Shareholder Service Fee All Other Expenses FPA Crescent Fund - Institutional and Investor Class Shares FPA Crescent Fund - Supra Institutional Class Shares FPA Flexible Fixed Income Fund - Institutional, Advisor and Investor Class FPA Crescent Fund FPA Flexible Fixed Income Fund Institutional Class Investor Class Supra Institutional Class Institutional Class Advisor Class Investor Class Market Risk [Member] Risks Associated with Investing in Equities [Member] Adjustable Rate Mortgage ("ARM") Risk [Member] Call Risk [Member] Risks Associated with Investing in Smaller-Cap and Mid-Cap Companies [Member] Risks Associated with Investing in Non-U.S. Securities [Member] Risks Associated with Investing in Emerging Markets [Member] Risks Associated with Short Selling [Member] Risks Associated with Value Investing [Member] Liquidity Risk [Member] Over-the-Counter ("OTC") Investments Risk [Member] U.S. Government Securities Risk [Member] Currency Transactions Risk [Member] Over-the-Counter ("OTC") Risk [Member] Mortgage-Related and Asset-Backed Securities Risk [Member] Collateralized Debt Obligations Risk [Member] Collateralized Loan Obligations Risk [Member] Risks Associated with Investing in High Yield Securities [Member] Risks Associated with Investing in Sovereign and Government-Related Debt [Member] Risks Associated with Investing in Convertible Securities [Member] Risks Associated with Investing in Repurchase Agreements [Member] Large Investor Risk [Member] Management Risk [Member] Private Placements and Restricted Securities Risk [Member] Recent Market Events [Member] Cybersecurity Risk [Member] Interest Rate Risk [Member] Credit Risk [Member] MSCI All Country World Index (reflects no deductions for fees, expenses, or taxes) S&P 500 Index (reflects no deductions for fees, expenses, or taxes) 60%/40% S&P 500 Index/Bloomberg U.S. Aggregate Bond Index (reflects no deductions for fees, expenses, or taxes) Consumer Price Index (reflects no deductions for fees, expenses, or taxes) S&P 500 (reflects no deductions for fees, expenses, or taxes) Bloomberg U.S. Universal Bond Index CPI + 200 Basis Points index_ SP_500_ Index_reflects_no_deductions_for_fees_expenses_or_taxes Member index_ CPI_200_ Basis_ Points Member Large Investor Risk Member C000249813 Member C000207154 Member CreditRiskMember Risks Associated With Short Selling Member Management Risk Member Risks Associated With Investing In High Yield Securities Member Cybersecurity Risk Member USGovernment Securities Risk Member index_ SP_500_reflects_no_deductions_for_fees_expenses_or_taxes Member Risks Associated With Investing In Sovereign And Government Related Debt Member Call Risk Member Risks Associated With Investing In Repurchase Agreements Member C000025975 Member index_ MSCI_ All_ Country_ World_ Index_reflects_no_deductions_for_fees_expenses_or_taxes Member Risks Associated With Value Investing Member Private Placements And Restricted Securities Risk Member doc_ FPA_ Flexible_ Fixed_ Income_ Fund_ Institutional_ Advisor_and_ Investor_ Class Member index_ Consumer_ Price_ Index_reflects_no_deductions_for_fees_expenses_or_taxes Member Collateralized Debt Obligations Risk Member Risks Associated With Investing In Equities Member index_ Bloomberg_ US_ Universal_ Bond_ Index Member Collateralized Loan Obligations Risk Member Risks Associated With Investing In Smaller Cap And Mid Cap Companies Member Risks Associated With Investing In Non USSecurities Member S000009495 Member C000227168 Member Overthe Counter OTCRisk Member C000221940 Member Risks Associated With Investing In Emerging Markets Member Liquidity Risk Member Market Risk Member Risks Associated With Investing In Convertible Securities Member doc_ FPA_ Crescent_ Fund_ Supra_ Institutional_ Class_ Shares Member Currency Transactions Risk Member index_6040_ SP_500_ Index Bloomberg_ US_ Aggregate_ Bond_ Index_reflects_no_deductions_for_fees_expenses_or_taxes Member Mortgage Related And Asset Backed Securities Risk Member InterestRateRiskMember doc_ FPA_ Crescent_ Fund_ Institutional_and_ Investor_ Class_ Shares Member C000262097 Member Adjustable Rate Mortgage ARMRisk Member Overthe Counter OTCInvestments Risk Member Recent Market Events Member S000064044 Member