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 - [Share Price Table] link:presentationLink link:definitionLink link:calculationLink 1005 - Disclosure - N-2 - [Capital Stock] link:presentationLink link:definitionLink link:calculationLink 1006 - Disclosure - N-2 - [Outstanding Securities] link:presentationLink link:definitionLink link:calculationLink Canadian Royalty Trust Risk [Member] China Investments Risk [Member] China Investments Risk China Risk Risk of Investing through Stock Connect [Member] China Risk — Risk of Investing through Stock Connect China Risk Value Added Tax [Member] China Risk — Value Added Tax China Risk Withholding Income Tax Risk [Member] China Risk — Withholding Income Tax Risk Commodities Market Risk [Member] Commodities Related Investments Risk [Member] Commodity Pricing Risk [Member] Common Stock Risk [Member] Concentration Risk [Member] Convertible Securities Risk [Member] Counterparty Credit Risk [Member] Debt Securities Risk [Member] Depletion and Exploration Risk [Member] Depositary Receipts Risk [Member] Derivatives Risk [Member] DividendPaying Equity Securities Risk [Member] Dollar Rolls Risk [Member] Emerging Markets Risk [Member] Energy and Natural Resources Risk [Member] Energy Sector Risk [Member] Equity Securities Risk [Member] Foreign Currency Transactions Risk [Member] Foreign Securities Risk [Member] Geographic Asset Class Risk [Member] Health Sciences and Healthcare Companies Risk [Member] High Yield Bonds Risk [Member] Illiquid Investments Risk [Member] Illiquidity Risk [Member] Initial Public Offerings (IPOs) Risk [Member] Innovative Securities Risk [Member] Investment and Market Discount Risk [Member] Investment Companies and ETFs Risk [Member] Investments in Unseasoned Companies [Member] Investment Style Risk [Member] Leverage Risk [Member] Limited Term Risk [Member] Market Risk and Selection Risk [Member] Market Risk [Member] Market Risk Master Limited Partnerships Risk [Member] Non Diversification Risk (BGR and BCX) [Member] Preferred Securities Risk [Member] REIT Investment Risk [Member] Repurchase Agreements and Purchase and Sale Contracts Risk [Member] Reverse Repurchase Agreements Risk [Member] Risk of Investing in the United States [Member] Risks Associated with Private Company Investments [Member] Risks of Investing in Utilities, Infrastructure and Power Opportunities Issuers [Member] Science and Technology Risk [Member] Securities Lending Risk [Member] Shareholder Activism Risk [Member] Short Sales Risk [Member] Small and Mid Capitalization Company Risk [Member] Structured Securities Risk [Member] Subsidiary Risk [Member] Supply and Demand Risk [Member] U.S. Government Obligations Risk [Member] Valuation Risk [Member] Warrants Risk [Member] WhenIssued and Delayed Delivery Securities and Forward Commitments Risk [Member] Common Shares [Member] Investment Objectives And Policies [Member] Investment Objectives [Member]