3.21.4 html 57 204 1 true 39 0 false 2 false false R1.htm 000000 - Document - Document and Entity Information {Elements} Sheet http://www.icsdelivery.com/role/DocumentDocumentandEntityInformationElements000000 Document and Entity Information 1 false false R2.htm 000041 - Disclosure - Risk/Return Detail Data {Elements} - Loomis Sayles Credit Income Fund Sheet http://www.icsdelivery.com/role/DisclosureRiskReturnDetailDataElementsLoomisSaylesCreditIncomeFund000041 Risk/Return Detail Data- Loomis Sayles Credit Income Fund 2 false false R3.htm 000061 - Disclosure - Risk/Return Detail Data {Elements} - Loomis Sayles Global Allocation Fund Sheet http://www.icsdelivery.com/role/DisclosureRiskReturnDetailDataElementsLoomisSaylesGlobalAllocationFund000061 Risk/Return Detail Data- Loomis Sayles Global Allocation Fund 3 false false R4.htm 000081 - Disclosure - Risk/Return Detail Data {Elements} - Loomis Sayles Growth Fund Sheet http://www.icsdelivery.com/role/DisclosureRiskReturnDetailDataElementsLoomisSaylesGrowthFund000081 Risk/Return Detail Data- Loomis Sayles Growth Fund 4 false false R5.htm 000121 - Disclosure - Risk/Return Detail Data {Elements} - Loomis Sayles Limited Term Government and Agency Fund Sheet http://www.icsdelivery.com/role/DisclosureRiskReturnDetailDataElementsLoomisSaylesLimitedTermGovernmentandAgencyFund000121 Risk/Return Detail Data- Loomis Sayles Limited Term Government and Agency Fund 5 false false R6.htm 000221 - Disclosure - Risk/Return Detail Data {Elements} - Loomis Sayles Small Cap Growth Fund Sheet http://www.icsdelivery.com/role/DisclosureRiskReturnDetailDataElementsLoomisSaylesSmallCapGrowthFund000221 Risk/Return Detail Data- Loomis Sayles Small Cap Growth Fund 6 false false R7.htm 000261 - Disclosure - Risk/Return Detail Data {Elements} - Loomis Sayles Small/Mid Cap Growth Fund Sheet http://www.icsdelivery.com/role/DisclosureRiskReturnDetailDataElementsLoomisSaylesSmallMidCapGrowthFund000261 Risk/Return Detail Data- Loomis Sayles Small/Mid Cap Growth Fund 7 false false All Reports Book All Reports d63218d485bpos.htm d63218dex99d4ii.htm d63218dex99d6ii.htm d63218dex99e10.htm d63218dex99h1viii.htm d63218dex99h2xli.htm d63218dex99h4i.htm d63218dex99h4iv.htm d63218dex99h6i.htm d63218dex99j1.htm d63218dex99j2.htm d63218dex99p1.htm d63218dex99p2.htm d63218dex99p3.htm d63218dex99q1.htm lsfii-20220127.xsd lsfii-20220127_cal.xml lsfii-20220127_def.xml lsfii-20220127_lab.xml lsfii-20220127_pre.xml g114761g0120093019866.jpg g274224g0120092229000.jpg g63218g1pr4025img001.jpg g63218g1pr4025img002.jpg g63218g1pr4025img003.jpg g63218g1pr4025img004.jpg g63218g1pr4025img005.jpg g63218g1pr4025img006.jpg g63218g1pr4025img007.jpg g63218g1pr4025img008.jpg g63218g2lo4026img0001.jpg g63218g2lo4026img00011.jpg g63218g2lo4026img0002.jpg g63218g2lo4026img0003.jpg g63218g2lo4026img0004.jpg g63218g2lo4026img0005.jpg g63218g2lo4026img0006.jpg g63218g2lo4026img0007.jpg g63218g2lo4026img0008.jpg g63218g2lo4026img0009.jpg http://xbrl.sec.gov/dei/2021 http://xbrl.sec.gov/rr/2021 true true