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Investment in Savoy (Narrative) (Details) (Savoy [Member])
Mar. 31, 2015
Sep. 30, 2014
Savoy [Member]
   
Equity method investment ownership percentage 40.00%us-gaap_EquityMethodInvestmentOwnershipPercentage
/ dei_LegalEntityAxis
= hnrg_SavoyMember
45.00%us-gaap_EquityMethodInvestmentOwnershipPercentage
/ dei_LegalEntityAxis
= hnrg_SavoyMember