affected by fluctuations in currency exchange rates. When the U.S. dollar strengthens relative to a foreign currency, the U.S. dollar value of an investment denominated in that currency will typically fall. ADRs indirectly bear currency risk because they represent an interest in securities that are not denominated in U.S. dollars.
Active Trading Strategy Risk. The Fund employs an active style that seeks to position the Fund with securities that offer the greatest price appreciation while minimizing risk. This style can result in higher turnover (exceeding 100%), may translate to higher transaction costs and may increase your tax liability.
Responsible Investing Risk. Investing primarily in responsible investments carries the risk that, under certain market conditions, the Fund may underperform funds that do not utilize a responsible investment strategy. The application of responsible investment principles may affect the Fund’s exposure to certain sectors or types of investments and may impact the Fund’s relative investment performance depending on whether such sectors or investments are in or out of favor in the market. A company’s ESG performance or the Advisor’s assessment of a company’s ESG performance may change over time, which could cause the Fund to temporarily hold securities that do not comply with the Fund’s responsible investment principles. In evaluating a company, the Advisor is dependent upon information and data that may be incomplete, inaccurate or unavailable, which could cause the Advisor to incorrectly assess a company’s ESG performance. Successful application of the Fund’s responsible investment strategy will depend on the Advisor’s skill in properly identifying and analyzing material ESG issues.
Futures Contracts Risk. The value of a futures contract tends to increase and decrease in tandem with the value of the underlying instrument. The price of futures can be highly volatile; using them could lower total return, and the potential loss from futures can exceed the Fund’s initial investment in such contracts. Futures contracts may not provide an effective hedge of the underlying securities or indexes because changes in the prices of futures contracts may not track those of the securities or indexes that they are intended to hedge.
Risk Lose Money [Text] rr_RiskLoseMoney You could lose money on your investment in the Fund, or the Fund could underperform, because of the risks described below.
Risk Nondiversified Status [Text] rr_RiskNondiversifiedStatus Non-Diversification Risk. Because the Fund may hold securities of a smaller number of issuers or invest a greater percentage of its assets in a particular issuer than a diversified fund, the gains or losses on a single bond may have greater impact on the Fund than on a diversified fund.
Risk Not Insured Depository Institution [Text] rr_RiskNotInsuredDepositoryInstitution An investment in the Fund is not a bank deposit and 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 following bar chart and table show the Fund’s annual returns and its long-term performance, which give some indication of the risks of investing in the Fund. The bar chart shows how the performance of the Class A shares has varied from year to year. The table compares the Fund’s performance over time with that of a benchmark and a performance average of similar mutual funds. The performance reflected in the bar chart and table assumes the reinvestment of dividends and capital gains distributions, if any.
The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. For updated performance information, visit www.calvert.com.
Pursuant to an Agreement and Plan of Reorganization, Class A shares of Calvert High Yield Bond Fund, a series of Summit Mutual Funds, Inc. (“SMF Calvert High Yield Bond Fund”), were reorganized into the Class A shares of an identical and newly created series of The Calvert Fund, Calvert High Yield Bond Fund, which commenced operations on September 18, 2009. The performance results prior to September 18, 2009, for Class A shares reflect the performance of SMF Calvert High Yield Bond Fund. In addition, performance results for Class A shares prior to February 1, 2007, the inception date for Class A shares of SMF Calvert High Yield Bond Fund, reflect the performance of Class I shares of SMF Calvert High Yield Bond Fund, adjusted for the 12b-1 distribution fees applicable to Class A.
Performance results for Class C shares prior to October 31, 2011 (the Class C shares’ inception date) reflect the performance of Class A shares at net asset value. Actual Class C share performance would have been lower than Class A share performance because Class C has higher class-specific expenses than Class A.
Performance results for Class Y shares prior to July 29, 2011 (the Class Y shares’ inception date) reflect the performance of Class A shares at net asset value. Actual Class Y share performance would have been higher than Class A share performance because Class Y has lower class-specific expenses than Class A.
The return for each of the Fund’s other Classes of shares will differ from the Class A returns shown in the bar chart, depending upon the expenses of that Class.
The bar chart does not reflect any sales charge that you may be required to pay upon purchase or redemption of the Fund’s shares. Any sales charge will reduce your return.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following bar chart and table show the Fund’s annual returns and its long-term performance, which give some indication of the risks of investing in the Fund.
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress www.calvert.com
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar Year Total Returns for Class A at NAV
Bar Chart Does Not Reflect Sales Loads [Text] rr_BarChartDoesNotReflectSalesLoads The bar chart does not reflect any sales charge that you may be required to pay upon purchase or redemption of the Fund’s shares. Any sales charge will reduce your return.
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
 
Quarter
Ended
 
Total
Return
Best Quarter (of periods shown)
6/30/09
 
10.92%
Worst Quarter (of periods shown)
12/31/08
 
-14.17%
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns (as of 12-31-15) (with maximum sales charge deducted, if any)
Performance Table Does Reflect Sales Loads rr_PerformanceTableDoesReflectSalesLoads The average total return table shows the Fund’s returns with the maximum sales charge deducted, and no sales charge has been applied to the indices used for comparison in the table.
Performance Table Uses Highest Federal Rate rr_PerformanceTableUsesHighestFederalRate After-tax returns are calculated using the historical highest individual federal marginal income tax rates, and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred rr_PerformanceTableNotRelevantToTaxDeferred The after-tax returns shown are not relevant to you if you hold your Fund shares through a tax-deferred arrangement such as a 401(k) plan or individual retirement account.
Performance Table Explanation after Tax Higher rr_PerformanceTableExplanationAfterTaxHigher The return after taxes on distributions and sale of Fund shares may be higher than the return before taxes because the calculation assumes that shareholders receive a tax benefit for capital losses incurred on the sale of their shares.
Performance Table Narrative rr_PerformanceTableNarrativeTextBlock
The average total return table shows the Fund’s returns with the maximum sales charge deducted, and no sales charge has been applied to the indices used for comparison in the table.
After-tax returns are calculated using the historical highest individual federal marginal income tax rates, and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. The after-tax returns shown are not relevant to you if you hold your Fund shares through a tax-deferred arrangement such as a 401(k) plan or individual retirement account. The return after taxes on distributions and sale of Fund shares may be higher than the return before taxes because the calculation assumes that shareholders receive a tax benefit for capital losses incurred on the sale of their shares.
Class A, C and Y | Calvert High Yield Bond Fund | BofA Merrill Lynch High Yield Master II Index (reflects no deduction for fees, expenses or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (4.64%)
5 Years rr_AverageAnnualReturnYear05 4.84%
10 Years rr_AverageAnnualReturnYear10 6.81%
Class A, C and Y | Calvert High Yield Bond Fund | Lipper High Yield Funds Avg. (reflects no deduction for taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (4.09%)
5 Years rr_AverageAnnualReturnYear05 4.08%
10 Years rr_AverageAnnualReturnYear10 5.58%
Class A, C and Y | Calvert High Yield Bond Fund | Class A  
Prospectus: rr_ProspectusTable  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 3.75%
Maximum Deferred Sales Charge (as a percentage) rr_MaximumDeferredSalesChargeOverOther none [7]
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.77% [8]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.37%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.39%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.32%) [9]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.07%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination January 31, 2017
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 480
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 766
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,076
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,953
Annual Return 2006 rr_AnnualReturn2006 10.55%
Annual Return 2007 rr_AnnualReturn2007 1.51%
Annual Return 2008 rr_AnnualReturn2008 (22.11%)
Annual Return 2009 rr_AnnualReturn2009 36.91%
Annual Return 2010 rr_AnnualReturn2010 15.71%
Annual Return 2011 rr_AnnualReturn2011 5.10%
Annual Return 2012 rr_AnnualReturn2012 14.78%
Annual Return 2013 rr_AnnualReturn2013 8.23%
Annual Return 2014 rr_AnnualReturn2014 (1.07%)
Annual Return 2015 rr_AnnualReturn2015 (2.45%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best Quarter (of periods shown)
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2009
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 10.92%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst Quarter (of periods shown)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (14.17%)
1 Year rr_AverageAnnualReturnYear01 (6.11%)
5 Years rr_AverageAnnualReturnYear05 3.93%
10 Years rr_AverageAnnualReturnYear10 5.32%
Class A, C and Y | Calvert High Yield Bond Fund | Class A | After Taxes on Distributions  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (8.15%)
5 Years rr_AverageAnnualReturnYear05 1.39%
10 Years rr_AverageAnnualReturnYear10 2.84%
Class A, C and Y | Calvert High Yield Bond Fund | Class A | After Taxes on Distributions and Sales  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (3.48%)
5 Years rr_AverageAnnualReturnYear05 1.99%
10 Years rr_AverageAnnualReturnYear10 3.10%
Class A, C and Y | Calvert High Yield Bond Fund | Class C  
Prospectus: rr_ProspectusTable  
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% [10]
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.77% [8]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 1.00%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.58%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 2.35%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.53%) [9]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.82%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination January 31, 2017
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 285
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 681
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,205
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 2,644
Expense Example, No Redemption, 1 Year rr_ExpenseExampleNoRedemptionYear01 185
Expense Example, No Redemption, 3 Years rr_ExpenseExampleNoRedemptionYear03 681
Expense Example, No Redemption, 5 Years rr_ExpenseExampleNoRedemptionYear05 1,205
Expense Example, No Redemption, 10 Years rr_ExpenseExampleNoRedemptionYear10 $ 2,644
1 Year rr_AverageAnnualReturnYear01 (4.36%)
5 Years rr_AverageAnnualReturnYear05 3.86%
10 Years rr_AverageAnnualReturnYear10 5.28%
Class A, C and Y | Calvert High Yield Bond Fund | Class Y  
Prospectus: rr_ProspectusTable  
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 0.77% [8]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.30%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.07%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.25%) [9]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.82%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination January 31, 2017
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 84
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 313
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 564
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,281
1 Year rr_AverageAnnualReturnYear01 (2.16%)
5 Years rr_AverageAnnualReturnYear05 4.98%
10 Years rr_AverageAnnualReturnYear10 5.85%
Class I | Calvert Income Fund  
Prospectus: rr_ProspectusTable  
Risk/Return [Heading] rr_RiskReturnHeading CALVERT INCOME FUND Class (Ticker):I (CINCX)  
Objective [Heading] rr_ObjectiveHeading INVESTMENT OBJECTIVE
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
The Fund seeks to maximize income, to the extent consistent with preservation of capital, through investment in bonds and income-producing securities.
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.
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 % 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 (“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 236% of its portfolio’s average value.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 236.00%
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 $1,000,000 in the Fund for the time periods indicated;
•
your investment has a 5% return each year;
•
the Fund’s operating expenses remain the same; and
•
any Calvert expense limitation is in effect for the period indicated in the fee table above.
Strategy [Heading] rr_StrategyHeading INVESTMENTS, RISKS AND PERFORMANCE Principal Investment Strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
The Fund typically invests at least 65% of its net assets in investment grade, U.S. dollar-denominated debt securities, as assessed at the time of purchase. A debt security is considered investment grade when assigned a credit quality rating of BBB- or higher by Standard & Poor’s Ratings Services (“Standard & Poor’s”) or an equivalent rating by another nationally recognized statistical rating organization (“NRSRO”), including Moody’s Investors Service or Fitch Ratings, or if unrated, considered to be of comparable credit quality by the Fund’s Advisor.
The Fund invests principally in bonds issued by U.S. corporations, the U.S. Government or its agencies, and U.S. government-sponsored enterprises (“GSEs”) such as the Federal National Mortgage Association (“FNMA”) and the Federal Home Loan Mortgage Corporation (“FHLMC”). The Fund also may invest in trust preferred securities, taxable municipal securities, leveraged loans and asset-backed securities (“ABS”), including commercial mortgage-backed securities.
The Fund may invest in securities that represent interests in pools of mortgage loans or other assets assembled for sale to investors by various U.S. governmental agencies, government-related organizations and private issuers. These investments may include securities such as collateralized mortgage obligations (“CMOs”) and ABS.
The Fund may invest up to 35% of its net assets in below-investment grade, high-yield debt securities (commonly known as “junk bonds”), including distressed securities that are in default. A debt security is considered below investment grade when assigned a credit quality rating below BBB- by Standard & Poor’s or an equivalent rating by another NRSRO, or if unrated, considered to be of comparable credit quality by the Fund’s Advisor.
The Fund may also invest up to 25% of its net assets in foreign debt securities. Foreign debt securities include American Depositary Receipts (“ADRs”).
The Fund is “non-diversified,” which means it may hold securities of a smaller number of issuers and invest a greater percentage of its assets in a particular issuer than a “diversified” fund.
The Fund uses an active trading strategy, seeking relative value to earn incremental income.
The Fund uses a hedging technique that includes the purchase and sale of U.S. Treasury securities and related futures contracts to manage the duration of the Fund and hedge interest rate risk.
Responsible Investing. In conjunction with Calvert’s financial analysis, Calvert’s comprehensive responsible investment principles guide our investment research processes and decision-making. The principles, which include the Advisor’s proprietary assessment of critical environmental, social and governance (“ESG”) issues, are applied across industries and to specific companies in order to inform our view of risk and opportunity factors that may affect investment performance.
Risk [Heading] rr_RiskHeading Principal Risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
You could lose money on your investment in the Fund, or the Fund could underperform, because of the risks described below. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Non-Diversification Risk. Because the Fund may hold securities of a smaller number of issuers or invest a greater percentage of its assets in a particular issuer than a diversified fund, the gains or losses on a single bond may have greater impact on the Fund than on a diversified fund.
Bond Market Risk. The market prices of bonds held by the Fund may fall.
Credit Risk. The credit quality of fixed-income securities may deteriorate, which could lead to default or bankruptcy of the issuer where the issuer becomes unable to pay its obligations when due.
Mortgage-Backed and Asset-Backed Securities Risk. The value of investments in mortgage-backed and asset-backed securities is subject to interest rate risk and credit risk. These securities are also subject to the risk that borrowers will prepay the principal on their loans more quickly than expected (prepayment risk) or more slowly than expected (extension risk), which will affect the yield, average life and price of the securities. In addition, faster than expected prepayments may cause the Fund to invest the prepaid principal in lower yielding securities and slower than expected prepayments may reduce the potential for the Fund to invest in higher yielding securities.
Mortgage-Backed Security Risk (Government-Sponsored Enterprises).  Debt and mortgage-backed securities issued by GSEs such as FNMA and FHLMC are neither insured nor guaranteed by the U.S. Treasury and are not backed by the full faith and credit of the U.S. government. Such securities are only supported by the credit of the applicable GSE. The U.S. government has provided financial support to FNMA and FHLMC, but there can be no assurance that it will support these or other GSEs in the future.
Leveraged Loan Risk. Leveraged loans are subject to the risks typically associated with debt securities, such as credit risk discussed above. The loans in which the Fund will invest are expected to be below-investment-grade quality and to bear interest at a floating rate that resets periodically. In addition, leveraged loans, which typically hold a senior position in the capital structure of a borrower, are subject to the risk that a court could subordinate such loans to presently existing or future indebtedness or take other action detrimental to the holders of leveraged loans. Leveraged loans are also subject to the risk that the value of the collateral, if any, securing a loan may decline, be insufficient to meet the obligations of the borrower, or be difficult to liquidate. Some leveraged loans are not as easily purchased or sold as publicly-traded securities and others are illiquid, which may make it more difficult for the Fund to value them or dispose of them at an acceptable price. Leveraged loans are usually more credit sensitive than investment-grade securities.
Management Risk. Individual investments of the Fund may not perform as expected, and the Fund’s portfolio management practices may not achieve the desired result.
Interest Rate Risk. A change in interest rates may adversely affect the value of fixed-income securities. When interest rates rise, the value of fixed-income securities will generally fall. Longer-term securities are subject to greater interest rate risk.
Portfolio Duration Risk. Duration is a measure of the expected life of a fixed-income security and its sensitivity to changes in interest rates. The longer a fund’s average portfolio duration, the more sensitive the fund will be to changes in interest rates.
Liquidity Risk. Liquidity risk exists when particular investments are difficult to sell. The Fund may be unable to sell illiquid securities at an advantageous time or price or achieve its desired level of exposure to a certain sector. Liquidity risk may result from the lack of an active market, reduced number and capacity of traditional market participants to make a market in fixed-income securities, and may be magnified in a rising interest rate environment or other circumstances where investor redemptions from fixed-income mutual funds may be higher than normal, causing increased supply in the market due to selling activity. Illiquid securities also may be difficult to value.
Junk Bond Risk. Investments in junk bonds can involve a substantial risk of loss. Junk bonds are considered to be speculative with respect to the issuer’s ability to pay interest and principal. These securities, which are rated below investment grade, have a higher risk of issuer default, are subject to greater price volatility than investment grade securities and may be illiquid.
Defaulted Bonds Risk. For bonds in default (those rated “D” by Standard & Poor’s or the equivalent by another NRSRO), there is a significant risk that these bonds will not achieve their original value.
Unrated Security Risk. Unrated securities may be less liquid than rated securities determined to be of comparable credit quality by the Advisor. When the Fund purchases unrated securities, it will depend on the Advisor’s analysis of credit risk without the assessment of an NRSRO.
Taxable Municipal Bond Risk. Taxable municipal bonds are subject to credit risk, interest rate risk and certain additional risks. The Fund may be more sensitive to adverse economic, business or political developments if it invests a substantial portion of its assets in the bonds of similar projects or industrial development bonds.
Trust Preferred Securities Risk. Trust preferred securities are preferred stocks issued by a special purpose trust subsidiary backed by subordinated debt of the corporate parent. Trust preferred securities are subject to unique risks, which include the fact that dividend payments will only be paid if interest payments on the underlying obligations are made, which interest payments are dependent on the financial condition of the parent corporation. There is also the risk that the underlying obligations, and thus the trust preferred securities, may be prepaid after a stated call date or as a result of certain tax or regulatory events, resulting in a lower yield to maturity.
Collateralized Mortgage Obligation and Structured Asset-Backed Securities Risk. A CMO is a multiclass bond that is backed by a pool of mortgage loans or mortgage-backed securities. A structured ABS is a multiclass bond that is typically backed by a pool of auto loans, credit card receivables, home equity loans or student loans. A CMO or structured ABS is subject to interest rate risk, credit risk, prepayment risk and extension risk. In addition, if the Fund holds a class of a CMO or a structured ABS that is subordinated to other classes backed by the same pool of collateral, the likelihood that the Fund will receive payments of principal may be substantially limited.
Foreign Securities Risk. Investing in foreign securities involves additional risks relating to political, social, and economic developments abroad. Other risks result from the differences between the regulations to which U.S. and foreign issuers and markets are subject, and the potential for foreign markets to be less liquid and more volatile than U.S. markets. Foreign securities include ADRs. Unsponsored ADRs involve additional risks because U.S. reporting requirements do not apply and the issuing bank will recover shareholder distribution costs from movement of share prices and payment of dividends.
Foreign Currency Risk. Securities that trade or are denominated in currencies other than the U.S. dollar may be adversely affected by fluctuations in currency exchange rates. When the U.S. dollar strengthens relative to a foreign currency, the U.S. dollar value of an investment denominated in that currency will typically fall. ADRs indirectly bear currency risk because they represent an interest in securities that are not denominated in U.S. dollars.
Active Trading Strategy Risk. The Fund employs an active style that seeks to position the Fund with securities that offer the greatest price appreciation while minimizing risk. This style can result in higher turnover (exceeding 100%), may translate to higher transaction costs and may increase your tax liability.
Responsible Investing Risk. Investing primarily in responsible investments carries the risk that, under certain market conditions, the Fund may underperform funds that do not utilize a responsible investment strategy. The application of responsible investment principles may affect the Fund’s exposure to certain sectors or types of investments and may impact the Fund’s relative investment performance depending on whether such sectors or investments are in or out of favor in the market. A company’s ESG performance or the Advisor’s assessment of a company’s ESG performance may change over time, which could cause the Fund to temporarily hold securities that do not comply with the Fund’s responsible investment principles. In evaluating a company, the Advisor is dependent upon information and data that may be incomplete, inaccurate or unavailable, which could cause the Advisor to incorrectly assess a company’s ESG performance. Successful application of the Fund’s responsible investment strategy will depend on the Advisor’s skill in properly identifying and analyzing material ESG issues.
Futures Contracts Risk. The value of a futures contract tends to increase and decrease in tandem with the value of the underlying instrument. The price of futures can be highly volatile; using them could lower total return, and the potential loss from futures can exceed the Fund’s initial investment in such contracts. Futures contracts may not provide an effective hedge of the underlying securities or indexes because changes in the prices of futures contracts may not track those of the securities or indexes that they are intended to hedge.
Risk Lose Money [Text] rr_RiskLoseMoney You could lose money on your investment in the Fund, or the Fund could underperform, because of the risks described below.
Risk Nondiversified Status [Text] rr_RiskNondiversifiedStatus Non-Diversification Risk. Because the Fund may hold securities of a smaller number of issuers or invest a greater percentage of its assets in a particular issuer than a diversified fund, the gains or losses on a single bond may have greater impact on the Fund than on a diversified fund.
Risk Not Insured Depository Institution [Text] rr_RiskNotInsuredDepositoryInstitution An investment in the Fund is not a bank deposit and 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 following bar chart and table show the Fund’s annual returns and its long-term performance, which give some indication of the risks of investing in the Fund. The bar chart shows how the performance has varied from year to year. The table compares the Fund’s performance over time with that of a benchmark and a performance average of similar mutual funds. The performance reflected in the bar chart and table assumes the reinvestment of dividends and capital gains distributions, if any.
The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. For updated performance information, visit www.calvert.com.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following bar chart and table show the Fund’s annual returns and its long-term performance, which give some indication of the risks of investing in the Fund.
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress www.calvert.com
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar Year Total Returns
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
 
Quarter
Ended
 
Total
Return
Best Quarter (of periods shown)
6/30/09
 
8.03%
Worst Quarter (of periods shown)
12/31/08
 
-7.52%
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns (as of 12-31-15)
Performance Table Uses Highest Federal Rate rr_PerformanceTableUsesHighestFederalRate After-tax returns are calculated using the historical highest individual federal marginal income tax rates, and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred rr_PerformanceTableNotRelevantToTaxDeferred The after-tax returns shown are not relevant to you if you hold your Fund shares through a tax-deferred arrangement such as a 401(k) plan or individual retirement account.
Performance Table Explanation after Tax Higher rr_PerformanceTableExplanationAfterTaxHigher The return after taxes on distributions and sale of Fund shares may be higher than the return before taxes because the calculation assumes that shareholders receive a tax benefit for capital losses incurred on the sale of their shares.
Performance Table Narrative rr_PerformanceTableNarrativeTextBlock
After-tax returns are calculated using the historical highest individual federal marginal income tax rates, and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. The after-tax returns shown are not relevant to you if you hold your Fund shares through a tax-deferred arrangement such as a 401(k) plan or individual retirement account. The return after taxes on distributions and sale of Fund shares may be higher than the return before taxes because the calculation assumes that shareholders receive a tax benefit for capital losses incurred on the sale of their shares.
Class I | Calvert Income Fund | Barclays U.S. Credit Index (reflects no deduction for fees, expenses or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (0.77%)
5 Years rr_AverageAnnualReturnYear05 4.38%
10 Years rr_AverageAnnualReturnYear10 5.18%
Class I | Calvert Income Fund | Lipper Corporate Debt Funds BBB Rated Avg. (reflects no deduction for taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (1.71%)
5 Years rr_AverageAnnualReturnYear05 4.11%
10 Years rr_AverageAnnualReturnYear10 4.91%
Class I | Calvert Income Fund | Class I  
Prospectus: rr_ProspectusTable  
Shareholder Fee, Other rr_ShareholderFeeOther none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.52% [11]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.14%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.66%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.02%) [12]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.64%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 6,540
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 20,708
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 36,366
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 81,859
Annual Return 2006 rr_AnnualReturn2006 5.42%
Annual Return 2007 rr_AnnualReturn2007 5.71%
Annual Return 2008 rr_AnnualReturn2008 (11.35%)
Annual Return 2009 rr_AnnualReturn2009 17.12%
Annual Return 2010 rr_AnnualReturn2010 7.23%
Annual Return 2011 rr_AnnualReturn2011 3.30%
Annual Return 2012 rr_AnnualReturn2012 9.19%
Annual Return 2013 rr_AnnualReturn2013 (0.01%)
Annual Return 2014 rr_AnnualReturn2014 5.50%
Annual Return 2015 rr_AnnualReturn2015 (0.55%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best Quarter (of periods shown)
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2009
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 8.03%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst Quarter (of periods shown)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (7.52%)
1 Year rr_AverageAnnualReturnYear01 (0.55%)
5 Years rr_AverageAnnualReturnYear05 3.42%
10 Years rr_AverageAnnualReturnYear10 3.91%
Class I | Calvert Income Fund | Class I | After Taxes on Distributions  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (2.00%)
5 Years rr_AverageAnnualReturnYear05 1.94%
10 Years rr_AverageAnnualReturnYear10 2.24%
Class I | Calvert Income Fund | Class I | After Taxes on Distributions and Sales  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (0.33%)
5 Years rr_AverageAnnualReturnYear05 2.01%
10 Years rr_AverageAnnualReturnYear10 2.36%
Class I | Calvert Short Duration Income Fund  
Prospectus: rr_ProspectusTable  
Risk/Return [Heading] rr_RiskReturnHeading CALVERT SHORT DURATION INCOME FUND Class (Ticker):I (CDSIX)  
Objective [Heading] rr_ObjectiveHeading INVESTMENT OBJECTIVE
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
The Fund seeks to maximize income, to the extent consistent with preservation of capital, through investment in short-term bonds and income-producing securities.
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.
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 % 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 (“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 206% of its portfolio’s average value.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 206.00%
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 $1,000,000 in the Fund for the time periods indicated;
•
your investment has a 5% return each year;
•
the Fund’s operating expenses remain the same; and
•
any Calvert expense limitation is in effect for the period indicated in the fee table above.
Strategy [Heading] rr_StrategyHeading INVESTMENTS, RISKS AND PERFORMANCE Principal Investment Strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
The Fund typically invests at least 65% of its net assets in investment grade, U.S. dollar-denominated debt securities, as assessed at the time of purchase. A debt security is considered investment grade when assigned a credit quality rating of BBB- or higher by Standard & Poor’s Ratings Services (“Standard & Poor’s”) or an equivalent rating by another nationally recognized statistical rating organization (“NRSRO”), including Moody’s Investors Service or Fitch Ratings, or if unrated, considered to be of comparable credit quality by the Fund’s Advisor.
The Fund invests principally in bonds issued by U.S. corporations, the U.S. Government or its agencies, and U.S. government-sponsored enterprises (“GSEs”) such as the Federal National Mortgage Association (“FNMA”) and the Federal Home Loan Mortgage Corporation (“FHLMC”). The Fund also may invest in trust preferred securities, taxable municipal securities, leveraged loans and asset-backed securities (“ABS”), including commercial mortgage-backed securities.
The Fund may invest in securities that represent interests in pools of mortgage loans or other assets assembled for sale to investors by various U.S. governmental agencies, government-related organizations and private issuers. These investments may include securities such as collateralized mortgage obligations (“CMOs”) and ABS.
The Fund may invest up to 35% of its net assets in below-investment grade, high-yield debt securities (commonly known as “junk bonds”), including distressed securities that are in default. A debt security is considered below investment grade when assigned a credit quality rating below BBB- by Standard & Poor’s or an equivalent rating by another NRSRO, or if unrated, considered to be of comparable credit quality by the Fund’s Advisor.
The Fund may also invest up to 25% of its net assets in foreign debt securities. Foreign debt securities include American Depositary Receipts (“ADRs”).
The Fund is “non-diversified,” which means it may hold securities of a smaller number of issuers and invest a greater percentage of its assets in a particular issuer than a “diversified” fund.
Under normal circumstances, the Fund’s average portfolio duration will range from one to three years.
The Fund uses an active trading strategy, seeking relative value to earn incremental income.
The Fund uses a hedging technique that includes the purchase and sale of U.S. Treasury securities and related futures contracts to manage the duration of the Fund and hedge interest rate risk.
Responsible Investing. In conjunction with Calvert’s financial analysis, Calvert’s comprehensive responsible investment principles guide our investment research processes and decision-making. The principles, which include the Advisor’s proprietary assessment of critical environmental, social and governance (“ESG”) issues, are applied across industries and to specific companies in order to inform our view of risk and opportunity factors that may affect investment performance.

Risk [Heading] rr_RiskHeading Principal Risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
You could lose money on your investment in the Fund, or the Fund could underperform, because of the risks described below. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Non-Diversification Risk. Because the Fund may hold securities of a smaller number of issuers or invest a greater percentage of its assets in a particular issuer than a diversified fund, the gains or losses on a single bond may have greater impact on the Fund than on a diversified fund.
Bond Market Risk. The market prices of bonds held by the Fund may fall.
Credit Risk. The credit quality of fixed-income securities may deteriorate, which could lead to default or bankruptcy of the issuer where the issuer becomes unable to pay its obligations when due.
Mortgage-Backed and Asset-Backed Securities Risk. The value of investments in mortgage-backed and asset-backed securities is subject to interest rate risk and credit risk. These securities are also subject to the risk that borrowers will prepay the principal on their loans more quickly than expected (prepayment risk) or more slowly than expected (extension risk), which will affect the yield, average life and price of the securities. In addition, faster than expected prepayments may cause the Fund to invest the prepaid principal in lower yielding securities and slower than expected prepayments may reduce the potential for the Fund to invest in higher yielding securities.
Mortgage-Backed Security Risk (Government-Sponsored Enterprises).  Debt and mortgage-backed securities issued by GSEs such as FNMA and FHLMC are neither insured nor guaranteed by the U.S. Treasury and are not backed by the full faith and credit of the U.S. government. Such securities are only supported by the credit of the applicable GSE. The U.S. government has provided financial support to FNMA and FHLMC, but there can be no assurance that it will support these or other GSEs in the future.
Leveraged Loan Risk. Leveraged loans are subject to the risks typically associated with debt securities, such as credit risk discussed above. The loans in which the Fund will invest are expected to be below-investment-grade quality and to bear interest at a floating rate that resets periodically. In addition, leveraged loans, which typically hold a senior position in the capital structure of a borrower, are subject to the risk that a court could subordinate such loans to presently existing or future indebtedness or take other action detrimental to the holders of leveraged loans. Leveraged loans are also subject to the risk that the value of the collateral, if any, securing a loan may decline, be insufficient to meet the obligations of the borrower, or be difficult to liquidate. Some leveraged loans are not as easily purchased or sold as publicly-traded securities and others are illiquid, which may make it more difficult for the Fund to value them or dispose of them at an acceptable price. Leveraged loans are usually more credit sensitive than investment-grade securities.
Management Risk. Individual investments of the Fund may not perform as expected, and the Fund’s portfolio management practices may not achieve the desired result.
Interest Rate Risk. A change in interest rates may adversely affect the value of fixed-income securities. When interest rates rise, the value of fixed-income securities will generally fall. Longer-term securities are subject to greater interest rate risk.
Portfolio Duration Risk. Duration is a measure of the expected life of a fixed-income security and its sensitivity to changes in interest rates. The longer a fund’s average portfolio duration, the more sensitive the fund will be to changes in interest rates.
Liquidity Risk. Liquidity risk exists when particular investments are difficult to sell. The Fund may be unable to sell illiquid securities at an advantageous time or price or achieve its desired level of exposure to a certain sector. Liquidity risk may result from the lack of an active market, reduced number and capacity of traditional market participants to make a market in fixed-income securities, and may be magnified in a rising interest rate environment or other circumstances where investor redemptions from fixed-income mutual funds may be higher than normal, causing increased supply in the market due to selling activity. Illiquid securities also may be difficult to value.
Junk Bond Risk. Investments in junk bonds can involve a substantial risk of loss. Junk bonds are considered to be speculative with respect to the issuer’s ability to pay interest and principal. These securities, which are rated below investment grade, have a higher risk of issuer default, are subject to greater price volatility than investment grade securities and may be illiquid.
Defaulted Bonds Risk. For bonds in default (those rated “D” by Standard & Poor’s or the equivalent by another NRSRO), there is a significant risk that these bonds will not achieve their original value.
Unrated Security Risk. Unrated securities may be less liquid than rated securities determined to be of comparable credit quality by the Advisor. When the Fund purchases unrated securities, it will depend on the Advisor’s analysis of credit risk without the assessment of an NRSRO.
Taxable Municipal Bond Risk. Taxable municipal bonds are subject to credit risk, interest rate risk and certain additional risks. The Fund may be more sensitive to adverse economic, business or political developments if it invests a substantial portion of its assets in the bonds of similar projects or industrial development bonds.
Trust Preferred Securities Risk. Trust preferred securities are preferred stocks issued by a special purpose trust subsidiary backed by subordinated debt of the corporate parent. Trust preferred securities are subject to unique risks, which include the fact that dividend payments will only be paid if interest payments on the underlying obligations are made, which interest payments are dependent on the financial condition of the parent corporation. There is also the risk that the underlying obligations, and thus the trust preferred securities, may be prepaid after a stated call date or as a result of certain tax or regulatory events, resulting in a lower yield to maturity.
Collateralized Mortgage Obligation and Structured Asset-Backed Securities Risk. A CMO is a multiclass bond that is backed by a pool of mortgage loans or mortgage-backed securities. A structured ABS is a multiclass bond that is typically backed by a pool of auto loans, credit card receivables, home equity loans or student loans. A CMO or structured ABS is subject to interest rate risk, credit risk, prepayment risk and extension risk. In addition, if the Fund holds a class of a CMO or a structured ABS that is subordinated to other classes backed by the same pool of collateral, the likelihood that the Fund will receive payments of principal may be substantially limited.
Foreign Securities Risk. Investing in foreign securities involves additional risks relating to political, social, and economic developments abroad. Other risks result from the differences between the regulations to which U.S. and foreign issuers and markets are subject, and the potential for foreign markets to be less liquid and more volatile than U.S. markets. Foreign securities include ADRs. Unsponsored ADRs involve additional risks because U.S. reporting requirements do not apply and the issuing bank will recover shareholder distribution costs from movement of share prices and payment of dividends.
Foreign Currency Risk. Securities that trade or are denominated in currencies other than the U.S. dollar may be adversely affected by fluctuations in currency exchange rates. When the U.S. dollar strengthens relative to a foreign currency, the U.S. dollar value of an investment denominated in that currency will typically fall. ADRs indirectly bear currency risk because they represent an interest in securities that are not denominated in U.S. dollars.
Active Trading Strategy Risk. The Fund employs an active style that seeks to position the Fund with securities that offer the greatest price appreciation while minimizing risk. This style can result in higher turnover (exceeding 100%), may translate to higher transaction costs and may increase your tax liability.
Responsible Investing Risk. Investing primarily in responsible investments carries the risk that, under certain market conditions, the Fund may underperform funds that do not utilize a responsible investment strategy. The application of responsible investment principles may affect the Fund’s exposure to certain sectors or types of investments and may impact the Fund’s relative investment performance depending on whether such sectors or investments are in or out of favor in the market. A company’s ESG performance or the Advisor’s assessment of a company’s ESG performance may change over time, which could cause the Fund to temporarily hold securities that do not comply with the Fund’s responsible investment principles. In evaluating a company, the Advisor is dependent upon information and data that may be incomplete, inaccurate or unavailable, which could cause the Advisor to incorrectly assess a company’s ESG performance. Successful application of the Fund’s responsible investment strategy will depend on the Advisor’s skill in properly identifying and analyzing material ESG issues.
Futures Contracts Risk. The value of a futures contract tends to increase and decrease in tandem with the value of the underlying instrument. The price of futures can be highly volatile; using them could lower total return, and the potential loss from futures can exceed the Fund’s initial investment in such contracts. Futures contracts may not provide an effective hedge of the underlying securities or indexes because changes in the prices of futures contracts may not track those of the securities or indexes that they are intended to hedge.
Risk Lose Money [Text] rr_RiskLoseMoney You could lose money on your investment in the Fund, or the Fund could underperform, because of the risks described below.
Risk Nondiversified Status [Text] rr_RiskNondiversifiedStatus Non-Diversification Risk. Because the Fund may hold securities of a smaller number of issuers or invest a greater percentage of its assets in a particular issuer than a diversified fund, the gains or losses on a single bond may have greater impact on the Fund than on a diversified fund.
Risk Not Insured Depository Institution [Text] rr_RiskNotInsuredDepositoryInstitution An investment in the Fund is not a bank deposit and 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 following bar chart and table show the Fund’s annual returns and its long-term performance, which give some indication of the risks of investing in the Fund. The bar chart shows how the performance has varied from year to year. The table compares the Fund’s performance over time with that of a benchmark and a performance average of similar mutual funds. The performance reflected in the bar chart and table assumes the reinvestment of dividends and capital gains distributions, if any.
The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. For updated performance information, visit www.calvert.com.
There were no shareholders in Class I for the period November 7, 2005, through April 21, 2006. Performance results for Class I shares for this period reflect the performance of Class A shares at net asset value. The Fund’s Class A shares are offered in a separate prospectus. Because Class I shares are invested in the same portfolio of securities, returns for Class I shares would have been substantially similar to those of Class A shares and differ only to the extent that the Classes have different expenses; actual Class I share performance would have been higher than Class A share performance because Class I has lower class-specific expenses than Class A.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following bar chart and table show the Fund’s annual returns and its long-term performance, which give some indication of the risks of investing in the Fund. The bar chart shows how the performance has varied from year to year.
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress www.calvert.com
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar Year Total Returns
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
 
Quarter
Ended
 
Total
Return
Best Quarter (of periods shown)
6/30/09
 
5.16%
Worst Quarter (of periods shown)
12/31/08
 
-1.45%
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns (as of 12-31-15)
Performance Table Uses Highest Federal Rate rr_PerformanceTableUsesHighestFederalRate After-tax returns are calculated using the historical highest individual federal marginal income tax rates, and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred rr_PerformanceTableNotRelevantToTaxDeferred The after-tax returns shown are not relevant to you if you hold your Fund shares through a tax-deferred arrangement such as a 401(k) plan or individual retirement account.
Performance Table Explanation after Tax Higher rr_PerformanceTableExplanationAfterTaxHigher The return after taxes on distributions and sale of Fund shares may be higher than the return before taxes because the calculation assumes that shareholders receive a tax benefit for capital losses incurred on the sale of their shares.
Performance Table Narrative rr_PerformanceTableNarrativeTextBlock
After-tax returns are calculated using the historical highest individual federal marginal income tax rates, and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. The after-tax returns shown are not relevant to you if you hold your Fund shares through a tax-deferred arrangement such as a 401(k) plan or individual retirement account. The return after taxes on distributions and sale of Fund shares may be higher than the return before taxes because the calculation assumes that shareholders receive a tax benefit for capital losses incurred on the sale of their shares.
Class I | Calvert Short Duration Income Fund | Barclays 1-5 Year U.S. Credit Index (reflects no deduction for fees, expenses or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 1.06%
5 Years rr_AverageAnnualReturnYear05 2.55%
10 Years rr_AverageAnnualReturnYear10 4.07%
Class I | Calvert Short Duration Income Fund | Lipper Short Investment Grade Debt Funds Avg. (reflects no deduction for taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 0.24%
5 Years rr_AverageAnnualReturnYear05 1.33%
10 Years rr_AverageAnnualReturnYear10 2.52%
Class I | Calvert Short Duration Income Fund | Class I  
Prospectus: rr_ProspectusTable  
Shareholder Fee, Other rr_ShareholderFeeOther none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.45% [13]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.06%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.51%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.02%) [14]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.49%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 5,010
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 15,942
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 28,112
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 63,651
Annual Return 2006 rr_AnnualReturn2006 5.61%
Annual Return 2007 rr_AnnualReturn2007 5.96%
Annual Return 2008 rr_AnnualReturn2008 (0.57%)
Annual Return 2009 rr_AnnualReturn2009 12.62%
Annual Return 2010 rr_AnnualReturn2010 4.34%
Annual Return 2011 rr_AnnualReturn2011 0.95%
Annual Return 2012 rr_AnnualReturn2012 6.97%
Annual Return 2013 rr_AnnualReturn2013 1.30%
Annual Return 2014 rr_AnnualReturn2014 1.30%
Annual Return 2015 rr_AnnualReturn2015 0.80%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best Quarter (of periods shown)
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2009
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 5.16%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst Quarter (of periods shown)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (1.45%)
1 Year rr_AverageAnnualReturnYear01 0.80%
5 Years rr_AverageAnnualReturnYear05 2.24%
10 Years rr_AverageAnnualReturnYear10 3.86%
Class I | Calvert Short Duration Income Fund | Class I | After Taxes on Distributions  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (0.22%)
5 Years rr_AverageAnnualReturnYear05 1.14%
10 Years rr_AverageAnnualReturnYear10 2.44%
Class I | Calvert Short Duration Income Fund | Class I | After Taxes on Distributions and Sales  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 0.69%
5 Years rr_AverageAnnualReturnYear05 1.33%
10 Years rr_AverageAnnualReturnYear10 2.48%
Class I | Calvert Long-Term Income Fund  
Prospectus: rr_ProspectusTable  
Risk/Return [Heading] rr_RiskReturnHeading CALVERT LONG-TERM INCOME FUND Class (Ticker):I (CLDIX)  
Objective [Heading] rr_ObjectiveHeading INVESTMENT OBJECTIVE
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
The Fund seeks to maximize income, to the extent consistent with preservation of capital, through investments in longer-dated securities.
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.
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 % of the value of your investment) [15]
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 (“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 290% of its portfolio’s average value.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 290.00%
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 $1,000,000 in the Fund for the time periods indicated;
•
your investment has a 5% return each year;
•
the Fund’s operating expenses remain the same; and
•
any Calvert expense limitation is in effect for the period indicated in the fee table above.
Strategy [Heading] rr_StrategyHeading INVESTMENTS, RISKS AND PERFORMANCE Principal Investment Strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
The Fund typically invests at least 65% of its net assets in investment grade, U.S. dollar-denominated debt securities, as assessed at the time of purchase. A debt security is considered investment grade when assigned a credit quality rating of BBB- or higher by Standard & Poor’s Ratings Services (“Standard & Poor’s”) or an equivalent rating by another nationally recognized statistical rating organization (“NRSRO”), including Moody’s Investors Service or Fitch Ratings, or if unrated, considered to be of comparable credit quality by the Fund’s Advisor.
The Fund invests principally in bonds issued by U.S. corporations, the U.S. Government or its agencies, and U.S. government-sponsored enterprises (“GSEs”) such as the Federal National Mortgage Association (“FNMA”) and the Federal Home Loan Mortgage Corporation (“FHLMC”). The Fund also may invest in trust preferred securities, taxable municipal securities, leveraged loans and asset-backed securities (“ABS”), including commercial mortgage-backed securities.
The Fund may invest in securities that represent interests in pools of mortgage loans or other assets assembled for sale to investors by various U.S. governmental agencies, government-related organizations and private issuers. These investments may include securities such as collateralized mortgage obligations (“CMOs”) and ABS.
The Fund may invest up to 35% of its net assets in below-investment grade, high-yield debt securities (commonly known as “junk bonds”), including distressed securities that are in default. A debt security is considered below investment grade when assigned a credit quality rating below BBB- by Standard & Poor’s or an equivalent rating by another NRSRO, or if unrated, considered to be of comparable credit quality by the Fund’s Advisor.
The Fund may also invest up to 25% of its net assets in foreign debt securities. Foreign debt securities include American Depositary Receipts (“ADRs”).
The Fund is “non-diversified,” which means it may hold securities of a smaller number of issuers and invest a greater percentage of its assets in a particular issuer than a “diversified” fund.
Under normal circumstances, the Fund will have a dollar-weighted average portfolio maturity of ten years or more.
The Fund uses an active trading strategy, seeking relative value to earn incremental income.
The Fund uses a hedging technique that includes the purchase and sale of U.S. Treasury securities and related futures contracts to manage the duration of the Fund and hedge interest rate risk.
Responsible Investing. In conjunction with Calvert’s financial analysis, Calvert’s comprehensive responsible investment principles guide our investment research processes and decision-making. The principles, which include the Advisor’s proprietary assessment of critical environmental, social and governance (“ESG”) issues, are applied across industries and to specific companies in order to inform our view of risk and opportunity factors that may affect investment performance.
Risk [Heading] rr_RiskHeading Principal Risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
You could lose money on your investment in the Fund, or the Fund could underperform, because of the risks described below. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Non-Diversification Risk. Because the Fund may hold securities of a smaller number of issuers or invest a greater percentage of its assets in a particular issuer than a diversified fund, the gains or losses on a single bond may have greater impact on the Fund than on a diversified fund.

Bond Market Risk. The market prices of bonds held by the Fund may fall.
Credit Risk. The credit quality of fixed-income securities may deteriorate, which could lead to default or bankruptcy of the issuer where the issuer becomes unable to pay its obligations when due.
Mortgage-Backed and Asset-Backed Securities Risk. The value of investments in mortgage-backed and asset-backed securities is subject to interest rate risk and credit risk. These securities are also subject to the risk that borrowers will prepay the principal on their loans more quickly than expected (prepayment risk) or more slowly than expected (extension risk), which will affect the yield, average life and price of the securities. In addition, faster than expected prepayments may cause the Fund to invest the prepaid principal in lower yielding securities and slower than expected prepayments may reduce the potential for the Fund to invest in higher yielding securities.
Mortgage-Backed Security Risk (Government-Sponsored Enterprises).  Debt and mortgage-backed securities issued by GSEs such as FNMA and FHLMC are neither insured nor guaranteed by the U.S. Treasury and are not backed by the full faith and credit of the U.S. government. Such securities are only supported by the credit of the applicable GSE. The U.S. government has provided financial support to FNMA and FHLMC, but there can be no assurance that it will support these or other GSEs in the future.
Leveraged Loan Risk. Leveraged loans are subject to the risks typically associated with debt securities, such as credit risk discussed above. The loans in which the Fund will invest are expected to be below-investment-grade quality and to bear interest at a floating rate that resets periodically. In addition, leveraged loans, which typically hold a senior position in the capital structure of a borrower, are subject to the risk that a court could subordinate such loans to presently existing or future indebtedness or take other action detrimental to the holders of leveraged loans. Leveraged loans are also subject to the risk that the value of the collateral, if any, securing a loan may decline, be insufficient to meet the obligations of the borrower, or be difficult to liquidate. Some leveraged loans are not as easily purchased or sold as publicly-traded securities and others are illiquid, which may make it more difficult for the Fund to value them or dispose of them at an acceptable price. Leveraged loans are usually more credit sensitive than investment-grade securities.
Management Risk. Individual investments of the Fund may not perform as expected, and the Fund’s portfolio management practices may not achieve the desired result.
Interest Rate Risk. A change in interest rates may adversely affect the value of fixed-income securities. When interest rates rise, the value of fixed-income securities will generally fall. Longer-term securities are subject to greater interest rate risk.
Portfolio Maturity Risk. Average weighted portfolio maturity is the length of time, in days or years, until the securities held by a fund, on average, will mature or be redeemed by their issuers. The average portfolio maturity is weighted according to the dollar amounts invested in the various securities held by a fund. In general, the longer a fund’s average weighted portfolio maturity, the more its share price will fluctuate in response to changing interest rates.
Liquidity Risk. Liquidity risk exists when particular investments are difficult to sell. The Fund may be unable to sell illiquid securities at an advantageous time or price or achieve its desired level of exposure to a certain sector. Liquidity risk may result from the lack of an active market, reduced number and capacity of traditional market participants to make a market in fixed-income securities, and may be magnified in a rising interest rate environment or other circumstances where investor redemptions from fixed-income mutual funds may be higher than normal, causing increased supply in the market due to selling activity. Illiquid securities also may be difficult to value.
Junk Bond Risk. Investments in junk bonds can involve a substantial risk of loss. Junk bonds are considered to be speculative with respect to the issuer’s ability to pay interest and principal. These securities, which are rated below investment grade, have a higher risk of issuer default, are subject to greater price volatility than investment grade securities and may be illiquid.
Defaulted Bonds Risk. For bonds in default (those rated “D” by Standard & Poor’s or the equivalent by another NRSRO), there is a significant risk that these bonds will not achieve their original value.
Unrated Security Risk. Unrated securities may be less liquid than rated securities determined to be of comparable credit quality by the Advisor. When the Fund purchases unrated securities, it will depend on the Advisor’s analysis of credit risk without the assessment of an NRSRO.
Taxable Municipal Bond Risk. Taxable municipal bonds are subject to credit risk, interest rate risk and certain additional risks. The Fund may be more sensitive to adverse economic, business or political developments if it invests a substantial portion of its assets in the bonds of similar projects or industrial development bonds.
Trust Preferred Securities Risk. Trust preferred securities are preferred stocks issued by a special purpose trust subsidiary backed by subordinated debt of the corporate parent. Trust preferred securities are subject to unique risks, which include the fact that dividend payments will only be paid if interest payments on the underlying obligations are made, which interest payments are dependent on the financial condition of the parent corporation. There is also the risk that the underlying obligations, and thus the trust preferred securities, may be prepaid after a stated call date or as a result of certain tax or regulatory events, resulting in a lower yield to maturity.
Collateralized Mortgage Obligation and Structured Asset-Backed Securities Risk. A CMO is a multiclass bond that is backed by a pool of mortgage loans or mortgage-backed securities. A structured ABS is a multiclass bond that is typically backed by a pool of auto loans, credit card receivables, home equity loans or student loans. A CMO or structured ABS is subject to interest rate risk, credit risk, prepayment risk and extension risk. In addition, if the Fund holds a class of a CMO or a structured ABS that is subordinated to other classes backed by the same pool of collateral, the likelihood that the Fund will receive payments of principal may be substantially limited.
Foreign Securities Risk. Investing in foreign securities involves additional risks relating to political, social, and economic developments abroad. Other risks result from the differences between the regulations to which U.S. and foreign issuers and markets are subject, and the potential for foreign markets to be less liquid and more volatile than U.S. markets. Foreign securities include ADRs. Unsponsored ADRs involve additional risks because U.S. reporting requirements do not apply and the issuing bank will recover shareholder distribution costs from movement of share prices and payment of dividends.
Foreign Currency Risk.Securities that trade or are denominated in currencies other than the U.S. dollar may be adversely affected by fluctuations in currency exchange rates. When the U.S. dollar strengthens relative to a foreign currency, the U.S. dollar value of an investment denominated in that currency will typically fall. ADRs indirectly bear currency risk because they represent an interest in securities that are not denominated in U.S. dollars.
Active Trading Strategy Risk. The Fund employs an active style that seeks to position the Fund with securities that offer the greatest price appreciation while minimizing risk. This style can result in higher turnover (exceeding 100%), may translate to higher transaction costs and may increase your tax liability.
Responsible Investing Risk. Investing primarily in responsible investments carries the risk that, under certain market conditions, the Fund may underperform funds that do not utilize a responsible investment strategy. The application of responsible investment principles may affect the Fund’s exposure to certain sectors or types of investments and may impact the Fund’s relative investment performance depending on whether such sectors or investments are in or out of favor in the market. A company’s ESG performance or the Advisor’s assessment of a company’s ESG performance may change over time, which could cause the Fund to temporarily hold securities that do not comply with the Fund’s responsible investment principles. In evaluating a company, the Advisor is dependent upon information and data that may be incomplete, inaccurate or unavailable, which could cause the Advisor to incorrectly assess a company’s ESG performance. Successful application of the Fund’s responsible investment strategy will depend on the Advisor’s skill in properly identifying and analyzing material ESG issues.
Futures Contracts Risk. The value of a futures contract tends to increase and decrease in tandem with the value of the underlying instrument. The price of futures can be highly volatile; using them could lower total return, and the potential loss from futures can exceed the Fund’s initial investment in such contracts. Futures contracts may not provide an effective hedge of the underlying securities or indexes because changes in the prices of futures contracts may not track those of the securities or indexes that they are intended to hedge.
Risk Lose Money [Text] rr_RiskLoseMoney You could lose money on your investment in the Fund, or the Fund could underperform, because of the risks described below.
Risk Nondiversified Status [Text] rr_RiskNondiversifiedStatus Non-Diversification Risk. Because the Fund may hold securities of a smaller number of issuers or invest a greater percentage of its assets in a particular issuer than a diversified fund, the gains or losses on a single bond may have greater impact on the Fund than on a diversified fund.
Risk Not Insured Depository Institution [Text] rr_RiskNotInsuredDepositoryInstitution An investment in the Fund is not a bank deposit and 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 following bar chart and table show the Fund’s annual returns and its long-term performance, which give some indication of the risks of investing in the Fund. The bar chart shows how the performance has varied from year to year. The table compares the Fund’s performance over time with that of a benchmark and a performance average of similar mutual funds. The performance reflected in the bar chart and table assumes the reinvestment of dividends and capital gains distributions, if any.
The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. For updated performance information, visit www.calvert.com.
Performance results for Class I shares prior to January 31, 2015 (the Class I shares’ inception date) reflect the performance of Class A shares at net asset value. The Fund’s Class A shares are offered in a separate prospectus. Because Class I shares are invested in the same portfolio of securities, returns for Class I shares would have been substantially similar to those of Class A shares and differ only to the extent that the Classes have different expenses; actual Class I share performance would have been higher than Class A share performance because Class I has lower class-specific expenses than Class A.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following bar chart and table show the Fund’s annual returns and its long-term performance, which give some indication of the risks of investing in the Fund.
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress www.calvert.com
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar Year Total Returns
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
 
Quarter
Ended
 
Total
Return
Best Quarter (of periods shown)
9/30/09
 
8.33%
Worst Quarter (of periods shown)
06/30/15
 
-6.81%
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns (as of 12-31-15)
Performance Table Uses Highest Federal Rate rr_PerformanceTableUsesHighestFederalRate After-tax returns are calculated using the historical highest individual federal marginal income tax rates, and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred rr_PerformanceTableNotRelevantToTaxDeferred The after-tax returns shown are not relevant to you if you hold your Fund shares through a tax-deferred arrangement such as a 401(k) plan or individual retirement account.
Performance Table Explanation after Tax Higher rr_PerformanceTableExplanationAfterTaxHigher The return after taxes on distributions and sale of Fund shares may be higher than the return before taxes because the calculation assumes that shareholders receive a tax benefit for capital losses incurred on the sale of their shares.
Performance Table Narrative rr_PerformanceTableNarrativeTextBlock
After-tax returns are calculated using the historical highest individual federal marginal income tax rates, and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. The after-tax returns shown are not relevant to you if you hold your Fund shares through a tax-deferred arrangement such as a 401(k) plan or individual retirement account. The return after taxes on distributions and sale of Fund shares may be higher than the return before taxes because the calculation assumes that shareholders receive a tax benefit for capital losses incurred on the sale of their shares.
Class I | Calvert Long-Term Income Fund | Barclays Long U.S. Credit Index (reflects no deduction for fees, expenses or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (4.56%)
5 Years rr_AverageAnnualReturnYear05 6.49%
10 Years rr_AverageAnnualReturnYear10 6.19%
Class I | Calvert Long-Term Income Fund | Lipper Corporate Debt Funds BBB Rated Avg. (reflects no deduction for taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (1.71%)
5 Years rr_AverageAnnualReturnYear05 4.11%
10 Years rr_AverageAnnualReturnYear10 4.91%
Class I | Calvert Long-Term Income Fund | Class I  
Prospectus: rr_ProspectusTable  
Shareholder Fee, Other rr_ShareholderFeeOther none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.52% [16]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 167.25%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 167.77%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (167.22%) [17]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.55%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 5,622
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 48,665
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 94,329
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 221,029
Annual Return 2006 rr_AnnualReturn2006 5.43%
Annual Return 2007 rr_AnnualReturn2007 8.28%
Annual Return 2008 rr_AnnualReturn2008 5.63%
Annual Return 2009 rr_AnnualReturn2009 17.09%
Annual Return 2010 rr_AnnualReturn2010 10.28%
Annual Return 2011 rr_AnnualReturn2011 9.47%
Annual Return 2012 rr_AnnualReturn2012 11.94%
Annual Return 2013 rr_AnnualReturn2013 (5.47%)
Annual Return 2014 rr_AnnualReturn2014 15.15%
Annual Return 2015 rr_AnnualReturn2015 (3.34%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best Quarter (of periods shown)
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Sep. 30, 2009
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 8.33%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst Quarter (of periods shown)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Jun. 30, 2015
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (6.81%)
1 Year rr_AverageAnnualReturnYear01 (3.34%)
5 Years rr_AverageAnnualReturnYear05 5.21%
10 Years rr_AverageAnnualReturnYear10 7.22%
Class I | Calvert Long-Term Income Fund | Class I | After Taxes on Distributions  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (4.71%)
5 Years rr_AverageAnnualReturnYear05 3.07%
10 Years rr_AverageAnnualReturnYear10 4.92%
Class I | Calvert Long-Term Income Fund | Class I | After Taxes on Distributions and Sales  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (1.90%)
5 Years rr_AverageAnnualReturnYear05 3.29%
10 Years rr_AverageAnnualReturnYear10 4.83%
Class I | Calvert Ultra-Short Income Fund  
Prospectus: rr_ProspectusTable  
Risk/Return [Heading] rr_RiskReturnHeading CALVERT ULTRA-SHORT INCOME FUND Class (Ticker):I (CULIX)  
Objective [Heading] rr_ObjectiveHeading INVESTMENT OBJECTIVE
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
The Fund seeks to maximize income, to the extent consistent with preservation of capital, through investment in short-term bonds and income-producing securities.
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.
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 % 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 (“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 66% of its portfolio’s average value.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 66.00%
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 $1,000,000 in the Fund for the time periods indicated;
•
your investment has a 5% return each year;
•
the Fund’s operating expenses remain the same; and
•
any Calvert expense limitation is in effect for the period indicated in the fee table above.
Strategy [Heading] rr_StrategyHeading INVESTMENTS, RISKS AND PERFORMANCE Principal Investment Strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
The Fund seeks to achieve its investment objective by investing, under normal circumstances, at least 80% of its net assets (including borrowings for investment purposes) in a portfolio of floating-rate securities (e.g., corporate floating-rate securities) and securities with durations of less than or equal to one year. The Fund will provide shareholders with at least 60 days’ notice before changing this 80% policy.
The Fund typically invests at least 65% of its net assets in investment grade, U.S. dollar-denominated debt securities, as assessed at the time of purchase. A debt security is investment grade when assigned a credit quality rating of BBB- or higher by Standard & Poor’s Ratings Services (“Standard & Poor’s”) or an equivalent rating by another nationally recognized statistical rating organization (‘‘NRSRO”), including Moody’s Investors Service or Fitch Ratings, or if unrated, considered to be of comparable credit quality by the Fund’s Advisor.
The Fund invests principally in bonds issued by U.S. corporations, the U.S. Government or its agencies, and U.S. government-sponsored enterprises (“GSEs”) such as the Federal National Mortgage Association (“FNMA”) and the Federal Home Loan Mortgage Corporation (“FHLMC”). The Fund also may invest in trust preferred securities, taxable municipal securities, leveraged loans and asset-backed securities (“ABS”), including commercial mortgage-backed securities.
The Fund may invest in securities that represent interests in pools of mortgage loans or other assets assembled for sale to investors by various U.S. governmental agencies, government-related organizations and private issuers. These investments may include securities such as collateralized mortgage obligations (“CMOs”) and ABS.
The Fund may invest up to 35% of its net assets in below-investment grade, high-yield debt securities (commonly known as “junk bonds”), including distressed securities that are in default. A debt security is below investment grade when assigned a credit quality rating below BBB- by Standard & Poor’s or an equivalent rating by another NRSRO, or if unrated, considered to be of comparable credit quality by the Fund’s Advisor.
The Fund may also invest up to 25% of its net assets in foreign debt securities. Foreign debt securities include American Depositary Receipts (“ADRs”).
The Fund is “non-diversified,” which means it may hold securities of a smaller number of issuers and invest a greater percentage of its assets in a particular issuer than a “diversified” fund.
Under normal circumstances, the Fund’s average portfolio duration will be less than one year.
The Fund uses an active trading strategy, seeking relative value to earn incremental income.
The Fund uses a hedging technique that includes the purchase and sale of U.S. Treasury securities and related futures contracts to manage the duration of the Fund and hedge interest rate risk.
Responsible Investing. In conjunction with Calvert’s financial analysis, Calvert’s comprehensive responsible investment principles guide our investment research processes and decision-making. The principles, which include the Advisor’s proprietary assessment of critical environmental, social and governance (“ESG”) issues, are applied across industries and to specific companies in order to inform our view of risk and opportunity factors that may affect investment performance.

Risk [Heading] rr_RiskHeading Principal Risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
You could lose money on your investment in the Fund, or the Fund could underperform, because of the risks described below. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Non-Diversification Risk. Because the Fund may hold securities of a smaller number of issuers or invest a greater percentage of its assets in a particular issuer than a diversified fund, the gains or losses on a single bond may have greater impact on the Fund than on a diversified fund.

Bond Market Risk. The market prices of bonds held by the Fund may fall.
Credit Risk. The credit quality of fixed-income securities may deteriorate, which could lead to default or bankruptcy of the issuer where the issuer becomes unable to pay its obligations when due.
Mortgage-Backed and Asset-Backed Securities Risk. The value of investments in mortgage-backed and asset-backed securities is subject to interest rate risk and credit risk. These securities are also subject to the risk that borrowers will prepay the principal on their loans more quickly than expected (prepayment risk) or more slowly than expected (extension risk), which will affect the yield, average life and price of the securities. In addition, faster than expected prepayments may cause the Fund to invest the prepaid principal in lower yielding securities and slower than expected prepayments may reduce the potential for the Fund to invest in higher yielding securities.
Mortgage-Backed Security Risk (Government-Sponsored Enterprises).  Debt and mortgage-backed securities issued by GSEs such as FNMA and FHLMC are neither insured nor guaranteed by the U.S. Treasury and are not backed by the full faith and credit of the U.S. government. Such securities are only supported by the credit of the applicable GSE. The U.S. government has provided financial support to FNMA and FHLMC, but there can be no assurance that it will support these or other GSEs in the future.
Leveraged Loan Risk. Leveraged loans are subject to the risks typically associated with debt securities, such as credit risk discussed above. The loans in which the Fund will invest are expected to be below-investment-grade quality and to bear interest at a floating rate that resets periodically. In addition, leveraged loans, which typically hold a senior position in the capital structure of a borrower, are subject to the risk that a court could subordinate such loans to presently existing or future indebtedness or take other action detrimental to the holders of leveraged loans. Leveraged loans are also subject to the risk that the value of the collateral, if any, securing a loan may decline, be insufficient to meet the obligations of the borrower, or be difficult to liquidate. Some leveraged loans are not as easily purchased or sold as publicly-traded securities and others are illiquid, which may make it more difficult for the Fund to value them or dispose of them at an acceptable price. Leveraged loans are usually more credit sensitive than investment-grade securities.
Management Risk. The individual investments of the Fund may not perform as expected, and the Fund’s portfolio management practices may not achieve the desired result.
Interest Rate Risk. A change in interest rates may adversely affect the value of fixed-income securities. When interest rates rise, the value of fixed-income securities will generally fall. Because a significant portion of securities held by the Fund may have variable or floating interest rates, the amounts of the Fund’s monthly distributions to shareholders are expected to vary with fluctuations in market interest rates. Generally, when market interest rates fall, the amount of the distributions to shareholders will likewise decrease.
Portfolio Duration Risk. Duration is a measure of the expected life of a fixed-income security and its sensitivity to changes in interest rates. The longer a fund’s average portfolio duration, the more sensitive the fund will be to changes in interest rates.
Lag Risk for Interest Payments. There may be a lag between an actual change in the underlying interest rate benchmark and the reset time for an interest payment for a floating-rate security, which could harm or benefit the Fund, depending on the circumstances. For example, a floating-rate security that does not reset immediately would prevent the Fund from taking full advantage of rising interest rates. In a declining interest rate environment, however, the Fund would benefit from the lag since the Fund would not immediately be impacted by a decline in interest rates.
Liquidity Risk. Liquidity risk exists when particular investments are difficult to sell. The Fund may be unable to sell illiquid securities at an advantageous time or price or achieve its desired level of exposure to a certain sector. Liquidity risk may result from the lack of an active market, reduced number and capacity of traditional market participants to make a market in fixed-income securities, and may be magnified in a rising interest rate environment or other circumstances where investor redemptions from fixed-income mutual funds may be higher than normal, causing increased supply in the market due to selling activity. Illiquid securities also may be difficult to value.
Junk Bond Risk. Investments in junk bonds can involve a substantial risk of loss. Junk bonds are considered to be speculative with respect to the issuer’s ability to pay interest and principal. These securities, which are rated below investment grade, have a higher risk of issuer default, are subject to greater price volatility than investment grade securities and may be illiquid.
Defaulted Bonds Risk. For bonds in default (rated “D” by Standard & Poor’s or the equivalent by another NRSRO), there is a significant risk that these bonds will not achieve their original value.
Unrated Security Risk. Unrated securities may be less liquid than rated securities determined to be of comparable credit quality by the Advisor. When the Fund purchases unrated securities, it will depend on the Advisor’s analysis of credit risk without the assessment of an NRSRO.
Taxable Municipal Bond Risk. Taxable municipal bonds are subject to credit risk, interest rate risk and certain additional risks. The Fund may be more sensitive to adverse economic, business or political developments if it invests a substantial portion of its assets in the bonds of similar projects or industrial development bonds.
Trust Preferred Securities Risk. Trust preferred securities are preferred stocks issued by a special purpose trust subsidiary backed by subordinated debt of the corporate parent. Trust preferred securities are subject to unique risks, which include the fact that dividend payments will only be paid if interest payments on the underlying obligations are made, which interest payments are dependent on the financial condition of the parent corporation. There is also the risk that the underlying obligations, and thus the trust preferred securities, may be prepaid after a stated call date or as a result of certain tax or regulatory events, resulting in a lower yield to maturity.
Collateralized Mortgage Obligation and Structured Asset-Backed Securities Risk. A CMO is a multiclass bond that is backed by a pool of mortgage loans or mortgage-backed securities. A structured ABS is a multiclass bond that is typically backed by a pool of auto loans, credit card receivables, home equity loans or student loans. A CMO or structured ABS is subject to interest rate risk, credit risk, prepayment risk and extension risk. In addition, if the Fund holds a class of a CMO or a structured ABS that is subordinated to other classes backed by the same pool of collateral, the likelihood that the Fund will receive payments of principal may be substantially limited.
Foreign Securities Risk. Investing in foreign securities involves additional risks relating to political, social, and economic developments abroad. Other risks result from the differences between the regulations to which U.S. and foreign issuers and markets are subject, and the potential for foreign markets to be less liquid and more volatile than U.S. markets. Foreign securities include ADRs. Unsponsored ADRs involve additional risks because U.S. reporting requirements do not apply and the issuing bank will recover shareholder distribution costs from movement of share prices and payment of dividends.
Foreign Currency Risk. Securities that trade or are denominated in currencies other than the U.S. dollar may be adversely affected by fluctuations in currency exchange rates. When the U.S. dollar strengthens relative to a foreign currency, the U.S. dollar value of an investment denominated in that currency will typically fall. ADRs indirectly bear currency risk because they represent an interest in securities that are not denominated in U.S. dollars.
Active Trading Strategy Risk. The Fund employs an active style that seeks to position the Fund with securities that offer the greatest price appreciation while minimizing risk. This style can result in higher turnover (exceeding 100%), may translate to higher transaction costs and may increase your tax liability.
Responsible Investing Risk. Investing primarily in responsible investments carries the risk that, under certain market conditions, the Fund may underperform funds that do not utilize a responsible investment strategy. The application of responsible investment principles may affect the Fund’s exposure to certain sectors or types of investments and may impact the Fund’s relative investment performance depending on whether such sectors or investments are in or out of favor in the market. A company’s ESG performance or the Advisor’s assessment of a company’s ESG performance may change over time, which could cause the Fund to temporarily hold securities that do not comply with the Fund’s responsible investment principles. In evaluating a company, the Advisor is dependent upon information and data that may be incomplete, inaccurate or unavailable, which could cause the Advisor to incorrectly assess a company’s ESG performance. Successful application of the Fund’s responsible investment strategy will depend on the Advisor’s skill in properly identifying and analyzing material ESG issues.
Futures Contracts Risk. The value of a futures contract tends to increase and decrease in tandem with the value of the underlying instrument. The price of futures can be highly volatile; using them could lower total return, and the potential loss from futures can exceed the Fund’s initial investment in such contracts. Futures contracts may not provide an effective hedge of the underlying securities or indexes because changes in the prices of futures contracts may not track those of the securities or indexes that they are intended to hedge.
Risk Lose Money [Text] rr_RiskLoseMoney You could lose money on your investment in the Fund, or the Fund could underperform, because of the risks described below.
Risk Nondiversified Status [Text] rr_RiskNondiversifiedStatus Non-Diversification Risk. Because the Fund may hold securities of a smaller number of issuers or invest a greater percentage of its assets in a particular issuer than a diversified fund, the gains or losses on a single bond may have greater impact on the Fund than on a diversified fund.
Risk Not Insured Depository Institution [Text] rr_RiskNotInsuredDepositoryInstitution An investment in the Fund is not a bank deposit and 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 Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following bar chart and table show the Fund’s annual returns and its long-term performance, which give some indication of the risks of investing in the Fund. The bar chart shows how the performance has varied from year to year.
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress www.calvert.com
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar Year Total Returns
Bar Chart Narrative [Text Block] rr_BarChartNarrativeTextBlock
The following bar chart and table show the Fund’s annual returns and its long-term performance, which give some indication of the risks of investing in the Fund. The bar chart shows how the performance has varied from year to year. The table compares the Fund’s performance over time with that of a benchmark and a performance average of similar mutual funds. The performance reflected in the bar chart and table assumes the reinvestment of dividends and capital gains distributions, if any.
The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. For updated performance information, visit www.calvert.com.
Performance results for Class I shares prior to January 31, 2014 (the Class I shares’ inception date) reflect the performance of Class A shares at net asset value. The Fund’s Class A shares are offered in a separate prospectus. Because Class I shares are invested in the same portfolio of securities, returns for Class I shares would have been substantially similar to those of Class A shares and differ only to the extent that the Classes have different expenses; actual Class I share performance would have been higher than Class A share performance because Class I has lower class-specific expenses than Class A.
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
 
Quarter
Ended
 
Total
Return
Best Quarter (of periods shown)
6/30/09
 
3.25%
Worst Quarter (of periods shown)
9/30/11
 
-0.78%
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns (as of 12-31-15)
Performance Table Uses Highest Federal Rate rr_PerformanceTableUsesHighestFederalRate After-tax returns are calculated using the historical highest individual federal marginal income tax rates, and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred rr_PerformanceTableNotRelevantToTaxDeferred The after-tax returns shown are not relevant to you if you hold your Fund shares through a tax-deferred arrangement such as a 401(k) plan or individual retirement account.
Performance Table Explanation after Tax Higher rr_PerformanceTableExplanationAfterTaxHigher The return after taxes on distributions and sale of Fund shares may be higher than the return before taxes because the calculation assumes that shareholders receive a tax benefit for capital losses incurred on the sale of their shares.
Performance Table Narrative rr_PerformanceTableNarrativeTextBlock
After-tax returns are calculated using the historical highest individual federal marginal income tax rates, and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. The after-tax returns shown are not relevant to you if you hold your Fund shares through a tax-deferred arrangement such as a 401(k) plan or individual retirement account. The return after taxes on distributions and sale of Fund shares may be higher than the return before taxes because the calculation assumes that shareholders receive a tax benefit for capital losses incurred on the sale of their shares.
Class I | Calvert Ultra-Short Income Fund | Barclays Short Treasury Index 9-12 months (reflects no deduction for fees, expenses or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 0.20%
5 Years rr_AverageAnnualReturnYear05 0.27%
Since Inception rr_AverageAnnualReturnSinceInception 1.51%
Inception Date rr_AverageAnnualReturnInceptionDate Oct. 31, 2006
Class I | Calvert Ultra-Short Income Fund | Lipper Ultra-Short Obligations Funds Avg. (reflects no deduction for taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 0.13%
5 Years rr_AverageAnnualReturnYear05 0.66%
Since Inception rr_AverageAnnualReturnSinceInception 1.61%
Inception Date rr_AverageAnnualReturnInceptionDate Oct. 31, 2006
Class I | Calvert Ultra-Short Income Fund | Class I  
Prospectus: rr_ProspectusTable  
Shareholder Fee, Other rr_ShareholderFeeOther none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.42% [18]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.71%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.13%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.63%) [19]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.50%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 4,704
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 29,044
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 55,535
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 131,272
Annual Return 2007 rr_AnnualReturn2007 5.20%
Annual Return 2008 rr_AnnualReturn2008 2.98%
Annual Return 2009 rr_AnnualReturn2009 7.29%
Annual Return 2010 rr_AnnualReturn2010 2.30%
Annual Return 2011 rr_AnnualReturn2011 0.20%
Annual Return 2012 rr_AnnualReturn2012 2.46%
Annual Return 2013 rr_AnnualReturn2013 0.90%
Annual Return 2014 rr_AnnualReturn2014 0.74%
Annual Return 2015 rr_AnnualReturn2015 0.62%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best Quarter (of periods shown)
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2009
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 3.25%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst Quarter (of periods shown)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Sep. 30, 2011
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (0.78%)
1 Year rr_AverageAnnualReturnYear01 0.62%
5 Years rr_AverageAnnualReturnYear05 0.98%
Since Inception rr_AverageAnnualReturnSinceInception 2.54%
Inception Date rr_AverageAnnualReturnInceptionDate Oct. 31, 2006
Class I | Calvert Ultra-Short Income Fund | Class I | After Taxes on Distributions  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 0.16%
5 Years rr_AverageAnnualReturnYear05 0.52%
Since Inception rr_AverageAnnualReturnSinceInception 1.75%
Inception Date rr_AverageAnnualReturnInceptionDate Oct. 31, 2006
Class I | Calvert Ultra-Short Income Fund | Class I | After Taxes on Distributions and Sales  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 0.35%
5 Years rr_AverageAnnualReturnYear05 0.57%
Since Inception rr_AverageAnnualReturnSinceInception 1.67%
Inception Date rr_AverageAnnualReturnInceptionDate Oct. 31, 2006
Class I | Calvert High Yield Bond Fund  
Prospectus: rr_ProspectusTable  
Risk/Return [Heading] rr_RiskReturnHeading CALVERT HIGH YIELD BOND FUND Class (Ticker):I (CYBIX)  
Objective [Heading] rr_ObjectiveHeading INVESTMENT OBJECTIVE
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
The Fund seeks high current income
Objective, Secondary [Text Block] rr_ObjectiveSecondaryTextBlock
and capital appreciation, secondarily.
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.
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 % 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 (“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 198% of its portfolio’s average value.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 198.00%
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 $1,000,000 in the Fund for the time periods indicated;
•
your investment has a 5% return each year;
•
the Fund’s operating expenses remain the same; and
•
any Calvert expense limitation is in effect for the period indicated in the fee table above.
Strategy [Heading] rr_StrategyHeading INVESTMENTS, RISKS AND PERFORMANCE Principal Investment Strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
The Fund invests primarily in high-yield, high-risk bonds, with varying maturities, including distressed securities that are in default. The Fund’s duration and maturity will be managed tactically based on the Advisor’s outlook for the fixed-income markets. For its investments, the Fund seeks to identify high yield bonds of companies that have the ability to make timely payments of principal and interest. Using fundamental credit analysis of companies, the Fund seeks to invest in companies whose financial condition gives them greater value relative to other companies in the high yield market, providing the further potential for capital appreciation. Consequently, capital appreciation is a secondary objective of the Fund. Under normal circumstances, the Fund will invest at least 80% of its net assets (including borrowings for investment purposes) in high yield, high risk bonds, also known as “junk” bonds. The Fund will provide shareholders with at least 60 days’ notice before changing this 80% policy.
The Advisor will actively manage the Fund to take advantage of relative values of various sectors of the high yield market in order to seek high current income and secondarily, capital appreciation. The Fund will buy and sell securities based on its overall objective of achieving the highest possible total return.
The Fund also may invest in trust preferred securities, taxable municipal securities, leveraged loans and asset-backed securities (“ABS”), including commercial mortgage-backed securities. In addition, the Fund may invest in foreign debt securities.
The Fund may invest in securities that represent interests in pools of mortgage loans or other assets assembled for sale to investors by various U.S. governmental agencies, government-related organizations and private issuers. These investments may include securities such as collateralized mortgage obligations (“CMOs”) and ABS.
The Fund is “non-diversified,” which means it may hold securities of a smaller number of issuers and invest a greater percentage of its assets in a particular issuer than a “diversified” fund.
Under certain market conditions, the Fund may opportunistically use a hedging technique that includes the purchase and sale of U.S. Treasury securities and related futures contracts to manage the duration of the Fund and hedge interest rate risk.
When a corporation issues a bond, it generally submits the security to one or more nationally recognized statistical rating organizations (“NRSROs”), such as Moody’s Investors Service (“Moody’s”) or Standard & Poor’s Ratings Services (“Standard & Poor’s”). These services evaluate the creditworthiness of the issuer and assign a rating, based on their evaluation of the issuer’s ability to repay the bond. Bonds with ratings below Baa3 (Moody’s) or BBB- (Standard & Poor’s) are considered below investment grade and are commonly referred to as junk bonds. Some bonds are not rated at all. The Advisor determines the comparable rating quality of bonds that are not rated.
Responsible Investing. In conjunction with Calvert’s financial analysis, Calvert’s comprehensive responsible investment principles guide our investment research processes and decision-making. The principles, which include the Advisor’s proprietary assessment of critical environmental, social and governance (“ESG”) issues, are applied across industries and to specific companies in order to inform our view of risk and opportunity factors that may affect investment performance.
Risk [Heading] rr_RiskHeading Principal Risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
You could lose money on your investment in the Fund, or the Fund could underperform, because of the risks described below. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Non-Diversification Risk. Because the Fund may hold securities of a smaller number of issuers or invest a greater percentage of its assets in a particular issuer than a diversified fund, the gains or losses on a single bond may have greater impact on the Fund than on a diversified fund.

Bond Market Risk. The market prices of bonds held by the Fund may fall.
Credit Risk. The credit quality of fixed-income securities may deteriorate, which could lead to default or bankruptcy of the issuer where the issuer becomes unable to pay its obligations when due.
Junk Bond Risk. Investments in junk bonds can involve a substantial risk of loss. Junk bonds are considered to be speculative with respect to the issuer’s ability to pay interest and principal. These securities, which are rated below investment grade, have a higher risk of issuer default, are subject to greater price volatility than investment grade securities and may be illiquid.
Mortgage-Backed and Asset-Backed Securities Risk. The value of investments in mortgage-backed and asset-backed securities is subject to interest rate risk and credit risk. These securities are also subject to the risk that borrowers will prepay the principal on their loans more quickly than expected (prepayment risk) or more slowly than expected (extension risk), which will affect the yield, average life and price of the securities. In addition, faster than expected prepayments may cause the Fund to invest the prepaid principal in lower yielding securities and slower than expected prepayments may reduce the potential for the Fund to invest in higher yielding securities.
Mortgage-Backed Security Risk (Government-Sponsored Enterprises).  Debt and mortgage-backed securities issued by government-sponsored enterprises (“GSEs”) such as the Federal National Mortgage Association (“FNMA”) and the Federal Home Loan Mortgage Corporation (“FHLMC”) are neither insured nor guaranteed by the U.S. Treasury and are not backed by the full faith and credit of the U.S. Government. Such securities are only supported by the credit of the applicable GSE. The U.S. government has provided financial support to FNMA and FHLMC, but there can be no assurance that it will support these or other GSEs in the future.
Leveraged Loan Risk. Leveraged loans are subject to the risks typically associated with debt securities, such as credit risk discussed above. The loans in which the Fund will invest are expected to be below-investment-grade quality and to bear interest at a floating rate that resets periodically. In addition, leveraged loans, which typically hold a senior position in the capital structure of a borrower, are subject to the risk that a court could subordinate such loans to presently existing or future indebtedness or take other action detrimental to the holders of leveraged loans. Leveraged loans are also subject to the risk that the value of the collateral, if any, securing a loan may decline, be insufficient to meet the obligations of the borrower, or be difficult to liquidate. Some leveraged loans are not as easily purchased or sold as publicly-traded securities and others are illiquid, which may make it more difficult for the Fund to value them or dispose of them at an acceptable price. Leveraged loans are usually more credit sensitive than investment-grade securities.
Management Risk. The individual investments of the Fund may not perform as expected, and the Fund’s portfolio management practices may not achieve the desired result.
Interest Rate Risk. A change in interest rates may adversely affect the value of fixed-income securities. When interest rates rise, the value of fixed-income securities will generally fall. Longer-term securities are subject to greater interest rate risk.
Portfolio Duration Risk. Duration is a measure of the expected life of a fixed-income security and its sensitivity to changes in interest rates. The longer a fund’s average portfolio duration, the more sensitive the fund will be to changes in interest rates.
Liquidity Risk. Liquidity risk exists when particular investments are difficult to sell. The Fund may be unable to sell illiquid securities at an advantageous time or price or achieve its desired level of exposure to a certain sector. Liquidity risk may result from the lack of an active market, reduced number and capacity of traditional market participants to make a market in fixed-income securities, and may be magnified in a rising interest rate environment or other circumstances where investor redemptions from fixed-income mutual funds may be higher than normal, causing increased supply in the market due to selling activity. Illiquid securities also may be difficult to value.
Defaulted Bonds Risk. For bonds in default (rated “D” by Standard & Poor’s or the equivalent by another NRSRO), there is a significant risk that these bonds will not achieve their original value.
Unrated Security Risk. Unrated securities may be less liquid than rated securities determined to be of comparable credit quality by the Advisor. When the Fund purchases unrated securities, it will depend on the Advisor’s analysis of credit risk without the assessment of an NRSRO.
Taxable Municipal Bond Risk. Taxable municipal bonds are subject to credit risk, interest rate risk and certain additional risks. The Fund may be more sensitive to adverse economic, business or political developments if it invests a substantial portion of its assets in the bonds of similar projects or industrial development bonds.
Trust Preferred Securities Risk. Trust preferred securities are preferred stocks issued by a special purpose trust subsidiary backed by subordinated debt of the corporate parent. Trust preferred securities are subject to unique risks, which include the fact that dividend payments will only be paid if interest payments on the underlying obligations are made, which interest payments are dependent on the financial condition of the parent corporation. There is also the risk that the underlying obligations, and thus the trust preferred securities, may be prepaid after a stated call date or as a result of certain tax or regulatory events, resulting in a lower yield to maturity. There can be no assurance as to the liquidity of trust preferred securities and the ability of holders of such securities to sell their holdings.
Collateralized Mortgage Obligation and Structured Asset-Backed Securities Risk. A CMO is a multiclass bond that is backed by a pool of mortgage loans or mortgage-backed securities. A structured ABS is a multiclass bond that is typically backed by a pool of auto loans, credit card receivables, home equity loans or student loans. A CMO or structured ABS is subject to interest rate risk, credit risk, prepayment risk and extension risk. In addition, if the Fund holds a class of a CMO or a structured ABS that is subordinated to other classes backed by the same pool of collateral, the likelihood that the Fund will receive payments of principal may be substantially limited.
Foreign Securities Risk. Investing in foreign securities involves additional risks relating to political, social, and economic developments abroad. Other risks result from the differences between the regulations to which U.S. and foreign issuers and markets are subject, and more volatile than U.S. markets. Foreign securities include ADRs. Unsponsored ADRs involve additional risks because U.S. reporting requirements do not apply and the issuing bank will recover shareholder distribution costs from movement of share prices and payment of dividends.
Foreign Currency Risk. Securities that trade or are denominated in currencies other than the U.S. dollar may be adversely affected by fluctuations in currency exchange rates. When the U.S. dollar strengthens relative to a foreign currency, the U.S. dollar value of an investment denominated in that currency will typically fall. ADRs indirectly bear currency risk because they represent an interest in securities that are not denominated in U.S. dollars.
Active Trading Strategy Risk. The Fund employs an active style that seeks to position the Fund with securities that offer the greatest price appreciation while minimizing risk. This style can result in higher turnover (exceeding 100%), may translate to higher transaction costs and may increase your tax liability.
Responsible Investing Risk. Investing primarily in responsible investments carries the risk that, under certain market conditions, the Fund may underperform funds that do not utilize a responsible investment strategy. The application of responsible investment principles may affect the Fund’s exposure to certain sectors or types of investments and may impact the Fund’s relative investment performance depending on whether such sectors or investments are in or out of favor in the market. A company’s ESG performance or the Advisor’s assessment of a company’s ESG performance may change over time, which could cause the Fund to temporarily hold securities that do not comply with the Fund’s responsible investment principles. In evaluating a company, the Advisor is dependent upon information and data that may be incomplete, inaccurate or unavailable, which could cause the Advisor to incorrectly assess a company’s ESG performance. Successful application of the Fund’s responsible investment strategy will depend on the Advisor’s skill in properly identifying and analyzing material ESG issues.
Futures Contracts Risk. The value of a futures contract tends to increase and decrease in tandem with the value of the underlying instrument. The price of futures can be highly volatile; using them could lower total return, and the potential loss from futures can exceed the Fund’s initial investment in such contracts. Futures contracts may not provide an effective hedge of the underlying securities or indexes because changes in the prices of futures contracts may not track those of the securities or indexes that they are intended to hedge.
Risk Lose Money [Text] rr_RiskLoseMoney You could lose money on your investment in the Fund, or the Fund could underperform, because of the risks described below.
Risk Nondiversified Status [Text] rr_RiskNondiversifiedStatus Non-Diversification Risk. Because the Fund may hold securities of a smaller number of issuers or invest a greater percentage of its assets in a particular issuer than a diversified fund, the gains or losses on a single bond may have greater impact on the Fund than on a diversified fund.
Risk Not Insured Depository Institution [Text] rr_RiskNotInsuredDepositoryInstitution An investment in the Fund is not a bank deposit and 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 following bar chart and table show the Fund’s annual returns and its long-term performance, which give some indication of the risks of investing in the Fund. The bar chart shows how the performance has varied from year to year. The table compares the Fund’s performance over time with that of a benchmark and a performance average of similar mutual funds. The performance reflected in the bar chart and table assumes the reinvestment of dividends and capital gains distributions, if any.
The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. For updated performance information, visit www.calvert.com.
Pursuant to an Agreement and Plan of Reorganization, Class I shares of Calvert High Yield Bond Fund, a series of Summit Mutual Funds, Inc. (“SMF Calvert High Yield Bond Fund”), were reorganized into the Class I shares of an identical and newly created series of The Calvert Fund, Calvert High Yield Bond Fund, which commenced operations on September 18, 2009. The performance results prior to September 18, 2009, for Class I shares reflect the performance of SMF Calvert High Yield Bond Fund.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following bar chart and table show the Fund’s annual returns and its long-term performance, which give some indication of the risks of investing in the Fund. The bar chart shows how the performance has varied from year to year. The table compares the Fund’s performance over time with that of a benchmark and a performance average of similar mutual funds. The performance reflected in the bar chart and table assumes the reinvestment of dividends and capital gains distributions, if any.
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress www.calvert.com
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar Year Total Returns
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
 
Quarter
Ended
 
Total
Return
Best Quarter (of periods shown)
6/30/09
 
11.06%
Worst Quarter (of periods shown)
12/31/08
 
-14.15%
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns (as of 12-31-15)
Performance Table Uses Highest Federal Rate rr_PerformanceTableUsesHighestFederalRate After-tax returns are calculated using the historical highest individual federal marginal income tax rates, and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred rr_PerformanceTableNotRelevantToTaxDeferred The after-tax returns shown are not relevant to you if you hold your Fund shares through a tax-deferred arrangement such as a 401(k) plan or individual retirement account.
Performance Table Explanation after Tax Higher rr_PerformanceTableExplanationAfterTaxHigher The return after taxes on distributions and sale of Fund shares may be higher than the return before taxes because the calculation assumes that shareholders receive a tax benefit for capital losses incurred on the sale of their shares.
Performance Table Narrative rr_PerformanceTableNarrativeTextBlock
After-tax returns are calculated using the historical highest individual federal marginal income tax rates, and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. The after-tax returns shown are not relevant to you if you hold your Fund shares through a tax-deferred arrangement such as a 401(k) plan or individual retirement account. The return after taxes on distributions and sale of Fund shares may be higher than the return before taxes because the calculation assumes that shareholders receive a tax benefit for capital losses incurred on the sale of their shares.
Class I | Calvert High Yield Bond Fund | BofA Merrill Lynch High Yield Master II Index (reflects no deduction for fees, expenses or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (4.64%)
5 Years rr_AverageAnnualReturnYear05 4.84%
10 Years rr_AverageAnnualReturnYear10 6.81%
Class I | Calvert High Yield Bond Fund | Lipper High Yield Funds Avg. (reflects no deduction for taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (4.09%)
5 Years rr_AverageAnnualReturnYear05 4.08%
10 Years rr_AverageAnnualReturnYear10 5.58%
Class I | Calvert High Yield Bond Fund | Class I  
Prospectus: rr_ProspectusTable  
Shareholder Fee, Other rr_ShareholderFeeOther none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.77% [20]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.18%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.95%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.21%) [21]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.74%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 7,558
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 27,968
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 50,296
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 114,526
Annual Return 2006 rr_AnnualReturn2006 10.80%
Annual Return 2007 rr_AnnualReturn2007 1.75%
Annual Return 2008 rr_AnnualReturn2008 (21.89%)
Annual Return 2009 rr_AnnualReturn2009 37.58%
Annual Return 2010 rr_AnnualReturn2010 16.50%
Annual Return 2011 rr_AnnualReturn2011 5.94%
Annual Return 2012 rr_AnnualReturn2012 15.40%
Annual Return 2013 rr_AnnualReturn2013 8.55%
Annual Return 2014 rr_AnnualReturn2014 (0.77%)
Annual Return 2015 rr_AnnualReturn2015 (2.13%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best Quarter (of periods shown)
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2009
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 11.06%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst Quarter (of periods shown)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (14.15%)
1 Year rr_AverageAnnualReturnYear01 (2.13%)
5 Years rr_AverageAnnualReturnYear05 5.21%
10 Years rr_AverageAnnualReturnYear10 6.17%
Class I | Calvert High Yield Bond Fund | Class I | After Taxes on Distributions  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (4.41%)
5 Years rr_AverageAnnualReturnYear05 2.44%
10 Years rr_AverageAnnualReturnYear10 3.46%
Class I | Calvert High Yield Bond Fund | Class I | After Taxes on Distributions and Sales  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (1.24%)
5 Years rr_AverageAnnualReturnYear05 2.89%
10 Years rr_AverageAnnualReturnYear10 3.68%
Class R | Calvert Income Fund  
Prospectus: rr_ProspectusTable  
Risk/Return [Heading] rr_RiskReturnHeading CALVERT INCOME FUND Class (Ticker):R (CICRX)  
Objective [Heading] rr_ObjectiveHeading INVESTMENT OBJECTIVE
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
The Fund seeks to maximize income, to the extent consistent with preservation of capital, through investment in bonds and income-producing securities.
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.
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 % 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 (“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 236% of its portfolio’s average value.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 236.00%
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;
•
your investment has a 5% return each year;
•
the Fund’s operating expenses remain the same; and
•
any Calvert expense limitation is in effect for the period indicated in the fee table above.
Although your actual costs may be higher or lower, under these assumptions your costs would be:
Strategy [Heading] rr_StrategyHeading INVESTMENTS, RISKS AND PERFORMANCE Principal Investment Strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
The Fund typically invests at least 65% of its net assets in investment grade, U.S. dollar-denominated debt securities, as assessed at the time of purchase. A debt security is considered investment grade when assigned a credit quality rating of BBB- or higher by Standard & Poor’s Ratings Services (“Standard & Poor’s”) or an equivalent rating by another nationally recognized statistical rating organization (“NRSRO”), including Moody’s Investors Service or Fitch Ratings, or if unrated, considered to be of comparable credit quality by the Fund’s Advisor.
The Fund invests principally in bonds issued by U.S. corporations, the U.S. Government or its agencies, and U.S. government-sponsored enterprises (“GSEs”) such as the Federal National Mortgage Association (“FNMA”) and the Federal Home Loan Mortgage Corporation (“FHLMC”). The Fund also may invest in trust preferred securities, taxable municipal securities, leveraged loans and asset-backed securities (“ABS”), including commercial mortgage-backed securities.
The Fund may invest in securities that represent interests in pools of mortgage loans or other assets assembled for sale to investors by various U.S. governmental agencies, government-related organizations and private issuers. These investments may include securities such as collateralized mortgage obligations (“CMOs”) and ABS.
The Fund may invest up to 35% of its net assets in below-investment grade, high-yield debt securities (commonly known as “junk bonds”), including distressed securities that are in default. A debt security is considered below investment grade when assigned a credit quality rating below BBB- by Standard & Poor’s or an equivalent rating by another NRSRO, or if unrated, considered to be of comparable credit quality by the Fund’s Advisor.
The Fund may also invest up to 25% of its net assets in foreign debt securities. Foreign debt securities include American Depositary Receipts (“ADRs”).
The Fund is “non-diversified,” which means it may hold securities of a smaller number of issuers and invest a greater percentage of its assets in a particular issuer than a “diversified” fund.
The Fund uses an active trading strategy, seeking relative value to earn incremental income.
The Fund uses a hedging technique that includes the purchase and sale of U.S. Treasury securities and related futures contracts to manage the duration of the Fund and hedge interest rate risk.
Responsible Investing. In conjunction with Calvert’s financial analysis, Calvert’s comprehensive responsible investment principles guide our investment research processes and decision-making. The principles, which include the Advisor’s proprietary assessment of critical environmental, social and governance (“ESG”) issues, are applied across industries and to specific companies in order to inform our view of risk and opportunity factors that may affect investment performance.
Risk [Heading] rr_RiskHeading Principal Risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
You could lose money on your investment in the Fund, or the Fund could underperform, because of the risks described below. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Non-Diversification Risk. Because the Fund may hold securities of a smaller number of issuers or invest a greater percentage of its assets in a particular issuer than a diversified fund, the gains or losses on a single bond may have greater impact on the Fund than on a diversified fund.
Bond Market Risk. The market prices of bonds held by the Fund may fall.
Credit Risk. The credit quality of fixed-income securities may deteriorate, which could lead to default or bankruptcy of the issuer where the issuer becomes unable to pay its obligations when due.
Mortgage-Backed and Asset-Backed Securities Risk. The value of investments in mortgage-backed and asset-backed securities is subject to interest rate risk and credit risk. These securities are also subject to the risk that borrowers will prepay the principal on their loans more quickly than expected (prepayment risk) or more slowly than expected (extension risk), which will affect the yield, average life and price of the securities. In addition, faster than expected prepayments may cause the Fund to invest the prepaid principal in lower yielding securities and slower than expected prepayments may reduce the potential for the Fund to invest in higher yielding securities.
Mortgage-Backed Security Risk (Government-Sponsored Enterprises).  Debt and mortgage-backed securities issued by GSEs such as FNMA and FHLMC are neither insured nor guaranteed by the U.S. Treasury and are not backed by the full faith and credit of the U.S. government. Such securities are only supported by the credit of the applicable GSE. The U.S. government has provided financial support to FNMA and FHLMC, but there can be no assurance that it will support these or other GSEs in the future.
Leveraged Loan Risk. Leveraged loans are subject to the risks typically associated with debt securities, such as credit risk discussed above. The loans in which the Fund will invest are expected to be below-investment-grade quality and to bear interest at a floating rate that resets periodically. In addition, leveraged loans, which typically hold a senior position in the capital structure of a borrower, are subject to the risk that a court could subordinate such loans to presently existing or future indebtedness or take other action detrimental to the holders of leveraged loans. Leveraged loans are also subject to the risk that the value of the collateral, if any, securing a loan may decline, be insufficient to meet the obligations of the borrower, or be difficult to liquidate. Some leveraged loans are not as easily purchased or sold as publicly-traded securities and others are illiquid, which may make it more difficult for the Fund to value them or dispose of them at an acceptable price. Leveraged loans are usually more credit sensitive than investment-grade securities.
Management Risk. Individual investments of the Fund may not perform as expected, and the Fund’s portfolio management practices may not achieve the desired result.
Interest Rate Risk. A change in interest rates may adversely affect the value of fixed-income securities. When interest rates rise, the value of fixed-income securities will generally fall. Longer-term securities are subject to greater interest rate risk.
Portfolio Duration Risk. Duration is a measure of the expected life of a fixed-income security and its sensitivity to changes in interest rates. The longer a fund’s average portfolio duration, the more sensitive the fund will be to changes in interest rates.
Liquidity Risk. Liquidity risk exists when particular investments are difficult to sell. The Fund may be unable to sell illiquid securities at an advantageous time or price or achieve its desired level of exposure to a certain sector. Liquidity risk may result from the lack of an active market, reduced number and capacity of traditional market participants to make a market in fixed-income securities, and may be magnified in a rising interest rate environment or other circumstances where investor redemptions from fixed-income mutual funds may be higher than normal, causing increased supply in the market due to selling activity. Illiquid securities also may be difficult to value.
Junk Bond Risk. Investments in junk bonds can involve a substantial risk of loss. Junk bonds are considered to be speculative with respect to the issuer’s ability to pay interest and principal. These securities, which are rated below investment grade, have a higher risk of issuer default, are subject to greater price volatility than investment grade securities and may be illiquid.
Defaulted Bonds Risk. For bonds in default (those rated “D” by Standard & Poor’s or the equivalent by another NRSRO), there is a significant risk that these bonds will not achieve their original value.
Unrated Security Risk. Unrated securities may be less liquid than rated securities determined to be of comparable credit quality by the Advisor. When the Fund purchases unrated securities, it will depend on the Advisor’s analysis of credit risk without the assessment of a nationally recognized statistical rating organization.
Taxable Municipal Bond Risk. Taxable municipal bonds are subject to credit risk, interest rate risk and certain additional risks. The Fund may be more sensitive to adverse economic, business or political developments if it invests a substantial portion of its assets in the bonds of similar projects or industrial development bonds.
Trust Preferred Securities Risk. Trust preferred securities are preferred stocks issued by a special purpose trust subsidiary backed by subordinated debt of the corporate parent. Trust preferred securities are subject to unique risks, which include the fact that dividend payments will only be paid if interest payments on the underlying obligations are made, which interest payments are dependent on the financial condition of the parent corporation. There is also the risk that the underlying obligations, and thus the trust preferred securities, may be prepaid after a stated call date or as a result of certain tax or regulatory events, resulting in a lower yield to maturity.
Collateralized Mortgage Obligation and Structured Asset-Backed Securities Risk. A CMO is a multiclass bond that is backed by a pool of mortgage loans or mortgage-backed securities. A structured ABS is a multiclass bond that is typically backed by a pool of auto loans, credit card receivables, home equity loans or student loans. A CMO or structured ABS is subject to interest rate risk, credit risk, prepayment risk and extension risk. In addition, if the Fund holds a class of a CMO or a structured ABS that is subordinated to other classes backed by the same pool of collateral, the likelihood that the Fund will receive payments of principal may be substantially limited.
Foreign Securities Risk. Investing in foreign securities involves additional risks relating to political, social, and economic developments abroad. Other risks result from the differences between the regulations to which U.S. and foreign issuers and markets are subject, and the potential for foreign markets to be less liquid and more volatile than U.S. markets. Foreign securities include ADRs. Unsponsored ADRs involve additional risks because U.S. reporting requirements do not apply and the issuing bank will recover shareholder distribution costs from movement of share prices and payment of dividends.
Foreign Currency Risk. Securities that trade or are denominated in currencies other than the U.S. dollar may be adversely affected by fluctuations in currency exchange rates. When the U.S. dollar strengthens relative to a foreign currency, the U.S. dollar value of an investment denominated in that currency will typically fall. ADRs indirectly bear currency risk because they represent an interest in securities that are not denominated in U.S. dollars.
Active Trading Strategy Risk. The Fund employs an active style that seeks to position the Fund with securities that offer the greatest price appreciation while minimizing risk. This style can result in higher turnover (exceeding 100%), may translate to higher transaction costs and may increase your tax liability.
Futures Contracts Risk. The value of a futures contract tends to increase and decrease in tandem with the value of the underlying instrument. The price of futures can be highly volatile; using them could lower total return, and the potential loss from futures can exceed the Fund’s initial investment in such contracts. Futures contracts may not provide an effective hedge of the underlying securities or indexes because changes in the prices of futures contracts may not track those of the securities or indexes that they are intended to hedge.
Responsible Investing Risk. Investing primarily in responsible investments carries the risk that, under certain market conditions, the Fund may underperform funds that do not utilize a responsible investment strategy. The application of responsible investment principles may affect the Fund’s exposure to certain sectors or types of investments and may impact the Fund’s relative investment performance depending on whether such sectors or investments are in or out of favor in the market. A company’s ESG performance or the Advisor’s assessment of a company’s ESG performance may change over time, which could cause the Fund to temporarily hold securities that do not comply with the Fund’s responsible investment principles. In evaluating a company, the Advisor is dependent upon information and data that may be incomplete, inaccurate or unavailable, which could cause the Advisor to incorrectly assess a company’s ESG performance. Successful application of the Fund’s responsible investment strategy will depend on the Advisor’s skill in properly identifying and analyzing material ESG issues.

Risk Lose Money [Text] rr_RiskLoseMoney You could lose money on your investment in the Fund, or the Fund could underperform, because of the risks described below.
Risk Nondiversified Status [Text] rr_RiskNondiversifiedStatus Non-Diversification Risk. Because the Fund may hold securities of a smaller number of issuers or invest a greater percentage of its assets in a particular issuer than a diversified fund, the gains or losses on a single bond may have greater impact on the Fund than on a diversified fund.
Risk Not Insured Depository Institution [Text] rr_RiskNotInsuredDepositoryInstitution An investment in the Fund is not a bank deposit and 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 following bar chart and table show the Fund’s annual returns and its long-term performance, which give some indication of the risks of investing in the Fund. The bar chart shows how the performance has varied from year to year. The table compares the Fund’s performance over time with that of a benchmark and a performance average of similar mutual funds. The performance reflected in the bar chart and table assumes the reinvestment of dividends and capital gains distributions, if any.
The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. For updated performance information, visit www.calvert.com.
Performance results for Class R shares prior to October 31, 2006, the inception date for Class R shares, reflect the performance of Class A shares at net asset value. The Fund’s Class A shares are offered in a separate prospectus. Because Class A shares are invested in the same portfolio of securities, returns for Class R shares would have been substantially similar to those of Class A shares and differ only to the extent that the Classes have different expenses; actual Class R share performance would have been lower than Class A share performance because Class R has higher class-specific expenses than Class A.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following bar chart and table show the Fund’s annual returns and its long-term performance, which give some indication of the risks of investing in the Fund.
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress www.calvert.com
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar Year Total Returns
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
 
Quarter
Ended
 
Total
Return
Best Quarter (of periods shown)
6/30/09
 
7.81%
Worst Quarter (of periods shown)
12/31/08
 
-7.79%
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns (as of 12-31-15)
Performance Table Uses Highest Federal Rate rr_PerformanceTableUsesHighestFederalRate After-tax returns are calculated using the historical highest individual federal marginal income tax rates, and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred rr_PerformanceTableNotRelevantToTaxDeferred The after-tax returns shown are not relevant to you if you hold your Fund shares through a tax-deferred arrangement such as a 401(k) plan or individual retirement account.
Performance Table Explanation after Tax Higher rr_PerformanceTableExplanationAfterTaxHigher The return after taxes on distributions and sale of Fund shares may be higher than the return before taxes because the calculation assumes that shareholders receive a tax benefit for capital losses incurred on the sale of their shares.
Performance Table Narrative rr_PerformanceTableNarrativeTextBlock
After-tax returns are calculated using the historical highest individual federal marginal income tax rates, and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. The after-tax returns shown are not relevant to you if you hold your Fund shares through a tax-deferred arrangement such as a 401(k) plan or individual retirement account. The return after taxes on distributions and sale of Fund shares may be higher than the return before taxes because the calculation assumes that shareholders receive a tax benefit for capital losses incurred on the sale of their shares.
Class R | Calvert Income Fund | Barclays U.S. Credit Index (reflects no deduction for fees, expenses or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (0.77%)
5 Years rr_AverageAnnualReturnYear05 4.38%
10 Years rr_AverageAnnualReturnYear10 5.18%
Class R | Calvert Income Fund | Lipper Corporate Debt Funds BBB Rated Avg. (reflects no deduction for taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (1.71%)
5 Years rr_AverageAnnualReturnYear05 4.11%
10 Years rr_AverageAnnualReturnYear10 4.91%
Class R | Calvert Income Fund | Class R  
Prospectus: rr_ProspectusTable  
Shareholder Fee, Other rr_ShareholderFeeOther none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.52% [22]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.50%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.74%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.76%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.29%) [23]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.47%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 150
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 526
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 927
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 2,049
Annual Return 2006 rr_AnnualReturn2006 4.77%
Annual Return 2007 rr_AnnualReturn2007 4.69%
Annual Return 2008 rr_AnnualReturn2008 (12.21%)
Annual Return 2009 rr_AnnualReturn2009 16.13%
Annual Return 2010 rr_AnnualReturn2010 6.16%
Annual Return 2011 rr_AnnualReturn2011 2.44%
Annual Return 2012 rr_AnnualReturn2012 8.36%
Annual Return 2013 rr_AnnualReturn2013 (0.80%)
Annual Return 2014 rr_AnnualReturn2014 4.65%
Annual Return 2015 rr_AnnualReturn2015 (1.44%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best Quarter (of periods shown)
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2009
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 7.81%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst Quarter (of periods shown)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (7.79%)
1 Year rr_AverageAnnualReturnYear01 (1.44%)
5 Years rr_AverageAnnualReturnYear05 2.58%
10 Years rr_AverageAnnualReturnYear10 3.03%
Class R | Calvert Income Fund | Class R | After Taxes on Distributions  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (2.51%)
5 Years rr_AverageAnnualReturnYear05 1.46%
10 Years rr_AverageAnnualReturnYear10 1.72%
Class R | Calvert Income Fund | Class R | After Taxes on Distributions and Sales  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (0.82%)
5 Years rr_AverageAnnualReturnYear05 1.52%
10 Years rr_AverageAnnualReturnYear10 1.83%
Class A | Calvert Long-Term Income Fund  
Prospectus: rr_ProspectusTable  
Risk/Return [Heading] rr_RiskReturnHeading CALVERT LONG-TERM INCOME FUND Class (Ticker):A (CLDAX)  
Objective [Heading] rr_ObjectiveHeading INVESTMENT OBJECTIVE
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
The Fund seeks to maximize income, to the extent consistent with preservation of capital, through investments in longer-dated securities.
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 sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in Calvert mutual funds. More information about these and other discounts is available from your financial professional and under “Choosing a Share Class” on page 47 and “Reduced Sales Charges” on page 50 of this Prospectus, and under “Method of Distribution” on page 40 of the Fund’s Statement of Additional Information.
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 % 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 (“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 290% of its portfolio’s average value.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 290.00%
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 $50,000 in Calvert mutual funds.
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;
•
your investment has a 5% return each year; and
•
the Fund’s operating expenses remain the same.
Strategy [Heading] rr_StrategyHeading INVESTMENTS, RISKS AND PERFORMANCE Principal Investment Strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
The Fund typically invests at least 65% of its net assets in investment grade, U.S. dollar-denominated debt securities, as assessed at the time of purchase. A debt security is considered investment grade when assigned a credit quality rating of BBB- or higher by Standard & Poor’s Ratings Services (“Standard & Poor’s”) or an equivalent rating by another nationally recognized statistical rating organization (“NRSRO”), including Moody’s Investors Service or Fitch Ratings, or if unrated, considered to be of comparable credit quality by the Fund’s Advisor.
The Fund invests principally in bonds issued by U.S. corporations, the U.S. Government or its agencies, and U.S. government-sponsored enterprises (“GSEs”) such as the Federal National Mortgage Association (“FNMA”) and the Federal Home Loan Mortgage Corporation (“FHLMC”). The Fund also may invest in trust preferred securities, taxable municipal securities, leveraged loans and asset-backed securities (“ABS”), including commercial mortgage-backed securities.
The Fund may invest in securities that represent interests in pools of mortgage loans or other assets assembled for sale to investors by various U.S. governmental agencies, government-related organizations and private issuers. These investments may include securities such as collateralized mortgage obligations (“CMOs”) and ABS.
The Fund may invest up to 35% of its net assets in below-investment grade, high-yield debt securities (commonly known as “junk bonds”), including distressed securities that are in default. A debt security is considered below investment grade when assigned a credit quality rating below BBB- by Standard & Poor’s or an equivalent rating by another NRSRO, or if unrated, considered to be of comparable credit quality by the Fund’s Advisor.
The Fund may also invest up to 25% of its net assets in foreign debt securities. Foreign debt securities include American Depositary Receipts (“ADRs”).
The Fund is “non-diversified,” which means it may hold securities of a smaller number of issuers and invest a greater percentage of its assets in a particular issuer than a “diversified” fund.
Under normal circumstances, the Fund will have a dollar-weighted average portfolio maturity of ten years or more.
The Fund uses an active trading strategy, seeking relative value to earn incremental income.
The Fund uses a hedging technique that includes the purchase and sale of U.S. Treasury securities and related futures contracts to manage the duration of the Fund and hedge interest rate risk.
Responsible Investing. In conjunction with Calvert’s financial analysis, Calvert’s comprehensive responsible investment principles guide our investment research processes and decision-making. The principles, which include the Advisor’s proprietary assessment of critical environmental, social and governance (“ESG”) issues, are applied across industries and to specific companies in order to inform our view of risk and opportunity factors that may affect investment performance.
Risk [Heading] rr_RiskHeading Principal Risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
You could lose money on your investment in the Fund, or the Fund could underperform, because of the risks described below. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Non-Diversification Risk. Because the Fund may hold securities of a smaller number of issuers or invest a greater percentage of its assets in a particular issuer than a diversified fund, the gains or losses on a single bond may have greater impact on the Fund than on a diversified fund.

Bond Market Risk. The market prices of bonds held by the Fund may fall.
Credit Risk. The credit quality of fixed-income securities may deteriorate, which could lead to default or bankruptcy of the issuer where the issuer becomes unable to pay its obligations when due.
Mortgage-Backed and Asset-Backed Securities Risk. The value of investments in mortgage-backed and asset-backed securities is subject to interest rate risk and credit risk. These securities are also subject to the risk that borrowers will prepay the principal on their loans more quickly than expected (prepayment risk) or more slowly than expected (extension risk), which will affect the yield, average life and price of the securities. In addition, faster than expected prepayments may cause the Fund to invest the prepaid principal in lower yielding securities and slower than expected prepayments may reduce the potential for the Fund to invest in higher yielding securities.
Mortgage-Backed Security Risk (Government-Sponsored Enterprises).  Debt and mortgage-backed securities issued by GSEs such as FNMA and FHLMC are neither insured nor guaranteed by the U.S. Treasury and are not backed by the full faith and credit of the U.S. government. Such securities are only supported by the credit of the applicable GSE. The U.S. government has provided financial support to FNMA and FHLMC, but there can be no assurance that it will support these or other GSEs in the future.
Leveraged Loan Risk. Leveraged loans are subject to the risks typically associated with debt securities, such as credit risk discussed above. The loans in which the Fund will invest are expected to be below-investment-grade quality and to bear interest at a floating rate that resets periodically. In addition, leveraged loans, which typically hold a senior position in the capital structure of a borrower, are subject to the risk that a court could subordinate such loans to presently existing or future indebtedness or take other action detrimental to the holders of leveraged loans. Leveraged loans are also subject to the risk that the value of the collateral, if any, securing a loan may decline, be insufficient to meet the obligations of the borrower, or be difficult to liquidate. Some leveraged loans are not as easily purchased or sold as publicly-traded securities and others are illiquid, which may make it more difficult for the Fund to value them or dispose of them at an acceptable price. Leveraged loans are usually more credit sensitive than investment-grade securities.
Management Risk. Individual investments of the Fund may not perform as expected, and the Fund’s portfolio management practices may not achieve the desired result.
Interest Rate Risk. A change in interest rates may adversely affect the value of fixed-income securities. When interest rates rise, the value of fixed-income securities will generally fall. Longer-term securities are subject to greater interest rate risk.
Portfolio Maturity Risk. Average weighted portfolio maturity is the length of time, in days or years, until the securities held by a fund, on average, will mature or be redeemed by their issuers. The average portfolio maturity is weighted according to the dollar amounts invested in the various securities held by a fund. In general, the longer a fund’s average weighted portfolio maturity, the more its share price will fluctuate in response to changing interest rates.
Liquidity Risk. Liquidity risk exists when particular investments are difficult to sell. The Fund may be unable to sell illiquid securities at an advantageous time or price or achieve its desired level of exposure to a certain sector. Liquidity risk may result from the lack of an active market, reduced number and capacity of traditional market participants to make a market in fixed-income securities, and may be magnified in a rising interest rate environment or other circumstances where investor redemptions from fixed-income mutual funds may be higher than normal, causing increased supply in the market due to selling activity. Illiquid securities also may be difficult to value.
Junk Bond Risk. Investments in junk bonds can involve a substantial risk of loss. Junk bonds are considered to be speculative with respect to the issuer’s ability to pay interest and principal. These securities, which are rated below investment grade, have a higher risk of issuer default, are subject to greater price volatility than investment grade securities and may be illiquid.
Defaulted Bonds Risk. For bonds in default (those rated “D” by Standard & Poor’s or the equivalent by another NRSRO), there is a significant risk that these bonds will not achieve their original value.
Unrated Security Risk. Unrated securities may be less liquid than rated securities determined to be of comparable credit quality by the Advisor. When the Fund purchases unrated securities, it will depend on the Advisor’s analysis of credit risk without the assessment of an NRSRO.
Taxable Municipal Bond Risk. Taxable municipal bonds are subject to credit risk, interest rate risk and certain additional risks. The Fund may be more sensitive to adverse economic, business or political developments if it invests a substantial portion of its assets in the bonds of similar projects or industrial development bonds.
Trust Preferred Securities Risk. Trust preferred securities are preferred stocks issued by a special purpose trust subsidiary backed by subordinated debt of the corporate parent. Trust preferred securities are subject to unique risks, which include the fact that dividend payments will only be paid if interest payments on the underlying obligations are made, which interest payments are dependent on the financial condition of the parent corporation. There is also the risk that the underlying obligations, and thus the trust preferred securities, may be prepaid after a stated call date or as a result of certain tax or regulatory events, resulting in a lower yield to maturity.
Collateralized Mortgage Obligation and Structured Asset-Backed Securities Risk. A CMO is a multiclass bond that is backed by a pool of mortgage loans or mortgage-backed securities. A structured ABS is a multiclass bond that is typically backed by a pool of auto loans, credit card receivables, home equity loans or student loans. A CMO or structured ABS is subject to interest rate risk, credit risk, prepayment risk and extension risk. In addition, if the Fund holds a class of a CMO or a structured ABS that is subordinated to other classes backed by the same pool of collateral, the likelihood that the Fund will receive payments of principal may be substantially limited.
Foreign Securities Risk. Investing in foreign securities involves additional risks relating to political, social, and economic developments abroad. Other risks result from the differences between the regulations to which U.S. and foreign issuers and markets are subject, and the potential for foreign markets to be less liquid and more volatile than U.S. markets. Foreign securities include ADRs. Unsponsored ADRs involve additional risks because U.S. reporting requirements do not apply and the issuing bank will recover shareholder distribution costs from movement of share prices and payment of dividends.
Foreign Currency Risk. Securities that trade or are denominated in currencies other than the U.S. dollar may be adversely affected by fluctuations in currency exchange rates. When the U.S. dollar strengthens relative to a foreign currency, the U.S. dollar value of an investment denominated in that currency will typically fall. ADRs indirectly bear currency risk because they represent an interest in securities that are not denominated in U.S. dollars.
Active Trading Strategy Risk. The Fund employs an active style that seeks to position the Fund with securities that offer the greatest price appreciation while minimizing risk. This style can result in higher turnover (exceeding 100%), may translate to higher transaction costs and may increase your tax liability.
Responsible Investing Risk. Investing primarily in responsible investments carries the risk that, under certain market conditions, the Fund may underperform funds that do not utilize a responsible investment strategy. The application of responsible investment principles may affect the Fund’s exposure to certain sectors or types of investments and may impact the Fund’s relative investment performance depending on whether such sectors or investments are in or out of favor in the market. A company’s ESG performance or the Advisor’s assessment of a company’s ESG performance may change over time, which could cause the Fund to temporarily hold securities that do not comply with the Fund’s responsible investment principles. In evaluating a company, the Advisor is dependent upon information and data that may be incomplete, inaccurate or unavailable, which could cause the Advisor to incorrectly assess a company’s ESG performance. Successful application of the Fund’s responsible investment strategy will depend on the Advisor’s skill in properly identifying and analyzing material ESG issues.
Futures Contracts Risk.The value of a futures contract tends to increase and decrease in tandem with the value of the underlying instrument. The price of futures can be highly volatile; using them could lower total return, and the potential loss from futures can exceed the Fund’s initial investment in such contracts. Futures contracts may not provide an effective hedge of the underlying securities or indexes because changes in the prices of futures contracts may not track those of the securities or indexes that they are intended to hedge.
Risk Lose Money [Text] rr_RiskLoseMoney You could lose money on your investment in the Fund, or the Fund could underperform, because of the risks described below.
Risk Nondiversified Status [Text] rr_RiskNondiversifiedStatus Non-Diversification Risk. Because the Fund may hold securities of a smaller number of issuers or invest a greater percentage of its assets in a particular issuer than a diversified fund, the gains or losses on a single bond may have greater impact on the Fund than on a diversified fund.
Risk Not Insured Depository Institution [Text] rr_RiskNotInsuredDepositoryInstitution An investment in the Fund is not a bank deposit and 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 following bar chart and table show the Fund’s annual returns and its long-term performance, which give some indication of the risks of investing in the Fund. The bar chart shows how the performance of the Class A shares has varied from year to year. The table compares the Fund’s performance over time with that of a benchmark and a performance average of similar mutual funds. The performance reflected in the bar chart and table assumes the reinvestment of dividends and capital gains distributions, if any.
The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. For updated performance information, visit www.calvert.com.
The bar chart does not reflect any sales charge that you may be required to pay upon purchase or redemption of the Fund’s shares. Any sales charge will reduce your return.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following bar chart and table show the Fund’s annual returns and its long-term performance, which give some indication of the risks of investing in the Fund.
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress www.calvert.com
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar Year Total Returns for Class A at NAV
Bar Chart Does Not Reflect Sales Loads [Text] rr_BarChartDoesNotReflectSalesLoads The bar chart does not reflect any sales charge that you may be required to pay upon purchase or redemption of the Fund’s shares. Any sales charge will reduce your return.
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
 
Quarter
Ended
 
Total
Return
Best Quarter (of periods shown)
9/30/09
 
8.33%
Worst Quarter (of periods shown)
06/30/15
 
-6.81%
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns (as of 12-31-15) (with maximum sales charge deducted, if any)
Performance Table Does Reflect Sales Loads rr_PerformanceTableDoesReflectSalesLoads The average total return table shows the Fund’s returns with the maximum sales charge deducted, and no sales charge has been applied to the indices used for comparison in the table.
Performance Table Uses Highest Federal Rate rr_PerformanceTableUsesHighestFederalRate After-tax returns are calculated using the historical highest individual federal marginal income tax rates, and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred rr_PerformanceTableNotRelevantToTaxDeferred The after-tax returns shown are not relevant to you if you hold your Fund shares through a tax-deferred arrangement such as a 401(k) plan or individual retirement account.
Performance Table Explanation after Tax Higher rr_PerformanceTableExplanationAfterTaxHigher The return after taxes on distributions and sale of Fund shares may be higher than the return before taxes because the calculation assumes that shareholders receive a tax benefit for capital losses incurred on the sale of their shares.
Performance Table Narrative rr_PerformanceTableNarrativeTextBlock
The average total return table shows the Fund’s returns with the maximum sales charge deducted, and no sales charge has been applied to the indices used for comparison in the table. After-tax returns are calculated using the historical highest individual federal marginal income tax rates, and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. The after-tax returns shown are not relevant to you if you hold your Fund shares through a tax-deferred arrangement such as a 401(k) plan or individual retirement account. The return after taxes on distributions and sale of Fund shares may be higher than the return before taxes because the calculation assumes that shareholders receive a tax benefit for capital losses incurred on the sale of their shares.
Class A | Calvert Long-Term Income Fund | Barclays Long U.S. Credit Index (reflects no deduction for fees, expenses or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (4.56%)
5 Years rr_AverageAnnualReturnYear05 6.49%
10 Years rr_AverageAnnualReturnYear10 6.19%
Class A | Calvert Long-Term Income Fund | Lipper Corporate Debt Funds BBB Rated Avg. (reflects no deduction for taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (1.71%)
5 Years rr_AverageAnnualReturnYear05 4.11%
10 Years rr_AverageAnnualReturnYear10 4.91%
Class A | Calvert Long-Term Income Fund | Class A  
Prospectus: rr_ProspectusTable  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 3.75%
Maximum Deferred Sales Charge (as a percentage) rr_MaximumDeferredSalesChargeOverOther none [24]
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.52% [25]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.36%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.13%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 486
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 721
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 974
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,698
Annual Return 2006 rr_AnnualReturn2006 5.43%
Annual Return 2007 rr_AnnualReturn2007 8.28%
Annual Return 2008 rr_AnnualReturn2008 5.63%
Annual Return 2009 rr_AnnualReturn2009 17.09%
Annual Return 2010 rr_AnnualReturn2010 10.28%
Annual Return 2011 rr_AnnualReturn2011 9.47%
Annual Return 2012 rr_AnnualReturn2012 11.94%
Annual Return 2013 rr_AnnualReturn2013 (5.47%)
Annual Return 2014 rr_AnnualReturn2014 15.15%
Annual Return 2015 rr_AnnualReturn2015 (3.92%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best Quarter (of periods shown)
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Sep. 30, 2009
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 8.33%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst Quarter (of periods shown)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Jun. 30, 2015
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (6.81%)
1 Year rr_AverageAnnualReturnYear01 (7.52%)
5 Years rr_AverageAnnualReturnYear05 4.29%
10 Years rr_AverageAnnualReturnYear10 6.75%
Class A | Calvert Long-Term Income Fund | Class A | After Taxes on Distributions  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (8.61%)
5 Years rr_AverageAnnualReturnYear05 2.22%
10 Years rr_AverageAnnualReturnYear10 4.49%
Class A | Calvert Long-Term Income Fund | Class A | After Taxes on Distributions and Sales  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (4.26%)
5 Years rr_AverageAnnualReturnYear05 2.60%
10 Years rr_AverageAnnualReturnYear10 4.45%
Class A and Y | Calvert Ultra-Short Income Fund  
Prospectus: rr_ProspectusTable  
Risk/Return [Heading] rr_RiskReturnHeading CALVERT ULTRA-SHORT INCOME FUND Class (Ticker):A (CULAX)Y (CULYX) 
Objective [Heading] rr_ObjectiveHeading INVESTMENT OBJECTIVE
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
The Fund seeks to maximize income, to the extent consistent with preservation of capital, through investment in short-term bonds and income-producing securities.
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 sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in Calvert mutual funds. More information about these and other discounts is available from your financial professional and under “Choosing a Share Class” on page 47 and “Reduced Sales Charges” on page 50 of this Prospectus, and under “Method of Distribution” on page 40 of the Fund’s Statement of Additional Information.
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 % 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 (“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 66% of its portfolio’s average value.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 66.00%
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 $50,000 in Calvert mutual funds.
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;
•
your investment has a 5% return each year; and
•
the Fund’s operating expenses remain the same;
Strategy [Heading] rr_StrategyHeading INVESTMENTS, RISKS AND PERFORMANCE Principal Investment Strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
The Fund seeks to achieve its investment objective by investing, under normal circumstances, at least 80% of its net assets (including borrowings for investment purposes) in a portfolio of floating-rate securities (e.g., corporate floating-rate securities) and securities with durations of less than or equal to one year. The Fund will provide shareholders with at least 60 days’ notice before changing this 80% policy.
The Fund typically invests at least 65% of its net assets in investment grade, U.S. dollar-denominated debt securities, as assessed at the time of purchase. A debt security is investment grade when assigned a credit quality rating of BBB- or higher by Standard & Poor’s Ratings Services (“Standard & Poor’s”) or an equivalent rating by another nationally recognized statistical rating organization (‘‘NRSRO”), including Moody’s Investors Service or Fitch Ratings, or if unrated, considered to be of comparable credit quality by the Fund’s Advisor.
The Fund invests principally in bonds issued by U.S. corporations, the U.S. Government or its agencies, and U.S. government-sponsored enterprises (“GSEs”) such as the Federal National Mortgage Association (“FNMA”) and the Federal Home Loan Mortgage Corporation (“FHLMC”). The Fund also may invest in trust preferred securities, taxable municipal securities, leveraged loans and asset-backed securities (“ABS”), including commercial mortgage-backed securities.
The Fund may invest in securities that represent interests in pools of mortgage loans or other assets assembled for sale to investors by various U.S. governmental agencies, government-related organizations and private issuers. These investments may include securities such as collateralized mortgage obligations (“CMOs”) and ABS.
The Fund may invest up to 35% of its net assets in below-investment grade, high-yield debt securities (commonly known as “junk bonds”), including distressed securities that are in default. A debt security is below investment grade when assigned a credit quality rating below BBB- by Standard & Poor’s or an equivalent rating by another NRSRO, or if unrated, considered to be of comparable credit quality by the Fund’s Advisor.
The Fund may also invest up to 25% of its net assets in foreign debt securities. Foreign debt securities include American Depositary Receipts (“ADRs”).
The Fund is “non-diversified,” which means it may hold securities of a smaller number of issuers and invest a greater percentage of its assets in a particular issuer than a “diversified” fund.
Under normal circumstances, the Fund’s average portfolio duration will be less than one year.
The Fund uses an active trading strategy, seeking relative value to earn incremental income.
The Fund uses a hedging technique that includes the purchase and sale of U.S. Treasury securities and related futures contracts to manage the duration of the Fund and hedge interest rate risk.
Responsible Investing. In conjunction with Calvert’s financial analysis, Calvert’s comprehensive responsible investment principles guide our investment research processes and decision-making. The principles, which include the Advisor’s proprietary assessment of critical environmental, social and governance (“ESG”) issues, are applied across industries and to specific companies in order to inform our view of risk and opportunity factors that may affect investment performance.
Risk [Heading] rr_RiskHeading Principal Risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
You could lose money on your investment in the Fund, or the Fund could underperform, because of the risks described below. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Non-Diversification Risk. Because the Fund may hold securities of a smaller number of issuers or invest a greater percentage of its assets in a particular issuer than a diversified fund, the gains or losses on a single bond may have greater impact on the Fund than on a diversified fund.

Bond Market Risk. The market prices of bonds held by the Fund may fall.
Credit Risk. The credit quality of fixed-income securities may deteriorate, which could lead to default or bankruptcy of the issuer where the issuer becomes unable to pay its obligations when due.
Mortgage-Backed and Asset-Backed Securities Risk. The value of investments in mortgage-backed and asset-backed securities is subject to interest rate risk and credit risk. These securities are also subject to the risk that borrowers will prepay the principal on their loans more quickly than expected (prepayment risk) or more slowly than expected (extension risk), which will affect the yield, average life and price of the securities. In addition, faster than expected prepayments may cause the Fund to invest the prepaid principal in lower yielding securities and slower than expected prepayments may reduce the potential for the Fund to invest in higher yielding securities.
Mortgage-Backed Security Risk (Government-Sponsored Enterprises).  Debt and mortgage-backed securities issued by GSEs such as FNMA and FHLMC are neither insured nor guaranteed by the U.S. Treasury and are not backed by the full faith and credit of the U.S. government. Such securities are only supported by the credit of the applicable GSE. The U.S. government has provided financial support to FNMA and FHLMC, but there can be no assurance that it will support these or other GSEs in the future.
Leveraged Loan Risk. Leveraged loans are subject to the risks typically associated with debt securities, such as credit risk discussed above. The loans in which the Fund will invest are expected to be below-investment-grade quality and to bear interest at a floating rate that resets periodically. In addition, leveraged loans, which typically hold a senior position in the capital structure of a borrower, are subject to the risk that a court could subordinate such loans to presently existing or future indebtedness or take other action detrimental to the holders of leveraged loans. Leveraged loans are also subject to the risk that the value of the collateral, if any, securing a loan may decline, be insufficient to meet the obligations of the borrower, or be difficult to liquidate. Some leveraged loans are not as easily purchased or sold as publicly-traded securities and others are illiquid, which may make it more difficult for the Fund to value them or dispose of them at an acceptable price. Leveraged loans are usually more credit sensitive than investment-grade securities.
Management Risk. The individual investments of the Fund may not perform as expected, and the Fund’s portfolio management practices may not achieve the desired result.
Interest Rate Risk. A change in interest rates may adversely affect the value of fixed-income securities. When interest rates rise, the value of fixed-income securities will generally fall. Because a significant portion of securities held by the Fund may have variable or floating interest rates, the amounts of the Fund’s monthly distributions to shareholders are expected to vary with fluctuations in market interest rates. Generally, when market interest rates fall, the amount of the distributions to shareholders will likewise decrease.
Portfolio Duration Risk. Duration is a measure of the expected life of a fixed-income security and its sensitivity to changes in interest rates. The longer a fund’s average portfolio duration, the more sensitive the fund will be to changes in interest rates.
Lag Risk for Interest Payments. There may be a lag between an actual change in the underlying interest rate benchmark and the reset time for an interest payment for a floating-rate security, which could harm or benefit the Fund, depending on the circumstances. For example, a floating-rate security that does not reset immediately would prevent the Fund from taking full advantage of rising interest rates. In a declining interest rate environment, however, the Fund would benefit from the lag since the Fund would not immediately be impacted by a decline in interest rates.
Liquidity Risk. Liquidity risk exists when particular investments are difficult to sell. The Fund may be unable to sell illiquid securities at an advantageous time or price or achieve its desired level of exposure to a certain sector. Liquidity risk may result from the lack of an active market, reduced number and capacity of traditional market participants to make a market in fixed-income securities, and may be magnified in a rising interest rate environment or other circumstances where investor redemptions from fixed-income mutual funds may be higher than normal, causing increased supply in the market due to selling activity. Illiquid securities also may be difficult to value.
Junk Bond Risk. Investments in junk bonds can involve a substantial risk of loss. Junk bonds are considered to be speculative with respect to the issuer’s ability to pay interest and principal. These securities, which are rated below investment grade, have a higher risk of issuer default, are subject to greater price volatility than investment grade securities and may be illiquid.
Defaulted Bonds Risk. For bonds in default (rated “D” by Standard & Poor’s or the equivalent by another NRSRO), there is a significant risk that these bonds will not achieve their original value.
Unrated Security Risk. Unrated securities may be less liquid than rated securities determined to be of comparable credit quality by the Advisor. When the Fund purchases unrated securities, it will depend on the Advisor’s analysis of credit risk without the assessment of an NRSRO.
Taxable Municipal Bond Risk. Taxable municipal bonds are subject to credit risk, interest rate risk and certain additional risks. The Fund may be more sensitive to adverse economic, business or political developments if it invests a substantial portion of its assets in the bonds of similar projects or industrial development bonds.
Trust Preferred Securities Risk. Trust preferred securities are preferred stocks issued by a special purpose trust subsidiary backed by subordinated debt of the corporate parent. Trust preferred securities are subject to unique risks, which include the fact that dividend payments will only be paid if interest payments on the underlying obligations are made, which interest payments are dependent on the financial condition of the parent corporation. There is also the risk that the underlying obligations, and thus the trust preferred securities, may be prepaid after a stated call date or as a result of certain tax or regulatory events, resulting in a lower yield to maturity.
Collateralized Mortgage Obligation and Structured Asset-Backed Securities Risk. A CMO is a multiclass bond that is backed by a pool of mortgage loans or mortgage-backed securities. A structured ABS is a multiclass bond that is typically backed by a pool of auto loans, credit card receivables, home equity loans or student loans. A CMO or structured ABS is subject to interest rate risk, credit risk, prepayment risk and extension risk. In addition, if the Fund holds a class of a CMO or a structured ABS that is subordinated to other classes backed by the same pool of collateral, the likelihood that the Fund will receive payments of principal may be substantially limited.
Foreign Securities Risk. Investing in foreign securities involves additional risks relating to political, social, and economic developments abroad. Other risks result from the differences between the regulations to which U.S. and foreign issuers and markets are subject, and the potential for foreign markets to be less liquid and more volatile than U.S. markets. Foreign securities include ADRs. Unsponsored ADRs involve additional risks because U.S. reporting requirements do not apply and the issuing bank will recover shareholder distribution costs from movement of share prices and payment of dividends.
Foreign Currency Risk. Securities that trade or are denominated in currencies other than the U.S. dollar may be adversely affected by fluctuations in currency exchange rates. When the U.S. dollar strengthens relative to a foreign currency, the U.S. dollar value of an investment denominated in that currency will typically fall. ADRs indirectly bear currency risk because they represent an interest in securities that are not denominated in U.S. dollars.
Active Trading Strategy Risk. The Fund employs an active style that seeks to position the Fund with securities that offer the greatest price appreciation while minimizing risk. This style can result in higher turnover (exceeding 100%), may translate to higher transaction costs and may increase your tax liability.
Responsible Investing Risk. Investing primarily in responsible investments carries the risk that, under certain market conditions, the Fund may underperform funds that do not utilize a responsible investment strategy. The application of responsible investment principles may affect the Fund’s exposure to certain sectors or types of investments and may impact the Fund’s relative investment performance depending on whether such sectors or investments are in or out of favor in the market. A company’s ESG performance or the Advisor’s assessment of a company’s ESG performance may change over time, which could cause the Fund to temporarily hold securities that do not comply with the Fund’s responsible investment principles. In evaluating a company, the Advisor is dependent upon information and data that may be incomplete, inaccurate or unavailable, which could cause the Advisor to incorrectly assess a company’s ESG performance. Successful application of the Fund’s responsible investment strategy will depend on the Advisor’s skill in properly identifying and analyzing material ESG issues.
Futures Contracts Risk. The value of a futures contract tends to increase and decrease in tandem with the value of the underlying instrument. The price of futures can be highly volatile; using them could lower total return, and the potential loss from futures can exceed the Fund’s initial investment in such contracts. Futures contracts may not provide an effective hedge of the underlying securities or indexes because changes in the prices of futures contracts may not track those of the securities or indexes that they are intended to hedge.
Risk Lose Money [Text] rr_RiskLoseMoney You could lose money on your investment in the Fund, or the Fund could underperform, because of the risks described below.
Risk Nondiversified Status [Text] rr_RiskNondiversifiedStatus Non-Diversification Risk. Because the Fund may hold securities of a smaller number of issuers or invest a greater percentage of its assets in a particular issuer than a diversified fund, the gains or losses on a single bond may have greater impact on the Fund than on a diversified fund.
Risk Not Insured Depository Institution [Text] rr_RiskNotInsuredDepositoryInstitution An investment in the Fund is not a bank deposit and 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 following bar chart and table show the Fund’s annual returns and its long-term performance, which give some indication of the risks of investing in the Fund. The bar chart shows how the performance of the Class A shares has varied from year to year. The table compares the Fund’s performance over time with that of a benchmark and a performance average of similar mutual funds. The performance reflected in the bar chart and table assumes the reinvestment of dividends and capital gains distributions, if any.
The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. For updated performance information, visit www.calvert.com.
Performance results for Class Y shares prior to May 28, 2010 (the Class Y shares’ inception date) reflect the performance of Class A shares at net asset value. Actual Class Y share performance would have been higher than Class A share performance because Class Y has lower class-specific expenses than Class A.
The return for each of the Fund’s other Classes of shares will differ from the Class A returns shown in the bar chart, depending upon the expenses of that Class. The bar chart does not reflect any sales charge that you may be required to pay upon purchase or redemption of the Fund’s shares. Any sales charge will reduce your return.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following bar chart and table show the Fund’s annual returns and its long-term performance, which give some indication of the risks of investing in the Fund.
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress www.calvert.com
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar Year Total Returns for Class A at NAV
Bar Chart Does Not Reflect Sales Loads [Text] rr_BarChartDoesNotReflectSalesLoads The bar chart does not reflect any sales charge that you may be required to pay upon purchase or redemption of the Fund’s shares. Any sales charge will reduce your return.
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
 
Quarter
Ended
 
Total
Return
Best Quarter (of periods shown)
6/30/09
 
3.25%
Worst Quarter (of periods shown)
09/30/11
 
-0.78%
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns (as of 12-31-15) (with maximum sales charge deducted, if any)
Performance Table Does Reflect Sales Loads rr_PerformanceTableDoesReflectSalesLoads The average total return table shows the Fund’s returns with the maximum sales charge deducted, and no sales charge has been applied to the indices used for comparison in the table.
Performance Table Uses Highest Federal Rate rr_PerformanceTableUsesHighestFederalRate After-tax returns are calculated using the historical highest individual federal marginal income tax rates, and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred rr_PerformanceTableNotRelevantToTaxDeferred The after-tax returns shown are not relevant to you if you hold your Fund shares through a tax-deferred arrangement such as a 401(k) plan or individual retirement account.
Performance Table Explanation after Tax Higher rr_PerformanceTableExplanationAfterTaxHigher The return after taxes on distributions and sale of Fund shares may be higher than the return before taxes because the calculation assumes that shareholders receive a tax benefit for capital losses incurred on the sale of their shares.
Performance Table Narrative rr_PerformanceTableNarrativeTextBlock
The average total return table shows the Fund’s returns with the maximum sales charge deducted, and no sales charge has been applied to the indices used for comparison in the table.
After-tax returns are calculated using the historical highest individual federal marginal income tax rates, and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. The after-tax returns shown are not relevant to you if you hold your Fund shares through a tax-deferred arrangement such as a 401(k) plan or individual retirement account. The return after taxes on distributions and sale of Fund shares may be higher than the return before taxes because the calculation assumes that shareholders receive a tax benefit for capital losses incurred on the sale of their shares.
Class A and Y | Calvert Ultra-Short Income Fund | Barclays Short Treasury Index 9-12 months (reflects no deduction for fees, expenses or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 0.20%
5 Years rr_AverageAnnualReturnYear05 0.27%
Since Inception rr_AverageAnnualReturnSinceInception 1.51%
Inception Date rr_AverageAnnualReturnInceptionDate Oct. 31, 2006
Class A and Y | Calvert Ultra-Short Income Fund | Lipper Ultra-Short Obligations Funds Avg. (reflects no deduction for taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 0.13%
5 Years rr_AverageAnnualReturnYear05 0.66%
Since Inception rr_AverageAnnualReturnSinceInception 1.61%
Inception Date rr_AverageAnnualReturnInceptionDate Oct. 31, 2006
Class A and Y | Calvert Ultra-Short Income Fund | Class A  
Prospectus: rr_ProspectusTable  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 1.25%
Maximum Deferred Sales Charge (as a percentage) rr_MaximumDeferredSalesChargeOverOther none [26]
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.42% [27]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.20%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.87%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination January 31, 2017
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 213
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 399
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 601
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,184
Annual Return 2007 rr_AnnualReturn2007 5.20%
Annual Return 2008 rr_AnnualReturn2008 2.98%
Annual Return 2009 rr_AnnualReturn2009 7.29%
Annual Return 2010 rr_AnnualReturn2010 2.30%
Annual Return 2011 rr_AnnualReturn2011 0.20%
Annual Return 2012 rr_AnnualReturn2012 2.46%
Annual Return 2013 rr_AnnualReturn2013 0.90%
Annual Return 2014 rr_AnnualReturn2014 0.55%
Annual Return 2015 rr_AnnualReturn2015 0.21%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best Quarter (of periods shown)
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2009
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 3.25%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst Quarter (of periods shown)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Sep. 30, 2011
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (0.78%)
1 Year rr_AverageAnnualReturnYear01 (1.07%)
5 Years rr_AverageAnnualReturnYear05 0.60%
Since Inception rr_AverageAnnualReturnSinceInception 2.33%
Inception Date rr_AverageAnnualReturnInceptionDate Oct. 31, 2006
Class A and Y | Calvert Ultra-Short Income Fund | Class A | After Taxes on Distributions  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (1.38%)
5 Years rr_AverageAnnualReturnYear05 0.19%
Since Inception rr_AverageAnnualReturnSinceInception 1.57%
Inception Date rr_AverageAnnualReturnInceptionDate Oct. 31, 2006
Class A and Y | Calvert Ultra-Short Income Fund | Class A | After Taxes on Distributions and Sales  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (0.60%)
5 Years rr_AverageAnnualReturnYear05 0.30%
Since Inception rr_AverageAnnualReturnSinceInception 1.52%
Inception Date rr_AverageAnnualReturnInceptionDate Oct. 31, 2006
Class A and Y | Calvert Ultra-Short Income Fund | Class Y  
Prospectus: rr_ProspectusTable  
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% [27]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.14%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.56%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination January 31, 2017
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 57
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 179
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 313
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 701
1 Year rr_AverageAnnualReturnYear01 0.47%
5 Years rr_AverageAnnualReturnYear05 1.07%
Since Inception rr_AverageAnnualReturnSinceInception 2.60%
Inception Date rr_AverageAnnualReturnInceptionDate Oct. 31, 2006
[1] Purchases of Class A shares at net asset value for accounts with $1,000,000 or more on which a finder’s fee has been paid by the Fund’s distributor are subject to a one-year contingent deferred sales charge of 0.80%.
[2] Management fees are restated to reflect current contractual fees rather than the fees paid during the previous fiscal year.
[3] The contingent deferred sales charge decreases over time.
[4] Purchases of Class A shares at net asset value for accounts with $250,000 or more on which a finder’s fee has been paid by the Fund’s distributor are subject to a one-year contingent deferred sales charge of 0.50%.
[5] Management fees are restated to reflect current contractual fees rather than the fees paid during the previous fiscal year.
[6] The contingent deferred sales charge decreases over time.
[7] Purchases of Class A shares at net asset value for accounts with $1,000,000 or more on which a finder’s fee has been paid by the Fund’s distributor are subject to a one-year contingent deferred sales charge of 0.80%.
[8] Management fees are restated to reflect current contractual fees rather than the fees paid during the previous fiscal year.
[9] The investment advisor has agreed to contractually limit direct net annual fund operating expenses through January 31, 2017. Direct net operating expenses will not exceed 1.07% for Class A, 1.82% for Class C, and 0.82% for Class Y. Calvert has further agreed to contractually limit direct net annual fund operating expenses for Class Y to 3.00% through January 31, 2023. Only the Board of Trustees of the Fund may terminate the Fund’s expense limitation before the contractual period expires, upon 60 days’ prior notice to shareholders. The contractual administrative fee is 0.12%. Calvert has agreed to contractually waive 0.02% of the administrative fee through January 31, 2018.
[10] The contingent deferred sales charge decreases over time.
[11] Management fees are restated to reflect current contractual fees rather than the fees paid during the previous fiscal year.
[12] The contractual administrative fee is 0.12%. Calvert has agreed to contractually waive 0.02% of the administrative fee through January 31, 2018.
[13] Management fees are restated to reflect current contractual fees rather than the fees paid during the previous fiscal year.
[14] The contractual administrative fee is 0.12%. Calvert has agreed to contractually waive 0.02% of the administrative fee through January 31, 2018.
[15] Based on actual expenses for the past fiscal year, adjusted for estimates of Class I specific expenses.
[16] Management fees are restated to reflect current contractual fees rather than the fees paid during the previous fiscal year.
[17] The investment advisor has agreed to contractually limit direct net annual fund operating expenses through January 31, 2017. Direct net operating expenses will not exceed 0.55% for Class I. Calvert has further agreed to contractually limit direct net annual fund operating expenses for Class I to 2.00% through January 31, 2026. Only the Board of Trustees of the Fund may terminate the Fund’s expense limitation before the contractual period expires, upon 60 days’ prior notice to shareholders. The contractual administrative fee is 0.12%. Calvert has agreed to contractually waive 0.02% of the administrative fee through January 31, 2018.
[18] Management fees are restated to reflect current contractual fees rather than the fees paid during the previous fiscal year.
[19] The investment advisor has agreed to contractually limit direct net annual fund operating expenses through January 31, 2017. Direct net operating expenses will not exceed 0.50% for Class I. Only the Board of Trustees of the Fund may terminate the Fund’s expense limitation before the contractual period expires, upon 60 days’ prior notice to shareholders. The contractual administrative fee is 0.12%. Calvert has agreed to contractually waive 0.02% of the administrative fee through January 31, 2018.
[20] Management fees are restated to reflect current contractual fees rather than the fees paid during the previous fiscal year.
[21] The investment advisor has agreed to contractually limit direct net annual fund operating expenses through January 31, 2017. Direct net operating expenses will not exceed 0.74% for Class I. Only the Board of Trustees of the Fund may terminate the Fund’s expense limitation before the contractual period expires, upon 60 days’ prior notice to shareholders. The contractual administrative fee is 0.12%. Calvert has agreed to contractually waive 0.02% of the administrative fee through January 31, 2018.
[22] Management fees are restated to reflect current contractual fees rather than the fees paid during the previous fiscal year.
[23] The investment advisor has agreed to contractually limit direct net annual fund operating expenses through January 31, 2017. Direct net operating expenses will not exceed 1.47% for Class R. Only the Board of Trustees of the Fund may terminate the Fund’s expense limitation before the contractual period expires, upon 60 days’ prior notice to shareholders.
[24] Purchases of Class A shares at net asset value for accounts with $1,000,000 or more on which a finder’s fee has been paid by the Fund’s distributor are subject to a one-year contingent deferred sales charge of 0.80%.
[25] Management fees are restated to reflect current contractual fees rather than the fees paid during the previous fiscal year.
[26] Purchases of Class A shares at net asset value for accounts with $250,000 or more on which a finder’s fee has been paid by the Fund’s distributor are subject to a one-year contingent deferred sales charge of 0.15%.
[27] Management fees are restated to reflect current contractual fees rather than the fees paid during the previous fiscal year.