0001 - Document - Cover link:presentationLink link:definitionLink link:calculationLink 0002 - Disclosure - Summary of Fees & Expenses And Example Table link:presentationLink link:definitionLink link:calculationLink 0003 - Disclosure - Senior Securities link:presentationLink link:definitionLink link:calculationLink 0004 - Disclosure - General Description of Registrant link:presentationLink link:definitionLink link:calculationLink 0005 - Disclosure - Capital Stock Long Term Debt And Other Securities link:presentationLink link:definitionLink link:calculationLink Common Shares [Member] Stock that is subordinate to all other stock of the issuer. Developing Industries Risk [Member] Energy Infrastructure Sector Risk [Member] Energy Infrastructure Sector Risk [Member] Fee For Open Market Purchases Of Common Shares [Member] Fee For Open Market Purchases Of Common Shares [Member] Fee For Optional Shares Purchases [Member] Fee For Optional Shares Purchases [Member] Preferred Shares [Member] Preferred shares may provide a preferential dividend to the dividend on common stock and may take precedence over common stock in the event of a liquidation. Preferred shares typically represent an ownership interest in the company. Sales Of Shares Held In Dividend Reinvestment Account [Member] Sales Of Shares Held In Dividend Reinvestment Account [Member] Utility Sector Risk [Member] Utility Sector Risk [Member] Class of Stock [Domain] Debt Instrument Name [Domain]