Loomis Sayles High Income Fund Loomis Sayles High Income Fund Loomis Sayles International Growth Fund Loomis Sayles International Growth Fund Loomis Sayles Investment Grade Bond Fund Loomis Sayles Investment Grade Bond Fund Loomis Sayles Strategic Income Fund Loomis Sayles Strategic Income Fund Dloomisharrisstatutoryprospectus_4833 LOOMIS SAYLES FUNDS II Dloomisharrisfundssai_4822 5-1 Loomis Harris Funds_SAI Class A - C000018231 Class A Class B - C000018232 Class B Class C - C000018233 Class C Class N - C000175112 Class N Class T - C000188536 Class T Class Y - C000069253 Class Y Class A - C000223747 Class A Class C - C000223748 Class C Class N - C000223749 Class N Class Y - C000223746 Class Y Class A - C000018234 Class A Class B - C000018235 Class B Class C - C000018236 Class C Class N - C000125485 Class N Class T - C000188537 Class T Class Y - C000018238 Class Y Class Admin - C000082998 Admin Class Class A - C000018251 Class A Class B - C000018252 Class B Class C - C000018253 Class C Class N - C000125487 Class N Class T - C000188539 Class T Class Y - C000018254 Class Y Class Admin - C000082999 Admin Class Convertible Securities Risk Convertible Securities Risk [Member] Bloomberg U.S. Corporate High Yield Bond Index Bloomberg U.S. Corporate High Yield Bond Index MSCI All Country World ex USA Index (Net) MSCI All Country World ex USA Index (Net) Bloomberg U.S. Aggregate Bond Index Bloomberg U.S. Aggregate Bond Index Bank Loans Risk Bank Loans Risk [Member] Below Investment Grade Fixed-Income Securities Risk Below Investment Grade Fixed-Income Securities Risk [Member] Derivatives Risk Derivatives Risk [Member] Interest Rate Risk Interest Rate Risk [Member] Leverage Risk Leverage Risk [Member] Mortgage-Related and Asset-Backed Securities Risk Mortgage-Related and Asset-Backed Securities Risk [Member] Portfolio Turnover Rate Risk Portfolio Turnover Rate Risk [Member] Currency Risk Currency Risk [Member] Equity Securities Risk Equity Securities Risk [Member] Market/Issuer Risk Market/Issuer Risk [Member] Management Risk Management Risk [Member] Large Shareholder Transaction Risk Large Shareholder Transaction Risk [Member] Liquidity Risk Liquidity Risk [Member] Small- and Mid-Capitalization Companies Risk Small- and Mid-Capitalization Companies Risk [Member] Credit/Counterparty Risk Credit/Counterparty Risk [Member] Cybersecurity and Technology Risk Cybersecurity and Technology Risk [Member] Emerging Markets Risk Emerging Markets Risk [Member] Foreign Securities Risk Foreign Securities Risk [Member] REITs Risk REITs Risk [Member]