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Regulatory Matters - Summary of Utilities Rate Plans (Pike-Gas) (Detail) (Pike County Light & Power Company (Pike) [Member], Gas [Member], USD $)
 12 Months Ended
Mar. 31, 2010
Aug. 31, 2015
Public Utilities, General Disclosures [Line Items]    
Base rate changes $ 300,000ed_BaseRateIncreaseDecrease  
Scenario, Forecast [Member]
    
Public Utilities, General Disclosures [Line Items]    
Base rate changes   $ 100,000ed_BaseRateIncreaseDecrease
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