2.2.0.25truefalse040000 - Disclosure - Risk/Return Detail Data {Elements}truetruefalse1falsefalsefalsefalse1/18/2011 - 1/18/2011 Duration_1_18_2011_To_1_18_2011http://www.sec.gov/CIK0000701039duration2011-01-18T00:00:002011-01-18T00:00:002falsefalseUSDtruefalse{dei_LegalEntityAxis} : S000027100 Member {rr_ProspectusShareClassAxis} : C000081597 Member 1/18/2011 - 1/18/2011 USD ($) $Duration_1_18_2011_To_1_18_20115http://www.sec.gov/CIK0000701039duration2011-01-18T00:00:002011-01-18T00:00:00falsefalseCALVERT GOVERNMENT FUNDdei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldicik001380786_S000027100Memberdei_LegalEntityAxisexplicitMemberfalsefalseClass Arr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldicik001380786_C000081597Memberrr_ProspectusShareClassAxisexplicitMemberUnit1Standardhttp://www.xbrl.org/2003/instancepurexbrli0Unit12Standardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$3falsefalsetruefalse{dei_LegalEntityAxis} : S000027100 Member {rr_ProspectusShareClassAxis} : C000081597 Member {rr_PerformanceMeasureAxis} : Return after taxes on distributions 1/18/2011 - 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1/18/2011 Duration_1_18_2011_To_1_18_201173http://www.sec.gov/CIK0000701039duration2011-01-18T00:00:002011-01-18T00:00:00falsefalseCALVERT GOVERNMENT FUNDdei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldicik001380786_S000027100Memberdei_LegalEntityAxisexplicitMemberfalsefalseBarclays Capital U.S. Government Indexrr_PerformanceMeasureAxisxbrldihttp://xbrl.org/2006/xbrldicik001380786_MerrillLynchFixedRatePreferredSecuritiesIndexMemberrr_PerformanceMeasureAxisexplicitMemberUnit1Standardhttp://www.xbrl.org/2003/instancepurexbrli010falsefalsetruefalse{dei_LegalEntityAxis} : S000027100 Member {rr_PerformanceMeasureAxis} : Lipper General U.S. Government Funds Avg. Member 1/18/2011 - 1/18/2011 Duration_1_18_2011_To_1_18_201172http://www.sec.gov/CIK0000701039duration2011-01-18T00:00:002011-01-18T00:00:00falsefalseCALVERT GOVERNMENT FUNDdei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldicik001380786_S000027100Memberdei_LegalEntityAxisexplicitMemberfalsefalseLipper General U.S. Government Funds Avg.rr_PerformanceMeasureAxisxbrldihttp://xbrl.org/2006/xbrldicik001380786_LipperCorporateDebtBbbRatedFundsCategoryAverageMemberrr_PerformanceMeasureAxisexplicitMemberUnit1Standardhttp://www.xbrl.org/2003/instancepurexbrli02true0rr_RiskReturnAbstractrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsetruefalse3falsefalsefalse00falsefalsefalsetruefalse4falsefalsefalse00falsefalsefalsetruefalse5falsefalsefalse00falsefalsefalsetruefalse6falsefalsefalse00falsefalsefalsetruefalse7falsefalsefalse00falsefalsefalsetruefalse9falsefalsefalse00falsefalsefalsetruefalse10falsefalsefalse00falsefalsefalsetruefalse11falsefalsefalse00falsefalsefalsetruefalseOtherxbrli:stringItemTypestringNo definition available.falsefalseRisk/Return:3false0dei_DocumentTypedeifalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00485BPOS485BPOSfalsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsetruefalse3falsefalsefalse00falsefalsefalsetruefalse4falsefalsefalse00falsefalsefalsetruefalse5falsefalsefalse00falsefalsefalsetruefalse6falsefalsefalse00falsefalsefalsetruefalse7falsefalsefalse00falsefalsefalsetruefalse9falsefalsefalse00falsefalsefalsetruefalse10falsefalsefalse00falsefalsefalsetruefalse11falsefalsefalse00falsefalsefalsetruefalseOtherus-types:SECReportItemTypenaThe type of document being provided (such as 10-K, 10-Q, N-1A, etc). The document type should be limited to the same value as the supporting SEC submission type. The acceptable values are as follows: S-1, S-3, S-4, S-11, F-1, F-3, F-4, F-9, F-10, 6-K, 8-K, 10, 10-K, 10-Q, 20-F, 40-F, N-1A, 485BPOS, NCSR, N-Q, and Other.No authoritative reference available.falsefalseDocument Type4false0dei_DocumentPeriodEndDatedeifalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse002010-09-302010-09-30falsefalsetruefalsefalse2falsefalsefalse00falsefalsetruetruefalse3falsefalsefalse00falsefalsetruetruefalse4falsefalsefalse00falsefalsetruetruefalse5falsefalsefalse00falsefalsetruetruefalse6falsefalsefalse00falsefalsetruetruefalse7falsefalsefalse00falsefalsetruetruefalse9falsefalsefalse00falsefalsetruetruefalse10falsefalsefalse00falsefalsetruetruefalse11falsefalsefalse00falsefalsetruetruefalseOtherxbrli:dateItemTypedateThe end date of the period reflected on the cover page if a periodic report. For all other reports and registration statements this will be the filing date. The format of the date is CCYY-MM-DD.No authoritative reference available.falsefalseDocument Period End Date5false0dei_EntityRegistrantNamedeifalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00CALVERT FUNDCALVERT FUNDfalsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsetruefalse3falsefalsefalse00falsefalsefalsetruefalse4falsefalsefalse00falsefalsefalsetruefalse5falsefalsefalse00falsefalsefalsetruefalse6falsefalsefalse00falsefalsefalsetruefalse7falsefalsefalse00falsefalsefalsetruefalse9falsefalsefalse00falsefalsefalsetruefalse10falsefalsefalse00falsefalsefalsetruefalse11falsefalsefalse00falsefalsefalsetruefalseOtherxbrli:normalizedStringItemTypenormalizedstringThe exact name of the entity filing the report as specified in its charter, which is required by forms filed with the SEC.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation 12B -Number 240 -Section 12b -Subsection 1 falsefalseRegistrant Name6false0dei_EntityCentralIndexKeydeifalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse0000007010390000701039falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsetruefalse3falsefalsefalse00falsefalsefalsetruefalse4falsefalsefalse00falsefalsefalsetruefalse5falsefalsefalse00falsefalsefalsetruefalse6falsefalsefalse00falsefalsefalsetruefalse7falsefalsefalse00falsefalsefalsetruefalse9falsefalsefalse00falsefalsefalsetruefalse10falsefalsefalse00falsefalsefalsetruefalse11falsefalsefalse00falsefalsefalsetruefalseOtherus-types:centralIndexKeyItemTypenaA unique 10-digit SEC-issued value to identify entities that have filed disclosures with the SEC. It is commonly abbreviated as CIK.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation 12B -Number 240 -Section 12b -Subsection 1 falsefalseCentral Index Key7false0dei_AmendmentFlagdeifalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsetruefalse3falsefalsefalse00falsefalsefalsetruefalse4falsefalsefalse00falsefalsefalsetruefalse5falsefalsefalse00falsefalsefalsetruefalse6falsefalsefalse00falsefalsefalsetruefalse7falsefalsefalse00falsefalsefalsetruefalse9falsefalsefalse00falsefalsefalsetruefalse10falsefalsefalse00falsefalsefalsetruefalse11falsefalsefalse00falsefalsefalsetruefalseOtherxbrli:booleanItemTypenaIf the value is true, then the document as an amendment to previously-filed/accepted document.No authoritative reference available.falsefalseAmendment Flag8false0dei_DocumentCreationDatedeifalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse002011-01-182011-01-18falsefalsetruefalsefalse2falsefalsefalse00falsefalsetruetruefalse3falsefalsefalse00falsefalsetruetruefalse4falsefalsefalse00falsefalsetruetruefalse5falsefalsefalse00falsefalsetruetruefalse6falsefalsefalse00falsefalsetruetruefalse7falsefalsefalse00falsefalsetruetruefalse9falsefalsefalse00falsefalsetruetruefalse10falsefalsefalse00falsefalsetruetruefalse11falsefalsefalse00falsefalsetruetruefalseOtherxbrli:dateItemTypedateThe date the document was made available and submitted, in CCYY-MM-DD format. The date of submission, date of acceptance by the recipient, and the document effective date are all potentially different.No authoritative reference available.falsefalseDocument Creation Date9false0dei_DocumentEffectiveDatedeifalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse002011-01-182011-01-18falsefalsetruefalsefalse2falsefalsefalse00falsefalsetruetruefalse3falsefalsefalse00falsefalsetruetruefalse4falsefalsefalse00falsefalsetruetruefalse5falsefalsefalse00falsefalsetruetruefalse6falsefalsefalse00falsefalsetruetruefalse7falsefalsefalse00falsefalsetruetruefalse9falsefalsefalse00falsefalsetruetruefalse10falsefalsefalse00falsefalsetruetruefalse11falsefalsefalse00falsefalsetruetruefalseOtherxbrli:dateItemTypedateThe date when a document, upon receipt and acceptance, becomes officially effective, in CCYY-MM-DD format. Usually it is a system-assigned date time value, but it may be declared by the submitter in some cases.No authoritative reference available.falsefalseDocument Effective Date10false0rr_ProspectusDaterrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse002011-01-182011-01-18falsefalsetruefalsefalse2falsefalsefalse00falsefalsetruetruefalse3falsefalsefalse00falsefalsetruetruefalse4falsefalsefalse00falsefalsetruetruefalse5falsefalsefalse00falsefalsetruetruefalse6falsefalsefalse00falsefalsetruetruefalse7falsefalsefalse00falsefalsetruetruefalse9falsefalsefalse00falsefalsetruetruefalse10falsefalsefalse00falsefalsetruetruefalse11falsefalsefalse00falsefalsetruetruefalseOtherxbrli:dateItemTypedateThe date of the prospectus.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 1 -Paragraph 3 -Subsection a falsefalseProspectus Date11false0rr_RiskReturnHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsetruefalse3falsefalsefalse00falsefalsefalsetruefalse4falsefalsefalse00falsefalsefalsetruefalse5falsefalsefalse00falsefalsefalsetruefalse6falsefalsefalse00falsefalsefalsetruefalse7falsefalsefalse00falsefalsefalsetruefalse9falsefalsefalse00<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 GOVERNMENT FUND</font></p></div>CALVERT GOVERNMENT FUNDfalsefalsefalsetruefalse10falsefalsefalse00falsefalsefalsetruefalse11falsefalsefalse00falsefalsefalsetruefalseOtherxbrli: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]12false0rr_ObjectiveHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsetruefalse3falsefalsefalse00falsefalsefalsetruefalse4falsefalsefalse00falsefalsefalsetruefalse5falsefalsefalse00falsefalsefalsetruefalse6falsefalsefalse00falsefalsefalsetruefalse7falsefalsefalse00falsefalsefalsetruefalse9falsefalsefalse00 <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>Investment Objectivefalsefalsefalsetruefalse10falsefalsefalse00falsefalsefalsetruefalse11falsefalsefalse00falsefalsefalsetruefalseOtherxbrli: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]13false0rr_ObjectivePrimaryTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsetruefalse3falsefalsefalse00falsefalsefalsetruefalse4falsefalsefalse00falsefalsefalsetruefalse5falsefalsefalse00falsefalsefalsetruefalse6falsefalsefalse00falsefalsefalsetruefalse7falsefalsefalse00falsefalsefalsetruefalse9falsefalsefalse00<div><p>The Fund seeks to maximize income, to the extent consistent with preservation of capital, primarily through investment in debt securities issued or guaranteed by the U.S. government, its agencies or instrumentalities.</p></div>The Fund seeks to maximize income, to the extent consistent with preservation of capital, primarily through investment in debt securities issued or guaranteedfalsefalsefalsetruefalse10falsefalsefalse00falsefalsefalsetruefalse11falsefalsefalse00falsefalsefalsetruefalseOtherus-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]14false0rr_ExpenseHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsetruefalse3falsefalsefalse00falsefalsefalsetruefalse4falsefalsefalse00falsefalsefalsetruefalse5falsefalsefalse00falsefalsefalsetruefalse6falsefalsefalse00falsefalsefalsetruefalse7falsefalsefalse00falsefalsefalsetruefalse9falsefalsefalse00<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>Fees and Expenses of the Fundfalsefalsefalsetruefalse10falsefalsefalse00falsefalsefalsetruefalse11falsefalsefalse00falsefalsefalsetruefalseOtherxbrli: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]15false0rr_ExpenseNarrativeTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsetruefalse3falsefalsefalse00falsefalsefalsetruefalse4falsefalsefalse00falsefalsefalsetruefalse5falsefalsefalse00falsefalsefalsetruefalse6falsefalsefalse00falsefalsefalsetruefalse7falsefalsefalse00falsefalsefalsetruefalse9falsefalsefalse00<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>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 yourfalsefalsefalsetruefalse10falsefalsefalse00falsefalsefalsetruefalse11falsefalsefalse00falsefalsefalsetruefalseOtherus-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]16false0rr_ShareholderFeesCaptionrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsetruefalse3falsefalsefalse00falsefalsefalsetruefalse4falsefalsefalse00falsefalsefalsetruefalse5falsefalsefalse00falsefalsefalsetruefalse6falsefalsefalse00falsefalsefalsetruefalse7falsefalsefalse00falsefalsefalsetruefalse9falsefalsefalse00<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>Shareholder Fees (fees paid directly from your investment)falsefalsefalsetruefalse10falsefalsefalse00falsefalsefalsetruefalse11falsefalsefalse00falsefalsefalsetruefalseOtherxbrli: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]17false0rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPricerrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsetruetrue00falsefalsefalsefalsefalse2truetruetrue0.03750.0375falsefalsefalsetruefalse3falsetruetrue00falsefalsefalsetruefalse4falsetruetrue00falsefalsefalsetruefalse5truetruetrue00falsefalsefalsetruefalse6falsetruetrue00falsefalsefalsetruefalse7falsetruetrue00falsefalsefalsetruefalse9falsetruetrue00falsefalsefalsetruefalse10falsetruetrue00falsefalsefalsetruefalse11falsetruetrue00falsefalsefalsetruefalseOtherrr: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)18false0rr_MaximumDeferredSalesChargeOverOfferingPricerrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsetruetrue00falsefalsefalsefalsefalse2truetruetrue00[1]falsefalsefalsetruefalse3falsetruetrue00falsefalsefalsetruefalse4falsetruetrue00falsefalsefalsetruefalse5truetruetrue0.010.01[1]falsefalsefalsetruefalse6falsetruetrue00falsefalsefalsetruefalse7falsetruetrue00falsefalsefalsetruefalse9falsetruetrue00falsefalsefalsetruefalse10falsetruetrue00falsefalsefalsetruefalse11falsetruetrue00falsefalsefalsetruefalseOtherrr: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)19false0rr_ExchangeFeeOverRedemptionrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1falsetruetrue00falsefalsefalsefalsefalse2truetruetrue0.020.02falsefalsefalsetruefalse3falsetruetrue00falsefalsefalsetruefalse4falsetruetrue00falsefalsefalsetruefalse5truetruetrue0.020.02falsefalsefalsetruefalse6falsetruetrue00falsefalsefalsetruefalse7falsetruetrue00falsefalsefalsetruefalse9falsetruetrue00falsefalsefalsetruefalse10falsetruetrue00falsefalsefalsetruefalse11falsetruetrue00falsefalsefalsetruefalseOtherrr: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 with in 30 days of purchase)20false0rr_OperatingExpensesCaptionrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsetruefalse3falsefalsefalse00falsefalsefalsetruefalse4falsefalsefalse00falsefalsefalsetruefalse5falsefalsefalse00falsefalsefalsetruefalse6falsefalsefalse00falsefalsefalsetruefalse7falsefalsefalse00falsefalsefalsetruefalse9falsefalsefalse00<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>Annual Fund Operating Expenses(expenses that you pay each year as a % of the value of your investment)falsefalsefalsetruefalse10falsefalsefalse00falsefalsefalsetruefalse11falsefalsefalse00falsefalsefalsetruefalseOtherxbrli: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]21false0rr_ManagementFeesOverAssetsrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsetruetrue00falsefalsefalsefalsefalse2truetruetrue0.00550.0055falsefalsefalsetruefalse3falsetruetrue00falsefalsefalsetruefalse4falsetruetrue00falsefalsefalsetruefalse5truetruetrue0.00550.0055falsefalsefalsetruefalse6falsetruetrue00falsefalsefalsetruefalse7falsetruetrue00falsefalsefalsetruefalse9falsetruetrue00falsefalsefalsetruefalse10falsetruetrue00falsefalsefalsetruefalse11falsetruetrue00falsefalsefalsetruefalseOtherrr: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 fees22false0rr_DistributionAndService12b1FeesOverAssetsrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsetruetrue00falsefalsefalsefalsefalse2truetruetrue0.00250.0025falsefalsefalsetruefalse3falsetruetrue00falsefalsefalsetruefalse4falsetruetrue00falsefalsefalsetruefalse5truetruetrue0.010.01falsefalsefalsetruefalse6falsetruetrue00falsefalsefalsetruefalse7falsetruetrue00falsefalsefalsetruefalse9falsetruetrue00falsefalsefalsetruefalse10falsetruetrue00falsefalsefalsetruefalse11falsetruetrue00falsefalsefalsetruefalseOtherrr: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) fees23false0rr_OtherExpensesOverAssetsrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsetruetrue00falsefalsefalsefalsefalse2truetruetrue0.03010.0301falsefalsefalsetruefalse3falsetruetrue00falsefalsefalsetruefalse4falsetruetrue00falsefalsefalsetruefalse5truetruetrue0.05580.0558falsefalsefalsetruefalse6falsetruetrue00falsefalsefalsetruefalse7falsetruetrue00falsefalsefalsetruefalse9falsetruetrue00falsefalsefalsetruefalse10falsetruetrue00falsefalsefalsetruefalse11falsetruetrue00falsefalsefalsetruefalseOtherrr: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 expenses24false0rr_ExpensesOverAssetsrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsetruetrue00falsefalsefalsefalsefalse2truetruetrue0.03810.0381falsefalsefalsetruefalse3falsetruetrue00falsefalsefalsetruefalse4falsetruetrue00falsefalsefalsetruefalse5truetruetrue0.07130.0713falsefalsefalsetruefalse6falsetruetrue00falsefalsefalsetruefalse7falsetruetrue00falsefalsefalsetruefalse9falsetruetrue00falsefalsefalsetruefalse10falsetruetrue00falsefalsefalsetruefalse11falsetruetrue00falsefalsefalsetruefalseOtherrr: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 falsefalseTotal annual fund operating expenses25false0rr_FeeWaiverOrReimbursementOverAssetsrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsetruetrue00falsefalsefalsefalsefalse2truetruetrue-0.0277-0.0277[2]falsefalsefalsetruefalse3falsetruetrue00falsefalsefalsetruefalse4falsetruetrue00falsefalsefalsetruefalse5truetruetrue-0.0509-0.0509[2]falsefalsefalsetruefalse6falsetruetrue00falsefalsefalsetruefalse7falsetruetrue00falsefalsefalsetruefalse9falsetruetrue00falsefalsefalsetruefalse10falsetruetrue00falsefalsefalsetruefalse11falsetruetrue00falsefalsefalsetruefalseOtherrr: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 reimbursement26false0rr_NetExpensesOverAssetsrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsetruetrue00falsefalsefalsefalsefalse2truetruetrue0.01040.0104falsefalsefalsetruefalse3falsetruetrue00falsefalsefalsetruefalse4falsetruetrue00falsefalsefalsetruefalse5truetruetrue0.02040.0204falsefalsefalsetruefalse6falsetruetrue00falsefalsefalsetruefalse7falsetruetrue00falsefalsefalsetruefalse9falsetruetrue00falsefalsefalsetruefalse10falsetruetrue00falsefalsefalsetruefalse11falsetruetrue00falsefalsefalsetruefalseOtherrr: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 falsefalseNet expenses27false0rr_FeeWaiverOrReimbursementOverAssetsDateOfTerminationrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsetruefalse3falsefalsefalse00falsefalsefalsetruefalse4falsefalsefalse00falsefalsefalsetruefalse5falsefalsefalse00falsefalsefalsetruefalse6falsefalsefalse00falsefalsefalsetruefalse7falsefalsefalse00falsefalsefalsetruefalse9falsefalsefalse00<font class="_mt">January&nbsp;31, 2013</font>January&nbsp;31, 2013falsefalsefalsetruefalse10falsefalsefalse00falsefalsefalsetruefalse11falsefalsefalse00falsefalsefalsetruefalseOtherus-types:dateStringItemTypenormalizedstringThis element represents the date of expected termination of any expense reimbursement or fee waiver arrangements that reduce any Fund operating expenses (SEC Form N-1A 2006-09-14 A.3.table.1.11 Total Annual Fund Operating Expenses A.3.instructions.3.e).Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 3 -Subparagraph e -Subsection instructions falsefalseFee Waiver or Reimbursement over Assets, Date of Termination28false0rr_PortfolioTurnoverHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsetruefalse3falsefalsefalse00falsefalsefalsetruefalse4falsefalsefalse00falsefalsefalsetruefalse5falsefalsefalse00falsefalsefalsetruefalse6falsefalsefalse00falsefalsefalsetruefalse7falsefalsefalse00falsefalsefalsetruefalse9falsefalsefalse00<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>Portfolio Turnoverfalsefalsefalsetruefalse10falsefalsefalse00falsefalsefalsetruefalse11falsefalsefalse00falsefalsefalsetruefalseOtherxbrli: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]29false0rr_PortfolioTurnoverTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsetruefalse3falsefalsefalse00falsefalsefalsetruefalse4falsefalsefalse00falsefalsefalsetruefalse5falsefalsefalse00falsefalsefalsetruefalse6falsefalsefalse00falsefalsefalsetruefalse7falsefalsefalse00falsefalsefalsetruefalse9falsefalsefalse00<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 was 401% of its portfolio's average value. </p> </div>The Fund pays transaction costs, such as commissions, when it buys and sells securities ('turns over' its portfolio). A higher portfolio turnover rate mayfalsefalsefalsetruefalse10falsefalsefalse00falsefalsefalsetruefalse11falsefalsefalse00falsefalsefalsetruefalseOtherus-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]30false0rr_ExpenseBreakpointDiscountsrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsetruefalse3falsefalsefalse00falsefalsefalsetruefalse4falsefalsefalse00falsefalsefalsetruefalse5falsefalsefalse00falsefalsefalsetruefalse6falsefalsefalse00falsefalsefalsetruefalse7falsefalsefalse00falsefalsefalsetruefalse9falsefalsefalse00<font class="_mt">You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $<font class="_mt">50,000</font> in the fund or in other calvert Mutual Funds.</font>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 the fund or in other calvertfalsefalsefalsetruefalse10falsefalsefalse00falsefalsefalsetruefalse11falsefalsefalse00falsefalsefalsetruefalseOtherxbrli:stringItemTypestringInclude 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.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subparagraph b -Subsection instructions falsefalseExpense Breakpoint Discounts [Text]31false0rr_ExpenseBreakpointMinimumInvestmentRequiredAmountrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsetruefalse3falsefalsefalse00falsefalsefalsetruefalse4falsefalsefalse00falsefalsefalsetruefalse5falsefalsefalse00falsefalsefalsetruefalse6falsefalsefalse00falsefalsefalsetruefalse7falsefalsefalse00falsefalsefalsetruefalse9truefalsefalse5000050000falsetruefalsetruefalse10falsefalsefalse00falsefalsefalsetruefalse11falsefalsefalse00falsefalsefalsetruefalseMonetaryxbrli:monetaryItemTypemonetaryThis element represents the minimum level of investment required to qualify for discounted sales charges or fund expenses (SEC Form N-1A 2006-09-14 A.3.instructions.1.b).Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subparagraph b -Subsection instructions falsefalseExpense Breakpoint, Minimum Investment Required [Amount]32false0rr_ExpenseExampleHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsetruefalse3falsefalsefalse00falsefalsefalsetruefalse4falsefalsefalse00falsefalsefalsetruefalse5falsefalsefalse00falsefalsefalsetruefalse6falsefalsefalse00falsefalsefalsetruefalse7falsefalsefalse00falsefalsefalsetruefalse9falsefalsefalse00<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>Examplefalsefalsefalsetruefalse10falsefalsefalse00falsefalsefalsetruefalse11falsefalsefalse00falsefalsefalsetruefalseOtherxbrli: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]33false0rr_ExpenseExampleNarrativeTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsetruefalse3falsefalsefalse00falsefalsefalsetruefalse4falsefalsefalse00falsefalsefalsetruefalse5falsefalsefalse00falsefalsefalsetruefalse6falsefalsefalse00falsefalsefalsetruefalse7falsefalsefalse00falsefalsefalsetruefalse9falsefalsefalse00<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 and then either sell or hold your shares at the end of those periods; </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>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 assumesfalsefalsefalsetruefalse10falsefalsefalse00falsefalsefalsetruefalse11falsefalsefalse00falsefalsefalsetruefalseOtherus-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]34false0rr_ExpenseExampleByYearCaptionrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsetruefalse3falsefalsefalse00falsefalsefalsetruefalse4falsefalsefalse00falsefalsefalsetruefalse5falsefalsefalse00falsefalsefalsetruefalse6falsefalsefalse00falsefalsefalsetruefalse7falsefalsefalse00falsefalsefalsetruefalse9falsefalsefalse00<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>Number of Years Investment is Heldfalsefalsefalsetruefalse10falsefalsefalse00falsefalsefalsetruefalse11falsefalsefalse00falsefalsefalsetruefalseOtherxbrli: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]35false0rr_ExpenseExampleYear01rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1falsefalsetrue00falsefalsefalsefalsefalse2truefalsetrue477477falsefalsefalsetruefalse3falsefalsetrue00falsefalsefalsetruefalse4falsefalsetrue00falsefalsefalsetruefalse5falsefalsetrue00falsefalsefalsetruefalse6truefalsetrue307307falsefalsefalsetruefalse7truefalsetrue207207falsefalsefalsetruefalse9falsefalsetrue00falsefalsefalsetruefalse10falsefalsetrue00falsefalsefalsetruefalse11falsefalsetrue00falsefalsefalsetruefalseMonetaryrr: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 Year36false0rr_ExpenseExampleYear03rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1falsefalsetrue00falsefalsefalsefalsefalse2truefalsetrue12491249falsefalsefalsetruefalse3falsefalsetrue00falsefalsefalsetruefalse4falsefalsetrue00falsefalsefalsetruefalse5falsefalsetrue00falsefalsefalsetruefalse6truefalsetrue12371237falsefalsefalsetruefalse7truefalsetrue12371237falsefalsefalsetruefalse9falsefalsetrue00falsefalsefalsetruefalse10falsefalsetrue00falsefalsefalsetruefalse11falsefalsetrue00falsefalsefalsetruefalseMonetaryrr: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 Years37false0rr_ExpenseExampleYear05rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1falsefalsetrue00falsefalsefalsefalsefalse2truefalsetrue20392039falsefalsefalsetruefalse3falsefalsetrue00falsefalsefalsetruefalse4falsefalsetrue00falsefalsefalsetruefalse5falsefalsetrue00falsefalsefalsetruefalse6truefalsetrue22662266falsefalsefalsetruefalse7truefalsetrue22662266falsefalsefalsetruefalse9falsefalsetrue00falsefalsefalsetruefalse10falsefalsetrue00falsefalsefalsetruefalse11falsefalsetrue00falsefalsefalsetruefalseMonetaryrr: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 Years38false0rr_ExpenseExampleYear10rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1falsefalsetrue00falsefalsefalsefalsefalse2truefalsetrue40984098falsetruefalsetruefalse3falsefalsetrue00falsefalsefalsetruefalse4falsefalsetrue00falsefalsefalsetruefalse5falsefalsetrue00falsefalsefalsetruefalse6truefalsetrue48404840falsetruefalsetruefalse7truefalsetrue48404840falsetruefalsetruefalse9falsefalsetrue00falsefalsefalsetruefalse10falsefalsetrue00falsefalsefalsetruefalse11falsefalsetrue00falsefalsefalsetruefalseMonetaryrr: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 Years39false0rr_ExpenseExampleNoRedemptionByYearCaptionrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsetruefalse3falsefalsefalse00falsefalsefalsetruefalse4falsefalsefalse00falsefalsefalsetruefalse5falsefalsefalse00falsefalsefalsetruefalse6falsefalsefalse00falsefalsefalsetruefalse7falsefalsefalse00falsefalsefalsetruefalse9falsefalsefalse00<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>falsefalsefalsetruefalse10falsefalsefalse00falsefalsefalsetruefalse11falsefalsefalse00falsefalsefalsetruefalseOtherxbrli: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]40false0rr_StrategyHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsetruefalse3falsefalsefalse00falsefalsefalsetruefalse4falsefalsefalse00falsefalsefalsetruefalse5falsefalsefalse00falsefalsefalsetruefalse6falsefalsefalse00falsefalsefalsetruefalse7falsefalsefalse00falsefalsefalsetruefalse9falsefalsefalse00 <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>INVESTMENTS, RISKS AND PERFORMANCE Principal Investment Strategiesfalsefalsefalsetruefalse10falsefalsefalse00falsefalsefalsetruefalse11falsefalsefalse00falsefalsefalsetruefalseOtherxbrli: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]41false0rr_StrategyNarrativeTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsetruefalse3falsefalsefalse00falsefalsefalsetruefalse4falsefalsefalse00falsefalsefalsetruefalse5falsefalsefalse00falsefalsefalsetruefalse6falsefalsefalse00falsefalsefalsetruefalse7falsefalsefalse00falsefalsefalsetruefalse9falsefalsefalse00<div><p> Under normal circumstances, the Fund will invest at least 80% of its net assets (including borrowings for investment purposes) in debt securities issued or guaranteed by the U.S. government, its agencies or instrumentalities ('U.S. Government Securities'), futures contracts related to U.S. Government Securities and repurchase agreements collateralized by U.S. Government Securities. The Fund will provide shareholders with at least 60 days' notice before changing this 80% policy. </p><p> The Fund uses an active strategy, seeking relative value to earn incremental income. The investment advisor allocates the Fund's assets among different market sectors (e.g., U.S. Treasury or U.S. government agency) and different maturities based on its view of the relative value of each sector or maturity. There is no limit on the Fund's average maturity. </p><p> The Fund also may invest in corporate debt securities, 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 is non-diversified. </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> </p> </div> Under normal circumstances, the Fund will invest at least 80% of its net assets (including borrowings for investment purposes) in debt securities issued orfalsefalsefalsetruefalse10falsefalsefalse00falsefalsefalsetruefalse11falsefalsefalse00falsefalsefalsetruefalseOtherus-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]42false0rr_StrategyPortfolioConcentrationrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsetruefalse3falsefalsefalse00falsefalsefalsetruefalse4falsefalsefalse00falsefalsefalsetruefalse5falsefalsefalse00falsefalsefalsetruefalse6falsefalsefalse00falsefalsefalsetruefalse7falsefalsefalse00falsefalsefalsetruefalse9falsefalsefalse00<font class="_mt"><font style="font-family: 'Arial','sans-serif'; font-size: 10pt;" class="_mt">Under normal market conditions, the fund invests at least 80% of its net assets in preferred securities. </font></font>Under normal market conditions, the fund invests at least 80% of its net assets in preferred securities.falsefalsefalsetruefalse10falsefalsefalse00falsefalsefalsetruefalse11falsefalsefalse00falsefalsefalsetruefalseOtherxbrli: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 Portfolio Concentration [Text]43false0rr_RiskHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsetruefalse3falsefalsefalse00falsefalsefalsetruefalse4falsefalsefalse00falsefalsefalsetruefalse5falsefalsefalse00falsefalsefalsetruefalse6falsefalsefalse00falsefalsefalsetruefalse7falsefalsefalse00falsefalsefalsetruefalse9falsefalsefalse00<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>Principal Risksfalsefalsefalsetruefalse10falsefalsefalse00falsefalsefalsetruefalse11falsefalsefalse00falsefalsefalsetruefalseOtherxbrli:stringItemTypestringNarrative Risk Disclosure.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 1 -Subsection b falsefalseRisk [Heading]44false0rr_RiskNarrativeTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsetruefalse3falsefalsefalse00falsefalsefalsetruefalse4falsefalsefalse00falsefalsefalsetruefalse5falsefalsefalse00falsefalsefalsetruefalse6falsefalsefalse00falsefalsefalsetruefalse7falsefalsefalse00falsefalsefalsetruefalse9falsefalsefalse00<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 the Federal National Mortgage Association ('FNMA') and the Federal Home Loan Mortgage Corporation ('FHLMC') are neither insured nor guaranteed by the U.S. Treasury and are not backed by the full faith and credit of the U.S. government. Such securities are only supported by the credit of 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. Longer-term securities are subject to greater interest rate risk. </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 a nationally recognized statistical rating organization. </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 >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 > </div>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 afalsefalsefalsetruefalse10falsefalsefalse00falsefalsefalsetruefalse11falsefalsefalse00falsefalsefalsetruefalseOtherus-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]45false0rr_RiskLoseMoneyrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsetruefalse3falsefalsefalse00falsefalsefalsetruefalse4falsefalsefalse00falsefalsefalsetruefalse5falsefalsefalse00falsefalsefalsetruefalse6falsefalsefalse00falsefalsefalsetruefalse7falsefalsefalse00falsefalsefalsetruefalse9falsefalsefalse00<font class="_mt"><font style="font-family: 'Arial','sans-serif'; font-size: 10pt;" class="_mt">As with any mutual fund investment, loss of money is a risk of investing. </font></font>As with any mutual fund investment, loss of money is a risk of investing.falsefalsefalsetruefalse10falsefalsefalse00falsefalsefalsetruefalse11falsefalsefalse00falsefalsefalsetruefalseOtherxbrli:stringItemTypestringSummarize the principal risks of investing in the Fund, including the risks to which the Fund's portfolio as a whole is subject and the circumstances reasonably likely to affect adversely the Fund's net asset value, yield, and total return. Unless the Fund is a Money Market Fund, disclose that loss of money is a risk of investing in the Fund. 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 -Subsection b falsefalseRisk Lose Money [Text]46false0rr_RiskNotInsuredDepositoryInstitutionrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsetruefalse3falsefalsefalse00falsefalsefalsetruefalse4falsefalsefalse00falsefalsefalsetruefalse5falsefalsefalse00falsefalsefalsetruefalse6falsefalsefalse00falsefalsefalsetruefalse7falsefalsefalse00falsefalsefalsetruefalse9falsefalsefalse00<font class="_mt">An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.</font>An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmentfalsefalsefalsetruefalse10falsefalsefalse00falsefalsefalsetruefalse11falsefalsefalse00falsefalsefalsetruefalseOtherxbrli:stringItemTypestringIf the Fund is advised by or sold through an insured depository institution, state that An investment in the Fund is not a deposit of the bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. A Money Market Fund that is advised by or sold through an insured depository institution should combine the disclosure required by Items 2(c)(1)(ii) and (iii) in a single statement.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 1 -Subparagraph iii -Subsection b falsefalseRisk Not Insured Depository Institution [Text]47false0rr_BarChartAndPerformanceTableHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsetruefalse3falsefalsefalse00falsefalsefalsetruefalse4falsefalsefalse00falsefalsefalsetruefalse5falsefalsefalse00falsefalsefalsetruefalse6falsefalsefalse00falsefalsefalsetruefalse7falsefalsefalse00falsefalsefalsetruefalse9falsefalsefalse00<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>Performancefalsefalsefalsetruefalse10falsefalsefalse00falsefalsefalsetruefalse11falsefalsefalse00falsefalsefalsetruefalseOtherxbrli: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]48false0rr_PerformanceNarrativeTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsetruefalse3falsefalsefalse00falsefalsefalsetruefalse4falsefalsefalse00falsefalsefalsetruefalse5falsefalsefalse00falsefalsefalsetruefalse6falsefalsefalse00falsefalsefalsetruefalse7falsefalsefalse00falsefalsefalsetruefalse9falsefalsefalse00<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> The return for each of the Fund's other Classes of shares will differ from the Class A returns shown in the bar chart, depending upon the expenses of that Class. The bar chart does not reflect any sales charge that you may be required to pay upon purchase or redemption of the Fund's shares. Any sales charge will reduce your return. </p> </div>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 thefalsefalsefalsetruefalse10falsefalsefalse00falsefalsefalsetruefalse11falsefalsefalse00falsefalsefalsetruefalseOtherus-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]49false0rr_PerformanceInformationIllustratesVariabilityOfReturnsrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsetruefalse3falsefalsefalse00falsefalsefalsetruefalse4falsefalsefalse00falsefalsefalsetruefalse5falsefalsefalse00falsefalsefalsetruefalse6falsefalsefalse00falsefalsefalsetruefalse7falsefalsefalse00falsefalsefalsetruefalse9falsefalsefalse00<font class="_mt"><font style="font-family: 'Arial','sans-serif'; font-size: 10pt;" class="_mt">The table below shows the variability of the fund's average annual returns and how they compare over the time periods indicated with those of a broad measure of market performance and an index of funds with similar investment objectives.&nbsp;</font></font>The table below shows the variability of the fund's average annual returns and how they compare over the time periods indicated with those of a broad measurefalsefalsefalsetruefalse10falsefalsefalse00falsefalsefalsetruefalse11falsefalsefalse00falsefalsefalsetruefalseOtherxbrli:stringItemTypestringInclude the bar chart and table required by paragraphs (b)(2)(ii) and (iii) of this section. Provide a brief explanation of how the information illustrates the variability of the Fund's returns (e.g., by stating that the information provides some indication of the risks of investing in the Fund by showing changes in the Fund's performance from year to year and by showing how the Fund's average annual returns for 1, 5, and 10 years compare with those of a broad measure of market performance). Provide a statement to the effect that the Fund's past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph i -Subsection b falsefalsePerformance Information Illustrates Variability of Returns [Text]50false0rr_PerformanceAvailabilityPhonerrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsetruefalse3falsefalsefalse00falsefalsefalsetruefalse4falsefalsefalse00falsefalsefalsetruefalse5falsefalsefalse00falsefalsefalsetruefalse6falsefalsefalse00falsefalsefalsetruefalse7falsefalsefalse00falsefalsefalsetruefalse9falsefalsefalse00<font class="_mt">(800) 257-8787</font>(800) 257-8787falsefalsefalsetruefalse10falsefalsefalse00falsefalsefalsetruefalse11falsefalsefalse00falsefalsefalsetruefalseOtherxbrli:stringItemTypestringIf applicable, include a statement explaining that updated performance information is available and providing a Web site address and/or toll-free (or collect) telephone number where the updated information may be obtained.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph i -Subsection b falsefalsePerformance Availability Phone [Text]51false0rr_PerformanceAvailabilityWebSiteAddressrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsetruefalse3falsefalsefalse00falsefalsefalsetruefalse4falsefalsefalse00falsefalsefalsetruefalse5falsefalsefalse00falsefalsefalsetruefalse6falsefalsefalse00falsefalsefalsetruefalse7falsefalsefalse00falsefalsefalsetruefalse9falsefalsefalse00<font class="_mt">www.calvert.com/MF/products/performancesummary.aspx</font>www.calvert.com/MF/products/performancesummary.aspxfalsefalsefalsetruefalse10falsefalsefalse00falsefalsefalsetruefalse11falsefalsefalse00falsefalsefalsetruefalseOtherxbrli:stringItemTypestringIf applicable, include a statement explaining that updated performance information is available and providing a Website address and/or toll-free (or collect) telephone number where the updated information may be obtained.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph i -Subsection b falsefalsePerformance Availability Website Address [Text]52false0rr_PerformancePastDoesNotIndicateFuturerrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsetruefalse3falsefalsefalse00falsefalsefalsetruefalse4falsefalsefalse00falsefalsefalsetruefalse5falsefalsefalse00falsefalsefalsetruefalse6falsefalsefalse00falsefalsefalsetruefalse7falsefalsefalse00falsefalsefalsetruefalse9falsefalsefalse00<font class="_mt">The fund's past performance (before and after taxes) is not necessarily an indication of how the fund will perform in the future.</font>The fund's past performance (before and after taxes) is not necessarily an indication of how the fund will perform in the future.falsefalsefalsetruefalse10falsefalsefalse00falsefalsefalsetruefalse11falsefalsefalse00falsefalsefalsetruefalseOtherxbrli:stringItemTypestringInclude the bar chart and table required by paragraphs (b)(2)(ii) and (iii) of this section. Provide a brief explanation of how the information illustrates the variability of the Fund's returns (e.g., by stating that the information provides some indication of the risks of investing in the Fund by showing changes in the Fund's performance from year to year and by showing how the Fund's average annual returns for 1, 5, and 10 years compare with those of a broad measure of market performance). Provide a statement to the effect that the Fund's past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph i -Subsection b falsefalsePerformance Past Does Not Indicate Future [Text]53false0rr_BarChartHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsetruefalse3falsefalsefalse00falsefalsefalsetruefalse4falsefalsefalse00falsefalsefalsetruefalse5falsefalsefalse00falsefalsefalsetruefalse6falsefalsefalse00falsefalsefalsetruefalse7falsefalsefalse00falsefalsefalsetruefalse9falsefalsefalse00<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>Calendar Year Total Returns for Class A at NAVfalsefalsefalsetruefalse10falsefalsefalse00falsefalsefalsetruefalse11falsefalsefalse00falsefalsefalsetruefalseOtherxbrli: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]54false0rr_BarChartDoesNotReflectSalesLoadsrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsetruefalse3falsefalsefalse00falsefalsefalsetruefalse4falsefalsefalse00falsefalsefalsetruefalse5falsefalsefalse00falsefalsefalsetruefalse6falsefalsefalse00falsefalsefalsetruefalse7falsefalsefalse00falsefalsefalsetruefalse9falsefalsefalse00<font class="_mt"><font style="font-family: 'Arial','sans-serif'; font-size: 10pt;" class="_mt">The bar chart below shows the fund's performance for Class A shares. The bar chart and highest/lowest quarterly returns that follow do not reflect sales charges, and if these charges were reflected, the returns would be less than those shown.</font></font>The bar chart below shows the fund's performance for Class A shares. The bar chart and highest/lowest quarterly returns that follow do not reflect salesfalsefalsefalsetruefalse10falsefalsefalse00falsefalsefalsetruefalse11falsefalsefalse00falsefalsefalsetruefalseOtherxbrli:stringItemTypestringInclude the bar chart and table required by Item 4 (b)(2)(ii) and (iii) of this section. Provide a brief explanation of how the information illustrates the variability of the Fund's returns (e.g., by stating that the information provides some indication of the risks of investing in the Fund by showing changes in the Fund's performance from year to year and by showing how the Fund's average annual returns for 1, 5, and 10 years compare with those of a broad measure of market performance). Provide a statement to the effect that the Fund's past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future. Provide annual total returns beginning with the earliest calendar year. Calculate annual returns using the Instructions to Item 8(a), except that the calculations should be based on calendar years. If a Fund's shares are sold subject to a sales load or account fees, state that sales loads or account fees are not reflected in the bar chart and that, if these amounts were reflected, returns would be less than those shown.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph i -Subsection b falsefalseBar Chart Does Not Reflect Sales Loads [Text]55false0rr_AnnualReturn2009rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsetruefalse00falsefalsefalsefalsefalse2truetruefalse0.07790.0779falsefalsefalsetruefalse3falsetruefalse00falsefalsefalsetruefalse4falsetruefalse00falsefalsefalsetruefalse5falsetruefalse00falsefalsefalsetruefalse6falsetruefalse00falsefalsefalsetruefalse7falsetruefalse00falsefalsefalsetruefalse9falsetruefalse00falsefalsefalsetruefalse10falsetruefalse00falsefalsefalsetruefalse11falsetruefalse00falsefalsefalsetruefalseOtherxbrli: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 200956false0rr_AnnualReturn2010rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsetruefalse00falsefalsefalsefalsefalse2truetruefalse0.08180.0818falsefalsefalsetruefalse3falsetruefalse00falsefalsefalsetruefalse4falsetruefalse00falsefalsefalsetruefalse5falsetruefalse00falsefalsefalsetruefalse6falsetruefalse00falsefalsefalsetruefalse7falsetruefalse00falsefalsefalsetruefalse9falsetruefalse00falsefalsefalsetruefalse10falsetruefalse00falsefalsefalsetruefalse11falsetruefalse00falsefalsefalsetruefalseOtherxbrli: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 201057false0rr_BarChartClosingTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsetruefalse3falsefalsefalse00falsefalsefalsetruefalse4falsefalsefalse00falsefalsefalsetruefalse5falsefalsefalse00falsefalsefalsetruefalse6falsefalsefalse00falsefalsefalsetruefalse7falsefalsefalse00falsefalsefalsetruefalse9falsefalsefalse00<div> <p> Best Quarter (of periods shown) 9/30/2009 4.42% Worst Quarter (of periods shown) 6/30/2009 -0.88% </p> </div>Best Quarter (of periods shown) 9/30/2009 4.42% Worst Quarter (of periods shown) 6/30/2009 -0.88%falsefalsefalsetruefalse10falsefalsefalse00falsefalsefalsetruefalse11falsefalsefalse00falsefalsefalsetruefalseOtherus-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]58false0rr_HighestQuarterlyReturnLabelrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00<font class="_mt">highest</font>highestfalsefalsefalsetruefalse3falsefalsefalse00falsefalsefalsetruefalse4falsefalsefalse00falsefalsefalsetruefalse5falsefalsefalse00falsefalsefalsetruefalse6falsefalsefalse00falsefalsefalsetruefalse7falsefalsefalse00falsefalsefalsetruefalse9falsefalsefalse00falsefalsefalsetruefalse10falsefalsefalse00falsefalsefalsetruefalse11falsefalsefalse00falsefalsefalsetruefalseOtherxbrli:stringItemTypestringIf 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 falsefalseHighest Quarterly Return, Label59false0rr_BarChartHighestQuarterlyReturnDaterrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsetruefalsefalse2falsefalsefalse002010-03-312010-03-31falsefalsetruetruefalse3falsefalsefalse00falsefalsetruetruefalse4falsefalsefalse00falsefalsetruetruefalse5falsefalsefalse00falsefalsetruetruefalse6falsefalsefalse00falsefalsetruetruefalse7falsefalsefalse00falsefalsetruetruefalse9falsefalsefalse00falsefalsetruetruefalse10falsefalsefalse00falsefalsetruetruefalse11falsefalsefalse00falsefalsetruetruefalseOtherxbrli:dateItemTypedateIf 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 falsefalseHighest Quarterly Return, Date60false0rr_BarChartHighestQuarterlyReturnrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsetruefalse00falsefalsefalsefalsefalse2truetruefalse0.08390.0839falsefalsefalsetruefalse3falsetruefalse00falsefalsefalsetruefalse4falsetruefalse00falsefalsefalsetruefalse5falsetruefalse00falsefalsefalsetruefalse6falsetruefalse00falsefalsefalsetruefalse7falsetruefalse00falsefalsefalsetruefalse9falsetruefalse00falsefalsefalsetruefalse10falsetruefalse00falsefalsefalsetruefalse11falsetruefalse00falsefalsefalsetruefalseOtherxbrli: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.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph ii -Subsection b falsefalseHighest Quarterly Return61false0rr_LowestQuarterlyReturnLabelrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00<font class="_mt">lowest</font>lowestfalsefalsefalsetruefalse3falsefalsefalse00falsefalsefalsetruefalse4falsefalsefalse00falsefalsefalsetruefalse5falsefalsefalse00falsefalsefalsetruefalse6falsefalsefalse00falsefalsefalsetruefalse7falsefalsefalse00falsefalsefalsetruefalse9falsefalsefalse00falsefalsefalsetruefalse10falsefalsefalse00falsefalsefalsetruefalse11falsefalsefalse00falsefalsefalsetruefalseOtherxbrli:stringItemTypestringIf 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 falsefalseLowest Quarterly Return, Label62false0rr_BarChartLowestQuarterlyReturnDaterrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsetruefalsefalse2falsefalsefalse002010-06-302010-06-30falsefalsetruetruefalse3falsefalsefalse00falsefalsetruetruefalse4falsefalsefalse00falsefalsetruetruefalse5falsefalsefalse00falsefalsetruetruefalse6falsefalsefalse00falsefalsetruetruefalse7falsefalsefalse00falsefalsetruetruefalse9falsefalsefalse00falsefalsetruetruefalse10falsefalsefalse00falsefalsetruetruefalse11falsefalsefalse00falsefalsetruetruefalseOtherxbrli:dateItemTypedateIf 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 falsefalseLowest Quarterly Return, Date63false0rr_BarChartLowestQuarterlyReturnrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsetruefalse00falsefalsefalsefalsefalse2truetruefalse-0.0193-0.0193falsefalsefalsetruefalse3falsetruefalse00falsefalsefalsetruefalse4falsetruefalse00falsefalsefalsetruefalse5falsetruefalse00falsefalsefalsetruefalse6falsetruefalse00falsefalsefalsetruefalse7falsetruefalse00falsefalsefalsetruefalse9falsetruefalse00falsefalsefalsetruefalse10falsetruefalse00falsefalsefalsetruefalse11falsetruefalse00falsefalsefalsetruefalseOtherxbrli: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.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph ii -Subsection b falsefalseLowest Quarterly Return64false0rr_PerformanceTableHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsetruefalse3falsefalsefalse00falsefalsefalsetruefalse4falsefalsefalse00falsefalsefalsetruefalse5falsefalsefalse00falsefalsefalsetruefalse6falsefalsefalse00falsefalsefalsetruefalse7falsefalsefalse00falsefalsefalsetruefalse9falsefalsefalse00<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>Average Annual Total Returns (as of 12-31-10) (with maximum sales charge deducted, if any)falsefalsefalsetruefalse10falsefalsefalse00falsefalsefalsetruefalse11falsefalsefalse00falsefalsefalsetruefalseOtherxbrli: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 Heading65false0rr_PerformanceTableUsesHighestFederalRaterrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsetruefalse3falsefalsefalse00falsefalsefalsetruefalse4falsefalsefalse00falsefalsefalsetruefalse5falsefalsefalse00falsefalsefalsetruefalse6falsefalsefalse00falsefalsefalsetruefalse7falsefalsefalse00falsefalsefalsetruefalse9falsefalsefalse00<font class="_mt">All after-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of any state or local taxes.</font>All after-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of any state orfalsefalsefalsetruefalse10falsefalsefalse00falsefalsefalsetruefalse11falsefalsefalse00falsefalsefalsetruefalseOtherxbrli:stringItemTypestringProvide a brief explanation that 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.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph iii -Subsection b falsefalsePerformance Table Uses Highest Federal Rate66false0rr_PerformanceTableNotRelevantToTaxDeferredrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsetruefalse3falsefalsefalse00falsefalsefalsetruefalse4falsefalsefalse00falsefalsefalsetruefalse5falsefalsefalse00falsefalsefalsetruefalse6falsefalsefalse00falsefalsefalsetruefalse7falsefalsefalse00falsefalsefalsetruefalse9falsefalsefalse00<font class="_mt"><font style="font-family: 'Arial','sans-serif'; font-size: 10pt;" class="_mt">After-tax returns are not relevant to investors who hold fund shares in tax-deferred accounts such as IRAs or employer-sponsored retirement plans.</font></font>After-tax returns are not relevant to investors who hold fund shares in tax-deferred accounts such as IRAs or employer-sponsored retirement plans.falsefalsefalsetruefalse10falsefalsefalse00falsefalsefalsetruefalse11falsefalsefalse00falsefalsefalsetruefalseOtherxbrli:stringItemTypestringProvide a brief explanation that the actual after-tax returns depend on an investor's tax situation and may differ from those shown, and after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph iv -Clause B -Subsection b falsefalsePerformance Table Not Relevant to Tax Deferred67false0rr_PerformanceTableOneClassOfAfterTaxShownrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsetruefalse3falsefalsefalse00falsefalsefalsetruefalse4falsefalsefalse00falsefalsefalsetruefalse5falsefalsefalse00falsefalsefalsetruefalse6falsefalsefalse00falsefalsefalsetruefalse7falsefalsefalse00falsefalsefalsetruefalse9falsefalsefalse00<font class="_mt">After-tax returns are shown for Class&nbsp;A shares only; after-tax returns for Class C, R3 and I shares will vary. </font>After-tax returns are shown for Class&nbsp;A shares only; after-tax returns for Class C, R3 and I shares will vary.falsefalsefalsetruefalse10falsefalsefalse00falsefalsefalsetruefalse11falsefalsefalse00falsefalsefalsetruefalseOtherxbrli:stringItemTypestringProvide a brief explanation that if the Fund is a Multiple Class Fund that offers more than one Class in the prospectus, after-tax returns are shown for only one Class and after-tax returns for other Classes will vary.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph iii -Subsection b Reference 2: 2 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph iv -Clause C -Subsection b falsefalsePerformance Table One Class of after Tax Shown [Text]68false0rr_PerformanceTableNarrativeTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsetruefalse3falsefalsefalse00falsefalsefalsetruefalse4falsefalsefalse00falsefalsefalsetruefalse5falsefalsefalse00falsefalsefalsetruefalse6falsefalsefalse00falsefalsefalsetruefalse7falsefalsefalse00falsefalsefalsetruefalse9falsefalsefalse00<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. After-tax returns are shown only for Class A shares; after-tax returns for other Classes will vary. </p > </div>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 forfalsefalsefalsetruefalse10falsefalsefalse00falsefalsefalsetruefalse11falsefalsefalse00falsefalsefalsetruefalseOtherus-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 Narrative69false0rr_AverageAnnualReturnYear01rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsetruetrue00falsefalsefalsefalsefalse2truetruetrue0.04120.0412falsefalsefalsetruefalse3truetruetrue0.03150.0315falsefalsefalsetruefalse4truetruetrue0.02670.0267falsefalsefalsetruefalse5truetruetrue0.06130.0613falsefalsefalsetruefalse6falsetruetrue00falsefalsefalsetruefalse7falsetruetrue00falsefalsefalsetruefalse9falsetruetrue00falsefalsefalsetruefalse10truetruetrue0.05520.0552[3]falsefalsefalsetruefalse11truetruetrue0.05920.0592falsefalsefalsetruefalseOtherxbrli:pureItemTypepureReturn Before Taxes.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph iii -Clause 1 -Exhibit 2 -Subsection b falsefalse1 Year70false0rr_AverageAnnualReturnSinceInceptionrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsetruetrue00falsefalsefalsefalsefalse2truetruetrue0.05960.0596falsefalsefalsetruefalse3truetruetrue0.04900.0490falsefalsefalsetruefalse4truetruetrue0.04480.0448falsefalsefalsetruefalse5truetruetrue0.07030.0703falsefalsefalsetruefalse6falsetruetrue00falsefalsefalsetruefalse7falsetruetrue00falsefalsefalsetruefalse9falsetruetrue00falsefalsefalsetruefalse10truetruetrue0.01590.0159[3]falsefalsefalsetruefalse11truetruetrue0.03520.0352falsefalsefalsetruefalseOtherxbrli:pureItemTypepureReturn Before Taxes.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph iii -Clause 1 -Exhibit 2 -Subsection b falsefalseSince Inception71false0rr_AverageAnnualReturnInceptionDaterrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsetruefalse00falsefalsetruefalsefalse2falsetruefalse002008-12-312008-12-31falsefalsetruetruefalse3falsetruefalse002008-12-312008-12-31falsefalsetruetruefalse4falsetruefalse002008-12-312008-12-31falsefalsetruetruefalse5falsetruefalse002008-12-312008-12-31falsefalsetruetruefalse6falsetruefalse00falsefalsetruetruefalse7falsetruefalse00falsefalsetruetruefalse9falsetruefalse00falsefalsetruetruefalse10falsetruefalse002008-12-312008-12-31[3]falsefalsetruetruefalse11falsetruefalse002008-12-312008-12-31falsefalsetruetruefalseOtherxbrli: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 Date1The contingent deferred sales charge reduces over time.2Calvert has agreed to contractually limit direct net annual fund operating expenses for Class A and Class C through January 31, 2012. Direct net operating expenses will not exceed 1.04% for Class A and 2.04% for Class C. Calvert has also agreed to contractually limit direct net operating expenses for Class C to 5.00% through January 31, 2020. Only the Board of Trustees of the Fund may terminate the Fund's expense cap before the contractual period expires.3 (Index reflects no deduction for fees, expenses or taxes. Lipper Average reflects no deduction for taxes.) 1070Risk/Return Detail Data (USD $)NoRoundingUnKnownUnKnownUnKnowntruetrue