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Label Element Value
Risk/Return: rr_RiskReturnAbstract  
Entity Registrant Name dei_EntityRegistrantName MAINSTAY FUNDS TRUST
Entity Central Index Key dei_EntityCentralIndexKey 0001469192
Document Creation Date dei_DocumentCreationDate Jun. 28, 2019
Document Effective Date dei_DocumentEffectiveDate Jun. 28, 2019
Prospectus Date rr_ProspectusDate Aug. 28, 2018