Bank Debt (Details) (USD $)	3 Months Ended
Mar. 31, 2015
Debt Instrument [Line Items]
Leverage ratio	263.00%hnrg_LeverageRatio
Debt maturity date	Aug. 29, 2019
Interest rat swaps net fair value	$ 1,967,000
Interest rate swap, long term asset	311,000
Interest rate swap, current liability	2,278,000
PNC Bank [Member]
Debt Instrument [Line Items]
Closing costs of debt	6,800,000
Loan initiation amortization period	5 years
Credit agreement, amount outstanding	292,000,000
Credit facility, maximum borrowing capacity	362,000,000
Maximum [Member]
Debt Instrument [Line Items]
Maximum leverage ratio	325.00%
Revolving Credit Facility [Member] \| PNC Bank [Member]
Debt Instrument [Line Items]
Credit agreement, amount outstanding	135,000,000
Credit facility, maximum borrowing capacity	250,000,000
Term Loan [Member] \| Debt Instrument, Redemption, Period Five [Member]
Debt Instrument [Line Items]
Loan annual amortization	20.00%
Term Loan [Member] \| Debt Instrument, Redemption, Period Four [Member]
Debt Instrument [Line Items]
Loan annual amortization	20.00%
Term Loan [Member] \| Debt Instrument, Redemption, Period One [Member]
Debt Instrument [Line Items]
Loan annual amortization	10.00%
Term Loan [Member] \| Debt Instrument, Redemption, Period Three [Member]
Debt Instrument [Line Items]
Loan annual amortization	15.00%
Term Loan [Member] \| Debt Instrument, Redemption, Period Two [Member]
Debt Instrument [Line Items]
Loan annual amortization	15.00%
Term Loan [Member] \| PNC Bank [Member]
Debt Instrument [Line Items]
Credit agreement, amount outstanding	157,000,000
Debt face amount	175,000,000
Sunrise Coal [Member] \| PNC Bank [Member]
Debt Instrument [Line Items]
Percentage decrease in amount of debt with maximum interest rate per quarter after commencement date	10.00%
Date that the percentage of debt with a maximum interest rate begins to decrease quarterly	Mar. 31, 2016
Sunrise Coal [Member] \| Maximum [Member] \| PNC Bank [Member]
Debt Instrument [Line Items]
Interest rate maximum	5.00%
Sunrise Coal [Member] \| Revolving Credit Facility [Member] \| PNC Bank [Member]
Debt Instrument [Line Items]
Amount of debt with maximum interest rate	100,000,000
Sunrise Coal [Member] \| Term Loan [Member] \| PNC Bank [Member]
Debt Instrument [Line Items]
Amount of debt with maximum interest rate	$ 175,000,000
Leverage Ratio Less Than 1 [Member] \| London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Debt, interest rate spread on variable rate	2.25%
Leverage Ratio Between 1 and 1.5 [Member] \| London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Debt, interest rate spread on variable rate	2.50%
Leverage Ratio Between 1.5 and 2 [Member] \| London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Debt, interest rate spread on variable rate	2.75%
Leverage Ratio Between 2 and 2.5 [Member] \| London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Debt, interest rate spread on variable rate	3.00%
Leverage Ratio Above 2.5 [Member] \| London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Debt, interest rate spread on variable rate	3.50%

Amount of debt with maximum interest rate

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Date that the percentage of debt with a maximum interest rate begins to decrease quarterly

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- Definition

Leverage Ratio

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- Definition

Loan Initiation Amortization Period - Years

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Maximum leverage ratio

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Percentage decrease in amount of debt with maximum interest rate

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The net increase(decrease) in interest income during the period representing the allocation of deferred loan origination fees less deferred loan origination costs using the effective interest method over the term of the debt arrangement to which they pertain taking into account the effect of prepayments.

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- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

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- Definition

Face (par) amount of debt instrument at time of issuance.

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- Definition

Maximum contractual interest rate for funds borrowed, under the debt agreement.

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- Definition

Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

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Percentage price of original principal amount of debt at which debt can be redeemed by the issuer.

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Fair value as of the balance sheet date of all derivative assets designated as interest rate fair value hedging instruments.

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Fair value of all derivatives designated as interest rate fair value hedging instruments.

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Fair value as of the balance sheet date of all derivative liabilities designated as interest rate fair value hedging instruments.

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Amount borrowed under the credit facility as of the balance sheet date.

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Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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