2.2.0.25truefalse061056 - Document - Risk/Return Summary {Unlabeled} (Mid-Term Bond Fund)falsefalsetrue1falsefalsetruefalse{dei_DocumentInformationDocumentAxis} : SummaryS000009394 Member {dei_LegalEntityAxis} : S000009394 Member 5/1/2011 - 5/1/2011 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996541_396840x-9990972http://www.sec.gov/CIK0000795259duration2011-05-01T00:00:002011-05-01T00:00:00falsefalseck0000795259_SummaryS000009394Memberdei_DocumentInformationDocumentAxisxbrldihttp://xbrl.org/2006/xbrldick0000795259_SummaryS000009394Memberdei_DocumentInformationDocumentAxisexplicitMemberfalsefalseck0000795259_S000009394Memberdei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldick0000795259_S000009394Memberdei_LegalEntityAxisexplicitMemberpureStandardhttp://www.xbrl.org/2003/instancepure01false0natruenanaNo definition available.falsetruefalsefalsefalsefalsefalsefalsefalsefalsehttp://www.mutualofamerica.com/role/riskreturn_s000009394member1falsefalsefalse00Mid-Term Bond Fund (Prospectus Summary) | Mid-Term Bond FundMid-Term Bond Fund (Prospectus Summary) | Mid-Term Bond Fundfalsefalsefalsefalsefalse1falsefalsetruefalse{dei_DocumentInformationDocumentAxis} : SummaryS000009394 Member {dei_LegalEntityAxis} : S000009394 Member 5/1/2011 - 5/1/2011 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996541_396840x-9990972http://www.sec.gov/CIK0000795259duration2011-05-01T00:00:002011-05-01T00:00:00falsefalseck0000795259_SummaryS000009394Memberdei_DocumentInformationDocumentAxisxbrldihttp://xbrl.org/2006/xbrldick0000795259_SummaryS000009394Memberdei_DocumentInformationDocumentAxisexplicitMemberfalsefalseck0000795259_S000009394Memberdei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldick0000795259_S000009394Memberdei_LegalEntityAxisexplicitMemberpureStandardhttp://www.xbrl.org/2003/instancepure0OthernaNo definition available.No authoritative reference available.falsefalse3false0rr_RiskReturnHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00Mid-Term Bond Fund May 1, 2011falsefalsefalsefalsefalseOtherxbrli: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 falsefalse4false0rr_ObjectiveHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00Investment Objective.falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringInvestment Objectives/Goals. Disclose the Fund's investment objectives or goals. A Fund also may identify its type or category (e.g., that it is a Money Market Fund or a balanced fund).Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 2 -Subsection a falsefalse5false0rr_ObjectivePrimaryTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<pre>The primary investment objective of the Fund is to produce a high level of current income.</pre>falsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringInvestment Objectives/Goals. Disclose the Fund's investment objectives or goals. A Fund also may identify its type or category (e.g., that it is a Money Market Fund or a balanced fund).Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 2 -Subsection a falsefalse6false0rr_ObjectiveSecondaryTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<pre>The secondary investment objective is the preservation of shareholders' capital.</pre>falsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringInvestment Objectives/Goals. Disclose the Fund's investment objectives or goals. A Fund also may identify its type or category (e.g., that it is a Money Market Fund or a balanced fund).Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 2 -Subsection a falsefalse7false0rr_ExpenseHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00Fees and Expenses of the Fund.falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringRisk/Return Summary Fee Table Includes the following information, in plain English under rule 421(d) under the Securities Act, after Item 2 Fees and expenses of the Fund This table describes the fees and expenses that you may pay if you buy and hold shared of the Fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $[_____] in [name of fund family] funds. Shareholder Fees (fees paid directly from your investment) Example This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then you redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return per year and that the Fund's operating expenses remained the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be You would pay the following expenses if you did not redeem your shares The Example does not reflect sales charges (loads) on reinvested dividends [and other distributions]. If these sales charges (loads) were included, your costs would be higher. Portfolio Turnover The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover may indicate higher transaction costs. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund's performance. During the most recent fiscal year, the Fund's portfolio turnover rate was __% of the average value of its whole portfolio. Instructions. A.3.instructions.6 New Funds. For purposes of this Item, a "New Fund" is a Fund that does not include in Form N-1A financial statements reporting operating results or that includes financial statements for the Fund's initial fiscal year reporting operating results for a period of 6 months or less. The following Instructions apply to New Funds.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subparagraph d -Subsection instructions falsefalse8false0rr_ExpenseNarrativeTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<pre>The table below describes the fees and expenses you may pay if you buy and hold Fund shares. The expenses shown do not include Separate Account expenses which would increase costs if included.</pre>falsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringThis table describes the fees and expenses that you may pay if you buy and hold shared of the Fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $[_____] in [name of fund family] funds. Include the narrative explanations in the order indicated. A Fund may modify the narrative explanations if the explanation contains comparable information to that shown.The narrative explanation regarding sales charge discounts is only required by a Fund that offers such discounts and should specify the minimum level of investment required to qualify for a discount. Modify the narrative explanation to state that Fund shares are sold on a national securities exchange at the end of the time periods indicated, and that brokerage commissions for buying and selling Fund shares through a broker are not reflected.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subparagraph b -Subsection instructions falsefalse9false0rr_ShareholderFeesCaptionrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00Shareholder Fees (fees paid directly from your investment) N/AfalsefalsefalsefalsefalseOtherxbrli: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 falsefalse10false0rr_OperatingExpensesCaptionrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringAnnual Fund Operating Expenses (ongoing expenses that you pay each year as a percentage of the value of your investment)Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subparagraph 7 -Subsection table falsefalse11false0rr_AnnualFundOperatingExpensesTableTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div style="display:none">~ http://www.mutualofamerica.com/role/OperatingExpensesData_S000009394Member column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div>falsefalse<div style="display:none">~ http://www.mutualofamerica.com/role/OperatingExpensesData_S000009394Member column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div>falsehttp://www.mutualofamerica.com/role/OperatingExpensesData_S000009394Memberfalsefalse061057 - Schedule - Annual Fund Operating Expensestruefalsefalse1falseColumnperiodPeriod*Columndei_LegalEntityAxisAxis*Columnrr_ProspectusShareClassAxisAxis*ColumnunitUnit*duration2011-05-01T00:00:002011-05-01T00:00:00falsefalseMid-Term Bond Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldick0000795259_S000009394Memberdei_LegalEntityAxisexplicitMemberfalsefalseMid-Term Bond Fund Classrr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldick0000795259_C000025738Memberrr_ProspectusShareClassAxisexplicitMemberMid-Term Bond FundMid-Term Bond Fund Classiso4217_USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170falseUSDfalsefalse$1falseRowprimaryElement*3false0rr_ManagementFeesOverAssetsrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.00400.0040falsefalsefalsetruefalseOtherrr: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 falsefalse0rr_ManagementFeesOverAssetstruefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.00400.0040falsefalsefalsetruefalseOthernanafalsefalse2falseRowprimaryElement*4false0rr_OtherExpensesOverAssetsrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.00170.0017falsefalsefalsetruefalseOtherrr: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 falsefalse0rr_OtherExpensesOverAssetstruefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.00170.0017falsefalsefalsetruefalseOthernanafalsefalse3falseRowprimaryElement*6false0rr_ExpensesOverAssetsrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.00570.0057falsefalsefalsetruefalseOtherrr: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 falsefalse0rr_ExpensesOverAssetstruefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.00570.0057falsefalsefalsetruefalseOthernanafalsefalse13Annual Fund Operating Expenses UnKnownUnKnownUnKnownUnKnownfalsetrueColumnperiodPeriod*Columndei_LegalEntityAxisAxis*Columnrr_ProspectusShareClassAxisAxis*ColumnunitUnit*RowprimaryElement*falsefalsefalseOtherus-types:textBlockItemTypestringContains a command for the SEC Viewer for the role corresponding to OperatingExpensesData.No authoritative reference available.falsefalse12false0rr_ExpenseExampleHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00Example.falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringHeading for Expense Example.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 4 -Subsection instructions falsefalse13false0rr_ExpenseExampleNarrativeTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<pre>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: (a) that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods, (b) a 5% return each year and (c) operating expenses remain the same. The expenses shown do not include Separate Account expenses which would increase costs if included.</pre>falsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringThe Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subparagraph 1 -Subsection example falsefalse14false0rr_ExpenseExampleByYearCaptionrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00Although your actual costs may be higher or lower, your cost based on these assumptions would be:falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringThe Example assumes that you invest $10,000 in the Fund for the time periods indicated and then you redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return per year and that the Fund's operating expenses remained the same. Although your actual costs may be higher or lower.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 1 -Subparagraph 2 -Subsection example falsefalse15false0rr_ExpenseExampleWithRedemptionTableTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div style="display:none">~ http://www.mutualofamerica.com/role/ExpenseExample_S000009394Member column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div>falsefalse<div style="display:none">~ http://www.mutualofamerica.com/role/ExpenseExample_S000009394Member column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div>truehttp://www.mutualofamerica.com/role/ExpenseExample_S000009394Memberfalsefalse061058 - Schedule - Expense Example {Transposed}truefalsefalse1falseColumnprimaryElement*3false0rr_ExpenseExampleYear01rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsetrue5858falsefalsefalsetruefalseMonetaryrr: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 falsefalsefalseUSDfalsefalse$2falseColumnprimaryElement*4false0rr_ExpenseExampleYear03rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsetrue184184falsefalsefalsetruefalseMonetaryrr: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 falsefalsefalseUSDfalsefalse$3falseColumnprimaryElement*5false0rr_ExpenseExampleYear05rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsetrue323323falsefalsefalsetruefalseMonetaryrr: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 falsefalsefalseUSDfalsefalse$4falseColumnprimaryElement*6false0rr_ExpenseExampleYear10rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsetrue735735falsefalsefalsetruefalseMonetaryrr: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 falsefalsefalseUSDfalsefalse$1falseRowperiodPeriod*Rowdei_LegalEntityAxisAxis*Rowrr_ProspectusShareClassAxisAxis*RowunitUnit*duration2011-05-01T00:00:002011-05-01T00:00:00falsefalseMid-Term Bond Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldick0000795259_S000009394Memberdei_LegalEntityAxisexplicitMemberfalsefalseMid-Term Bond Fund Classrr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldick0000795259_C000025738Memberrr_ProspectusShareClassAxisexplicitMemberMid-Term Bond FundMid-Term Bond Fund Classiso4217_USDStandardhttp://www.xbrl.org/2003/iso4217USDiso421700truefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsetrue5858falsefalsefalsetruefalse2truefalsetrue184184falsefalsefalsetruefalse3truefalsetrue323323falsefalsefalsetruefalse4truefalsetrue735735falsefalsefalsetruefalseOthernanafalsefalse41Expense Example (USD $)UnKnownUnKnownUnKnownUnKnownfalsetrueColumnprimaryElement*RowperiodPeriod*Rowdei_LegalEntityAxisAxis*Rowrr_ProspectusShareClassAxisAxis*RowunitUnit*falsefalsefalseOtherus-types:textBlockItemTypestringContains a command for the SEC Viewer for the role corresponding to ExpenseExample.No authoritative reference available.falsefalse16false0rr_PortfolioTurnoverHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00Portfolio Turnover.falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringDisclose the portfolio turnover rate provided in response to Item 14(a) for the most recent fiscal year (or for such shorter period as the Fund has been in operation). Disclose the period for which the information is provided if less than a full fiscal year. A Fund that is a Money Market Fund may omit the portfolio turnover information required by this Item.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 5 -Subsection instructions falsefalse17false0rr_PortfolioTurnoverTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<pre>The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may result in 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 Fund's most recently completed fiscal year, the Fund's portfolio turnover rate was 16.70% of the average value of its portfolio.</pre>falsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringDisclose the portfolio turnover rate provided in response to Item 14(a) for the most recent fiscal year (or for such shorter period as the Fund has been in operation). Disclose the period for which the information is provided if less than a full fiscal year. A Fund that is a Money Market Fund may omit the portfolio turnover information required by this Item.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 3 -Paragraph 3 -Subsection example falsefalse18false0rr_StrategyHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00Principal Investment Strategies.falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringPrincipal investment strategies of the Fund. Summarize how the Fund intends to achieve its investment objectives by identifying the Fund's principal investment strategies (including the type or types of securities in which the Fund invests or will invest principally) and any policy to concentrate in securities of issuers in a particular industry or group of industries.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection a falsefalse19false0rr_StrategyNarrativeTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<pre>The Fund invests primarily in publicly-traded, investment-grade debt securities. &#x2022; At least 80% of the Fund's total assets are invested in investment-grade bonds issued by U. S. corporations or by the U.S. Government or its agencies, such as bonds, notes, debentures, zero coupon securities and mortgage-backed securities. Bonds are debt instruments that can be issued by the federal government, government agencies and subdivisions, states, cities, corporations and other institutions. &#x2022; It is possible that certain corporate bonds in the Fund's portfolio can be below investment grade, commonly referred to as "junk bonds." &#x2022; The Fund's securities holdings will have an average maturity of three to seven years.</pre>falsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringPrincipal investment strategies of the Fund. Summarize how the Fund intends to achieve its investment objectives by identifying the Fund's principal investment strategies (including the type or types of securities in which the Fund invests or will invest principally) and any policy to concentrate in securities of issuers in a particular industry or group of industries.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Subsection a falsefalse20false0rr_RiskHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00Principal Investment Risks.falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringNarrative Risk Disclosure.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 1 -Subsection b falsefalse21false0rr_RiskNarrativeTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<pre>An investment in the Fund is subject to the following risks which are described in more detail in the Prospectus. &#x2022; General risk: The Fund may not achieve its investment objective. An investment in the Fund could decline in value, and you could lose money by investing in the Fund. &#x2022; Market risk: The risk that prices of securities will go down because of the interplay of market forces may affect a single issuer, industry or sector of the economy or may affect the market as a whole. &#x2022; Mortgage risk: The duration of mortgage-related securities tends to be inversely related to changes in interest rates. As interest rates rise, the duration of mortgage-related securities extends and as interest rates fall, mortgage-related securities are prepaid at a faster rate. Because of interest rate changes, it is not possible to predict the realized yield or average life of a mortgage-backed security. Mortgage-backed securities issued by private corporations generally have more credit risk than securities issued by U.S. Government agencies. &#x2022; Zero Coupon risk: Zero coupon securities and discount notes do not pay interest prior to maturity and therefore may be more difficult to resell during periods of interest rate changes. The market value of debt securities declines as interest rates rise; therefore the Fund will lose value if it sells zero coupon securities prior to their maturity date. The longer the remaining term to maturity, the greater impact interest rate changes will have on the value of the security. &#x2022; Fixed Income risk: The value of your investment will go up or down depending on movements in the bond markets. The Fund's investment results may differ from the results of a comparable bond market and from the results of other funds that invest in the same types of securities. Mortgage-backed securities or certificates are subject to prepayment or extension risk when interest rates fall or rise, respectively. The prices of debt securities may be subject to significant volatility. Fixed income securities have an inverse relationship to interest rates, such that as interest rates rise, bond values decrease. During economic uncertainty, the value of corporate debt securities may decline relative to the value of U.S. government debt securities. Debt obligations are subject to the risk that issuers may not be able to pay off the principal and interest when due. Non-investment grade debt obligations, known as "junk bonds", are affected by adverse economic conditions, have a high risk of default and are less liquid.</pre>falsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringNarrative Risk Disclosure. A Fund may, in responding to this Item, describe the types of investors for whom the Fund is intended or the types of investment goals that may be consistent with an investment in the Fund.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 1 -Subparagraph i -Clause instruction -Subsection b falsefalse22false0rr_BarChartAndPerformanceTableHeadingrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00Performance/Annual Return.falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringRisk/Return Bar Chart and Table.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subsection b falsefalse23false0rr_PerformanceNarrativeTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<pre>The bar chart and table below show the annual return and average annual returns of the Fund. Below the bar chart are the Fund's highest and lowest total returns for any calendar quarter during the period covered by the chart, showing the volatility of the Fund's total returns. The numbers in parentheses are negative, representing a loss of principal. The information indicates some 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 one, five, and ten years compare to those of a broad-based, unmanaged index for those periods. As of May 1, 2011, the Fund's benchmark was changed to the Barclays Intermediate Government/Credit Bond Fund Index (the "Barclays Index"), which seeks investment results that correspond generally to the price and yield performance, before fees and expenses, of the investment grade credit sector of the United States bond market and the total United States Treasury market as defined by the Barclays Capital U.S. Intermediate Government/Credit Bond Index. The Barclays Index is more closely aligned with the Fund's effective duration and average life of the Fund's portfolio and is expected to be more consistent with the Fund's investment objective and strategies than the previous index, the Citigroup Bond Index. The Citigroup Bond Index (formerly known as the Salomon Brothers Government/Corporate Bond Index) for 3-7 years is a portion of the Citigroup Broad Investment-Grade Bond Index for the maturities indicated. The Citigroup Broad Investment-Grade Bond Index includes Treasury, Agency, mortgage and corporate bonds with maturities of one year or longer. A fund's past performance does not necessarily indicate how it will perform in the future. The total returns and average annual total returns shown do not include charges against the assets of the Separate Accounts that purchase Fund shares. If these charges were reflected, returns would be less than those shown. Updated performance information is available at no cost online at http://www.mutualofamerica.com or by calling 1-800-468-3785.</pre>falsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringRisk/Return Bar Chart and Table.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subsection b falsefalse24false0rr_BarChartNarrativeTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<pre>The bar chart and table below show the annual return and average annual returns of the Fund.</pre>falsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringProvide 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 falsefalse25false0rr_BarChartTableTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div style="display:none">~ http://www.mutualofamerica.com/role/BarChartData_S000009394Member column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div>falsefalseBarChart10.jpg<div style="display:none">~ http://www.mutualofamerica.com/role/BarChartData_S000009394Member column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div>falsehttp://www.mutualofamerica.com/role/BarChartData_S000009394Memberfalsefalse061059 - Schedule - Annual Total Returnstruefalsefalse1falseColumnperiodPeriod*Columndei_LegalEntityAxisAxis*Columnrr_ProspectusShareClassAxisAxis*ColumnunitUnit*duration2011-05-01T00:00:002011-05-01T00:00:00falsefalseMid-Term Bond Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldick0000795259_S000009394Memberdei_LegalEntityAxisexplicitMemberfalsefalseMid-Term Bond Fund Classrr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldick0000795259_C000025738Memberrr_ProspectusShareClassAxisexplicitMemberMid-Term Bond FundMid-Term Bond Fund Classiso4217_USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170falseUSDfalsefalse$1falseRowprimaryElement*3false0rr_AnnualReturn2001rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse0.10440.1044falsefalsefalsetruefalseOtherxbrli: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 falsefalse0rr_AnnualReturn2001truefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse0.10440.1044falsefalsefalsetruefalseOthernanafalsefalse2falseRowprimaryElement*4false0rr_AnnualReturn2002rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse0.09660.0966falsefalsefalsetruefalseOtherxbrli: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 falsefalse0rr_AnnualReturn2002truefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse0.09660.0966falsefalsefalsetruefalseOthernanafalsefalse3falseRowprimaryElement*5false0rr_AnnualReturn2003rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse0.02760.0276falsefalsefalsetruefalseOtherxbrli: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 falsefalse0rr_AnnualReturn2003truefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse0.02760.0276falsefalsefalsetruefalseOthernanafalsefalse4falseRowprimaryElement*6false0rr_AnnualReturn2004rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse0.02260.0226falsefalsefalsetruefalseOtherxbrli: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 falsefalse0rr_AnnualReturn2004truefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse0.02260.0226falsefalsefalsetruefalseOthernanafalsefalse5falseRowprimaryElement*7false0rr_AnnualReturn2005rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse0.00770.0077falsefalsefalsetruefalseOtherxbrli: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 falsefalse0rr_AnnualReturn2005truefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse0.00770.0077falsefalsefalsetruefalseOthernanafalsefalse6falseRowprimaryElement*8false0rr_AnnualReturn2006rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse0.04220.0422falsefalsefalsetruefalseOtherxbrli: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 falsefalse0rr_AnnualReturn2006truefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse0.04220.0422falsefalsefalsetruefalseOthernanafalsefalse7falseRowprimaryElement*9false0rr_AnnualReturn2007rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse0.07220.0722falsefalsefalsetruefalseOtherxbrli: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 falsefalse0rr_AnnualReturn2007truefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse0.07220.0722falsefalsefalsetruefalseOthernanafalsefalse8falseRowprimaryElement*10false0rr_AnnualReturn2008rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse0.01840.0184falsefalsefalsetruefalseOtherxbrli: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 falsefalse0rr_AnnualReturn2008truefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse0.01840.0184falsefalsefalsetruefalseOthernanafalsefalse9falseRowprimaryElement*11false0rr_AnnualReturn2009rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse0.11220.1122falsefalsefalsetruefalseOtherxbrli: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 falsefalse0rr_AnnualReturn2009truefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse0.11220.1122falsefalsefalsetruefalseOthernanafalsefalse10falseRowprimaryElement*12false0rr_AnnualReturn2010rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse0.06930.0693falsefalsefalsetruefalseOtherxbrli: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 falsefalse0rr_AnnualReturn2010truefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse0.06930.0693falsefalsefalsetruefalseOthernanafalsefalse110Annual Total Returns UnKnownUnKnownUnKnownUnKnownfalsetrueColumnperiodPeriod*Columndei_LegalEntityAxisAxis*Columnrr_ProspectusShareClassAxisAxis*ColumnunitUnit*RowprimaryElement*falsefalsefalseOtherus-types:textBlockItemTypestringContains a command for the SEC Viewer for the role corresponding to BarChartData.No authoritative reference available.falsefalse26false0rr_BarChartClosingTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<pre>Best and Worst Performing Quarters Quarter/Year Total Return Best First quarter 2001 4.79 % Worst Second quarter 2004 (2.87)%</pre>falsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringIf the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph ii -Subsection b falsefalse27false0rr_AverageAnnualReturnCaptionrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsetruefalse00Average Annual Total Returns (for periods ended December 31, 2010)falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringThis item represents Average Anuual Total Returns. If a Multiple Class Fund offers a Class in the prospectus that converts into another Class after a stated period, compute average annual total returns in the table by using the returns of the other Class for the period after conversion.Reference 1: 1 -Publisher SEC -Name Form -Number N-1A -Chapter A -Section 4 -Paragraph 2 -Subparagraph instructions -Clause 5 -Subsection b falsefalse28false0rr_PerformanceTableTextBlockrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00<div style="display:none">~ http://www.mutualofamerica.com/role/PerformanceTableData_S000009394Member column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * column rr_PerformanceMeasureAxis compact * row primary compact * ~</div>falsefalse<div style="display:none">~ http://www.mutualofamerica.com/role/PerformanceTableData_S000009394Member column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * column rr_PerformanceMeasureAxis compact * row primary compact * ~</div>truehttp://www.mutualofamerica.com/role/PerformanceTableData_S000009394Memberfalsefalse061060 - Schedule - Average Annual Total Returns {Transposed}truefalsefalse1falseColumnprimaryElement*3false0rr_AverageAnnualReturnLabelrrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsetruefalse00Mid-Term Bond Fund (commenced operations on February 5, 1993)falsefalsefalsetruefalse2falsetruefalse00Barclays Intermediate Government/Credit Bond Fund Index falsefalsefalsetruefalse3falsetruefalse00Citigroup 3-7 Year Bond Index (Index reflects no deduction of any charges against the assets) falsefalsefalsetruefalseOtherxbrli: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 iii -Clause 1 -Exhibit 2 -Subsection b falsefalsefalseUSDfalsefalse$2falseColumnprimaryElement*4false0rr_AverageAnnualReturnYear01rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.06930.0693falsefalsefalsetruefalse2truetruetrue0.05890.0589falsefalsefalsetruefalse3truetruetrue0.07050.0705falsefalsefalsetruefalseOtherxbrli: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 falsefalsefalseUSDfalsefalse$3falseColumnprimaryElement*5false0rr_AverageAnnualReturnYear05rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.06240.0624falsefalsefalsetruefalse2truetruetrue0.05530.0553falsefalsefalsetruefalse3truetruetrue0.06160.0616falsefalsefalsetruefalseOtherxbrli: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 falsefalsefalseUSDfalsefalse$4falseColumnprimaryElement*6false0rr_AverageAnnualReturnYear10rrfalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truetruetrue0.05670.0567falsefalsefalsetruefalse2truetruetrue0.05510.0551falsefalsefalsetruefalse3truetruetrue0.06030.0603falsefalsefalsetruefalseOtherxbrli: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 falsefalsefalseUSDfalsefalse$1falseRowperiodPeriod*Rowdei_LegalEntityAxisAxis*Rowrr_ProspectusShareClassAxisAxis*Rowrr_PerformanceMeasureAxisAxis*RowunitUnit*duration2011-05-01T00:00:002011-05-01T00:00:00falsefalseMid-Term Bond Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldick0000795259_S000009394Memberdei_LegalEntityAxisexplicitMemberfalsefalseMid-Term Bond Fund Classrr_ProspectusShareClassAxisxbrldihttp://xbrl.org/2006/xbrldick0000795259_C000025738Memberrr_ProspectusShareClassAxisexplicitMembertruefalseBefore Taxesrr_PerformanceMeasureAxisrr_PerformanceMeasureDomainrr_PerformanceMeasureAxisexplicitMemberMid-Term Bond FundMid-Term Bond Fund ClassBefore Taxesiso4217_USDStandardhttp://www.xbrl.org/2003/iso4217USDiso421700truefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsetruefalse00Mid-Term Bond Fund (commenced operations on February 5, 1993)Mid-Term Bond Fund (commenced operations on February 5, 1993)falsefalsefalsetruefalse2truetruetrue0.06930.0693falsefalsefalsetruefalse3truetruetrue0.06240.0624falsefalsefalsetruefalse4truetruetrue0.05670.0567falsefalsefalsetruefalseOthernanafalsefalse2falseRowperiodPeriod*Rowdei_LegalEntityAxisAxis*Rowrr_ProspectusShareClassAxisAxis*Rowrr_PerformanceMeasureAxisAxis*RowunitUnit*duration2011-05-01T00:00:002011-05-01T00:00:00falsefalseMid-Term Bond Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldick0000795259_S000009394Memberdei_LegalEntityAxisexplicitMembertruefalseShare Classesrr_ProspectusShareClassAxisrr_ShareClassDomainrr_ProspectusShareClassAxisexplicitMemberfalsefalseBarclays Intermediate Government/Credit Bond Fund Indexrr_PerformanceMeasureAxisxbrldihttp://xbrl.org/2006/xbrldick0000795259_RRINDEX00004Memberrr_PerformanceMeasureAxisexplicitMemberMid-Term Bond FundShare ClassesBarclays Intermediate Government/Credit Bond Fund IndexStandard00truefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsetruefalse00Barclays Intermediate Government/Credit Bond Fund Index Barclays Intermediate Government/Credit Bond Fund Indexfalsefalsefalsetruefalse2truetruetrue0.05890.0589falsefalsefalsetruefalse3truetruetrue0.05530.0553falsefalsefalsetruefalse4truetruetrue0.05510.0551falsefalsefalsetruefalseOthernanafalsefalse3falseRowperiodPeriod*Rowdei_LegalEntityAxisAxis*Rowrr_ProspectusShareClassAxisAxis*Rowrr_PerformanceMeasureAxisAxis*RowunitUnit*duration2011-05-01T00:00:002011-05-01T00:00:00falsefalseMid-Term Bond Funddei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldick0000795259_S000009394Memberdei_LegalEntityAxisexplicitMembertruefalseShare Classesrr_ProspectusShareClassAxisrr_ShareClassDomainrr_ProspectusShareClassAxisexplicitMemberfalsefalseCitigroup 3-7 Year Bond Indexrr_PerformanceMeasureAxisxbrldihttp://xbrl.org/2006/xbrldick0000795259_RRINDEX00005Memberrr_PerformanceMeasureAxisexplicitMemberMid-Term Bond FundShare ClassesCitigroup 3-7 Year Bond IndexStandard00truefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsetruefalse00Citigroup 3-7 Year Bond Index (Index reflects no deduction of any charges against the assets) Citigroup 3-7 Year Bond Index (Index reflects no deduction of any charges against the assets)falsefalsefalsetruefalse2truetruetrue0.07050.0705falsefalsefalsetruefalse3truetruetrue0.06160.0616falsefalsefalsetruefalse4truetruetrue0.06030.0603falsefalsefalsetruefalseOthernanafalsefalse43Average Annual Total Returns Mid-Term Bond FundUnKnownUnKnownUnKnownUnKnownfalsetrueColumnprimaryElement*RowperiodPeriod*Rowdei_LegalEntityAxisAxis*Rowrr_ProspectusShareClassAxisAxis*Rowrr_PerformanceMeasureAxisAxis*RowunitUnit*falsefalsefalseOtherus-types:textBlockItemTypestringContains a command for the SEC Viewer for the role corresponding to PerformanceTableData.No authoritative reference available.falsefalse127Risk/Return Summary (Mid-Term Bond Fund) (Mid-Term Bond Fund (Prospectus Summary), Mid-Term Bond Fund)UnKnownUnKnownUnKnownUnKnownfalsetrue