Preferred Shares [Member] Common Shares [Member] Investment and Market Discount Risk [Member] Limited Term Risk BTT [Member] Debt Securities Risk [Member] Municipal Securities Risks [Member] Taxability Risk [Member] Insurance Risk [Member] High Yield Bonds Risk [Member] U S Government Obligations Risk MYI [Member] Variable Rate Demand Obligations Risk MQY and MYI [Member] Defensive Investing Risk MQY [Member] Repurchase Agreements and Purchase and Sale Contracts Risk MUA [Member] Reverse Repurchase Agreements Risk MYI [Member] Dollar Rolls Risk MYI [Member] Economic Sector and Geographic Risk BTT [Member] Leverage Risk [Member] Investment Companies and ETFs Risk BTT [Member] Indexed and Inverse Securities Risk MQY and MYI [Member] Tender Option Bonds Risk [Member] Dollar Rolls Risk BTT [Member] Illiquid Investments Risk [Member] Risk of Investing in the United States [Member] Market Risk and Selection Risk [Member] Shareholder Activism [Member] TOBs [Member] VRDP Shares [Member] Derivatives Risks [Member] Note [Member] Illiquidity Risk [Member] Market Risks [Member] Valuation Risk [Member] Counterparty Credit Risk [Member] Geographic Asset Class Risk [Member]