3.22.0.1 html 24 192 1 true 17 0 false 2 false false R1.htm 000001 - Document - Document and Entity Information Sheet http://www.dreyfus.com/20220221/role/DocumentAndEntityInformation Document and Entity Information 1 false true R2.htm 020000 - Document - Risk/Return Summary {Unlabeled} - BNY Mellon S&P 500 Index Fund Sheet http://www.dreyfus.com/20220221/role/DocumentRiskReturnSummaryUnlabeledBNYMellonSP500IndexFund Risk/Return Summary- BNY Mellon S&P 500 Index Fund 2 false false R8.htm 020006 - Disclosure - Risk/Return Detail Data {Elements} - BNY Mellon S&P 500 Index Fund Sheet http://www.dreyfus.com/20220221/role/DisclosureRiskReturnDetailDataElementsBNYMellonSP500IndexFund Risk/Return Detail Data- BNY Mellon S&P 500 Index Fund 3 false true R9.htm 020007 - Document - Risk/Return Summary {Unlabeled} - BNY Mellon Midcap Index Fund, Inc. Sheet http://www.dreyfus.com/20220221/role/DocumentRiskReturnSummaryUnlabeledBNYMellonMidcapIndexFundInc Risk/Return Summary- BNY Mellon Midcap Index Fund, Inc. 4 false false R15.htm 020013 - Disclosure - Risk/Return Detail Data {Elements} - BNY Mellon Midcap Index Fund, Inc. Sheet http://www.dreyfus.com/20220221/role/DisclosureRiskReturnDetailDataElementsBNYMellonMidcapIndexFundInc Risk/Return Detail Data- BNY Mellon Midcap Index Fund, Inc. 5 false true R16.htm 020014 - Document - Risk/Return Summary {Unlabeled} - BNY Mellon Smallcap Stock Index Fund Sheet http://www.dreyfus.com/20220221/role/DocumentRiskReturnSummaryUnlabeledBNYMellonSmallcapStockIndexFund Risk/Return Summary- BNY Mellon Smallcap Stock Index Fund 6 false false R22.htm 020020 - Disclosure - Risk/Return Detail Data {Elements} - BNY Mellon Smallcap Stock Index Fund Sheet http://www.dreyfus.com/20220221/role/DisclosureRiskReturnDetailDataElementsBNYMellonSmallcapStockIndexFund Risk/Return Detail Data- BNY Mellon Smallcap Stock Index Fund 7 false true R23.htm 020021 - Document - Risk/Return Summary {Unlabeled} - BNY Mellon International Stock Index Fund Sheet http://www.dreyfus.com/20220221/role/DocumentRiskReturnSummaryUnlabeledBNYMellonInternationalStockIndexFund Risk/Return Summary- BNY Mellon International Stock Index Fund 8 false false R29.htm 020027 - Disclosure - Risk/Return Detail Data {Elements} - BNY Mellon International Stock Index Fund Sheet http://www.dreyfus.com/20220221/role/DisclosureRiskReturnDetailDataElementsBNYMellonInternationalStockIndexFund Risk/Return Detail Data- BNY Mellon International Stock Index Fund 9 false false R30.htm 040000 - Disclosure - Risk/Return Detail Data {Elements} Sheet http://xbrl.sec.gov/rr/role/RiskReturnDetailData Risk/Return Detail Data 10 false false All Reports Book All Reports ck0000875732-20220221.htm ck0000875732-20220221.xsd ck0000875732-20220221_cal.xml ck0000875732-20220221_def.xml ck0000875732-20220221_lab.xml ck0000875732-20220221_pre.xml j-eyconsent113.htm p1-ia045codeofethics3312021.htm powerofattorney.htm img_aaa1299b2f994f2.jpg img_adcff10780984f2.jpg img_dae736e6d22c4f2.jpg img_edc5052e4bd54f2.jpg img_edf5c27bf9904f2.jpg BarChart1.png BarChart2.png BarChart3.png BarChart4.png http://xbrl.sec.gov/dei/2021 http://xbrl.sec.gov/rr/2021 true true