2.2.0.25 true Sheet 001001 - Document - Document And Entity Information {Elements} Document And Entity Information http://www.mutualofamerica.com/role/DocumentDocumentandEntityInformation false R1.xml false Sheet 011002 - Document - Risk/Return Summary {Unlabeled} (Equity Index Fund) Risk/Return Summary (Equity Index Fund) http://www.mutualofamerica.com/role/RiskReturn_S000009389Member true R2.xml false Sheet 040000 - Disclosure - Risk/Return Detail Data {Elements} Risk/Return Detail Data http://xbrl.sec.gov/rr/role/RiskReturnDetailData false R7.xml false Sheet 061008 - Document - Risk/Return Summary {Unlabeled} (All America Fund) Risk/Return Summary (All America Fund) http://www.mutualofamerica.com/role/RiskReturn_S000009396Member true R8.xml false Sheet 061013 - Disclosure - Risk/Return Detail Data {Elements} (All America Fund) Risk/Return Detail Data (All America Fund) http://www.mutualofamerica.com/role/RiskReturnDetailData_S000009396Member false R13.xml false Sheet 061014 - Document - Risk/Return Summary {Unlabeled} (Small Cap Value Fund) Risk/Return Summary (Small Cap Value Fund) http://www.mutualofamerica.com/role/RiskReturn_S000009397Member true R14.xml false Sheet 061019 - Disclosure - Risk/Return Detail Data {Elements} (Small Cap Value Fund) Risk/Return Detail Data (Small Cap Value Fund) http://www.mutualofamerica.com/role/RiskReturnDetailData_S000009397Member false R19.xml false Sheet 061020 - Document - Risk/Return Summary {Unlabeled} (Small Cap Growth Fund) Risk/Return Summary (Small Cap Growth Fund) http://www.mutualofamerica.com/role/RiskReturn_S000009398Member true R20.xml false Sheet 061025 - Disclosure - Risk/Return Detail Data {Elements} (Small Cap Growth Fund) Risk/Return Detail Data (Small Cap Growth Fund) http://www.mutualofamerica.com/role/RiskReturnDetailData_S000009398Member false R25.xml false Sheet 061026 - Document - Risk/Return Summary {Unlabeled} (Mid Cap Value Fund) Risk/Return Summary (Mid Cap Value Fund) http://www.mutualofamerica.com/role/RiskReturn_S000009399Member true R26.xml false Sheet 061031 - Disclosure - Risk/Return Detail Data {Elements} (Mid Cap Value Fund) Risk/Return Detail Data (Mid Cap Value Fund) http://www.mutualofamerica.com/role/RiskReturnDetailData_S000009399Member false R31.xml false Sheet 061032 - Document - Risk/Return Summary {Unlabeled} (Mid-Cap Equity Index Fund) Risk/Return Summary (Mid-Cap Equity Index Fund) http://www.mutualofamerica.com/role/RiskReturn_S000009400Member true R32.xml false Sheet 061037 - Disclosure - Risk/Return Detail Data {Elements} (Mid-Cap Equity Index Fund) Risk/Return Detail Data (Mid-Cap Equity Index Fund) http://www.mutualofamerica.com/role/RiskReturnDetailData_S000009400Member false R37.xml false Sheet 061038 - Document - Risk/Return Summary {Unlabeled} (Composite Fund) Risk/Return Summary (Composite Fund) http://www.mutualofamerica.com/role/RiskReturn_S000009402Member true R38.xml false Sheet 061043 - Disclosure - Risk/Return Detail Data {Elements} (Composite Fund) Risk/Return Detail Data (Composite Fund) http://www.mutualofamerica.com/role/RiskReturnDetailData_S000009402Member false R43.xml false Sheet 061044 - Document - Risk/Return Summary {Unlabeled} (International Fund) Risk/Return Summary (International Fund) http://www.mutualofamerica.com/role/RiskReturn_S000017204Member true R44.xml false Sheet 061049 - Disclosure - Risk/Return Detail Data {Elements} (International Fund) Risk/Return Detail Data (International Fund) http://www.mutualofamerica.com/role/RiskReturnDetailData_S000017204Member false R49.xml false Sheet 061050 - Document - Risk/Return Summary {Unlabeled} (Money Market Fund) Risk/Return Summary (Money Market Fund) http://www.mutualofamerica.com/role/RiskReturn_S000009392Member true R50.xml false Sheet 061055 - Disclosure - Risk/Return Detail Data {Elements} (Money Market Fund) Risk/Return Detail Data (Money Market Fund) http://www.mutualofamerica.com/role/RiskReturnDetailData_S000009392Member false R55.xml false Sheet 061056 - Document - Risk/Return Summary {Unlabeled} (Mid-Term Bond Fund) Risk/Return Summary (Mid-Term Bond Fund) http://www.mutualofamerica.com/role/RiskReturn_S000009394Member true R56.xml false Sheet 061061 - Disclosure - Risk/Return Detail Data {Elements} (Mid-Term Bond Fund) Risk/Return Detail Data (Mid-Term Bond Fund) http://www.mutualofamerica.com/role/RiskReturnDetailData_S000009394Member false R61.xml false Sheet 061062 - Document - Risk/Return Summary {Unlabeled} (Bond Fund) Risk/Return Summary (Bond Fund) http://www.mutualofamerica.com/role/RiskReturn_S000009395Member true R62.xml false Sheet 061067 - Disclosure - Risk/Return Detail Data {Elements} (Bond Fund) Risk/Return Detail Data (Bond Fund) http://www.mutualofamerica.com/role/RiskReturnDetailData_S000009395Member false R67.xml false Sheet 061068 - Document - Risk/Return Summary {Unlabeled} (Retirement Income Fund) Risk/Return Summary (Retirement Income Fund) http://www.mutualofamerica.com/role/RiskReturn_S000017196Member true R68.xml false Sheet 061073 - Disclosure - Risk/Return Detail Data {Elements} (Retirement Income Fund) Risk/Return Detail Data (Retirement Income Fund) http://www.mutualofamerica.com/role/RiskReturnDetailData_S000017196Member false R73.xml false Sheet 061074 - Document - Risk/Return Summary {Unlabeled} (2010 Retirement Fund) Risk/Return Summary (2010 Retirement Fund) http://www.mutualofamerica.com/role/RiskReturn_S000017195Member true R74.xml false Sheet 061079 - Disclosure - Risk/Return Detail Data {Elements} (2010 Retirement Fund) Risk/Return Detail Data (2010 Retirement Fund) http://www.mutualofamerica.com/role/RiskReturnDetailData_S000017195Member false R79.xml false Sheet 061080 - Document - Risk/Return Summary {Unlabeled} (2015 Retirement Fund) Risk/Return Summary (2015 Retirement Fund) http://www.mutualofamerica.com/role/RiskReturn_S000017197Member true R80.xml false Sheet 061085 - Disclosure - Risk/Return Detail Data {Elements} (2015 Retirement Fund) Risk/Return Detail Data (2015 Retirement Fund) http://www.mutualofamerica.com/role/RiskReturnDetailData_S000017197Member false R85.xml false Sheet 061086 - Document - Risk/Return Summary {Unlabeled} (2020 Retirement Fund) Risk/Return Summary (2020 Retirement Fund) http://www.mutualofamerica.com/role/RiskReturn_S000017198Member true R86.xml false Sheet 061091 - Disclosure - Risk/Return Detail Data {Elements} (2020 Retirement Fund) Risk/Return Detail Data (2020 Retirement Fund) http://www.mutualofamerica.com/role/RiskReturnDetailData_S000017198Member false R91.xml false Sheet 061092 - Document - Risk/Return Summary {Unlabeled} (2025 Retirement Fund) Risk/Return Summary (2025 Retirement Fund) http://www.mutualofamerica.com/role/RiskReturn_S000017199Member true R92.xml false Sheet 061097 - Disclosure - Risk/Return Detail Data {Elements} (2025 Retirement Fund) Risk/Return Detail Data (2025 Retirement Fund) http://www.mutualofamerica.com/role/RiskReturnDetailData_S000017199Member false R97.xml false Sheet 061098 - Document - Risk/Return Summary {Unlabeled} (2030 Retirement Fund) Risk/Return Summary (2030 Retirement Fund) http://www.mutualofamerica.com/role/RiskReturn_S000017200Member true R98.xml false Sheet 061103 - Disclosure - Risk/Return Detail Data {Elements} (2030 Retirement Fund) Risk/Return Detail Data (2030 Retirement Fund) http://www.mutualofamerica.com/role/RiskReturnDetailData_S000017200Member false R103.xml false Sheet 061104 - Document - Risk/Return Summary {Unlabeled} (2035 Retirement Fund) Risk/Return Summary (2035 Retirement Fund) http://www.mutualofamerica.com/role/RiskReturn_S000017201Member true R104.xml false Sheet 061109 - Disclosure - Risk/Return Detail Data {Elements} (2035 Retirement Fund) Risk/Return Detail Data (2035 Retirement Fund) http://www.mutualofamerica.com/role/RiskReturnDetailData_S000017201Member false R109.xml false Sheet 061110 - Document - Risk/Return Summary {Unlabeled} (2040 Retirement Fund) Risk/Return Summary (2040 Retirement Fund) http://www.mutualofamerica.com/role/RiskReturn_S000017202Member true R110.xml false Sheet 061115 - Disclosure - Risk/Return Detail Data {Elements} (2040 Retirement Fund) Risk/Return Detail Data (2040 Retirement Fund) http://www.mutualofamerica.com/role/RiskReturnDetailData_S000017202Member false R115.xml false Sheet 061116 - Document - Risk/Return Summary {Unlabeled} (2045 Retirement Fund) Risk/Return Summary (2045 Retirement Fund) http://www.mutualofamerica.com/role/RiskReturn_S000017203Member true R116.xml false Sheet 061121 - Disclosure - Risk/Return Detail Data {Elements} (2045 Retirement Fund) Risk/Return Detail Data (2045 Retirement Fund) http://www.mutualofamerica.com/role/RiskReturnDetailData_S000017203Member false R121.xml false Sheet 061122 - Document - Risk/Return Summary {Unlabeled} (Conservative Allocation Fund) Risk/Return Summary (Conservative Allocation Fund) http://www.mutualofamerica.com/role/RiskReturn_S000009403Member true R122.xml false Sheet 061127 - Disclosure - Risk/Return Detail Data {Elements} (Conservative Allocation Fund) Risk/Return Detail Data (Conservative Allocation Fund) http://www.mutualofamerica.com/role/RiskReturnDetailData_S000009403Member false R127.xml false Sheet 061128 - Document - Risk/Return Summary {Unlabeled} (Moderate Allocation Fund) Risk/Return Summary (Moderate Allocation Fund) http://www.mutualofamerica.com/role/RiskReturn_S000009390Member true R128.xml false Sheet 061133 - Disclosure - Risk/Return Detail Data {Elements} (Moderate Allocation Fund) Risk/Return Detail Data (Moderate Allocation Fund) http://www.mutualofamerica.com/role/RiskReturnDetailData_S000009390Member false R133.xml false Sheet 061134 - Document - Risk/Return Summary {Unlabeled} (Aggressive Allocation Fund) Risk/Return Summary (Aggressive Allocation Fund) http://www.mutualofamerica.com/role/RiskReturn_S000009391Member true R134.xml false Sheet 061139 - Disclosure - Risk/Return Detail Data {Elements} (Aggressive Allocation Fund) Risk/Return Detail Data (Aggressive Allocation Fund) http://www.mutualofamerica.com/role/RiskReturnDetailData_S000009391Member false R139.xml false Book All Reports All Reports false 1 113 81 0 2 74 false false eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996534_396840x-9990965 32 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996532_429423x-9996555 15 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996526_396840x-9990957 31 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996523_429423x-9996546 15 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996537_396840x-9990968_429423x-9996560 6 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996523_429555x-9998685 4 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996525_429423x-9996548 15 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996529_429555x-9998778 4 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996541_429423x-9996564 21 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996526_429555x-9998778 4 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996527_429555x-9998694 4 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996544_429555x-9998694 5 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996536_396840x-9990967 32 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996544_396840x-9990975 32 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996538_396840x-9990969_429423x-9996561 6 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996524_396840x-9990955_429423x-9996547 6 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996537_429423x-9996560 17 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996534_396840x-9990965_429423x-9996557 6 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996544_429555x-9998778 5 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996544_429423x-9996567 20 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996532_429555x-9998778 4 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996524_396840x-9990955 32 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996531_429423x-9996554 15 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996539_396840x-9990970 31 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996523_396840x-9990954 32 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996533_396840x-9990964_429423x-9996556 6 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996542_396840x-9990973_429423x-9996565 6 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996545_429423x-9996568 17 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996535_429423x-9996558 22 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996524_429555x-9998778 4 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996539_429555x-9998778 5 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996530_429555x-9998694 4 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996539_429423x-9996562 22 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996541_429555x-9998692 4 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996533_429555x-9998778 5 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996531_429555x-9998693 4 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996530_429423x-9996553 15 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996542_429555x-9998693 4 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996543_396840x-9990974 32 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996543_429555x-9998778 5 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996525_396840x-9990956_429423x-9996548 6 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996528_429555x-9998694 4 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996531_429555x-9998778 4 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996535_396840x-9990966_429423x-9996558 6 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996537_396840x-9990968 31 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996542_396840x-9990973 32 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996532_429555x-9998694 4 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996535_429555x-9998687 5 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996543_429555x-9998694 5 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996538_429423x-9996561 17 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996542_429423x-9996565 21 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996525_429555x-9998778 4 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996527_429423x-9996550 15 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996543_396840x-9990974_429423x-9996566 6 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996537_429555x-9998689 5 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996527_429555x-9998778 4 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996529_429423x-9996552 15 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996533_429555x-9998694 5 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996532_396840x-9990963_429423x-9996555 6 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996530_396840x-9990961 32 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996528_429555x-9998778 4 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996541_429555x-9998691 4 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996526_429423x-9996549 15 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996536_429555x-9998688 5 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996544_396840x-9990975_429423x-9996567 6 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996531_429555x-9998694 4 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996530_396840x-9990961_429423x-9996553 6 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996527_396840x-9990958_429423x-9996550 6 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996541_396840x-9990972 33 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996526_396840x-9990957_429423x-9996549 6 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996545_429423x-9996568_429555x429511 5 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996540_429555x-9998694 5 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996533_429423x-9996556 20 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996533_396840x-9990964 32 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996538_429555x-9998690 5 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996539_396840x-9990970_429423x-9996562 6 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996545_396840x-9990976_429423x-9996568 6 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996540_396840x-9990971_429423x-9996563 6 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996525_396840x-9990956 32 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996530_429555x-9998686 4 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996534_429423x-9996557 22 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996536_396840x-9990967_429423x-9996559 6 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996535_396840x-9990966 32 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996531_396840x-9990962_429423x-9996554 6 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996529_396840x-9990960 32 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996543_429423x-9996566 20 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996529_396840x-9990960_429423x-9996552 6 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996524_429423x-9996547_429555x429511 4 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996524_429423x-9996547 11 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996532_396840x-9990963 31 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996530_429555x-9998778 4 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996536_429423x-9996559 17 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996545_429555x-9998778 5 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996541_396840x-9990972_429423x-9996564 6 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996524_429555x-9998694 4 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996529_429555x-9998694 4 eol_0001104659-11-023833_STD_1_20110501_0 8 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996528_429423x-9996551 15 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996545_396840x-9990976 32 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996532_429555x-9998686 4 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996531_396840x-9990962 31 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996538_396840x-9990969 32 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996526_429555x-9998694 4 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996528_396840x-9990959 31 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996527_396840x-9990958 31 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996523_396840x-9990954_429423x-9996546 6 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996540_429423x-9996563 22 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996534_429555x-9998778 5 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996534_429555x-9998694 5 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996534_429555x-9998693 5 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996528_396840x-9990959_429423x-9996551 6 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996540_396840x-9990971 32 eol_0001104659-11-023833_STD_1_20110501_0_396770x-9996525_429555x-9998694 4 true true