Amount of debt instrument to be converted to new instrument.

No definition available.

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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

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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 leverage ratio.

+ References

No definition available.

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Data Type:	xbrli:pureItemType
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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.

+ Details

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Data Type:	dtr-types:percentItemType
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- 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))
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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-Paragraph 4
-Subparagraph (b)(1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-4

+ Details

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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

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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
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-Subparagraph (SX 210.5-02.22)
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-Section 50
-Paragraph 3
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480848/942-470-50-3

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

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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

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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

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

- Definition

The cash inflow during the period from additional borrowings in aggregate debt. Includes proceeds from short-term and long-term debt.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 230
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 14
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482740/230-10-45-14

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

- Details

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Note 4 - Bank Debt (Details Textual) $ in Thousands		1 Months Ended	3 Months Ended	9 Months Ended
Note 4 - Bank Debt (Details Textual) $ in Thousands	Mar. 13, 2023 USD ($)	Mar. 31, 2024 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2023 USD ($)	Dec. 31, 2023 USD ($)	Aug. 02, 2023 USD ($)	Jun. 30, 2023	Dec. 31, 2022 USD ($)
Long-Term Debt, Gross			$ 61,750	$ 61,750				$ 85,213
Debt Issuance Costs, Net, Total			4,080	4,080				2,469
Revolving Credit Facility [Member] \| Credit Agreement [Member]
Line of Credit Facility, Maximum Borrowing Capacity								120,000
Credit Agreement [Member]
Debt Instrument, Unused Borrowing Capacity, Amount			63,800	63,800
Debt Instrument, Liquidity			66,400	66,400
Letters of Credit Outstanding, Amount			11,200	11,200
Debt Issuance Costs, Net, Total	$ 1,600		$ 4,100	$ 4,100		$ 4,300		2,500
Leverage Ratio			0.71	0.71
Debt Instrument, Covenant, Debt Service Coverage Ratio			2.25	2.25
Credit Agreement [Member] \| Secured Overnight Financing Rate (SOFR) [Member]
Debt Instrument, Basis Spread on Variable Rate				4.25%
Credit Agreement [Member] \| Minimum [Member]
Debt Instrument, Covenant, Debt Service Coverage Ratio							1.25
Credit Agreement [Member] \| Minimum [Member] \| Secured Overnight Financing Rate (SOFR) [Member]
Debt Instrument, Basis Spread on Variable Rate	4.00%
Credit Agreement [Member] \| Maximum [Member]
Debt Instrument, Covenant, Debt Service Coverage Ratio			3.75	3.75
Credit Agreement [Member] \| Maximum [Member] \| Secured Overnight Financing Rate (SOFR) [Member]
Debt Instrument, Basis Spread on Variable Rate	5.00%
Credit Agreement [Member] \| Term Loan [Member]
Line of Credit Facility, Maximum Borrowing Capacity			$ 75,000	$ 75,000
Debt Instrument, Increase (Decrease), Net				23,500
Long-Term Debt, Gross			61,800	61,800
Proceeds from Issuance of Debt				0
Debt Instrument, Periodic Payment			3,300
Credit Agreement [Member] \| Term Loan [Member] \| Forecast [Member]
Debt Instrument, Periodic Payment		$ 6,500
Credit Agreement [Member] \| Revolving Credit Facility [Member]
Debt Instrument, Amount to be Converted	$ 35,000					65,000
Line of Credit Facility, Maximum Borrowing Capacity						75,000		$ 85,000
Debt Instrument, Covenant, Maximum Annual Capital Expenditures			$ 1,500	$ 1,500	$ 75,000	$ 100,000