Amount of debt instrument to be converted to new instrument.

No definition available.

Name:	hnrg_DebtInstrumentAmountToBeConverted
Namespace Prefix:	hnrg_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents the debt instrument, covenant, debt service coverage ratio.

+ References

No definition available.

+ Details

Name:	hnrg_DebtInstrumentCovenantDebtServiceCoverageRatio
Namespace Prefix:	hnrg_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

The maximum capital expenditures per year under the covenant of the debt instrument.

+ References

No definition available.

+ Details

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Namespace Prefix:	hnrg_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The amount of liquidity under the debt instrument.

+ References

No definition available.

+ Details

Name:	hnrg_DebtInstrumentLiquidity
Namespace Prefix:	hnrg_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The debt service coverage ratio (consolidated adjusted EBITDA / annual debt service).

+ References

No definition available.

+ Details

Name:	hnrg_DebtServiceCoverageRatio
Namespace Prefix:	hnrg_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

The leverage ratio.

+ References

No definition available.

+ Details

Name:	hnrg_LeverageRatio
Namespace Prefix:	hnrg_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

The additional amount borrowed under a line of credit agreement.

+ References

No definition available.

+ Details

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Namespace Prefix:	hnrg_
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:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-SubTopic 10
-Topic 210
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 942
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479853/942-210-S99-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Subparagraph (b)(1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-4

+ Details

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

- Definition

Net increase or decrease in the carrying amount of the debt instrument for the period.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(f))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480678/235-10-S99-1

+ Details

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

- Definition

Amount of the required periodic payments including both interest and principal payments.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
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-SubTopic 470
-Section 50
-Paragraph 3
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480848/942-470-50-3

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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

Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482925/835-30-45-3

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1D
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1D

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

No definition available.

+ Details

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

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-SubTopic 10
-Topic 210
-Publisher FASB
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Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
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-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(16)(a)(2))
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-URI https://asc.fasb.org//1943274/2147479853/942-210-S99-1

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility.

+ References

+ Details

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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

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

- 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:	srt_StatementScenarioAxis=srt_ScenarioForecastMember
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Data Type:	na
Balance Type:
Period Type:

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Period Type:

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Note 4 - Bank Debt (Details Textual) $ in Thousands			1 Months Ended		2 Months Ended	3 Months Ended	8 Months Ended	9 Months Ended		12 Months Ended
Note 4 - Bank Debt (Details Textual) $ in Thousands	Mar. 13, 2023 USD ($)	Apr. 15, 2020	Apr. 30, 2024 USD ($)	Mar. 31, 2023 USD ($)	Mar. 12, 2023 USD ($)	Mar. 31, 2024 USD ($)	Dec. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)	Sep. 30, 2023	Dec. 31, 2022 USD ($)	Aug. 02, 2023 USD ($)
Long-Term Debt, Gross								$ 91,500		$ 85,213
Debt Issuance Costs, Net, Total								$ 3,609		2,469
Leverage Ratio								1.32
Credit Agreement [Member]
Debt Instrument, Increase (Decrease), Net										(26,500)
Debt Instrument, Liquidity								$ 26,200
Letters of Credit Outstanding, Amount								18,600
Debt Issuance Costs, Net, Total	$ 1,600							$ 3,600		2,500	$ 4,300
Leverage Ratio								2.25
Debt Service Coverage Ratio								3.3
Credit Agreement [Member] \| Term Loan [Member]
Long-Term Debt, Gross										$ 5,500
Debt Instrument, Periodic Payment, Total				$ 5,500		$ 5,000		$ 10,000
Credit Agreement [Member] \| Term Loan [Member] \| Forecast [Member]
Debt Instrument, Periodic Payment, Total			$ 6,500				$ 6,300
Credit Agreement [Member] \| Minimum [Member]
Debt Instrument, Covenant, Debt Service Coverage Ratio										1.25
Credit Agreement [Member] \| Secured Overnight Financing Rate (SOFR) [Member]
Debt Instrument, Basis Spread on Variable Rate									4.25%
Credit Agreement [Member] \| Secured Overnight Financing Rate (SOFR) [Member] \| Minimum [Member]
Debt Instrument, Basis Spread on Variable Rate	4.00%
Credit Agreement [Member] \| Secured Overnight Financing Rate (SOFR) [Member] \| Maximum [Member]
Debt Instrument, Basis Spread on Variable Rate	5.00%	4.00%
Credit Agreement [Member] \| Revolving Credit Facility [Member]
Debt Instrument, Amount to be Converted	$ 35,000										65,000
Line of Credit Facility, Maximum Borrowing Capacity	85,000									$ 120,000	75,000
Debt Instrument, Covenant, Maximum Annual Capital Expenditures								75,000			$ 100,000
Line of Credit, Additional Amount Borrowed					$ 17,000
Long-Term Line of Credit, Total										$ 79,700
Debt Instrument, Unused Borrowing Capacity, Amount								23,400
Credit Agreement [Member] \| Revolving Credit Facility [Member] \| Post August 2023 Amendment [Member]
Debt Instrument, Covenant, Maximum Annual Capital Expenditures								1,500
Term Loan [Member] \| Revolving Credit Facility [Member] \| Post March 2023 Amendment [Member]
Line of Credit Facility, Maximum Borrowing Capacity	85,000
Long-Term Debt, Gross	35,000
Line of Credit Facility, Current Borrowing Capacity	$ 40,200
Term Loan [Member] \| Revolving Credit Facility [Member] \| Post August 2023 Amendment [Member]
Line of Credit Facility, Maximum Borrowing Capacity								75,000
Long-Term Debt, Gross								58,500
Line of Credit Facility, Current Borrowing Capacity								$ 33,000