Amount of debt with maximum interest rate

No definition available.

Name:	hnrg_AmountOfDebtWithMaximumInterestRate
Namespace Prefix:	hnrg_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Debt service coverage ratio

+ References

No definition available.

+ Details

Name:	hnrg_DebtServiceCoverageRatio
Namespace Prefix:	hnrg_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Fixed charge coverage ratio

+ References

No definition available.

+ Details

Name:	hnrg_FixedChargeCoverageRatio
Namespace Prefix:	hnrg_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Liquidity

+ References

No definition available.

+ Details

Name:	hnrg_Liquidity
Namespace Prefix:	hnrg_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Loan Initiation Amortization Period - Years

+ References

No definition available.

+ Details

Name:	hnrg_LoanInitiationAmortizationPeriodYears
Namespace Prefix:	hnrg_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum leverage ratio

+ References

No definition available.

+ Details

Name:	hnrg_MaximumLeverageRatio
Namespace Prefix:	hnrg_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage decrease in amount of debt with maximum interest rate

+ References

No definition available.

+ Details

Name:	hnrg_PercentageDecreaseInAmountOfDebtWithMaximumInterestRate
Namespace Prefix:	hnrg_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3602-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.1)
-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Direct Loan Origination Costs
-URI http://asc.fasb.org/extlink&oid=6510860

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 20
-Section 30
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6378273&loc=d3e8446-111530

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 20
-Section 25
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6962437&loc=d3e7402-111529

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 20
-Section 35
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=65893827&loc=d3e8622-111531

+ Details

Name:	us-gaap_AmortizationOfDeferredLoanOriginationFeesNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

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

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

+ Details

Name:	us-gaap_DebtInstrumentInterestRateEffectivePercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

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

+ References

+ Details

Name:	us-gaap_DebtInstrumentMaturityDate
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of unused borrowing capacity under the long-term financing arrangement that is available to the entity as of the balance sheet date.

+ References

+ Details

Name:	us-gaap_DebtInstrumentUnusedBorrowingCapacityAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Fair value of the amount outstanding under the credit facility.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=73719730&loc=d3e13433-108611

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=73719730&loc=d3e13476-108611

+ Details

Name:	us-gaap_LineOfCreditFacilityFairValueOfAmountOutstanding
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

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.

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_LondonInterbankOfferedRateLIBORMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=hnrg_CreditAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=hnrg_TermLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=hnrg_SunriseCoalMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LineOfCreditFacilityAxis=hnrg_PncBankMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Bank Debt (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
Bank Debt (Narrative) (Details) - USD ($) $ in Millions	Mar. 31, 2017	Mar. 18, 2016	Mar. 17, 2016
Debt Instrument [Line Items]
Closing costs of debt	$ 9.1
Loan initiation amortization period	5 years
Credit agreement, amount outstanding	$ 232.0
Credit facility, maximum borrowing capacity		$ 200.0	$ 250.0
Debt, unused borrowing capacity	63.0
Liquidity	$ 84.0
Maximum leverage ratio	283.00%
Debt service coverage ratio	215.00%
Minimum [Member]
Debt Instrument [Line Items]
Fixed charge coverage ratio	125.00%
London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Debt, interest rate spread on variable rate	3.50%
London Interbank Offered Rate (LIBOR) [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Debt, interest rate spread on variable rate	2.25%
London Interbank Offered Rate (LIBOR) [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Debt, interest rate spread on variable rate	4.00%
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Credit agreement, amount outstanding	$ 137.0
Credit Agreement [Member]
Debt Instrument [Line Items]
Debt maturity date	Aug. 01, 2019
Debt instrument, interest rate, effective percentage	4.29%
Term Loan [Member]
Debt Instrument [Line Items]
Credit agreement, amount outstanding	$ 95.0
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%
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	$ 100.0