Allocation Risk [Member] Private Investment Risk [Member] Issuerand Non Diversification Risk [Member] Liquidity Risk [Member] Management Risk [Member] Changesin Trade Negotiations Risk [Member] Highly Volatile Markets Risk [Member] Legislationand Regulatory Risk [Member] Market Disruptions Risk [Member] U S Debt Ceilingand Budget Deficit Risks [Member] Failure Of Financial Institutions And Sustained Financial Market Llliquidity [Member] Repurchase Policy Risks [Member] Distribution Policy Risk [Member] Cybersecurity Risk [Member] Infrastructure Industry Risk [Member] Underlying Funds Risk [Member] Lackof Control Over Private Investment Fundsand Other Portfolio Investments [Member] Useof Leveragebythe Fund [Member] Useof Leverageby Underlying Funds [Member] Valuationof Private Investment Funds [Member] Preferred Securities Risk [Member] Convertible Securities Risk [Member] Fixed Income Risk [Member] Foreign Securitiesand Emerging Markets Risk [Member] Leveraging Risk [Member] Credit Risks [Member] Possible Competition Between Underlying Fundsand Betweenthe Fundandthe Underlying Funds [Member] Allocationof Investment Opportunities Risk [Member] U S Federal Income Tax Matters [Member] Distribution Policyand Dividend Reinvestment Plan [Member] Custodian [Member] Class A Shares [Member] Class C Shares [Member] One Year [Member] Three Year [Member] Five Year [Member] Ten Year [Member]