Corporate Bonds Risk [Member] Frontier Markets Risk [Member] Event Risk [Member] Deflation Risk [Member] Subsidiary Risk [Member] Legislation Risk [Member] Misconduct of Employees and of Service Providers Risk [Member] Yield and Ratings Risk [Member] REITs Risk [Member] U S Government Securities Risk [Member] Insolvency of Issuers of Indebtedness Risk [Member] Taxable Municipal Securities Risk [Member] Foreign Currency Risk [Member] Sovereign Government and Supranational Debt Risk [Member] Securities Lending Risk [Member] Inflation Risk [Member] Risk Associated with Recent Market Events [Member] Reference Rate Replacement Risk [Member] EMU and Redenomination Risk [Member] Market Disruption and Geopolitical Risk [Member] Regulation and Government Intervention Risk [Member] Regulation as a Commodity Pool [Member] Failures of Futures Commission Merchants and Clearing Organizations Risk [Member] Legal Tax and Regulatory Risks [Member] Potential Conflicts of Interest of the Advisor Sub Advisors and Others [Member] Defensive Investing Risk [Member] Decision Making Authority Risk [Member] Management Risk [Member] Valuation Risk [Member] Reliance on the Advisor and Sub Advisors Risk [Member] Reliance on Service Providers Risk [Member] Information Technology Systems Risk [Member] Operational and Technology Risks [Member] Misconduct of Employees and of Service Providers Risks [Member] Portfolio Turnover Risk [Member] Anti Takeover Provisions Risk [Member] Investment Company Act Regulations [Member] Common Shares [Member] Preferred Shares [Member]