dei_DocumentType

485BPOS

dei_EntityRegistrantName

Calvert Fund

Amendment Flag

dei_AmendmentFlag

false

Document Effective Date

dei_DocumentEffectiveDate

Jan. 31, 2015

Risk/Return [Heading]

rr_RiskReturnHeading

CALVERT INCOME FUND Class (Ticker):R (CICRX)

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 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.

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 [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 214% of its portfolio’s average value.

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Strategy [Heading]

rr_StrategyHeading

INVESTMENTS, RISKS AND PERFORMANCE Principal Investment Strategies

Risk [Heading]

rr_RiskHeading

Principal Risks

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 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.

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 R shares has varied from year to year. The table compares the Fund’s performance over time with that of a benchmark and a peer average. 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. 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 Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.calvert.com

Bar Chart [Heading]

rr_BarChartHeading

Calendar Year Total Returns

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Total Returns (as of 12-31-14)

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 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.

Risk/Return:

rr_RiskReturnAbstract

5 Years

rr_AverageAnnualReturnYear05

6.25%

1 Year

rr_AverageAnnualReturnYear01

7.07%

10 Years

rr_AverageAnnualReturnYear10

5.28%

Risk/Return:

rr_RiskReturnAbstract

Management Fees (as a percentage of Assets)

rr_ManagementFeesOverAssets

0.70%

Other Expenses (as a percentage of Assets):

rr_OtherExpensesOverAssets

0.49%

Fee Waiver or Reimbursement

rr_FeeWaiverOrReimbursementOverAssets

(0.22%)

^[1]

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

January 31, 2016

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

511

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

rr_AnnualReturn2006

rr_AnnualReturn2008

rr_AnnualReturn2010

rr_AnnualReturn2012

rr_AnnualReturn2014

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2009

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter (of periods shown)

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(7.79%)

5 Years

rr_AverageAnnualReturnYear05

4.11%

1 Year

rr_AverageAnnualReturnYear01

3.46%

10 Years

rr_AverageAnnualReturnYear10

2.17%

Risk/Return:

rr_RiskReturnAbstract

5 Years

rr_AverageAnnualReturnYear05

2.72%

Risk/Return [Heading]

rr_RiskReturnHeading

CALVERT INCOME FUND Class (Ticker):A (CFICX)B (CBINX)C (CIFCX)Y (CIFYX)

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 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 52 and “Reduced Sales Charges” on page 56 of this Prospectus, and under “Method of Distribution” on page 40 of the Fund’s Statement of Additional Information.

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 [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 214% of its portfolio’s average value.

Expenses Deferred Charges [Text Block]

rr_ExpensesDeferredChargesTextBlock

The contingent deferred sales charge decreases over time.

Expense Breakpoint, Minimum Investment Required [Amount]

rr_ExpenseBreakpointMinimumInvestmentRequiredAmount

50,000

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 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 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, asset-backed securities (“ABS”), including commercial mortgage-backed securities, and repurchase agreements.

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 derivative 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.

The Fund uses an active trading strategy, seeking relative value to earn incremental income. The Fund’s investment process is enhanced by the Advisor’s integrated investment research, which seeks to add value by complementing traditional fundamental security analysis with the Advisor’s proprietary assessment of critical environmental, social and governance (“ESG”) issues. The Fund seeks to apply ESG integration across sectors and holdings as part of its risk and opportunity assessment.

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.

Tobacco Exclusion. The Fund seeks to avoid investing in companies classified under the tobacco industry sector of the Barclays Global Aggregate Index, the Barclays U.S. High Yield Index or the Barclays Global Emerging Market Index; or, in the opinion of the Fund’s Advisor, any similar securities in the Barclays Municipal Index.

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.

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.

Repurchase Agreement Risk. A repurchase agreement exposes the Fund to the risk that the party that sells the security may default on its obligation to repurchase the security. The Fund may lose money because it cannot sell the security at the agreed-upon time and price or the security may lose value before it can be sold.

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.

ESG Strategy Risk. The ESG strategies used by an investment manager may fail to produce the intended result. In addition, information used to evaluate the ESG performance of issuers and industries may not be readily available, complete, or accurate, which could negatively impact both the investment manager's application of ESG standards and Fund performance.

Tobacco Exclusion Risk. Because the Fund avoids investing in certain tobacco-related securities, the Fund may forego a profitable investment opportunity and the associated return.

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.

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.

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 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 peer average.

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 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.

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Total Returns (as of 12-31-14) (with maximum sales charge deducted, if any)

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 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 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.

Risk/Return:

rr_RiskReturnAbstract

5 Years

rr_AverageAnnualReturnYear05

6.25%

1 Year

rr_AverageAnnualReturnYear01

7.07%

10 Years

rr_AverageAnnualReturnYear10

5.28%

Risk/Return:

rr_RiskReturnAbstract

Maximum Deferred Sales Charge (as a percentage)

rr_MaximumDeferredSalesChargeOverOther

none

^[2]

Distribution and Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Expenses (as a percentage of Assets)

rr_ExpensesOverAssets

1.25%

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

757

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

rr_AnnualReturn2006

rr_AnnualReturn2008

rr_AnnualReturn2010

rr_AnnualReturn2012

rr_AnnualReturn2014

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2009

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter (of periods shown)

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(7.72%)

5 Years

rr_AverageAnnualReturnYear05

3.53%

1 Year

rr_AverageAnnualReturnYear01

(0.29%)

10 Years

rr_AverageAnnualReturnYear10

1.87%

Risk/Return:

rr_RiskReturnAbstract

5 Years

rr_AverageAnnualReturnYear05

2.23%

Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Management Fees (as a percentage of Assets)

rr_ManagementFeesOverAssets

0.70%

Other Expenses (as a percentage of Assets):

rr_OtherExpensesOverAssets

0.47%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

620

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

1,164

Expense Example, No Redemption, 1 Year

rr_ExpenseExampleNoRedemptionYear01

220

Expense Example, No Redemption, 5 Years

rr_ExpenseExampleNoRedemptionYear05

1,164

1 Year

rr_AverageAnnualReturnYear01

(0.11%)

10 Years

rr_AverageAnnualReturnYear10

2.86%

Risk/Return:

rr_RiskReturnAbstract

Maximum Deferred Sales Charge (as a percentage)

rr_MaximumDeferredSalesChargeOverOther

1.00%

^[3]

Distribution and Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

1.00%

Expenses (as a percentage of Assets)

rr_ExpensesOverAssets

1.94%

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

609

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

2,264

Expense Example, No Redemption, 3 Years

rr_ExpenseExampleNoRedemptionYear03

609

Expense Example, No Redemption, 10 Years

rr_ExpenseExampleNoRedemptionYear10

2,264

5 Years

rr_AverageAnnualReturnYear05

3.59%

Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Management Fees (as a percentage of Assets)

rr_ManagementFeesOverAssets

0.70%

Other Expenses (as a percentage of Assets):

rr_OtherExpensesOverAssets

0.19%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

91

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

493

1 Year

rr_AverageAnnualReturnYear01

5.24%

10 Years

rr_AverageAnnualReturnYear10

4.00%

Risk/Return:

rr_RiskReturnAbstract

Objective [Heading]

rr_ObjectiveHeading

INVESTMENT OBJECTIVE

Expense [Heading]

rr_ExpenseHeading

FEES AND EXPENSES OF THE FUND

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder Fees (fees paid directly from your investment)

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio Turnover

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

214.00%

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; and


•	the Fund’s operating expenses remain the same.