Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	MUTUAL OF AMERICA INVESTMENT CORP
Prospectus Date	rr_ProspectusDate	May 01, 2015
Money Market Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	Money Market Fund May 1, 2015
Objective [Heading]	rr_ObjectiveHeading	Investment Objective.
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	The Fund seeks current income to the extent consistent with maintenance of liquidity, investment quality and stability of capital.
Expense [Heading]	rr_ExpenseHeading	Fees and Expenses of the Fund.
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	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.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	Shareholder Fees (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover.
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	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.
Expense Example [Heading]	rr_ExpenseExampleHeading	Example.
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes: (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. Although your actual costs may be higher or lower, your cost based on these assumptions would be:
Strategy [Heading]	rr_StrategyHeading	Principal Investment Strategies.
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund invests in money market instruments that meet certain requirements. The Fund does not maintain a stable net asset value. The dollar weighted average maturity of the instruments the Fund holds will be short-term — 60 days or less. The Fund will purchase only securities that are rated in one of the two highest rating categories by at least two rating agencies, and substantially all (at least 95%) that are rated in the highest category by at least two rating agencies. The Fund will diversify its investments, limiting holdings in the securities of any one issuer (except the U.S. Government or its agencies) to 5% of assets.
Risk [Heading]	rr_RiskHeading	Principal Investment Risks.
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	An investment in the Fund is subject to the following risks which are described in more detail in the Prospectus. 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. 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. Money Market risk: An investment in the Fund is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. The credit quality of the Fund's holdings can change rapidly in certain markets, and the default of a single holding could have an adverse impact on the Fund's share price. The actions of a few large investors may have a significant adverse effect on the share prices of all shares of the Fund. In addition, the Fund's returns can be adversely affected when yields on eligible investments are low.
Risk Lose Money [Text]	rr_RiskLoseMoney	An investment in the Fund could decline in value, and you could lose money by investing in the Fund.
Risk Money Market Fund [Text]	rr_RiskMoneyMarketFund	Money Market risk: An investment in the Fund is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. The credit quality of the Fund's holdings can change rapidly in certain markets, and the default of a single holding could have an adverse impact on the Fund's share price. The actions of a few large investors may have a significant adverse effect on the share prices of all shares of the Fund. In addition, the Fund's returns can be adversely affected when yields on eligible investments are low.
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	An investment in the Fund is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Performance/Annual Return.
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	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. Investors experienced negative returns and the Fund lost money for periods of time in each calendar year from 2009 through 2014. 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. 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.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The bar chart and table below show the annual return and average annual returns of the Fund.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.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	1-800-468-3785
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	http://www.mutualofamerica.com
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	A fund’s past performance does not necessarily indicate how it will perform in the future.
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	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.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Best and Worst Performing Quarters                                           Quarter/Year                              Total Return Best                                   Fourth quarter 2006                           1.30% Worst                                Fourth quarter 2011                           (0.05)%
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns (for periods ended December 31, 2014)
Money Market Fund | Money Market Fund Class
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees (fees paid directly from your investment)	rr_ShareholderFeeOther
Management Fees	rr_ManagementFeesOverAssets	0.15%
Other Expenses	rr_OtherExpensesOverAssets	0.09%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.24%
1 Year	rr_ExpenseExampleYear01	25
3 Years	rr_ExpenseExampleYear03	78
5 Years	rr_ExpenseExampleYear05	136
10 Years	rr_ExpenseExampleYear10	309
2005	rr_AnnualReturn2005	2.97%
2006	rr_AnnualReturn2006	4.89%
2007	rr_AnnualReturn2007	5.03%
2008	rr_AnnualReturn2008	2.34%
2009	rr_AnnualReturn2009	(0.08%)
2010	rr_AnnualReturn2010	(0.14%)
2011	rr_AnnualReturn2011	(0.17%)
2012	rr_AnnualReturn2012	(0.17%)
2013	rr_AnnualReturn2013	(0.16%)
2014	rr_AnnualReturn2014	(0.14%)
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Best
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Dec. 31, 2006
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	1.30%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Worst
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2011
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(0.05%)
Past One Year	rr_AverageAnnualReturnYear01	(0.14%)
Past Five Years	rr_AverageAnnualReturnYear05	(0.15%)
Past Ten Years	rr_AverageAnnualReturnYear10	1.42%
Money Market Fund | Citigroup 3 month Treasury Bill Index (Index reflects no deduction for fees and expenses)
Risk/Return:	rr_RiskReturnAbstract
Past One Year	rr_AverageAnnualReturnYear01	0.04%
Past Five Years	rr_AverageAnnualReturnYear05	0.07%
Past Ten Years	rr_AverageAnnualReturnYear10	1.47%