1001 - Disclosure - N-2 - [Fee Table] link:presentationLink link:definitionLink link:calculationLink 1002 - Disclosure - N-2 - [Investment Objectives] link:presentationLink link:definitionLink link:calculationLink 1003 - Disclosure - N-2 - [Risk Factors] link:presentationLink link:definitionLink link:calculationLink 1004 - Disclosure - N-2 - [Effects of Leverage] link:presentationLink link:definitionLink link:calculationLink 1005 - Disclosure - N-2 - [Share Price Table] link:presentationLink link:definitionLink link:calculationLink 1006 - Disclosure - N-2 - [Capital Stock] link:presentationLink link:definitionLink link:calculationLink Common Shares [Member] Preferred Shares [Member] Investment and Market Risk [Member] Below Investment Grade Securities Risk [Member] Municipal Securities Risk [Member] Tax-Exempt Securities Risk Inverse Floating Rate Securities and TOBs Risk [Member] Insurance Risk [Member] Credit Risks [Member] Credit Risk [Member] Prepayment Risks [Member] Prepayment Risk [Member] Counterparty Risk [Member] Credit Crisis Liquidity and Volatility Risk [Member] Government Intervention in Financial Markets Risk [Member] Focus of Investments Risks [Member] Municipal Leases Risk [Member] Derivatives Risk [Member] Leverage Risk [Member] Remarketing Risk [Member] Fund Distribution Risk [Member] Inflation/Deflation Risk Liquidity Risk [Member] Market Events Risk [Member] Portfolio Turnover Risk [Member] Management Risk [Member] Risks of Futures and Options on Futures [Member] Market Price Discount from Net Asset Value Risk [Member] Valuation Risk [Member] Tax Risks [Member] Anti-Takeover Provisions Risk [Member] Temporary Defensive Strategies Risk [Member] WhenIssued, Forward Commitment and Delayed Delivery Transactions Risk [Member] Operational Risk [Member] Cybersecurity Risk [Member]