v3.26.1
Label Element Value
Risk/Return: oef_RiskReturnAbstract  
Document Type dei_DocumentType 485BPOS
Document Period End Date dei_DocumentPeriodEndDate Mar. 31, 2026
Registrant Name dei_EntityRegistrantName BNY Mellon Short Term Municipal Bond Fund
Entity Central Index Key dei_EntityCentralIndexKey 0000810305
Amendment Flag dei_AmendmentFlag false
Document Creation Date dei_DocumentCreationDate Jul. 29, 2026
Document Effective Date dei_DocumentEffectiveDate Jul. 31, 2026
Entity Investment Company Type dei_EntityInvCompanyType N-1A
Prospectus Date oef_ProspectusDate Jul. 31, 2026
BNY Mellon Short Term Municipal Bond Fund | A  
Risk/Return: oef_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol DMBAX
BNY Mellon Short Term Municipal Bond Fund | D  
Risk/Return: oef_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol DSIBX
BNY Mellon Short Term Municipal Bond Fund | I  
Risk/Return: oef_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol DIMIX
BNY Mellon Short Term Municipal Bond Fund | Y  
Risk/Return: oef_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol DMYBX