This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year, that the operating expenses remain the same and that any expense reimbursement arrangement remains in place for the contractual period. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy Narrative

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Under normal circumstances, the Fund invests at least 80% of its net assets (including borrowings for investment purposes) in high-yield, high-risk bonds, also known as “junk” bonds (“80% Policy”). The Fund invests primarily in high-yield, high-risk bonds with varying maturities, including distressed securities that are in default, which are rated lower than investment grade (i.e., bonds rated lower than Baa by Moody’s Investors Service, Inc. (“Moody’s”) or lower than BBB by S&P Global Ratings (“S&P”) or Fitch Ratings (“Fitch”)). For purposes of ratings restrictions, the average of S&P, Moody’s and Fitch is used. The Fund’s duration and maturity is managed tactically based on the investment adviser’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.

The Fund also may invest in trust preferred securities, taxable municipal obligations and loans. In addition, the Fund may invest up to 35% of its net assets in foreign debt securities. Foreign debt securities include American Depositary Receipts (“ADRs”). The Fund may also invest in investment grade bonds (i.e., bonds rated Baa or higher by Moody’s or BBB or higher by S&P).

The Fund may engage in forward foreign currency exchange contracts to seek to hedge against the decline in the value of currencies in which its portfolio holdings are denominated against the U.S. dollar. The portfolio managers generally seek to hedge the Fund’s foreign currency exposure back to U.S. dollars, though the Fund may at any time have exposure to foreign currency.

The Fund may invest in asset-backed securities (“ABS”) and mortgage-backed securities (“MBS”) that represent interests in pools of mortgage loans (MBS) or other assets (ABS) assembled for sale to investors by various U.S. governmental agencies, government-related organizations and private issuers. MBS may include collateralized mortgage obligations (“CMOs”) and commercial mortgage-backed securities (“CMBS”). The Fund may invest up to 10% of its net assets in MBS and up to 10% of its net assets in 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 (which are a type of derivative instrument) to manage the duration of the Fund and hedge interest rate risk. The Fund may invest in money market instruments. The Fund may also lend its securities.

The investment adviser’s staff monitors the credit quality of securities held by the Fund and other securities available to the Fund. Although the investment adviser considers security ratings when making investment decisions, it performs its own credit and investment analysis utilizing various methodologies including “bottom up/top down” analysis and consideration of macroeconomic and technical factors, and does not rely primarily on the ratings assigned by the rating services. In conjunction with its financial analysis, investment decisions are made in consideration of the responsible investment criteria described below. The portfolio managers may also use sector rotation strategies in their management of the Fund. The portfolio managers may sell a security when the investment adviser’s valuation target is reached, the fundamentals of the investment change or to pursue more attractive investment options. A security will also be sold (in accordance with the investment adviser’s guidelines and at a time and in a manner that is determined to be in the best interests of shareholders) if the investment adviser determines that the issuer does not operate in a manner consistent with the Fund’s responsible investment criteria. The portfolio managers attempt to improve yield and preserve and enhance principal value through timely trading. The portfolio managers also consider the relative value of securities in the marketplace in making investment decisions.

Responsible Investing. The portfolio manager(s) seek to invest in companies that manage environmental, social and governance (“ESG”) risk exposures adequately and that are not exposed to excessive ESG risk through their principal business activities. Companies are analyzed by the investment adviser’s ESG analysts utilizing The Calvert Principles for Responsible Investment (“Principles”), a framework for considering ESG factors (a copy of which is included as an appendix to the Fund’s Prospectus). Each company is evaluated relative to an appropriate peer group based on material ESG factors as determined by the investment adviser. Pursuant to the Principles, the investment adviser seeks to identify companies and other issuers that operate in a manner that is consistent with or promotes environmental sustainability and resource efficiency, equitable societies and respect for human rights, and accountable governance and transparency. The Fund generally invests in issuers that are believed by the investment adviser to operate in accordance with the Principles and may also invest in issuers that the investment adviser believes are likely to operate in accordance with the Principles pending the investment adviser’s engagement activity with such issuer.

Risk

rr_RiskHeading

Principal Risks

Risk Lose Money

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The Fund is not a complete investment program and there is no guarantee that the Fund will achieve its investment objective. It is possible to lose money by investing in the Fund.

Bar Chart and Performance Table

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Performance

Performance Information Illustrates Variability of Returns

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The following bar chart and table provide some indication of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year and how the Fund’s average annual returns over time compare with those of a broad-based securities market index.

Performance Past Does Not Indicate Future

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

Annual Return Caption

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Calendar year-by-year total return

Performance Table Does Reflect Sales Loads

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These returns reflect a reduction to the Class A front-end sales charge effective April 29, 2022 and any applicable contingent deferred sales charge (“CDSC”) for Class C. Effective November 5, 2020, Class C shares automatically convert to Class A shares eight years after purchase. The average total returns listed for Class C reflect conversion to Class A shares after eight years. Prior to November 5, 2020, Class C shares automatically converted to Class A shares ten years after purchase.

Performance Table Not Relevant to Tax Deferred

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After-tax returns are not relevant to shareholders who hold shares in tax-deferred accounts or to shares held by non-taxable entities.

Performance Table Explanation after Tax Higher

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Return After Taxes on Distributions for a period may be the same as Return Before Taxes for that period because no taxable distributions were made during that period. Also, Return After Taxes on Distributions and Sale of Fund Shares for a period may be greater than or equal to Return Before Taxes and/or Return After Taxes on Distributions for the same period because of losses realized on the sale of Fund shares.

Performance Table Closing

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These returns reflect a reduction to the Class A front-end sales charge effective April 29, 2022 and any applicable contingent deferred sales charge (“CDSC”) for Class C. Effective November 5, 2020, Class C shares automatically convert to Class A shares eight years after purchase. The average total returns listed for Class C reflect conversion to Class A shares after eight years. Prior to November 5, 2020, Class C shares automatically converted to Class A shares ten years after purchase. The Class R6 performance shown above for the period prior to February 1, 2019 (commencement of operations) is the performance of Class I shares at net asset value without adjustment for any differences in the expenses of the two classes. If adjusted for such differences, returns would be different.. ICE® BofA® indices are not for redistribution or other uses; provided “as is,” without warranties, and with no liability. Eaton Vance has prepared this report and ICE Data Indices, LLC does not endorse it, or guarantee, review, or endorse Eaton Vance’s products. BofA® is a licensed registered trademark of Bank of America Corporation in the United States and other countries. Investors cannot invest directly in an Index.

After-tax returns are calculated using the highest historical individual federal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on a shareholder’s tax situation and the actual characterization of distributions, and may differ from those shown. After-tax returns are not relevant to shareholders who hold shares in tax-deferred accounts or to shares held by non-taxable entities. After-tax returns for other Classes of shares will vary from the after-tax returns presented for Class A shares. Return After Taxes on Distributions for a period may be the same as Return Before Taxes for that period because no taxable distributions were made during that period. Also, Return After Taxes on Distributions and Sale of Fund Shares for a period may be greater than or equal to Return Before Taxes and/or Return After Taxes on Distributions for the same period because of losses realized on the sale of Fund shares.

Index No Deduction for Fees, Expenses, Taxes

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(reflects no deduction for fees, expenses or taxes)

Five Years

rr_AverageAnnualReturnYear05

2.12%

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

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

3.25%

Management Fees

rr_ManagementFeesOverAssets

0.60%

Other Expenses

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0.17%

1 Year

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$ 426

5 Years

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870

1 Year

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426

5 Years

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870

2013

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8.24%

2015

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(2.45%)

2017

rr_AnnualReturn2017

5.78%

2019

rr_AnnualReturn2019

12.54%

2021

rr_AnnualReturn2021

3.39%

Highest Quarterly Return, Label

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highest quarterly total return

Highest Quarterly Return

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7.33%

Lowest Quarterly Return, Date

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Mar. 31, 2020

One Year

rr_AverageAnnualReturnYear01

(13.88%)

Ten Years

rr_AverageAnnualReturnYear10

2.36%

Prospectus [Line Items]

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Five Years

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(1.34%)

One Year

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(8.19%)

Ten Years

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0.75%

Prospectus [Line Items]

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Maximum Deferred Sales Charge (load) (as a percentage of the lower of net asset value at purchase or redemption)

rr_MaximumDeferredSalesChargeOverOfferingPrice

1.00%

Distribution and Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

1.00%

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

1.77%

3 Years

rr_ExpenseExampleYear03

557

10 Years

rr_ExpenseExampleYear10

1,886

3 Years

rr_ExpenseExampleNoRedemptionYear03

557

10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 1,886

Five Years

rr_AverageAnnualReturnYear05

0.39%

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

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Management Fees

rr_ManagementFeesOverAssets

0.60%

Other Expenses

rr_OtherExpensesOverAssets

0.17%

1 Year

rr_ExpenseExampleYear01

$ 79

5 Years

rr_ExpenseExampleYear05

428

1 Year

rr_ExpenseExampleNoRedemptionYear01

79

5 Years

rr_ExpenseExampleNoRedemptionYear05

428

One Year

rr_AverageAnnualReturnYear01

(10.76%)

Ten Years

rr_AverageAnnualReturnYear10

3.00%

Prospectus [Line Items]

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Maximum Deferred Sales Charge (load) (as a percentage of the lower of net asset value at purchase or redemption)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Distribution and Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

none

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

0.69%

3 Years

rr_ExpenseExampleYear03

221

10 Years

rr_ExpenseExampleYear10

859

3 Years

rr_ExpenseExampleNoRedemptionYear03

221

10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 859

Five Years

rr_AverageAnnualReturnYear05

1.48%

Inception Date

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Feb. 01, 2019

Prospectus [Line Items]

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Objective, Primary

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The Fund's investment objective is to seek to maximize income, to the extent consistent with preservation of capital, through investment in bonds and income-producing securities.

Expense Narrative

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This table describes the fees and expenses that you may pay if you buy, hold and sell shares of the Fund. Investors may also pay commissions or other fees to their financial intermediary, which are not reflected below. You may qualify for sales charge discounts on purchases of Class A shares if you and your family invest, or agree to invest over a 13-month period, at least $100,000 in Calvert mutual funds. Certain financial intermediaries also may offer variations in Fund sales charges to their customers as described in Appendix B - Financial Intermediary Sales Charge Variations in this Prospectus. More information about these and other discounts is available from your financial professional and under “Sales Charges” on page 79 of this Prospectus and page 25 of the Fund’s Statement of Additional Information.

Operating Expenses Caption

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Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Portfolio Turnover

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The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” the 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 51% of the average value of its portfolio.

Expense Breakpoint Discounts

rr_ExpenseBreakpointDiscounts

You may qualify for sales charge discounts on purchases of Class A shares if you and your family invest, or agree to invest over a 13-month period, at least $100,000 in Calvert mutual funds. Certain financial intermediaries also may offer variations in Fund sales charges to their customers as described in Appendix B - Financial Intermediary Sales Charge Variations in this Prospectus. More information about these and other discounts is available from your financial professional and under “Sales Charges” on page 79 of this Prospectus and page 25 of the Fund’s Statement of Additional Information.

Expense Example

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Example.

Strategy

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Principal Investment Strategies

Strategy Portfolio Concentration

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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 S&P Global Ratings (“S&P”) or an equivalent rating by another nationally recognized statistical rating organization (“NRSRO”), including Moody’s Investors Service, Inc. or Fitch Ratings, or Kroll Bond Rating Agency, LLC for securitized debt instruments only (such as asset-backed securities (“ABS”) and mortgage-backed securities (“MBS”)) or if unrated, considered to be of comparable credit quality by the Fund’s investment adviser. For purposes of rating restrictions, if securities are rated differently by two or more rating agencies, the highest rating is used.

Risk Narrative

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Market Risk. The value of investments held by the Fund may increase or decrease in response to social, economic, political, financial, public health crises or other disruptive events (whether real, expected or perceived) in the U.S. and global markets and include events such as war, natural disasters, epidemics and pandemics, terrorism, conflicts and social unrest. These events may negatively impact broad segments of businesses and populations and may exacerbate pre-existing risks to the Fund. The frequency and magnitude of resulting changes in the value of the Fund’s investments cannot be predicted. Certain securities and other investments held by the Fund may experience increased volatility,

illiquidity, or other potentially adverse effects in reaction to changing market conditions. Monetary and/or fiscal actions taken by U.S. or foreign governments to stimulate or stabilize the global economy may not be effective and could lead to high market volatility. No active trading market may exist for certain investments held by the Fund, which may impair the ability of the Fund to sell or to realize the full value of such investments in the event of the need to liquidate such assets.

Interest Rate Risk. In general, the value of income securities will fluctuate based on changes in interest rates. The value of these securities is likely to increase when interest rates fall and decline when interest rates rise. Duration measures a fixed-income security’s price sensitivity to changes in the general level of interest rates. Generally, securities with longer durations or maturities are more sensitive to changes in interest rates than securities with shorter durations or maturities, causing them to be more volatile. Conversely, fixed-income securities with shorter durations or maturities will be less volatile but may provide lower returns than fixed-income securities with longer durations or maturities. In a rising interest rate environment, the duration of income securities that have the ability to be prepaid or called by the issuer may be extended. In a declining interest rate environment, the proceeds from prepaid or maturing instruments may have to be reinvested at a lower interest rate.

LIBOR Risk. The London Interbank Offered Rate or LIBOR is used throughout global banking and financial industries to determine interest rates for a variety of financial instruments (such as debt instruments and derivatives) and borrowing arrangements. The ICE Benchmark Administration Limited, the administrator of LIBOR, ceased publishing certain LIBOR settings on December 31, 2021, and is expected to cease publishing the remaining LIBOR settings on June 30, 2023. The Fund has exposure to LIBOR-based instruments. Although the transition process away from LIBOR has become increasingly well defined, the impact on certain debt securities, derivatives and other financial instruments that utilize LIBOR remains uncertain. The transition process may involve, among other things, increased volatility or illiquidity in markets for instruments that currently rely on LIBOR, such as floating-rate debt obligations. Any effects of the transition away from LIBOR and the adoption of alternative reference rates, as well as other unforeseen effects, could result in losses to the Fund, and such effects may occur prior to the anticipated discontinuation of the remaining LIBOR settings in 2023. Furthermore, the risks associated with the discontinuation of LIBOR and transition to replacement rates may be exacerbated if an orderly transition to an alternative reference rate is not completed in a timely manner.

Credit Risk. Investments in debt securities (including bonds) and loans (referred to below as “debt instruments”) are subject to the risk of non-payment of scheduled principal and interest. Changes in economic conditions or other circumstances may reduce the capacity of the party obligated to make principal and interest payments on such instruments and may lead to defaults. Such non-payments and defaults may reduce the value of Fund shares and income distributions. The value of debt instruments also may decline because of concerns about the issuer’s ability to make principal and interest payments. In addition, the credit ratings of debt instruments may be lowered if the financial condition of the party obligated to make payments with respect to such instruments deteriorates. In the event of bankruptcy of the issuer of a debt instrument, the Fund could experience delays or limitations with respect to its ability to realize the benefits of any collateral securing the instrument. In order to enforce its rights in the event of a default, bankruptcy or similar situation, the Fund may be required to retain legal or similar counsel, which may increase the Fund’s operating expenses and adversely affect net asset value.

Mortgage- and Asset-Backed Securities Risk. Mortgage- and asset-backed securities represent interests in “pools” of commercial or residential mortgages or other assets, including consumer loans or receivables. Movements in interest rates (both increases and decreases) may quickly and significantly reduce the value of certain types of mortgage- and asset-backed securities. Although certain mortgage- and asset-backed securities are guaranteed as to timely payment of interest and principal by a government entity, the market price for such securities is not guaranteed and will fluctuate. The purchase of mortgage- and asset-backed securities issued by non-government entities may entail greater risk than such securities that are issued or guaranteed by a government entity. Mortgage- and asset-backed securities issued by non-government entities may offer higher yields than those issued by government entities, but may also be subject to greater volatility than government issues and can also be subject to greater credit risk and the risk of default on the underlying mortgages or other assets. Investments in mortgage- and asset-backed securities are subject to both extension risk, where borrowers pay off their debt obligations more slowly in times of rising interest rates, and prepayment risk, where borrowers pay off their debt obligations sooner than expected in times of declining interest rates.

U.S. Government Securities Risk. Although certain U.S. Government-sponsored agencies (such as the Federal Home Loan Mortgage Corporation and the Federal National Mortgage Association) may be chartered or sponsored by acts of Congress, their securities are neither issued nor guaranteed by the U.S. Treasury. U.S. Treasury securities generally have a lower return than other obligations because of their higher credit quality and market liquidity.

Convertible and Other Hybrid Securities Risk. Convertible and other hybrid securities (including preferred and convertible instruments) generally possess certain characteristics of both equity and debt securities. In addition to risks associated with investing in income securities, such as interest rate and credit risks, hybrid securities may be subject to issuer-specific and market risks generally applicable to equity securities. Convertible securities may also react to changes

in the value of the common stock into which they convert, and are thus subject to equity investing and market risks. A convertible security may be converted at an inopportune time, which may decrease the Fund’s return.

Preferred Stock Risk. Although preferred stocks represent an ownership interest in an issuer, preferred stocks generally do not have voting rights or have limited voting rights and have economic characteristics similar to fixed-income securities. Preferred stocks are subject to issuer-specific risks generally applicable to equity securities and credit and interest rate risks generally applicable to fixed-income securities. The value of preferred stock generally declines when interest rates rise and may react more significantly than bonds and other debt instruments to actual or perceived changes in the company’s financial condition or prospects.

Municipal Obligations Risk. The amount of public information available about municipal obligations is generally less than for corporate equities or bonds, meaning that the investment performance of municipal obligations may be more dependent on the analytical abilities of the investment adviser than stock or corporate bond investments. The secondary market for municipal obligations also tends to be less well-developed and less liquid than many other securities markets, which may limit the Fund’s ability to sell its municipal obligations at attractive prices. The differences between the price at which an obligation can be purchased and the price at which it can be sold may widen during periods of market distress. Less liquid obligations can become more difficult to value and be subject to erratic price movements. The increased presence of non-traditional participants (such as proprietary trading desks of investment banks and hedge funds) or the absence of traditional participants (such as individuals, insurance companies, banks and life insurance companies) in the municipal markets may lead to greater volatility in the markets because non-traditional participants may trade more frequently or in greater volume.

Additional Risks of Loans. Loans are traded in a private, unregulated inter-dealer or inter-bank resale market and are generally subject to contractual restrictions that must be satisfied before a loan can be bought or sold. These restrictions may impede the Fund’s ability to buy or sell loans (thus affecting their liquidity) and may negatively impact the transaction price. See also “Market Risk” above. It also may take longer than seven days for transactions in loans to settle. Due to the possibility of an extended loan settlement process, the Fund may hold cash, sell investments or temporarily borrow from banks or other lenders to meet short-term liquidity needs, such as to satisfy redemption requests from Fund shareholders. The types of covenants included in loan agreements generally vary depending on market conditions, the creditworthiness of the issuer, the nature of the collateral securing the loan and possibly other factors. Loans with fewer covenants that restrict activities of the borrower may provide the borrower with more flexibility to take actions that may be detrimental to the loan holders and provide fewer investor protections in the event of such actions or if covenants are breached. The Fund may experience relatively greater realized or unrealized losses or delays and expense in enforcing its rights with respect to loans with fewer restrictive covenants. Loans to entities located outside of the U.S. may have substantially different lender protections and covenants as compared to loans to U.S. entities and may involve greater risks. The Fund may have difficulties and incur expense enforcing its rights with respect to non-U.S. loans and such loans could be subject to bankruptcy laws that are materially different than in the U.S. Loans may be structured such that they are not securities under securities law, and in the event of fraud or misrepresentation by a borrower, lenders may not have the protection of the anti-fraud provisions of the federal securities laws. Loans are also subject to risks associated with other types of income investments, including credit risk and risks of lower rated investments.

Lower Rated Investments Risk. Investments rated below investment grade and comparable unrated investments (sometimes referred to as “junk”) have speculative characteristics because of the credit risk associated with their issuers. Changes in economic conditions or other circumstances typically have a greater effect on the ability of issuers of lower rated investments to make principal and interest payments than they do on issuers of higher rated investments. An economic downturn generally leads to a higher non-payment rate, and a lower rated investment may lose significant value before a default occurs. Lower rated investments typically are subject to greater price volatility and illiquidity than higher rated investments.

Foreign Investment Risk. Foreign investments can be adversely affected by political, economic and market developments abroad, including the imposition of economic and other sanctions by the United States or another country against a particular country or countries, organizations, entities and/or individuals. There may be less publicly available information about foreign issuers because they may not be subject to reporting practices, requirements or regulations comparable to those to which United States companies are subject. Adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund's investments. Foreign markets may be smaller, less liquid and more volatile than the major markets in the United States and, as a result, Fund share values may be more volatile. Trading in foreign markets typically involves higher expense than trading in the United States. The Fund may have difficulties enforcing its legal or contractual rights in a foreign country. Depositary receipts are subject to many of the risks associated with investing directly in foreign instruments.

Currency Risk. Exchange rates for currencies fluctuate daily. The value of foreign investments may be affected favorably or unfavorably by changes in currency exchange rates in relation to the U.S. dollar. Currency markets generally are not as regulated as securities markets and currency transactions are subject to settlement, custodial and other operational risks.

Restricted Securities Risk. Unless registered for sale to the public under applicable federal securities law, restricted securities can be sold only in private transactions to qualified purchasers pursuant to an exemption from registration. The sale price realized from a private transaction could be less than the Fund’s purchase price for the restricted security. It may be difficult to identify a qualified purchaser for a restricted security held by the Fund and such security could be deemed illiquid. It may also be more difficult to value such securities.

Liquidity Risk. The Fund is exposed to liquidity risk when trading volume, lack of a market maker or trading partner, large position size, market conditions, or legal restrictions impair its ability to sell particular investments or to sell them at advantageous market prices. Consequently, the Fund may have to accept a lower price to sell an investment or continue to hold it or keep the position open, sell other investments to raise cash or abandon an investment opportunity, any of which could have a negative effect on the Fund’s performance. These effects may be exacerbated during times of financial or political stress.

Derivatives Risk. The Fund’s exposure to derivatives involves risks different from, or possibly greater than, the risks associated with investing directly in securities and other investments. The use of derivatives can lead to losses because of adverse movements in the price or value of the security, instrument, index, currency, commodity, economic indicator or event underlying a derivative (“reference instrument”), due to failure of a counterparty or due to tax or regulatory constraints. Derivatives may create leverage in the Fund, which represents a non-cash exposure to the underlying reference instrument. Leverage can increase both the risk and return potential of the Fund. Derivatives risk may be more significant when derivatives are used to enhance return or as a substitute for a cash investment position, rather than solely to hedge the risk of a position held by the Fund. Use of derivatives involves the exercise of specialized skill and judgment, and a transaction may be unsuccessful in whole or in part because of market behavior or unexpected events. Changes in the value of a derivative (including one used for hedging) may not correlate perfectly with the underlying reference instrument. Derivative instruments traded in over-the-counter markets may be difficult to value, may be illiquid, and may be subject to wide swings in valuation caused by changes in the value of the underlying reference instrument. If a derivative’s counterparty is unable to honor its commitments, the value of Fund shares may decline and the Fund could experience delays in (or be unable to achieve) the return of collateral or other assets held by the counterparty. The loss on derivative transactions may substantially exceed the initial investment. A derivative investment also involves the risks relating to the reference instrument underlying the investment.

Money Market Instrument Risk. Money market instruments may be adversely affected by market and economic events, such as a sharp rise in prevailing short-term interest rates; adverse developments in the banking industry, which issues or guarantees many money market instruments; adverse economic, political or other developments affecting issuers of money market instruments; changes in the credit quality of issuers; and default by a counterparty.

Securities Lending Risk. Securities lending involves a possible delay in recovery of the loaned securities or a possible loss of rights in the collateral if the borrower fails financially. The Fund could also lose money if the value of the collateral decreases.

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 criteria 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. An investment’s ESG performance or the investment adviser's assessment of such performance may change over time, which could cause the Fund to temporarily hold securities that do not comply with the Fund’s responsible investment criteria. In evaluating an investment, the investment adviser is dependent upon information and data that may be incomplete, inaccurate or unavailable, which could adversely affect the analysis of the ESG factors relevant to a particular investment. Successful application of the Fund’s responsible investment strategy will depend on the investment adviser's skill in properly identifying and analyzing material ESG issues.

Risks Associated with Active Management. The success of the Fund’s investment strategy depends on portfolio management’s successful application of analytical skills and investment judgment. Active management involves subjective decisions and there is no guarantee that such decisions will produce the desired results or expected returns.

General Fund Investing Risks. The Fund is not a complete investment program and there is no guarantee that the Fund will achieve its investment objective. It is possible to lose money by investing in the Fund. The Fund is designed to be a long-term investment vehicle and is not suited for short-term trading. Investors in the Fund should have a long-term investment perspective and be able to tolerate potentially sharp declines in value. Purchase and redemption activities by

Fund shareholders may impact the management of the Fund and its ability to achieve its investment objective(s). In addition, the redemption by one or more large shareholders or groups of shareholders of their holdings in the Fund could have an adverse impact on the remaining shareholders in the Fund. The Fund relies on various service providers, including the investment adviser, in its operations and is susceptible to operational, information security and related events (such as public health crises, cyber or hacking attacks) that may affect the service providers or the services that they provide to the Fund. An investment in the Fund is not a deposit in a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Risk Not Insured Depository Institution

rr_RiskNotInsuredDepositoryInstitution

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

Performance Narrative

rr_PerformanceNarrativeTextBlock

The following bar chart and table provide some indication of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year and how the Fund’s average annual returns over time compare with those of a broad-based securities market index. The returns in the bar chart are for Class A shares and do not reflect a sales charge. If the sales charge was reflected, the returns would be lower. Past performance (both before and after taxes) is not necessarily an indication of how the Fund will perform in the future.

CRM became the investment adviser to the Fund on December 31, 2016. Performance reflected prior to such date is that of the Fund’s former investment adviser. The Fund’s performance reflects the effects of expense reductions for certain periods. Absent these reductions, performance would have been lower. Updated Fund performance information can be obtained by visiting www.calvert.com.

Performance Availability Website Address

rr_PerformanceAvailabilityWebSiteAddress

www.calvert.com

Bar Chart Does Not Reflect Sales Loads

rr_BarChartDoesNotReflectSalesLoads

The returns in the bar chart are for Class A shares and do not reflect a sales charge. If the sales charge was reflected, the returns would be lower.

Bar Chart Closing

rr_BarChartClosingTextBlock

For the ten years ended December 31, 2022, the highest quarterly total return for Class A was 8.34% for the quarter ended June 30, 2020 and the lowest quarterly return was -7.77% for the quarter ended June 30, 2022.

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the highest historical individual federal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on a shareholder’s tax situation and the actual characterization of distributions, and may differ from those shown.

Performance Table One Class of after Tax Shown

rr_PerformanceTableOneClassOfAfterTaxShown

After-tax returns for other Classes of shares will vary from the after-tax returns presented for Class A shares.

Performance Table Footnotes, Reason Performance Information for Class Different from Immediately Preceding Period

rr_PerformanceTableFootnotesReasonPerformanceInformationForClassDifferentFromImmediatelyPrecedingPeriod

The Class R6 performance shown above for the period prior to February 1, 2023 (commencement of operations) is the performance of Class I shares at net asset value without adjustment for any differences in the expenses of the two classes. If adjusted for such differences, returns would be different.

Average Annual Return, Caption

rr_AverageAnnualReturnCaption

Average Annual Total Returns as of December 31, 2022

Prospectus [Line Items]

rr_ProspectusLineItems

One Year

rr_AverageAnnualReturnYear01

(15.26%)

Ten Years

rr_AverageAnnualReturnYear10

1.82%

Prospectus [Line Items]

rr_ProspectusLineItems

Maximum Deferred Sales Charge (load) (as a percentage of the lower of net asset value at purchase or redemption)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

^[2]

Distribution and Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

0.91%

3 Years

rr_ExpenseExampleYear03

606

10 Years

rr_ExpenseExampleYear10

1,408

3 Years

rr_ExpenseExampleNoRedemptionYear03

606

10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 1,408

2014

rr_AnnualReturn2014

4.88%

2016

rr_AnnualReturn2016

5.60%

2018

rr_AnnualReturn2018

(3.36%)

2020

rr_AnnualReturn2020

8.25%

2022

rr_AnnualReturn2022

(15.57%)

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2020

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

lowest quarterly return

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(7.77%)

Five Years

rr_AverageAnnualReturnYear05

(0.06%)

One Year

rr_AverageAnnualReturnYear01

(19.50%)

Ten Years

rr_AverageAnnualReturnYear10

0.14%

Prospectus [Line Items]

rr_ProspectusLineItems

Five Years

rr_AverageAnnualReturnYear05

(0.67%)

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

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Management Fees

rr_ManagementFeesOverAssets

0.52%

Other Expenses

rr_OtherExpensesOverAssets

0.14%

^[3]

1 Year

rr_ExpenseExampleYear01

$ 269

5 Years

rr_ExpenseExampleYear05

902

1 Year

rr_ExpenseExampleNoRedemptionYear01

169

5 Years

rr_ExpenseExampleNoRedemptionYear05

902

One Year

rr_AverageAnnualReturnYear01

(17.03%)

Ten Years

rr_AverageAnnualReturnYear10

1.19%

Prospectus [Line Items]

rr_ProspectusLineItems

Maximum Deferred Sales Charge (load) (as a percentage of the lower of net asset value at purchase or redemption)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Distribution and Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

none

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

0.66%

3 Years

rr_ExpenseExampleYear03

211

10 Years

rr_ExpenseExampleYear10

822

3 Years

rr_ExpenseExampleNoRedemptionYear03

211

10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 822

Five Years

rr_AverageAnnualReturnYear05

0.87%

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

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Management Fees

rr_ManagementFeesOverAssets

0.52%

Other Expenses

rr_OtherExpensesOverAssets

0.08%

^[3]

1 Year

rr_ExpenseExampleYear01

$ 61

5 Years

rr_ExpenseExampleYear05

335

1 Year

rr_ExpenseExampleNoRedemptionYear01

61

5 Years

rr_ExpenseExampleNoRedemptionYear05

335

One Year

rr_AverageAnnualReturnYear01

(15.37%)

Ten Years

rr_AverageAnnualReturnYear10

2.19%

Objective

rr_ObjectiveHeading

Investment Objective

Expense

rr_ExpenseHeading

Fees and Expenses of the Fund

Shareholder Fees Caption

rr_ShareholderFeesCaption

Shareholder Fees (fees paid directly from your investment)

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

January 31, 2024

Portfolio Turnover

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” the 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 175% of the average value of its portfolio.

Expense Breakpoint Discounts

rr_ExpenseBreakpointDiscounts

You may qualify for sales charge discounts on purchases of Class A shares if you and your family invest, or agree to invest over a 13-month period, at least $100,000 in Calvert mutual funds. Certain financial intermediaries also may offer variations in Fund sales charges to their customers as described in Appendix B - Financial Intermediary Sales Charge Variations in this Prospectus. More information about these and other discounts is available from your financial professional and under “Sales Charges” on page 79 of this Prospectus and page 25 of the Fund’s Statement of Additional Information.

Expense Example

rr_ExpenseExampleHeading

Example.

Strategy

rr_StrategyHeading

Principal Investment Strategies

Strategy Portfolio Concentration

rr_StrategyPortfolioConcentration

The Fund typically invests at least 80% of its net assets in investment grade, U.S. dollar-denominated debt securities, as assessed at the time of purchase (the “80% Policy”). For purposes of the Fund’s 80% Policy, net assets include any borrowings for investment purposes. A debt security is considered investment grade when assigned a credit quality rating of BBB- or higher by S&P Global Ratings (“S&P”) or an equivalent rating by another nationally recognized statistical rating organization (“NRSRO”), including Moody’s Investors Service, Inc. or Fitch Ratings, or Kroll Bond Rating Agency, LLC for securitized debt instruments only (such as asset-backed securities (“ABS”) and mortgage-backed securities (“MBS”)) or if unrated, considered to be of comparable credit quality by the Fund’s investment adviser. For purposes of rating restrictions, if securities are rated differently by two or more rating agencies, the highest rating is used.

Risk Narrative

rr_RiskNarrativeTextBlock

Market Risk. The value of investments held by the Fund may increase or decrease in response to social, economic, political, financial, public health crises or other disruptive events (whether real, expected or perceived) in the U.S. and global markets and include events such as war, natural disasters, epidemics and pandemics, terrorism, conflicts and social unrest. These events may negatively impact broad segments of businesses and populations and may exacerbate pre-existing risks to the Fund. The frequency and magnitude of resulting changes in the value of the Fund’s investments cannot be predicted. Certain securities and other investments held by the Fund may experience increased volatility, illiquidity, or other potentially adverse effects in reaction to changing market conditions. Monetary and/or fiscal actions taken by U.S. or foreign governments to stimulate or stabilize the global economy may not be effective and could lead to high market volatility. No active trading market may exist for certain investments held by the Fund, which may impair the ability of the Fund to sell or to realize the full value of such investments in the event of the need to liquidate such assets.

Interest Rate Risk. In general, the value of income securities will fluctuate based on changes in interest rates. The value of these securities is likely to increase when interest rates fall and decline when interest rates rise. Duration measures a fixed-income security’s price sensitivity to changes in the general level of interest rates. Generally, securities with longer durations or maturities are more sensitive to changes in interest rates than securities with shorter durations or maturities, causing them to be more volatile. Conversely, fixed-income securities with shorter durations or maturities will be less volatile but may provide lower returns than fixed-income securities with longer durations or maturities. In a rising interest rate environment, the duration of income securities that have the ability to be prepaid or called by the issuer may be extended. In a declining interest rate environment, the proceeds from prepaid or maturing instruments may have to be reinvested at a lower interest rate. Certain instruments held by the Fund may pay an interest rate based on the London Interbank Offered Rate (“LIBOR”), which is the average offered rate for various maturities of short-term loans between certain major international banks. LIBOR is used throughout global banking and financial industries to determine interest rates for a variety of financial instruments (such as debt instruments and derivatives) and borrowing arrangements. The ICE Benchmark Administration Limited, the administrator of LIBOR, ceased publishing certain LIBOR settings on December 31, 2021, and is expected to cease publishing the remaining LIBOR settings on June 30, 2023. Although the transition process away from LIBOR has become increasingly well defined, the impact on certain debt securities, derivatives and other financial instruments that utilize LIBOR remains uncertain. The phase-out of LIBOR may result in, among other things, increased volatility or illiquidity in markets for instruments based on LIBOR and changes in the value of such instruments.

Credit Risk. Investments in debt securities (including bonds) and loans (referred to below as “debt instruments”) are subject to the risk of non-payment of scheduled principal and interest. Changes in economic conditions or other circumstances may reduce the capacity of the party obligated to make principal and interest payments on such instruments and may lead to defaults. Such non-payments and defaults may reduce the value of Fund shares and income distributions. The value of debt instruments also may decline because of concerns about the issuer’s ability to make principal and interest payments. In addition, the credit ratings of debt instruments may be lowered if the financial condition of the party obligated to make payments with respect to such instruments deteriorates. In the event of bankruptcy of the issuer of a debt instrument, the Fund could experience delays or limitations with respect to its ability to realize the benefits of any collateral securing the instrument. In order to enforce its rights in the event of a default, bankruptcy or similar situation, the Fund may be required to retain legal or similar counsel, which may increase the Fund’s operating expenses and adversely affect net asset value.

Mortgage- and Asset-Backed Securities Risk. Mortgage- and asset-backed securities represent interests in “pools” of commercial or residential mortgages or other assets, including consumer loans or receivables. Movements in interest rates (both increases and decreases) may quickly and significantly reduce the value of certain types of mortgage- and asset-backed securities. Although certain mortgage- and asset-backed securities are guaranteed as to timely payment of interest and principal by a government entity, the market price for such securities is not guaranteed and will fluctuate. The purchase of mortgage- and asset-backed securities issued by non-government entities may entail greater risk than such securities that are issued or guaranteed by a government entity. Mortgage- and asset-backed securities issued by non-government entities may offer higher yields than those issued by government entities, but may also be subject to greater volatility than government issues and can also be subject to greater credit risk and the risk of default on the underlying mortgages or other assets. Investments in mortgage- and asset-backed securities are subject to both extension risk, where borrowers pay off their debt obligations more slowly in times of rising interest rates, and prepayment risk, where borrowers pay off their debt obligations sooner than expected in times of declining interest rates.

U.S. Government Securities Risk. Although certain U.S. Government-sponsored agencies (such as the Federal Home Loan Mortgage Corporation and the Federal National Mortgage Association) may be chartered or sponsored by acts of Congress, their securities are neither issued nor guaranteed by the U.S. Treasury. U.S. Treasury securities generally have a lower return than other obligations because of their higher credit quality and market liquidity.

Convertible and Other Hybrid Securities Risk. Convertible and other hybrid securities (including preferred and convertible instruments) generally possess certain characteristics of both equity and debt securities. In addition to risks associated with investing in income securities, such as interest rate and credit risks, hybrid securities may be subject to issuer-specific and market risks generally applicable to equity securities. Convertible securities may also react to changes in the value of the common stock into which they convert, and are thus subject to equity investing and market risks. A convertible security may be converted at an inopportune time, which may decrease the Fund’s return.

Preferred Stock Risk. Although preferred stocks represent an ownership interest in an issuer, preferred stocks generally do not have voting rights or have limited voting rights and have economic characteristics similar to fixed-income securities. Preferred stocks are subject to issuer-specific risks generally applicable to equity securities and credit and interest rate risks generally applicable to fixed-income securities. The value of preferred stock generally declines when interest rates rise and may react more significantly than bonds and other debt instruments to actual or perceived changes in the company’s financial condition or prospects.

Municipal Obligations Risk. The amount of public information available about municipal obligations is generally less than for corporate equities or bonds, meaning that the investment performance of municipal obligations may be more dependent on the analytical abilities of the investment adviser than stock or corporate bond investments. The secondary market for municipal obligations also tends to be less well-developed and less liquid than many other securities markets, which may limit the Fund’s ability to sell its municipal obligations at attractive prices. The differences between the price at which an obligation can be purchased and the price at which it can be sold may widen during periods of market distress. Less liquid obligations can become more difficult to value and be subject to erratic price movements. The increased presence of non-traditional participants (such as proprietary trading desks of investment banks and hedge funds) or the absence of traditional participants (such as individuals, insurance companies, banks and life insurance companies) in the municipal markets may lead to greater volatility in the markets because non-traditional participants may trade more frequently or in greater volume.

Additional Risks of Loans. Loans are traded in a private, unregulated inter-dealer or inter-bank resale market and are generally subject to contractual restrictions that must be satisfied before a loan can be bought or sold. These restrictions may impede the Fund’s ability to buy or sell loans (thus affecting their liquidity) and may negatively impact the transaction price. See also “Market Risk” above. It also may take longer than seven days for transactions in loans to settle. Due to the possibility of an extended loan settlement process, the Fund may hold cash, sell investments or temporarily borrow from banks or other lenders to meet short-term liquidity needs, such as to satisfy redemption requests from Fund shareholders. The types of covenants included in loan agreements generally vary depending on market conditions, the creditworthiness of the issuer, the nature of the collateral securing the loan and possibly other factors. Loans with fewer covenants that restrict activities of the borrower may provide the borrower with more flexibility to take actions that may be detrimental to the loan holders and provide fewer investor protections in the event of such actions or if covenants are breached. The Fund may experience relatively greater realized or unrealized losses or delays and expense in enforcing its rights with respect to loans with fewer restrictive covenants. Loans to entities located outside of the U.S. may have substantially different lender protections and covenants as compared to loans to U.S. entities and may involve greater risks. The Fund may have difficulties and incur expense enforcing its rights with respect to non-U.S. loans and such loans could be subject to bankruptcy laws that are materially different than in the U.S. Loans may be structured such that they are not securities under securities law, and in the event of fraud or misrepresentation by a borrower, lenders may not have the protection of the anti-fraud provisions of the federal securities laws. Loans are also subject to risks associated with other types of income investments, including credit risk and risks of lower rated investments.

Lower Rated Investments Risk. Investments rated below investment grade and comparable unrated investments (sometimes referred to as “junk”) have speculative characteristics because of the credit risk associated with their issuers. Changes in economic conditions or other circumstances typically have a greater effect on the ability of issuers of lower rated investments to make principal and interest payments than they do on issuers of higher rated investments. An economic downturn generally leads to a higher non-payment rate, and a lower rated investment may lose significant value before a default occurs. Lower rated investments typically are subject to greater price volatility and illiquidity than higher rated investments.

Foreign Investment Risk. Foreign investments can be adversely affected by political, economic and market developments abroad, including the imposition of economic and other sanctions by the United States or another country against a particular country or countries, organizations, entities and/or individuals. There may be less publicly available information about foreign issuers because they may not be subject to reporting practices, requirements or regulations comparable to those to which United States companies are subject. Adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund's investments. Foreign markets may be smaller, less liquid and more volatile than the major markets in the United States and, as a result, Fund share values may be more volatile. Trading in foreign markets typically involves higher expense than trading in the United States. The Fund

may have difficulties enforcing its legal or contractual rights in a foreign country. Depositary receipts are subject to many of the risks associated with investing directly in foreign instruments.

Currency Risk. Exchange rates for currencies fluctuate daily. The value of foreign investments may be affected favorably or unfavorably by changes in currency exchange rates in relation to the U.S. dollar. Currency markets generally are not as regulated as securities markets and currency transactions are subject to settlement, custodial and other operational risks.

When-Issued and Forward Commitment Risk. Securities purchased on a when-issued or forward commitment basis are subject to the risk that when delivered they will be worth less than the agreed upon payment price.

Restricted Securities Risk. Unless registered for sale to the public under applicable federal securities law, restricted securities can be sold only in private transactions to qualified purchasers pursuant to an exemption from registration. The sale price realized from a private transaction could be less than the Fund’s purchase price for the restricted security. It may be difficult to identify a qualified purchaser for a restricted security held by the Fund and such security could be deemed illiquid. It may also be more difficult to value such securities.

Liquidity Risk. The Fund is exposed to liquidity risk when trading volume, lack of a market maker or trading partner, large position size, market conditions, or legal restrictions impair its ability to sell particular investments or to sell them at advantageous market prices. Consequently, the Fund may have to accept a lower price to sell an investment or continue to hold it or keep the position open, sell other investments to raise cash or abandon an investment opportunity, any of which could have a negative effect on the Fund’s performance. These effects may be exacerbated during times of financial or political stress.

Derivatives Risk. The Fund’s exposure to derivatives involves risks different from, or possibly greater than, the risks associated with investing directly in securities and other investments. The use of derivatives can lead to losses because of adverse movements in the price or value of the security, instrument, index, currency, commodity, economic indicator or event underlying a derivative (“reference instrument”), due to failure of a counterparty or due to tax or regulatory constraints. Derivatives may create leverage in the Fund, which represents a non-cash exposure to the underlying reference instrument. Leverage can increase both the risk and return potential of the Fund. Derivatives risk may be more significant when derivatives are used to enhance return or as a substitute for a cash investment position, rather than solely to hedge the risk of a position held by the Fund. Use of derivatives involves the exercise of specialized skill and judgment, and a transaction may be unsuccessful in whole or in part because of market behavior or unexpected events. Changes in the value of a derivative (including one used for hedging) may not correlate perfectly with the underlying reference instrument. Derivative instruments traded in over-the-counter markets may be difficult to value, may be illiquid, and may be subject to wide swings in valuation caused by changes in the value of the underlying reference instrument. If a derivative’s counterparty is unable to honor its commitments, the value of Fund shares may decline and the Fund could experience delays in (or be unable to achieve) the return of collateral or other assets held by the counterparty. The loss on derivative transactions may substantially exceed the initial investment. A derivative investment also involves the risks relating to the reference instrument underlying the investment.

Money Market Instrument Risk. Money market instruments may be adversely affected by market and economic events, such as a sharp rise in prevailing short-term interest rates; adverse developments in the banking industry, which issues or guarantees many money market instruments; adverse economic, political or other developments affecting issuers of money market instruments; changes in the credit quality of issuers; and default by a counterparty.

Securities Lending Risk. Securities lending involves a possible delay in recovery of the loaned securities or a possible loss of rights in the collateral if the borrower fails financially. The Fund could also lose money if the value of the collateral decreases.

Portfolio Turnover Risk. The annual portfolio turnover rate of the Fund may exceed 100%. A mutual fund with a high turnover rate (100% or more) may generate more capital gains and may involve greater expenses (which may reduce return) than a fund with a lower rate. Capital gains distributions will be made to shareholders if offsetting capital loss carry forwards do not exist.

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 criteria 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. An investment’s ESG performance or the investment adviser's assessment of such performance may change over time, which could cause the Fund to temporarily hold securities that do not comply with the Fund’s responsible investment criteria. In evaluating an investment, the investment adviser is dependent upon information and data that may be incomplete, inaccurate or unavailable, which could adversely affect the analysis of the ESG factors relevant to a particular investment. Successful application of the Fund’s responsible investment strategy will depend on the investment adviser's skill in properly identifying and analyzing material ESG issues.

Risks Associated with Active Management. The success of the Fund’s investment strategy depends on portfolio management’s successful application of analytical skills and investment judgment. Active management involves subjective decisions and there is no guarantee that such decisions will produce the desired results or expected returns.

General Fund Investing Risks. The Fund is not a complete investment program and there is no guarantee that the Fund will achieve its investment objective. It is possible to lose money by investing in the Fund. The Fund is designed to be a long-term investment vehicle and is not suited for short-term trading. Investors in the Fund should have a long-term investment perspective and be able to tolerate potentially sharp declines in value. Purchase and redemption activities by Fund shareholders may impact the management of the Fund and its ability to achieve its investment objective(s). In addition, the redemption by one or more large shareholders or groups of shareholders of their holdings in the Fund could have an adverse impact on the remaining shareholders in the Fund. The Fund relies on various service providers, including the investment adviser, in its operations and is susceptible to operational, information security and related events (such as public health crises, cyber or hacking attacks) that may affect the service providers or the services that they provide to the Fund. An investment in the Fund is not a deposit in a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Risk Not Insured Depository Institution

rr_RiskNotInsuredDepositoryInstitution

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

Performance Narrative

rr_PerformanceNarrativeTextBlock

The following bar chart and table provide some indication of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year and how the Fund’s average annual returns over time compare with those of a broad-based securities market index. The returns in the bar chart are for Class A shares and do not reflect a sales charge. If the sales charge was reflected, the returns would be lower. Past performance (both before and after taxes) is not necessarily an indication of how the Fund will perform in the future.

CRM became the investment adviser to the Fund on December 31, 2016. Performance reflected prior to such date is that of the Fund’s former investment adviser. The Fund’s performance reflects the effects of expense reductions. Absent these reductions, performance would have been lower. Updated Fund performance information can be obtained by visiting www.calvert.com.

Performance Availability Website Address

rr_PerformanceAvailabilityWebSiteAddress

www.calvert.com

Bar Chart Does Not Reflect Sales Loads

rr_BarChartDoesNotReflectSalesLoads

The returns in the bar chart are for Class A shares and do not reflect a sales charge. If the sales charge was reflected, the returns would be lower.

Bar Chart Closing

rr_BarChartClosingTextBlock

For the ten years ended December 31, 2022, the highest quarterly total return for Class A was 9.96% for the quarter ended June 30, 2020 and the lowest quarterly return was -6.81% for the quarter ended June 30, 2015.

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the highest historical individual federal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on a shareholder’s tax situation and the actual characterization of distributions, and may differ from those shown.

Performance Table One Class of after Tax Shown

rr_PerformanceTableOneClassOfAfterTaxShown

After-tax returns for other Classes of shares will vary from the after-tax returns presented for Class A shares.

Performance Table Footnotes, Reason Performance Information for Class Different from Immediately Preceding Period

rr_PerformanceTableFootnotesReasonPerformanceInformationForClassDifferentFromImmediatelyPrecedingPeriod

The Class I performance shown above for the period prior to January 31, 2015 (commencement of operations) is the performance of Class A shares at net asset value without adjustment for any differences in the expenses of the two classes. If adjusted for such differences, returns would be different.

Average Annual Return, Caption

rr_AverageAnnualReturnCaption

Average Annual Total Returns as of December 31, 2022

Prospectus [Line Items]

rr_ProspectusLineItems

One Year

rr_AverageAnnualReturnYear01

(13.01%)

Ten Years

rr_AverageAnnualReturnYear10

1.06%

Prospectus [Line Items]

rr_ProspectusLineItems

Maximum Deferred Sales Charge (load) (as a percentage of the lower of net asset value at purchase or redemption)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

^[4]

Distribution and Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

0.91%

Total Annual Fund Operating Expenses after Fee Waiver and/or Expense Reimbursement

rr_NetExpensesOverAssets

0.74%

3 Years

rr_ExpenseExampleYear03

589

10 Years

rr_ExpenseExampleYear10

$ 1,393

2014

rr_AnnualReturn2014

15.15%

2016

rr_AnnualReturn2016

6.78%

2018

rr_AnnualReturn2018

(5.73%)

2020

rr_AnnualReturn2020

14.55%

2022

rr_AnnualReturn2022

(13.14%)

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2020

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Jun. 30, 2015

One Year

rr_AverageAnnualReturnYear01

(15.97%)

Ten Years

rr_AverageAnnualReturnYear10

2.73%

Prospectus [Line Items]

rr_ProspectusLineItems

Five Years

rr_AverageAnnualReturnYear05

(0.02%)

One Year

rr_AverageAnnualReturnYear01

(9.44%)

Ten Years

rr_AverageAnnualReturnYear10

1.42%

Prospectus [Line Items]

rr_ProspectusLineItems

Maximum Deferred Sales Charge (load) (as a percentage of the lower of net asset value at purchase or redemption)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Distribution and Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

none

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

0.66%

Total Annual Fund Operating Expenses after Fee Waiver and/or Expense Reimbursement

rr_NetExpensesOverAssets

0.49%

3 Years

rr_ExpenseExampleYear03

194

10 Years

rr_ExpenseExampleYear10

$ 806

Five Years

rr_AverageAnnualReturnYear05

2.32%

Inception Date

rr_AverageAnnualReturnInceptionDate

Jan. 31, 2015

Prospectus [Line Items]

rr_ProspectusLineItems

Objective, Primary

rr_ObjectivePrimaryTextBlock

The Fund's investment objective is to seek to maximize income, to the extent consistent with preservation of capital, through investment in short-term bonds and income-producing securities.

Expense Narrative

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy, hold and sell shares of the Fund. Investors may also pay commissions or other fees to their financial intermediary, which are not reflected below. You may qualify for sales charge discounts on purchases of Class A shares if you and your family invest, or agree to invest over a 13-month period, at least $100,000 in Calvert mutual funds. Certain financial intermediaries also may offer variations in Fund sales charges to their customers as described in Appendix B - Financial Intermediary Sales Charge Variations in this Prospectus. More information about these and other discounts is available from your financial professional and under “Sales Charges” on page 79 of this Prospectus and page 25 of the Fund’s Statement of Additional Information.

Operating Expenses Caption

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Portfolio Turnover

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” the 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 71% of the average value of its portfolio.

Expense Breakpoint Discounts

rr_ExpenseBreakpointDiscounts

You may qualify for sales charge discounts on purchases of Class A shares if you and your family invest, or agree to invest over a 13-month period, at least $100,000 in Calvert mutual funds. Certain financial intermediaries also may offer variations in Fund sales charges to their customers as described in Appendix B - Financial Intermediary Sales Charge Variations in this Prospectus. More information about these and other discounts is available from your financial professional and under “Sales Charges” on page 79 of this Prospectus and page 25 of the Fund’s Statement of Additional Information.

Expense Example

rr_ExpenseExampleHeading

Example.

Strategy

rr_StrategyHeading

Principal Investment Strategies

Strategy Portfolio Concentration

rr_StrategyPortfolioConcentration

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 S&P Global Ratings (“S&P”) or an equivalent rating by another nationally recognized statistical rating organization (“NRSRO”), including Moody’s Investors Service, Inc. or Fitch Ratings, or Kroll Bond Rating Agency, LLC for securitized debt instruments only (such as asset-backed securities (“ABS”) and mortgage-backed securities (“MBS”)) or if unrated, considered to be of comparable credit quality by the Fund’s investment adviser. For purposes of rating restrictions, if securities are rated differently by two or more rating agencies, the highest rating is used.

Risk Narrative

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Market Risk. The value of investments held by the Fund may increase or decrease in response to social, economic, political, financial, public health crises or other disruptive events (whether real, expected or perceived) in the U.S. and global markets and include events such as war, natural disasters, epidemics and pandemics, terrorism, conflicts and social unrest. These events may negatively impact broad segments of businesses and populations and may exacerbate

pre-existing risks to the Fund. The frequency and magnitude of resulting changes in the value of the Fund’s investments cannot be predicted. Certain securities and other investments held by the Fund may experience increased volatility, illiquidity, or other potentially adverse effects in reaction to changing market conditions. Monetary and/or fiscal actions taken by U.S. or foreign governments to stimulate or stabilize the global economy may not be effective and could lead to high market volatility. No active trading market may exist for certain investments held by the Fund, which may impair the ability of the Fund to sell or to realize the full value of such investments in the event of the need to liquidate such assets.

Interest Rate Risk. In general, the value of income securities will fluctuate based on changes in interest rates. The value of these securities is likely to increase when interest rates fall and decline when interest rates rise. Duration measures a fixed-income security’s price sensitivity to changes in the general level of interest rates. Generally, securities with longer durations or maturities are more sensitive to changes in interest rates than securities with shorter durations or maturities, causing them to be more volatile. Conversely, fixed-income securities with shorter durations or maturities will be less volatile but may provide lower returns than fixed-income securities with longer durations or maturities. Funds with shorter average durations (including the Fund) may own individual investments that have longer durations than the average duration of the Fund. In a rising interest rate environment, the duration of income securities that have the ability to be prepaid or called by the issuer may be extended. In a declining interest rate environment, the proceeds from prepaid or maturing instruments may have to be reinvested at a lower interest rate.