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 - [Capital Stock] link:presentationLink link:definitionLink link:calculationLink Royalty Trust Risk [Member] Short Sales Risk [Member] Small Capitalization Risk [Member] Tax Risks of Investing in Equity Securities of MLPs [Member] The Fund's Ability to Use Loss Carryovers May Be Limited [Member] Valuation Risk [Member] Affiliated Party Risk [Member] Below Investment Grade (High Yield or Junk Bond) Securities Risk [Member] Cash Flow Risk [Member] Competition Risk [Member] Counterparty Risk [Member] Currency Risk [Member] Cybersecurity Risk [Member] Debt Securities Risks [Member] Derivatives Risk [Member] Energy and Energy Infrastructure Sector Risk [Member] Energy Sector Risks [Member] Equity Securities Risk [Member] Foreign Investment and Emerging Markets Risk [Member] Government Intervention in Financial Markets Risk [Member] Industry Specific Risks [Member] Inflation/Deflation Risk [Member] Investment and Market Risk [Member] Lack of Diversification of Customers and Suppliers [Member] Legal and Regulatory Risk [Member] Legal and Regulatory Risk One [Member] Legal and Regulatory Risk [Member] Leverage Risk [Member] Liquidity Risk [Member] Management Risk [Member] Market Discount from Net Asset Value Risk [Member] Market Events Risk [Member] Natural Resources Sector Risks [Member] Non-Diversification Risk [Member] Operational Risk [Member] Portfolio Turnover Risk [Member] Potential Conflicts of Interest Risk [Member] Privately Held Company Risk [Member] Redenomination Risk [Member] Restricted Securities Risk [Member] Risks of Investing in MLP Units [Member] Risks Related to Fund Distributions [Member] Common Shares [Member] Preferred Shares [Member] Revolving Credit Facilitys [Member] Revolving Credit Facility [Member] Senior O Senior Notes [Member] Series A MRPS [Member] Series A Senior Notes [Member] Series B MRPS [Member] Series B Senior Note [Member] Series B Senior Notes [Member] Series C MRPS [Member] Series C Senior Notes [Member] Series D MRPS [Member] Series D Senior Notes [Member] Series E MRPS [Member] Series E Senior Notes [Member] Series F MRPS [Member] Series F Senior Notes [Member] Series G MRPS [Member] Series G Senior Notes [Member] Series H MRPS [Member] Series H Senior Notes [Member] Series I MRPS [Member] Series I Senior Notes [Member] Series J MRPS [Member] Series J Senior Notes [Member] Series K MRPS [Member] Series K Senior Notes [Member] Series L MRPS [Member] Series L Senior Notes [Member] Series M MRPS [Member] Series M Senior Notes [Member] Series N MRPS [Member] Series N Senior Notes [Member] Series O MRPS [Member] Series O Senior Notes [Member] Series P MRPS [Member] Series Q MRPS [Member] Series R MRPS [Member]