2.2.0.25truefalse000021 - Document - Risk/Return Summary {Unlabeled}falsefalsetrue1falsefalseUSDtruefalse{dei_LegalEntityAxis} : S000027100 Member 1/18/2011 - 1/18/2011 USD ($) $Duration_1_18_2011_To_1_18_20113http://www.sec.gov/CIK0000701039duration2011-01-18T00:00:002011-01-18T00:00:00falsefalsecik001380786_S000027100Memberdei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldicik001380786_S000027100Memberdei_LegalEntityAxisexplicitMemberUnit12Standardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$3false0rr_RiskReturnHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div class="MetaData"> <p style="margin: 13.4pt 0in 0pt; font-family: 'Times New Roman','serif'; font-size: 12pt;"><font style="font-family: 'Arial','sans-serif'; font-size: 18pt;" class="_mt">CALVERT ULTRA-SHORT INCOME FUND</font></p></div>falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringRisk/Return Summary Investment Objectives/Goals Include the following information, in plain English under rule 421(d) under the Securities Act, in the order and subject matter indicatedReference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 2 falsefalseRisk/Return [Heading]4false0rr_ObjectiveHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00 <div class="MetaData"> <p style="margin: 0in 0in 0pt; font-family: 'Times New Roman','serif'; font-size: 12pt;"><font style="font-family: 'Arial','sans-serif';" class="_mt"><b>Investment Objective</b></font></p></div>falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringInvestment Objectives/Goals. Disclose the Fund's investment objectives or goals. A Fund also may identify its type or category (e.g., that it is a Money Market Fund or a balanced fund).Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 2 -Subsection a falsefalseObjective [Heading]5false0rr_ObjectivePrimaryTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div><p>The Fund seeks to maximize income, to the extent consistent with preservation of capital, through investment in short-term bonds and income-producing securities.</p></div>falsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringInvestment Objectives/Goals. Disclose the Fund's investment objectives or goals. A Fund also may identify its type or category (e.g., that it is a Money Market Fund or a balanced fund).Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 2 -Subsection a falsefalseObjective, Primary [Text Block]6false0rr_ExpenseHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div class="MetaData"> <p style="margin: 6pt 0in; font-family: 'Times New Roman','serif'; font-size: 12pt;"><font style="font-family: 'Arial','sans-serif';" class="_mt"><b>Fees and Expenses of the Fund</b></font></p></div>falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringRisk/Return Summary Fee Table Includes the following information, in plain English under rule 421(d) under the Securities Act, after Item 2 Fees and expenses of the Fund This table describes the fees and expenses that you may pay if you buy and hold shared 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 $[_____] in [name of fund family] funds. Shareholder Fees (fees paid directly from your investment) Example 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 you redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return per year and that the Fund's operating expenses remained the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be You would pay the following expenses if you did not redeem your shares The Example does not reflect sales charges (loads) on reinvested dividends [and other distributions]. If these sales charges (loads) were included, your costs would be higher. Portfolio Turnover The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover may indicate higher transaction costs. 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 __% of the average value of its whole portfolio. Instructions. A.3.instructions.6 New Funds. For purposes of this Item, a "New Fund" is a Fund that does not include in Form N-1A financial statements reporting operating results or that includes financial statements for the Fund's initial fiscal year reporting operating results for a period of 6 months or less. The following Instructions apply to New Funds.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subparagraph d -Subsection instructions falsefalseExpense [Heading]7false0rr_ExpenseNarrativeTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div> <p>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 non-money market mutual funds More information about these and other discounts is available from your financial professional and under 'Choosing a Share Class' on page 51 and 'Reduced Sales Charges' on page 55 of the Fund's Prospectus, and under 'Method of Distribution' on page 38 of the Fund's SAI.</p></div>falsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringThis table describes the fees and expenses that you may pay if you buy and hold shared 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 $[_____] in [name of fund family] funds. Include the narrative explanations in the order indicated. A Fund may modify the narrative explanations if the explanation contains comparable information to that shown.The narrative explanation regarding sales charge discounts is only required by a Fund that offers such discounts and should specify the minimum level of investment required to qualify for a discount. Modify the narrative explanation to state that Fund shares are sold on a national securities exchange at the end of the time periods indicated, and that brokerage commissions for buying and selling Fund shares through a broker are not reflected.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subparagraph b -Subsection instructions falsefalseExpense Narrative [Text Block]8false0rr_ShareholderFeesCaptionrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div class="MetaData"> <p style="margin: 6pt 0in 0pt; font-family: 'Times New Roman','serif'; font-size: 12pt;"><b><font style="font-family: 'Arial','sans-serif'; font-size: 10pt;" class="_mt">Shareholder Fees</font></b></p> <p style="margin: 0in 0in 0pt; font-family: 'Times New Roman','serif'; font-size: 12pt;"><font style="font-family: 'Arial','sans-serif'; font-size: 10pt;" class="_mt">(fees paid directly from your investment)</font></p></div>falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringShareholder Fees (fees paid directly from your investment).Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subsection table falsefalseShareholder Fees Caption [Text]9false0rr_ShareholderFeesTableTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div> &lt;div style="display:none;" &gt;~ http://www.calvert.com/role/ScheduleShareholderFeesCalvertHighYieldBondFund column period compact * column dei_LegalEntityAxis compact cik001380786_S000027100Member column rr_ProspectusShareClassAxis compact * row primary compact * ~&lt;/div&gt; </div>falsefalse<div> &lt;div style="display:none;" &gt;~ http://www.calvert.com/role/ScheduleShareholderFeesCalvertHighYieldBondFund column period compact * column dei_LegalEntityAxis compact cik001380786_S000027100Member column rr_ProspectusShareClassAxis compact * row primary compact * ~&lt;/div&gt; </div>falsehttp://www.calvert.com/role/ScheduleShareholderFeesCalvertHighYieldBondFundfalsefalse000022 - Schedule - Shareholder Feestruefalsefalse1falseColumnperiodPeriod*Columndei_LegalEntityAxisAxiscik001380786_S000027100MemberColumnrr_ProspectusShareClassAxisAxis*ColumnunitUnit*duration2011-01-18T00:00:002011-01-18T00:00:00falsefalseCALVERT ULTRA-SHORT INCOME FUNDdei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldicik001380786_S000027100Memberdei_LegalEntityAxisexplicitMemberfalsefalseClass Arr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldicik001380786_C000081597Memberrr_ProspectusShareClassAxisexplicitMemberCALVERT ULTRA-SHORT INCOME FUNDClass AUnit12Standardhttp://www.xbrl.org/2003/iso4217USDiso42170falseUSDfalsefalse$2falseColumnperiodPeriod*Columndei_LegalEntityAxisAxiscik001380786_S000027100MemberColumnrr_ProspectusShareClassAxisAxis*ColumnunitUnit*duration2011-01-18T00:00:002011-01-18T00:00:00falsefalseCALVERT ULTRA-SHORT INCOME FUNDdei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldicik001380786_S000027100Memberdei_LegalEntityAxisexplicitMemberfalsefalseClass Yrr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldicik001380786_C000081600Memberrr_ProspectusShareClassAxisexplicitMemberCALVERT ULTRA-SHORT INCOME FUNDClass YUnit12Standardhttp://www.xbrl.org/2003/iso4217USDiso42170falseUSDfalsefalse$1falseRowprimaryElement*5false0rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPricerrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.01250.0125falsefalsefalsetruefalse2truetruetrue00falsefalsefalsetruefalseOtherrr:NonNegativePure4TypepureMaximum Deferred Sales Charge (Load) (as a percentage of ____) A.3.instructions.2.a.i "Maximum Deferred Sales Charge (Load)" includes the maximum total deferred sales charge (load) payable upon redemption, in installments, or both, expressed as a percentage of the amount or amounts stated in response to Item 7(a), except that, for a sales charge (load) based on net asset value at the time of purchase, show the sales charge (load) as a percentage of the offering price at the time of purchase. A Fund may include in a footnote to the table, if applicable, a tabular presentation showing the amount of deferred sales charges (loads) over time or a narrative explanation of the sales charges (loads) (e.g., __% in the first year after purchase, declining to __% in the __ year and eliminated thereafter). A.3.instructions.2.a.ii If more than one type of sales charge (load) is imposed (e.g., a deferred sales charge (load) and a front-end sales charge (load)), the first caption in the table should read "Maximum Sales Charge (Load)" and show the maximum cumulative percentage. Show the percentage amounts and the terms of each sales charge (load) comprising that figure on separate lines below.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subparagraph 1 -Subsection table falsefalseMaximum sales charge (load) on purchases (as a % of offering price)0rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPricetruefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.01250.0125falsefalsefalsetruefalse2truetruetrue00falsefalsefalsetruefalseOthernanafalsefalseMaximum sales charge (load) on purchases (as a % of offering price)2falseRowprimaryElement*6false0rr_MaximumDeferredSalesChargeOverOfferingPricerrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue00falsefalsefalsetruefalse2truetruetrue00falsefalsefalsetruefalseOtherrr:NonNegativePure4TypepureMaximum Deferred Sales Charge (Load) (as a percentage of ____) A.3.instructions.2.a.i "Maximum Deferred Sales Charge (Load)" includes the maximum total deferred sales charge (load) payable upon redemption, in installments, or both, expressed as a percentage of the amount or amounts stated in response to Item 7(a), except that, for a sales charge (load) based on net asset value at the time of purchase, show the sales charge (load) as a percentage of the offering price at the time of purchase. A Fund may include in a footnote to the table, if applicable, a tabular presentation showing the amount of deferred sales charges (loads) over time or a narrative explanation of the sales charges (loads) (e.g., __% in the first year after purchase, declining to __% in the __ year and eliminated thereafter). A.3.instructions.2.a.ii If more than one type of sales charge (load) is imposed (e.g., a deferred sales charge (load) and a front-end sales charge (load)), the first caption in the table should read "Maximum Sales Charge (Load)" and show the maximum cumulative percentage. Show the percentage amounts and the terms of each sales charge (load) comprising that figure on separate lines below.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 2 -Subparagraph a -Clause i -Subsection instructions falsefalseMaximum deferred sales charge (load) (as a % of amount purchased or redeemed, whichever is lower)0rr_MaximumDeferredSalesChargeOverOfferingPricetruefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue00falsefalsefalsetruefalse2truetruetrue00falsefalsefalsetruefalseOthernanafalsefalseMaximum deferred sales charge (load) (as a % of amount purchased or redeemed, whichever is lower)3falseRowprimaryElement*7false0rr_ExchangeFeeOverRedemptionrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truetruetrue0.020.02falsefalsefalsetruefalse2truetruetrue0.020.02falsefalsefalsetruefalseOtherrr:NonNegativePure4TypepureExchange Fee includes the maximum fee charged for any exchange or transfer of interest from the Fund to another fund. The Fund may include in a footnote to the table, if applicable, a tabular presentation of the range of exchange fees or a narrative explanation of the fees.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 2 -Subparagraph c -Subsection instructions falsefalseRedemption fees (as % of amount redeemed or exchanged within 30 days of purchase)0rr_ExchangeFeeOverRedemptiontruefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.020.02falsefalsefalsetruefalse2truetruetrue0.020.02falsefalsefalsetruefalseOthernanafalsefalseRedemption fees (as % of amount redeemed or exchanged within 30 days of purchase)23Shareholder Fees CALVERT ULTRA-SHORT INCOME FUNDUnKnownUnKnownUnKnownUnKnownfalsetrueColumnperiodPeriod*Columndei_LegalEntityAxisAxiscik001380786_S000027100MemberColumnrr_ProspectusShareClassAxisAxis*ColumnunitUnit*RowprimaryElement*falsefalsefalseOtherus-types:textBlockItemTypestringContains a command for the SEC Viewer for the role corresponding to ShareholderFeesData.No authoritative reference available.falsefalseShareholder Fees [Table]10false0rr_OperatingExpensesCaptionrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div class="MetaData"> <p style="margin: 0in 0in 0pt; font-family: 'Times New Roman','serif'; font-size: 12pt;"><b><font style="font-family: 'Arial','sans-serif'; font-size: 10pt;" class="_mt">Annual Fund Operating Expenses</font></b></p><p style="margin: 0in 0in 0.85pt; font-family: 'Times New Roman','serif'; font-size: 12pt;"><font style="font-family: 'Arial','sans-serif'; font-size: 10pt;" class="_mt">(expenses that you pay each year as a % of the value of your investment)</font></p></div>falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringAnnual Fund Operating Expenses (ongoing expenses that you pay each year as a percentage of the value of your investment)Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subparagraph 7 -Subsection table falsefalseOperating Expenses Caption [Text]11false0rr_AnnualFundOperatingExpensesTableTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div> &lt;div style="display:none;" &gt;~ http://www.calvert.com/role/ScheduleAnnualFundOperatingExpensesCalvertHighYieldBondFund column period compact * column dei_LegalEntityAxis compact cik001380786_S000027100Member column rr_ProspectusShareClassAxis compact * row primary compact * ~&lt;/div&gt; </div>falsefalse<div> &lt;div style="display:none;" &gt;~ http://www.calvert.com/role/ScheduleAnnualFundOperatingExpensesCalvertHighYieldBondFund column period compact * column dei_LegalEntityAxis compact cik001380786_S000027100Member column rr_ProspectusShareClassAxis compact * row primary compact * ~&lt;/div&gt; </div>falsehttp://www.calvert.com/role/ScheduleAnnualFundOperatingExpensesCalvertHighYieldBondFundfalsefalse000023 - Schedule - Annual Fund Operating Expensestruefalsefalse1falseColumnperiodPeriod*Columndei_LegalEntityAxisAxiscik001380786_S000027100MemberColumnrr_ProspectusShareClassAxisAxis*ColumnunitUnit*duration2011-01-18T00:00:002011-01-18T00:00:00falsefalseCALVERT ULTRA-SHORT INCOME FUNDdei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldicik001380786_S000027100Memberdei_LegalEntityAxisexplicitMemberfalsefalseClass Arr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldicik001380786_C000081597Memberrr_ProspectusShareClassAxisexplicitMemberCALVERT ULTRA-SHORT INCOME FUNDClass AUnit12Standardhttp://www.xbrl.org/2003/iso4217USDiso42170falseUSDfalsefalse$2falseColumnperiodPeriod*Columndei_LegalEntityAxisAxiscik001380786_S000027100MemberColumnrr_ProspectusShareClassAxisAxis*ColumnunitUnit*duration2011-01-18T00:00:002011-01-18T00:00:00falsefalseCALVERT ULTRA-SHORT INCOME FUNDdei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldicik001380786_S000027100Memberdei_LegalEntityAxisexplicitMemberfalsefalseClass Yrr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldicik001380786_C000081600Memberrr_ProspectusShareClassAxisexplicitMemberCALVERT ULTRA-SHORT INCOME FUNDClass YUnit12Standardhttp://www.xbrl.org/2003/iso4217USDiso42170falseUSDfalsefalse$1falseRowprimaryElement*5false0rr_ManagementFeesOverAssetsrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.00550.0055falsefalsefalsetruefalse2truetruetrue0.00550.0055falsefalsefalsetruefalseOtherrr:NonNegativePure4TypepureManagement Fees include investment advisory fees (including any fees based on the Fund's performance), any other management fees payable to the investment adviser or its affiliates, and administrative fees payable to the investment adviser or its affiliates that are not included as "Other Expenses."Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 3 -Subparagraph a -Subsection instructions falsefalseManagement fees0rr_ManagementFeesOverAssetstruefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.00550.0055falsefalsefalsetruefalse2truetruetrue0.00550.0055falsefalsefalsetruefalseOthernanafalsefalseManagement fees2falseRowprimaryElement*6false0rr_DistributionAndService12b1FeesOverAssetsrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.00250.0025falsefalsefalsetruefalse2truetruetrue00falsefalsefalsetruefalseOtherrr:NonNegativePure4TypepureDistribution [and/or Service] (12b-1) Fees" include all distribution or other expenses incurred during the most recent fiscal year under a plan adopted pursuant to rule 12b-1 [17 CFR 270.12b-1]. Under an appropriate caption or a subcaption of "Other Expenses," disclose the amount of any distribution or similar expenses deducted from the Fund's assets other than pursuant to a rule 12b-1 plan.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subparagraph 9 -Subsection table falsefalseDistribution and service (12b-1) fees0rr_DistributionAndService12b1FeesOverAssetstruefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.00250.0025falsefalsefalsetruefalse2truetruetrue00falsefalsefalsetruefalseOthernanafalsefalseDistribution and service (12b-1) fees3falseRowprimaryElement*7false0rr_OtherExpensesOverAssetsrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.00280.0028falsefalsefalsetruefalse2truetruetrue0.00200.0020falsefalsefalsetruefalseOtherrr:NonNegativePure4Typepure"Other Expenses" include all expenses not otherwise disclosed in the table that are deducted from the Fund's assets or charged to all shareholder accounts. The amount of expenses deducted from the Fund's assets are the amounts shown as expenses in the Fund's statement of operations (including increases resulting from complying with paragraph 2(g) of rule 6-07 of Regulation S-X [17 CFR 210.6-07]). "Other Expenses" do not include extraordinary expenses as determined under generally accepted accounting principles (see Accounting Principles Board Opinion No. 30). If extraordinary expenses were incurred that materially affected the Fund's "Other Expenses," disclose in a footnote to the table what "Other Expenses" would have been had the extraordinary expenses been included.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 3 -Subparagraph c -Clause i -Subsection instructions falsefalseOther expenses0rr_OtherExpensesOverAssetstruefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.00280.0028falsefalsefalsetruefalse2truetruetrue0.00200.0020falsefalsefalsetruefalseOthernanafalsefalseOther expenses4falseRowprimaryElement*8false0rr_ExpensesOverAssetsrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalsetotallabel1truetruetrue0.01080.0108falsefalsefalsetruefalse2truetruetrue0.00750.0075falsefalsefalsetruefalseOtherrr:NonNegativePure4TypepureTotal Annual Fund Operating Expenses. If the Fund is a Feeder Fund, reflect the aggregate expenses of the Feeder Fund and the Master Fund in a single fee table using the captions provided. In a footnote to the fee table, state that the table and Example reflect the expenses of both the Feeder and Master Funds. If the prospectus offers more than one Class of a Multiple Class Fund or more than one Feeder Fund that invests in the same Master Fund, provide a separate response for each Class or Feeder Fund. Base the percentages of "Annual Fund Operating Expenses" on amounts incurred during the Fund's most recent fiscal year, but include in expenses amounts that would have been incurred absent expense reimbursement or fee waiver arrangements. If the Fund has changed its fiscal year and, as a result, the most recent fiscal year is less than three months, use the fiscal year prior to the most recent fiscal year as the basis for determining "Annual Fund Operating Expenses."Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 3 -Subparagraph d -Subsection instructions truefalseTotal annual fund operating expenses0rr_ExpensesOverAssetstruefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.01080.0108falsefalsefalsetruefalse2truetruetrue0.00750.0075falsefalsefalsetruefalseOthernanafalsefalseTotal annual fund operating expenses5falseRowprimaryElement*9false0rr_FeeWaiverOrReimbursementOverAssetsrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue-0.0019-0.0019[1]falsefalsefalsetruefalse2falsetruetrue00falsefalsefalsetruefalseOtherrr:NonPositivePure4TypepureTotal Annual Fund Operating Expenses. If there were expense reimbursement or fee waiver arrangements that reduced any Fund operating expenses and will continue to reduce them for no less than one year from the effective date of the Fund's registration statement, a Fund may add two captions to the table one caption showing the amount of the expense reimbursement or fee waiver, and a second caption showing the Fund's net expenses after subtracting the fee reimbursement or expense waiver from the total fund operating expenses. The Fund should place these additional captions directly below the "Total Annual Fund Operating Expenses" caption of the table and should use appropriate descriptive captions, such as "Fee Waiver [and/or Expense Reimbursement]" and "Total Annual Fund Operating Expenses After Fee Waiver [and/or Expense Reimbursement]," respectively. If the Fund provides this disclosure, also disclose the period for which the expense reimbursement or fee waiver arrangement is expected to continue, and briefly describe who can terminate the arrangement and under what circumstances.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subparagraph 11 -Subsection table falsefalseLess fee waiver and/or expense reimbursement0rr_FeeWaiverOrReimbursementOverAssetstruefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse[1]1truetruetrue-0.0019-0.0019falsefalsefalsetruefalse2falsefalsefalse00falsefalsefalsefalsefalseOthernanafalsefalseLess fee waiver and/or expense reimbursement6falseRowprimaryElement*10false0rr_NetExpensesOverAssetsrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalsetotallabel1truetruetrue0.00890.0089falsefalsefalsetruefalse2falsetruetrue00falsefalsefalsetruefalseOtherrr:NonNegativePure4TypepureTotal Annual Fund Operating Expenses.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subparagraph 11 -Subsection table truefalseNet expense0rr_NetExpensesOverAssetstruefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.00890.0089falsefalsefalsetruefalse2falsefalsefalse00falsefalsefalsefalsefalseOthernanafalsefalseNet expense1Calvert has agreed to contractually limit direct net annual fund operating expenses through January 31, 2012. Direct net operating expenses will not exceed 0.89% for Class A and 0.84% for Class Y. Only the Board of Trustees of the Fund may terminate the Fund's expense cap before the contractual period expires.26Annual Fund Operating Expenses CALVERT ULTRA-SHORT INCOME FUNDUnKnownUnKnownUnKnownUnKnownfalsetrueColumnperiodPeriod*Columndei_LegalEntityAxisAxiscik001380786_S000027100MemberColumnrr_ProspectusShareClassAxisAxis*ColumnunitUnit*RowprimaryElement*falsefalsefalseOtherus-types:textBlockItemTypestringContains a command for the SEC Viewer for the role corresponding to OperatingExpensesData.No authoritative reference available.falsefalseAnnual Fund Operating Expenses [Table]12false0rr_ExpenseExampleHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div class="MetaData"> <p style="margin: 0in 0in 6pt; font-family: 'Times New Roman','serif'; font-size: 12pt;"><b><font style="font-family: 'Arial','sans-serif'; font-size: 10pt;" class="_mt">Example</font></b></p></div>falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringHeading for Expense Example.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 4 -Subsection instructions falsefalseExpense Example [Heading]13false0rr_ExpenseExampleNarrativeTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div> <p> 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: </p><p> :you invest $10,000 in the Fund for the time periods indicated; </p><p> :your investment has a 5% return each year; </p><p> :the Fund's operating expenses remain the same; and </p><p> :any Calvert expense limitation is in effect for the period indicated in the fee table above. </p><p> </p><p> Although your actual costs may be higher or lower, under these assumptions your costs would be: </p> </div>falsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringThe Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subparagraph 1 -Subsection example falsefalseExpense Example Narrative [Text Block]14false0rr_ExpenseExampleByYearCaptionrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div class="MetaData"> <p style="margin: 0in 0in 0pt; font-family: 'Times New Roman','serif'; font-size: 12pt;"><b><font style="font-family: 'Arial','sans-serif'; font-size: 10pt;" class="_mt">Number of Years Investment is Held</font></b></p></div>falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringThe Example assumes that you invest $10,000 in the Fund for the time periods indicated and then you redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return per year and that the Fund's operating expenses remained the same. Although your actual costs may be higher or lower.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subparagraph 2 -Subsection example falsefalseExpense Example by, Year, Caption [Text]15false0rr_ExpenseExampleWithRedemptionTableTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div> &lt;div style="display:none;" &gt;~ http://www.calvert.com/role/ScheduleExpenseExampleTransposedCalvertHighYieldBondFund row period compact * row dei_LegalEntityAxis compact cik001380786_S000027100Member row rr_ProspectusShareClassAxis compact * column primary compact * ~&lt;/div&gt; </div>falsefalse<div> &lt;div style="display:none;" &gt;~ http://www.calvert.com/role/ScheduleExpenseExampleTransposedCalvertHighYieldBondFund row period compact * row dei_LegalEntityAxis compact cik001380786_S000027100Member row rr_ProspectusShareClassAxis compact * column primary compact * ~&lt;/div&gt; </div>truehttp://www.calvert.com/role/ScheduleExpenseExampleTransposedCalvertHighYieldBondFundfalsefalse000024 - Schedule - Expense Example {Transposed}truefalsefalse1falseColumnperiodPeriod*Columndei_LegalEntityAxisAxiscik001380786_S000027100MemberColumnrr_ProspectusShareClassAxisAxis*duration2011-01-18T00:00:002011-01-18T00:00:00falsefalseCALVERT ULTRA-SHORT INCOME FUNDdei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldicik001380786_S000027100Memberdei_LegalEntityAxisexplicitMemberfalsefalseClass Arr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldicik001380786_C000081597Memberrr_ProspectusShareClassAxisexplicitMemberCALVERT ULTRA-SHORT INCOME FUNDClass AfalseUSDfalsefalse$2falseColumnperiodPeriod*Columndei_LegalEntityAxisAxiscik001380786_S000027100MemberColumnrr_ProspectusShareClassAxisAxis*duration2011-01-18T00:00:002011-01-18T00:00:00falsefalseCALVERT ULTRA-SHORT INCOME FUNDdei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldicik001380786_S000027100Memberdei_LegalEntityAxisexplicitMemberfalsefalseClass Yrr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldicik001380786_C000081600Memberrr_ProspectusShareClassAxisexplicitMemberCALVERT ULTRA-SHORT INCOME FUNDClass YfalseUSDfalsefalse$1falseRowprimaryElement*RowunitUnit*5false0rr_ExpenseExampleYear01rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsetrue215215falsefalsefalsetruefalse2truefalsetrue7777falsefalsefalsetruefalseMonetaryrr:NonNegativeMonetaryTypemonetaryThe Example assumes that you invest $10,000 in the Fund for the time periods indicated and then you redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return per year and that the Fund's operating expenses remained the same. Although your actual costs may be higher or lower.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 4 -Subsection instructions falsefalse1 YearUnit12Standardhttp://www.xbrl.org/2003/iso4217USDiso421700rr_ExpenseExampleYear01truefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsetrue215215falsefalsefalsetruefalse2truefalsetrue7777falsefalsefalsetruefalseOthernanafalsefalse1 Year2falseRowprimaryElement*RowunitUnit*6false0rr_ExpenseExampleYear03rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsetrue446446falsefalsefalsetruefalse2truefalsetrue240240falsefalsefalsetruefalseMonetaryrr:NonNegativeMonetaryTypemonetaryThe Example assumes that you invest $10,000 in the Fund for the time periods indicated and then you redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return per year and that the Fund's operating expenses remained the same. Although your actual costs may be higher or lower.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subparagraph 2 -Subsection example falsefalse3 YearsUnit12Standardhttp://www.xbrl.org/2003/iso4217USDiso421700rr_ExpenseExampleYear03truefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsetrue446446falsefalsefalsetruefalse2truefalsetrue240240falsefalsefalsetruefalseOthernanafalsefalse3 Years3falseRowprimaryElement*RowunitUnit*7false0rr_ExpenseExampleYear05rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsetrue695695falsefalsefalsetruefalse2truefalsetrue417417falsefalsefalsetruefalseMonetaryrr:NonNegativeMonetaryTypemonetaryThe Example assumes that you invest $10,000 in the Fund for the time periods indicated and then you redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return per year and that the Fund's operating expenses remained the same. Although your actual costs may be higher or lower.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subparagraph 2 -Subsection example falsefalse5 YearsUnit12Standardhttp://www.xbrl.org/2003/iso4217USDiso421700rr_ExpenseExampleYear05truefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsetrue695695falsefalsefalsetruefalse2truefalsetrue417417falsefalsefalsetruefalseOthernanafalsefalse5 Years4falseRowprimaryElement*RowunitUnit*8false0rr_ExpenseExampleYear10rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsetrue14091409falsefalsefalsetruefalse2truefalsetrue930930falsefalsefalsetruefalseMonetaryrr:NonNegativeMonetaryTypemonetaryThe Example assumes that you invest $10,000 in the Fund for the time periods indicated and then you redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return per year and that the Fund's operating expenses remained the same. Although your actual costs may be higher or lower.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subparagraph 2 -Subsection example falsefalse10 YearsUnit12Standardhttp://www.xbrl.org/2003/iso4217USDiso421700rr_ExpenseExampleYear10truefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsetrue14091409falsefalsefalsetruefalse2truefalsetrue930930falsefalsefalsetruefalseOthernanafalsefalse10 Years24Expense Example CALVERT ULTRA-SHORT INCOME FUND (USD $)UnKnownUnKnownUnKnownUnKnownfalsetrueColumnperiodPeriod*Columndei_LegalEntityAxisAxiscik001380786_S000027100MemberColumnrr_ProspectusShareClassAxisAxis*RowprimaryElement*RowunitUnit*falsefalsefalseOtherus-types:textBlockItemTypestringContains a command for the SEC Viewer for the role corresponding to ExpenseExample.No authoritative reference available.falsefalseExpense Example, With Redemption [Table]16false0rr_ExpenseExampleNoRedemptionByYearCaptionrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div class="MetaData"> <p style="margin: 0in 0in 0pt; font-family: 'Times New Roman','serif'; font-size: 12pt;"><b><font style="font-family: 'Arial','sans-serif'; font-size: 10pt;" class="_mt"></font></b></p></div>falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringYou would pay the following expenses if you did not redeem your shares. Include the second 1-, 3-, 5-, and 10-year periods and related narrative explanation only if a sales charge (load) or other fee is charged upon redemption.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 2 -Subparagraph 1 -Subsection example falsefalseExpense Example, No Redemption, By Year, Caption [Text]17false0rr_PortfolioTurnoverHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div class="MetaData"> <p style="margin: 0in 0in 6pt; font-family: 'Times New Roman','serif'; font-size: 12pt;"><b><font style="font-family: 'Arial','sans-serif'; font-size: 10pt;" class="_mt">Portfolio Turnover</font></b></p></div>falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringDisclose the portfolio turnover rate provided in response to Item 14(a) for the most recent fiscal year (or for such shorter period as the Fund has been in operation). Disclose the period for which the information is provided if less than a full fiscal year. A Fund that is a Money Market Fund may omit the portfolio turnover information required by this Item.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 5 -Subsection instructions falsefalsePortfolio Turnover [Heading]18false0rr_PortfolioTurnoverTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div> <p>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 for Class A was 268% of its portfolio's average value and 62% for Class Y. </p> </div>falsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringDisclose the portfolio turnover rate provided in response to Item 14(a) for the most recent fiscal year (or for such shorter period as the Fund has been in operation). Disclose the period for which the information is provided if less than a full fiscal year. A Fund that is a Money Market Fund may omit the portfolio turnover information required by this Item.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 3 -Subsection example falsefalsePortfolio Turnover [Text Block]19false0rr_StrategyHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00 <div class="MetaData"> <p style="margin: 0in 0in 6pt; font-family: 'Times New Roman','serif'; font-size: 12pt;"><font style="font-family: 'Arial','sans-serif';" class="_mt"><b>INVESTMENTS, RISKS AND PERFORMANCE</b></font></p></div> <div class="MetaData"> <p style="margin: 0in 0in 6pt; font-family: 'Times New Roman','serif'; font-size: 12pt;"><font style="font-family: 'Arial','sans-serif';" class="_mt"><b>Principal Investment Strategies</b></font></p></div>falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringPrincipal investment strategies of the Fund. Summarize how the Fund intends to achieve its investment objectives by identifying the Fund's principal investment strategies (including the type or types of securities in which the Fund invests or will invest principally) and any policy to concentrate in securities of issuers in a particular industry or group of industries.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection a falsefalseStrategy [Heading]20false0rr_StrategyNarrativeTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div><p> The Fund seeks to achieve its investment objective by investing under normal circumstances, at least 80% of its net assets (including borrowings for investment purposes) in a portfolio of floating-rate securities and securities with durations of less than or equal to one year. The Fund will provide shareholders with at least 60 days' notice before changing this 80% policy. The Fund uses an active strategy, seeking relative value to earn incremental income. </p><p> 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 AND Poor's Ratings Services ('Standard AND 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. </p><p> The Fund invests principally in floating-rate securities and fixed-rate securities with durations of less than or equal to one year that are issued by U.S. corporations and by the U.S. government and its agencies (e.g., Government National Mortgage Association, the Federal National Mortgage Association ('FNMA') and the Federal Home Loan Mortgage Corporation ('FHLMC')). Floating-rate securities generally pay interest at rates that adjust whenever a specified interest rate changes and/or reset on predetermined dates (such as the last day of a month or calendar quarter). The Fund also may invest in taxable municipal securities, asset-backed securities ('ABS'), including commercial mortgage-backed securities, and repurchase agreements. </p><p> 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. </p><p> 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 bonds rated in default. A debt security is below investment grade when assigned a credit quality rating below BBB by Standard AND Poor's or an equivalent rating by another NRSRO, or if unrated, considered to be of comparable credit quality by the Fund's Advisor. </p><p> The Fund may also invest up to 25% of its net assets in foreign debt securities. Foreign debt securities include American Depositary Receipts ('ADRs'). </p><p> The Fund is non-diversified. </p><p> Under normal circumstances, the Fund's average portfolio duration will be less than one year. Duration is a measure of the expected average life of a fixed income security that is used to determine the sensitivity of a security's price to changes in interest rates. The longer a security's duration, the more sensitive it will be to changes in interest rates. Similarly, a Fund with a longer average portfolio duration will be more sensitive to changes in interest rates than a Fund with a shorter average portfolio duration. </p><p> The Fund may also use a hedging technique that includes the purchase and sale of U.S. Treasury securities and related futures contracts for the purpose of managing the duration of the Fund. </p><p> In addition, although the Fund may employ leverage by borrowing money and using it for the purchase of additional securities, the Fund does not currently intend to do so. </p><p> </p> </div> falsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringPrincipal investment strategies of the Fund. Summarize how the Fund intends to achieve its investment objectives by identifying the Fund's principal investment strategies (including the type or types of securities in which the Fund invests or will invest principally) and any policy to concentrate in securities of issuers in a particular industry or group of industries.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection a falsefalseStrategy Narrative [Text Block]21false0rr_RiskHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div class="MetaData"> <p style="margin: 0in 0in 6pt; font-family: 'Times New Roman','serif'; font-size: 12pt;"><font style="font-family: 'Arial','sans-serif';" class="_mt"><b>Principal Risks</b></font></p></div>falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringNarrative Risk Disclosure.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 1 -Subsection b falsefalseRisk [Heading]22false0rr_RiskNarrativeTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div> <p > 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. </p ><p > <i >Non-Diversification Risk.</i> The Fund may invest more of its assets in a smaller number of issuers than a diversified fund. Gains or losses on a single bond may have greater impact on the Fund. </p ><p > <i >Bond Market Risk. </i >The market prices of bonds held by the Fund may fall. </p ><p > <i >Credit Risk.</i > 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. </p ><p > <i >Mortgage-Backed and Asset-Backed Securities Risk.</i > 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 issuers will prepay the principal more quickly or more slowly than expected, which could cause the Fund to invest the proceeds in less attractive investments or increase the volatility of their prices. To the extent mortgage-backed and asset-backed securities held by the Fund are subordinated to other interests in the same mortgage or asset pool, the likelihood of the Fund receiving payments of principal or interest may be substantially limited. </p ><p > <i >Mortgage-Backed Security Risk of Government-Sponsored Enterprises.</i > Debt and mortgage-backed securities issued by government-sponsored enterprises ('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 GSE. The U.S. government recently provided financial support to FNMA and FHLMC, but there can be no assurance that it will support these or other GSEs in the future. Mortgage-backed securities also involve prepayment risk and extension risk. </p ><p > <i >Management Risk. </i >The individual bonds in the Fund may not perform as expected, due to credit, political or other risks and/or the Fund's portfolio management practices may not achieve the desired result. </p ><p > <i >Interest Rate Risk.</i > A change in interest rates may adversely affect the value of fixed-income securities. When interest rates rise, the value of fixed-income securities will generally fall. Because a significant portion of securities held by the Fund may have variable or floating interest rates, the amounts of the Fund's monthly distributions to shareholders are expected to vary with fluctuations in market interest rates. Generally, when market interest rates fall, the amount of the distributions to shareholders will likewise decrease. </p ><p > <i >Lag Risk for Interest Payments.</i > There may be a lag between an actual change in the underlying interest rate benchmark and the reset time for an interest payment for a floating-rate security, which could harm or benefit the Fund, depending on the circumstances. For example, a floating-rate security that does not reset immediately would prevent the Fund from taking full advantage of rising interest rates. In a declining interest rate environment, however, the Fund would benefit from the lag since the Fund would not immediately be impacted by a decline in interest rates. </p ><p > <i >Junk Bond Risk.</i > 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. </p ><p > <i >Defaulted Bonds Risk.</i > For bonds in default (rated 'D' by Standard AND Poor's or the equivalent by another NRSRO), there is a significant risk of not achieving full recovery. </p ><p > <i >Unrated Security Risk.</i > Unrated securities may be less liquid than rated securities determined to be of comparable quality. When the Fund purchases unrated securities, it will depend on the Advisor's analysis of credit risk without the assessment of an NRSRO. </p ><p > <i >Corporate and Taxable Municipal Bond Risk.</i > For corporate and taxable municipal bonds, there is credit risk in addition to the interest rate risk that affects all fixed-income securities. </p ><p > <i >Collateralized Mortgage Obligation Risk. </i >There are risks associated with CMOs that relate to the risks of the underlying mortgage pass-through securities (i.e., an increase or decrease in prepayment rates, resulting from a decrease or increase in mortgage interest rates, will affect the yield, average life, and price of CMOs). </p ><p > <i >Foreign Securities Risk.</i > 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. </p ><p > <i >Foreign Currency Risk.</i > 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. </p ><p > <i >American Depositary Receipt Risk.</i > The risks of ADRs include many risks associated with investing directly in foreign securities, such as individual country risk and liquidity risk. 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. </p ><p > <i >Repurchase Agreement Risk. </i >A repurchase agreement exposes the Fund to the risk that the party that sells the security may default on its obligation to repurchase it. The Fund may lose money because it cannot sell the security at the agreed-upon time and price or the security loses value before it can be sold. </p ><p > <i >Active Trading Strategy Risk. </i >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. </p ><p > <i >Futures Contracts Risk.</i > 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. </p ><p > <i >Leverage Risk.</i > If leverage were employed, borrowing would magnify the potential for gain or loss on the Fund's portfolio securities and would increase the possibility of fluctuation in the Fund's net asset value. Interest costs might not be recovered by appreciation of the securities purchased. </p > </div>falsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringNarrative Risk Disclosure. A Fund may, in responding to this Item, describe the types of investors for whom the Fund is intended or the types of investment goals that may be consistent with an investment in the Fund.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 1 -Subparagraph i -Clause instruction -Subsection b falsefalseRisk Narrative [Text Block]23false0rr_BarChartAndPerformanceTableHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div class="MetaData"> <p style="margin: 0in 0in 6pt; font-family: 'Times New Roman','serif'; font-size: 12pt;"><font style="font-family: 'Arial','sans-serif';" class="_mt"> <b>Performance</b></font></p></div>falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringRisk/Return Bar Chart and Table.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subsection b falsefalseBar Chart and Performance Table [Heading]24false0rr_PerformanceNarrativeTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div> <p> 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 an index and an average. </p><p> 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. </p><p> Performance results for Class Y shares prior to May 28, 2010 (the Class Y shares' inception date) reflect the performance of Class A shares at net asset value. Actual Class Y share performance would have been higher than Class A share performance because Class Y, unlike Class A, has no Rule 12b-1 fees. </p><p> The return for each of the Fund's other Classes of shares will differ from the Class A returns shown in the bar chart, depending upon the expenses of that Class. </p><p> 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. </p> </div>falsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringRisk/Return Bar Chart and Table.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subsection b falsefalsePerformance Narrative [Text Block]25false0rr_BarChartHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div class="MetaData"> <p style="text-align: center; margin: 10.05pt 0in 0pt; font-family: 'Times New Roman','serif'; font-size: 12pt;" align="center"><b><font style="font-family: 'Arial','sans-serif'; font-size: 10pt;" class="_mt">Calendar Year Total Returns for Class A at NAV</font></b></p></div>falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringRisk/Return Bar Chart and Table.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subsection b falsefalseBar Chart [Heading]26false0rr_BarChartTableTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div> &lt;div style="display:none;" &gt;~ http://www.calvert.com/role/ScheduleAnnualTotalReturnsBarChartCalvertHighYieldBondFund column period compact * column primary compact * row dei_LegalEntityAxis compact cik001380786_S000027100Member row rr_ProspectusShareClassAxis compact * ~&lt;/div&gt; </div>falsefalseBarChart1.jpg<div> &lt;div style="display:none;" &gt;~ http://www.calvert.com/role/ScheduleAnnualTotalReturnsBarChartCalvertHighYieldBondFund column period compact * column primary compact * row dei_LegalEntityAxis compact cik001380786_S000027100Member row rr_ProspectusShareClassAxis compact * ~&lt;/div&gt; </div>falsehttp://www.calvert.com/role/ScheduleAnnualTotalReturnsBarChartCalvertHighYieldBondFundfalsefalse000026 - Schedule - Annual Total Returnstruefalsefalse1falseColumnperiodPeriod*ColumnprimaryElement*ColumnunitUnit*5false0rr_AnnualReturn2007rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse0.05200.0520falsefalsefalsetruefalseOtherxbrli:pureItemTypepureIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart. When a Multiple Class Fund offers more than one Class in the prospectus, provide annual total returns in the bar chart for only one of those Classes. The Fund can select which Class to include (e.g., the oldest Class, the Class with the greatest net assets).Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph instructions -Clause 3 -Exhibit a -Subsection b falsefalseAnnual Return 2007duration2011-01-18T00:00:002011-01-18T00:00:00Unit12Standardhttp://www.xbrl.org/2003/iso4217USDiso42170falseUSDfalsefalse$2falseColumnperiodPeriod*ColumnprimaryElement*ColumnunitUnit*6false0rr_AnnualReturn2008rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse0.02980.0298falsefalsefalsetruefalseOtherxbrli:pureItemTypepureIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart. When a Multiple Class Fund offers more than one Class in the prospectus, provide annual total returns in the bar chart for only one of those Classes. The Fund can select which Class to include (e.g., the oldest Class, the Class with the greatest net assets).Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph ii -Subsection b falsefalseAnnual Return 2008duration2011-01-18T00:00:002011-01-18T00:00:00Unit12Standardhttp://www.xbrl.org/2003/iso4217USDiso42170falseUSDfalsefalse$3falseColumnperiodPeriod*ColumnprimaryElement*ColumnunitUnit*7false0rr_AnnualReturn2009rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse0.07290.0729falsefalsefalsetruefalseOtherxbrli:pureItemTypepureIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart. When a Multiple Class Fund offers more than one Class in the prospectus, provide annual total returns in the bar chart for only one of those Classes. The Fund can select which Class to include (e.g., the oldest Class, the Class with the greatest net assets).Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph instructions -Clause 3 -Exhibit a -Subsection b falsefalseAnnual Return 2009duration2011-01-18T00:00:002011-01-18T00:00:00Unit12Standardhttp://www.xbrl.org/2003/iso4217USDiso42170falseUSDfalsefalse$4falseColumnperiodPeriod*ColumnprimaryElement*ColumnunitUnit*8false0rr_AnnualReturn2010rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse0.02300.0230falsefalsefalsetruefalseOtherxbrli:pureItemTypepureIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart. When a Multiple Class Fund offers more than one Class in the prospectus, provide annual total returns in the bar chart for only one of those Classes. The Fund can select which Class to include (e.g., the oldest Class, the Class with the greatest net assets).Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph ii -Subsection b falsefalseAnnual Return 2010duration2011-01-18T00:00:002011-01-18T00:00:00Unit12Standardhttp://www.xbrl.org/2003/iso4217USDiso42170falseUSDfalsefalse$1falseRowdei_LegalEntityAxisAxiscik001380786_S000027100MemberRowrr_ProspectusShareClassAxisAxis*falsefalseCALVERT ULTRA-SHORT INCOME FUNDdei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldicik001380786_S000027100Memberdei_LegalEntityAxisexplicitMemberfalsefalseClass Arr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldicik001380786_C000081597Memberrr_ProspectusShareClassAxisexplicitMemberCALVERT ULTRA-SHORT INCOME FUNDClass A0truefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse0.05200.0520falsefalsefalsetruefalse2truetruefalse0.02980.0298falsefalsefalsetruefalse3truetruefalse0.07290.0729falsefalsefalsetruefalse4truetruefalse0.02300.0230falsefalsefalsetruefalseOthernanafalsefalseCALVERT ULTRA-SHORT INCOME FUND Class A41Annual Total Returns UnKnownUnKnownUnKnownUnKnownfalsetrueColumnperiodPeriod*ColumnprimaryElement*ColumnunitUnit*Rowdei_LegalEntityAxisAxiscik001380786_S000027100MemberRowrr_ProspectusShareClassAxisAxis*falsefalsefalseOtherus-types:textBlockItemTypestringContains a command for the SEC Viewer for the role corresponding to BarChartData.No authoritative reference available.falsefalseBar Chart [Table]27false0rr_BarChartClosingTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div> <p> Best Quarter (of periods shown) 6/30/2009 3.25% Worst Quarter (of periods shown) 6/30/2010 0.24% </p> </div>falsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph ii -Subsection b falsefalseBar Chart Closing [Text Block]28false0rr_PerformanceTableNarrativeTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div> <p > 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. </p ><p > 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. </p > </div>falsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringIf the Fund has annual returns for at least one calendar year, provide a table showing the Fund's (A) average annual total return; (B) average annual total return (after taxes on distributions); and (C) average annual total return (after taxes on distributions and redemption). A Money Market Fund should show only the returns described in clause (A) of the preceding sentence. All returns should be shown for 1-, 5-, and 10- calendar year periods ending on the date of the most recently completed calendar year (or for the life of the Fund, if shorter), but only for periods subsequent to the effective date of the Fund's registration statement. The table also shouldshow the returns of an appropriate broadbased securities market index as defined in Instruction 5 to Item 22(b)(7) for the same periods. A Fund that has been in existence for more than 10 years also may include returns for the life of the Fund. A Money Market Fund may provide the Fund's 7-day yield ending on the date of the most recent calendar year or disclose a toll-free (or collect) telephone number that investors can use to obtain the Fund's current 7-day yield. For a Fund (other than a Money Market Fund or a Fund described in General Instruction C.3.(d)(iii)), provide the information in the following table with the specified captions AVERAGE ANNUAL TOTAL RETURNS (For the periods ended December 31, _____). For a Fund that provides annual total returns for only one calendar year or for a Fund that does not include the bar chart because it does not have annual returns for a full calendar year, modify, as appropriate, the narrative explanation required by paragraph (c)(2)(i) (e.g., by stating that the information gives some indication of the risks of an investment in the Fund by comparing the Fund's performance with a broad measure of market performance).Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph iv -Subsection b falsefalsePerformance Table Narrative29false0rr_PerformanceTableHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div class="MetaData"> <p style="text-align: center; margin: 0in 0in 0pt; font-family: 'Times New Roman','serif'; font-size: 12pt;" align="center"><b><font style="font-family: 'Arial','sans-serif'; font-size: 10pt;" class="_mt">Average Annual Total Returns</font></b></p> <p style="text-align: center; margin: 0in 0in 0pt; font-family: 'Times New Roman','serif'; font-size: 12pt;" align="center"><b><font style="font-family: 'Arial','sans-serif'; font-size: 10pt;" class="_mt">(as of 12-31-10)</font></b></p> <p style="text-align: center; margin: 0in 0in 0pt; font-family: 'Times New Roman','serif'; font-size: 12pt;" align="center"><b><font style="font-family: 'Arial','sans-serif'; font-size: 10pt;" class="_mt">(with maximum sales charge deducted, if any)</font></b></p></div>falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringThis item represents Average Anuual Total Returns. If a Multiple Class Fund offers a Class in the prospectus that converts into another Class after a stated period, compute average annual total returns in the table by using the returns of the other Class for the period after conversion.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph instructions -Clause 3 -Exhibit c -Subsection b falsefalsePerformance Table Heading30false0rr_PerformanceTableTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div> &lt;div style="display:none;" &gt;~ http://www.calvert.com/role/ScheduleAverageAnnualTotalReturnsTransposedCalvertHighYieldBondFund row period compact * row primary compact * column dei_LegalEntityAxis compact cik001380786_S000027100Member column rr_ProspectusShareClassAxis compact * column rr_PerformanceMeasureAxis compact * ~&lt;/div&gt; </div>falsefalse<div> &lt;div style="display:none;" &gt;~ 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Inceptionduration2011-01-18T00:00:002011-01-18T00:00:00falseUSDfalsefalse$3falseColumnperiodPeriod*ColumnprimaryElement*7false0rr_AverageAnnualReturnInceptionDaterrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsetruefalse002006-10-31falsefalsetruetruefalse2falsetruefalse002006-10-31falsefalsetruetruefalse3falsetruefalse002006-10-31falsefalsetruetruefalse4falsetruefalse002006-10-31falsefalsetruetruefalse5falsetruefalse002006-10-31[1]falsefalsetruetruefalse6falsetruefalse002006-10-31falsefalsetruetruefalseOtherxbrli:dateItemTypedateReturn Before Taxes.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph instructions -Clause 4 -Subsection b falsefalseInception Dateduration2011-01-18T00:00:002011-01-18T00:00:00falseUSDfalsefalse$1falseRowdei_LegalEntityAxisAxiscik001380786_S000027100MemberRowrr_ProspectusShareClassAxisAxis*Rowrr_PerformanceMeasureAxisAxis*RowunitUnit*falsefalseCALVERT ULTRA-SHORT INCOME FUNDdei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldicik001380786_S000027100Memberdei_LegalEntityAxisexplicitMemberfalsefalseClass Arr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldicik001380786_C000081597Memberrr_ProspectusShareClassAxisexplicitMembertruefalseBefore Taxesrr_PerformanceMeasureAxisrr_PerformanceMeasureDomainrr_PerformanceMeasureAxisexplicitMemberCALVERT ULTRA-SHORT INCOME FUNDClass ABefore TaxesUnit12Standardhttp://www.xbrl.org/2003/iso4217USDiso421700truefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.01010.0101falsefalsefalsetruefalse2truetruetrue0.04130.0413falsefalsefalsetruefalse3falsetruefalse002006-10-312006-10-31falsefalsetruetruefalseOthernanafalsefalseClass A2falseRowdei_LegalEntityAxisAxiscik001380786_S000027100MemberRowrr_ProspectusShareClassAxisAxis*Rowrr_PerformanceMeasureAxisAxis*RowunitUnit*falsefalseCALVERT ULTRA-SHORT INCOME 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Lipper Average reflects no deduction for taxes.) 36Average Annual Total Returns CALVERT ULTRA-SHORT INCOME FUNDUnKnownUnKnownUnKnownUnKnownfalsetrueColumnperiodPeriod*ColumnprimaryElement*Rowdei_LegalEntityAxisAxiscik001380786_S000027100MemberRowrr_ProspectusShareClassAxisAxis*Rowrr_PerformanceMeasureAxisAxis*RowunitUnit*falsefalsefalseOtherus-types:textBlockItemTypestringContains a command for the SEC Viewer for the role corresponding to PerformanceTableData.No authoritative reference available.falsefalsePerformance [Table]128Risk/Return Summary (CALVERT ULTRA-SHORT INCOME FUND)UnKnownUnKnownUnKnownUnKnownfalsetrue