1001 - Disclosure - N-2 - [Fee Table] link:presentationLink link:definitionLink link:calculationLink 1002 - Disclosure - N-2 - [Senior Securities] link:presentationLink link:definitionLink link:calculationLink 1003 - Disclosure - N-2 - [Investment Objectives] link:presentationLink link:definitionLink link:calculationLink 1004 - Disclosure - N-2 - [Risk Factors] link:presentationLink link:definitionLink link:calculationLink 1005 - Disclosure - N-2 - [Effects of Leverage] link:presentationLink link:definitionLink link:calculationLink 1006 - Disclosure - N-2 - [Share Price Table] link:presentationLink link:definitionLink link:calculationLink 1007 - Disclosure - N-2 - [Outstanding Securities] link:presentationLink link:definitionLink link:calculationLink Common Share [Member] Adjustable Rate MuniFund Term Preferred AMTP Shares [Member] Variable Rate MuniFund Term Preferred VMTP Shares [Member] Interest And Other Related Expenses [Member] Call Risk [Member] Credit Risks [Member] Credit Spread Risk [Member] Defaulted or Distressed Securities Risk [Member] Deflation Risk [Member] Derivatives Risk [Member] Duration Risk [Member] Economic Sector Risk [Member] Financial Futures and Options Transactions Risk [Member] Floating and Variable Rate Securities Risk [Member] Hedging Risk [Member] Income Risk [Member] Inflation Risk [Member] Insurance Risk [Member] Inverse Floating Rate Securities Risk [Member] Municipal Securities Risk [Member] Municipal Securities Market Liquidity Risk [Member] Municipal Securities Market Risk [Member] Other Investment Companies Risk [Member] Puerto Rico Municipal Securities Market Risk [Member] Reinvestment Risk [Member] Restricted and Illiquid Investments Risk [Member] Special Considerations Related to Single State Concentration Risk [Member] Special Risks Related to Certain Municipal Obligations [Member] Structured Products Risk [Member] Swap Transactions Risk [Member] Tax Risk [Member] Taxability Risk [Member] Tobacco Settlement Bond Risk [Member] Unrated Securities Risk [Member] Valuation Risk [Member] When Issued and Delayed Delivery Transactions Risk [Member] Zero Coupon Bonds Risk. [Member] Anti Takeover Provisions [Member] Counterparty Risk [Member] Cybersecurity Risk [Member] Economic and Political Events Risk [Member] Fund Tax Risk [Member] Global Economic Risk [Member] Investment and Market Risk [Member] Legislation and Regulatory Risk [Member] Leverage Risk [Member] Market Discount from Net Asset Value [Member] Recent Market Conditions [Member] Reverse Repurchase Agreement Risk [Member] Alternative Minimum Tax Risk [Member] Below Investment Grade Risk [Member]